Tales from the Golden Age: The Telescopes of Sir Patrick Moore (1923-2012)

Sir Patrick Moore(1923-2012), seen here standing beside his 5 inch f/12 Cooke refractor. Image credit: Martin Mobberley.

The late Sir Patrick Moore(1923-2012) needs no introduction to the astronomical community. A towering figure for over half a century, he was adored (and sadly, disliked by a few) by a legion of fans the world over as the eccentric, silver tongued English writer and presenter of the longest running television series in history; BBC Sky at Night; with an encyclopedic knowledge of astronomy. Inexplicable to Americans, gin guzzling, pipe smoking, xenophobic, insensitive, incomprehensible to some, inflexible, irksome, he was also warm, passionate, generous to a fault, loyal to his friends, an institution in his own right, and a law unto himself!

As a fan of Sir Patrick from childhood, I bought, borrowed and read many of his books. He was the person who first sparked my interest in astronomy, and even as my hobby turned into a profession of sorts, he always returned my phone calls and promptly responded to my letters in his unique way; using an old fashioned type writer. But while there was hardly a telescope, amateur or professional, that the great man didn’t peer through during his prolific career, it pays to take a closer look at the kinds of instruments he personally owned.

Expressing an interest in the night sky since he was knee high to a proverbial grasshopper, Moore was lucky enough to live right across the road from the tycoon, Frederick J. Hanbury, at East Grinstead, West Sussex, who had a lavishly equipped observatory erected on his estate, with a 6.1 inch Cooke refractor as its Pièce de résistance. But Hanbury himself was far too busy to run the observatory from day to day, instead hiring a full time assistant, William Saddler Franks(1851-1935), to  demonstrate at the telescope, and tasked with entertaining Hanbury’s frequent guests and business acquaintances with the glories of the Sun, Moon, planets and distant stars. On quieter evenings, Franks would return to more routine work, measuring double stars with a filar micrometer and completing sketches of what he saw at the eyepiece. Franks struck up a strong bond of friendship with the young Patrick Moore and it was here that he probably enjoyed his first views of the night sky through a telescope.

Acting on a recommendation he received from the Dr. W.H. Steavenson (a prominent member of the British Astronomical Association in those days), Patrick, accompanied by his mother, took a train up to London to visit the workshops of the leading telescope maker for amateurs in the country; Broadhurst Clarkson, where he acquired his first proper instrument; a 3 inch achromatic refractor for the princely sum of £7 10 shillings. This was quite a bit of cash to splash out for the time. Martin Mobberley, writing in his excellent biography of Moore: It Came From Outer Space Wearing an RAF Blazer! estimates that it was the equivalent of about two weeks wages for an ordinary working man. But a fine telescope it was nonetheless!

Sir Patrick Moore’s newly restored 3″ f/12 Broadhurst Clarkson refractor.

Already almost a quarter of a century old (circa 1910 vintage), the shining, rolled brass tube, housed a very well figured 3 inch object glass with a focal length of three feet (so f/12). The instrument has a smooth, single wheel focuser (like all small refractors of the era) and came equipped with a few eyepieces for low, medium and high power work. Its Achilles’ Heel though, as Moore soon found out to his chagrin, was the flimsy ‘pillar and claw’ mount that accompanied it. While it looked rather ornate in the corner of a stately indoor space, it was next to useless for astronomical purposes. Moore referred to it discontentedly as the ‘blancmange’ but it was quickly replaced by a much more sturdy tripod of extendable height, at an additional cost of 30 shillings.

A rescued Broadhurst Clarkson 3″ f/12 achromat (1940s vintage), field tested by the author.

Though this author has not had the privilege of looking though Sir Patricks particular 3” f/12 achromatic telescope, he has sampled, as it were, a ‘system of particles‘ centred on an 80mm f/11 achromat, but also from shorter and longer ‘particles‘. But more specifically, this author partially restored an essentially identical instrument to Moore’s telescopic alma mater during the autumn of 2012, where he spent a few days testing its optics. The instrument produced very pleasing, high contrast images of the daytime landscape, with very little secondary spectrum. Night time tests showed that stars presented as tight pinpoints of light with almost identical Fraunhofer diffraction rings both inside and outside focus. Lunar views were crisp and sharp at powers up to approximately 150x, and a suite of suitable double stars were also well resolved at the highest magnifications employed. In short, this author was confident that such a telescope would show any experienced observer what the best modern 3 inch refractor could present.

Moore used the instrument extensively, where it presented him with all the showpieces of the night sky. This much is abundantly clear from his many references to the 3 inch in his voluminous published writings of later times. It was with this telescope that he learned his way around the battered face of the Moon; a study that would propel the young man to international notoriety in the years to come.  Indeed, he used his 3 inch Broadhurst Clarkson to suggest his first paper to the BAA entitled, Small Craterlets in the Mare Crisium, in 1937, at the tender age of 14! And while there is no official record of such a presentation, Moore most definitely studied this lunar region with his small telescope. Mobberley, who had the pleasure of examining Moore’s observational records show that while he demonstrated almost no artistic flare at school, his drawings of various lunar features made with the 3 inch and dated to 1940 show that he had, by that time, developed considerable ability to draw complex structures at the eyepiece. And though he would go on to make rapid progress within the ranks of the BAA in the post-war years, the 3 inch Broadhurst Clarkson was probably the only telescope he personally owned right up until about 1950!

While many astronomers consider the Moon to be a form of light pollution, Sir Patrick maintained a lifelong passion for exploring our nearest neighbour in space. For over half a century, astronomers working with some of the largest telescopes in the world were busy photographing its surface, but the relative insensitivity of photographic emulsions during that era meant that there was always visual work to do in fleshing out the finest selenographic details. This kind of work was ideally suited to moderately sized instruments that could be pressed into service fairly frequently. No doubt, it was this possibility that influenced Sir Patrick’s next telescope acquisition, and it would come from his new mentor, Hugh Percy Wilkins(1896–1960), a Welsh–born mechanical engineer and amateur astronomer.

From 1946 to 1956, Wilkins served as the Director of the Lunar Section of the BAA and it was through its meetings and publications that Moore became attracted to Wilkins’ work. Indeed, in many ways, Wilkins and Moore were very much alike. Both were extroverted, more than a little odd, and passionate about everything pertaining to our natural satellite. Wilkins had moved from his native Wales to put down roots at 35 Fairlawn Avenue, Bexleyheath, Kent, only 25 miles north of Moore’s abode at Glencathara, East Grinstead. There the young astronomer enjoyed many fine views through Wilkins’ 12.5 Newtonian. Over the years, Wilkins had produced truly colossal Moon maps, starting with a 24” completed in 1924, and, with the help of Moore, culminating with a 300” lunar map in 1951 and which was considered by some to represent “the culmination of the art of selenography prior to the space age.”

Sir Patrick looking through his trusty 12.5 inch f/6 Newtonian reflector nicknamed ‘Oscar.’ Early 1950s. Image credit: Martin Mobberley.

















When Wilkin’s decided to acquire a larger instrument (a 15.25 inch Newtonian), Moore, having tried and trusted the 12.5 inch, had no hesitation in buying it off him.  With a focal length of 72 inches (so f/6), its primary mirror was made by the noted British telescope maker, Henry Wildey(1913–2003). This new telescope, which Moore affectionately referred to as ‘Oscar,’ was mounted on a heavy duty altazimuth mount equipped, specially designed Ron Irving(1915–2005) with good slow motion controls. And while Moore intended to upgrade the mount to equatorial mode at some point in the future, the astronomical (pun intended) cost that it would incur stopped that project dead in the water. Indeed, ‘Oscar’ was to remain on its original altazimuth mounting for the remainder of Moore’s long life, housed inside a double–ended roll off shed at his home at East Grinstead. This 12.5 inch was arguably the instrument Moore used most often throughout his career to produce some of his finest work.

Oscar in old age, being inspected by the crew of BBC Sky at Night. Image credit: Martin Mobberley.


To say that Sir Patrick Moore was more of a showman, as some of his more envious contemporaries would have claimed, than an observer, would be very far from the truth. One need look no further than his observing logbooks to see that not only was he a regular observer, but he was also capable of great bouts of stamina, well above and beyond the efforts of many amateurs today. One example this author stumbled upon was an entry he made in March 1967 while he was serving as Director of Armagh Planetarium, Northern Ireland. These notes, which are very neat and tidy, show that, despite having access to a very good 10 inch Grubb refractor at the Observatory annexed to the Planetarium, he was using Oscar and a 8.5 inch With Browning Newtonian (acquired sometime in the early 1960s), both of which he had shipped over to Northern Ireland, to make some excellent Jupiter observations, recoding details of both the Jovian disk as well as several transits of the Galilean satellites watched continually over a complete rotation of the planet (so about 10 hours)!

To be continued………..

De Fideli.

What I’m Reading













Kindle form Highly recommended!

Introduction to Evolutionary Informatics is a lucid, entertaining, even witty discussion of important themes in evolutionary computation, relating them to information theory. It’s far more than that, however. It is an assessment of how things might have come to be the way they are, applying an appropriate scientific skepticism to the hypothesis that random processes can explain many observed phenomena. Thus the book is appropriate for the expert and non-expert alike. –Donald Wunsch, Distinguished Professor and Director of the Applied Computational Intelligence Lab, Missouri University of Science & Technology, USA

Evolution requires the origin of new information. In this book, information experts Bob Marks, Bill Dembski, and Winston Ewert provide a comprehensive introduction to the models underlying evolution and the science of design. The authors demonstrate clearly that all evolutionary models rely implicitly on information that comes from intelligent design, and that unguided evolution cannot deliver what its promoters advertise. Though mathematically rigorous, the book is written primarily for non-mathematicians. I recommend it highly. –Jonathan Wells, Senior Fellow, Discovery Institute

Introduction to Evolutionary Informatics helps the non-expert reader grapple with a fundamental problem in science today: We cannot model information in the same way as we model matter and energy because there is no relationship between the metrics. As a result, much effort goes into attempting to explain information away. The authors show, using clear and simple illustrations, why that approach not only does not work but [that it also] impedes understanding of our universe. –Denyse O’Leary, Science Writer

About the Author

Robert J Marks II is Distinguished Professor of Engineering in the Department of Engineering at Baylor University, USA. Marks’s professional awards include a NASA Tech Brief Award and a best paper award from the American Brachytherapy Society for prostate cancer research. He is Fellow of both IEEE and The Optical Society of America. His consulting activities include: Microsoft Corporation, DARPA, and Boeing Computer Services. He is listed as one of the 50 Most Influential Scientists in the World Today by TheBestSchools.org. (2014). His contributions include: the Zhao-Atlas-Marks (ZAM) time-frequency distribution in the field of signal processing, and the Cheung-Marks theorem in Shannon sampling theory.

Marks’s research has been funded by organizations such as the National Science Foundation, General Electric, Southern California Edison, the Air Force Office of Scientific Research, the Office of Naval Research, the United States Naval Research Laboratory, the Whitaker Foundation, Boeing Defense, the National Institutes of Health, The Jet Propulsion Lab, Army Research Office, and NASA. His books include Handbook of Fourier Analysis and Its Applications (Oxford University Press), Introduction to Shannon Sampling and Interpolation Theory (Springer Verlag), and Neural Smithing: Supervised Learning in Feedforward Artificial Neural Networks (MIT Press) with Russ Reed. Marks has edited/co-edited five other volumes in fields such as power engineering, neural networks, and fuzzy logic. He was instrumental in defining the discipline of computational intelligence (CI) and is a co-editor of the first book using CI in the title: Computational Intelligence: Imitating Life (IEEE Press, 1994). His authored/coauthored book chapters include nine papers reprinted in collections of classic papers. Other book chapters include contributions to Michael Arbib’s The Handbook of Brain Theory and Neural Networks (MIT Press, 1996), and Michael Licona et al.’s Evidence for God (Baker Books, 2010), Marks has also authored/co-authored hundreds of peer-reviewed conference and journal papers.

William A Dembski is Senior Research Scientist at the Evolutionary Informatics Lab in McGregor, Texas; and also an entrepreneur developing educational websites and software. He holds a BA in Psychology, MS in Statistics, PhD in Philosophy, and a PhD in Mathematics (awarded in 1988 by the University of Chicago, Chicago, Illinois, USA), and an MDiv degree from Princeton Theological Seminary (1996, New Jersey, USA). Dembski’s work experience includes being an Associate Research Professor with the Conceptual Foundations of Science, Baylor University, Waco, Texas, USA. He has taught at Northwestern University, Evanston, Illinois, USA; the University of Notre Dame, Notre Dame, Indiana, USA; and the University of Dallas, Irving, Texas, USA. He has done postdoctoral work in mathematics with the Massachusetts Institute of Technology, Cambridge, USA; in physics with the University of Chicago, USA; and in computer science with Princeton University, Princeton, New Jersey, USA. He is a Mathematician and Philosopher. He has held National Science Foundation graduate and postdoctoral fellowships, and has published articles in mathematics, engineering, philosophy, and theology journals and is the author/editor of more than twenty books.

Winston Ewert is currently a Software Engineer in Vancouver, Canada. He is a Senior Research Scientist at the Evolutionary Informatics Lab. Ewert holds a PhD from Baylor University, Waco, Texas, USA. He has written a number of papers relating to search, information, and complexity including studies of computer models purporting to describe Darwinian evolution and developing information theoretic models to measure specified complexity.


De Fideli.


A Newtonian Travel ‘Scope

Wednesday, February 3 2016: SkyWatcher has established a solid international reputation for producing high quality Newtonian optics for the modern amateur astronomer, and at prices that won’t break the bank. Having been thoroughly satisfied with a 8″ f/6 Skyliner Dob, I became very curious about a smaller, model – the Heritage 130P (a 5.1″ f/5 Newtonian with a parabolic primary) tabletop Dobsonian – which promises to provide decent light grasp and resolution in an ultra-portable package for take anywhere travel and short grab ‘n’ go excursions to the back garden.

The telescope was purchased new from Rother Valley Optics on Tuesday morning, February 2, and arrived in the mid-afternoon today. The price, inclusive of postage, was £129.

The telescope came double-boxed and involved no assembly. The optics looked clean and streak-free. A neat instruction manual accompanied the instrument.

The Heritage 130P Dobsonian as received.

The Heritage 130P Dobsonian as received.











The ‘scope, weighing about 6 kilos with the mount, has a built-in carrying handle for swift transport into and out of the house.

Following along the same lines as their extremely successful flextube line of larger Dobs, the Heritage 130P can be extended to reveal the upper tube assembly, lengthening the tube from just 38cm to about 61cm. The lower assembly is adorned with the names of time-honoured astronomers, celebrating four centuries of telescopic astronomy. While some folk might find this ‘tacky,’ I rather liked it.

The Heritage 130P fully extended.

The Heritage 130P fully extended.










Remarkably, the telescope was almost perfectly collimated out of the box, as evidenced by the just slightly offset red dot from the centre-marked spot on the primary mirror. That’s a nice touch, as one can imagine the reaction of a complete novice were he/she to discover that the optics were delivering iffy views as a result of mis-aligned optical components. It might be enough to put someone off the hobby for good.

Note the position of the red dot from the laser collimator; just a shade out of whack.

Note the position of the red dot from the laser collimator; just a shade out of whack.

Once the collimation was tweaked, I investigated retracting and extending the tube assembly several times to investigate the rigidity of the structure. I am pleased to report that the collimation held quite well but might still require last-minute tweaking for more demanding tasks, such as obtaining the best lunar and planetary views, as well as double star work. Overall though, this is a very well thought out piece of kit and certainly better than I had anticipated.





The telescope primary and secondary mirrors are fully adjustable and can be aligned in a matter of minutes. Unlike the three ultra-thin spider vanes on larger models, the secondary mirror on the Heritage 130P is affixed to a single vane, which is a good bit thicker than the latter; a necessary design compromise to maintain that little bit more stability to the optical train.

The adjustment screws behind the f/5 parabolic primary mirror.

The adjustment screws behind the f/5 parabolic primary mirror.

The secondary support is of high quality and is easily adjustable with a user supplied hex wrench.

The secondary support is of high quality and is easily adjustable with a user supplied hex wrench.




















The focuser is unusual. Unlike standard rack and pinion or Crayford type focusing mechanisms, the Heritage 130P employs a simple helical focuser which involves rotating the eyepiece either clockwise or ant-clockwise to bring objects to a sharp focus. In addition, the length of the upper tube can also be adjusted to accommodate cameras and other equipment. In short, any eyepiece will reach focus using a combination of these procedures. Only 1.25″ oculars can be used with the instrument, however.

The unusual helical focuser on the Heritage 130P Dobsonian.

The unusual helical focuser on the Heritage 130P Dobsonian.











Some observers may find reaching precise focus a little fiddly, but with a bit of practice, it works smoothly and accurately.

The Heritage 130P also came with a simple red dot finder (RDF) to aid in locating objects quickly under a dark sky.

The basic but useable red dot finder is easily attached to the upper tube assembly with a small screw driver.

The basic but useable red dot finder is easily affixed to the upper tube assembly with a small screw driver.

A particularly attractive feature of the instrument as received is the dovetail mounting of the optical tube assembly which enables one to remove the tube assembly from the mount proper for even easier storage.

The optical tube can be removed from the mount if necessary to aid storage/transportation.

The optical tube can be removed from the mount if necessary to aid storage/transportation.

In addition, the dovetail plate allows the user to mount the instrument separately on other types of mounts such as this author’s ergonomical Vixen Porta II alt-azimuth for an alternative style of observing. What a nice touch!

The SkyWatcher Heritage 130P mounted on the author's Vixen Porta II alt-azimuth mount; a particularly stable configuration.

The SkyWatcher Heritage 130P mounted on the author’s Vixen Porta II alt-azimuth mount; a particularly stable configuration.























Optical testing: Although the instrument suffers from the introduction of considerable amounts of stray light during daylight use without employing some sort of light shroud, I set the instrument up in the late afternoon, aiming the instrument at a roof top about 100 yards distant. I didn’t wait around to use the supplied oculars (which are adequate but not great for testing) but instead decided to push the ‘scope as hard as I could. To that end, I ran inside and affixed a good quality 6mm orthoscopic to a 2.25x Baader shorty Barlow lens, which would deliver a power of 244 diameters. Inserting these into the helical focuser, I carefully rotated it until best focus was achieved. Although the view was a bit drowned out with extraneous light, I am happy to report that the image of the terracotta roof tiles came into very sharp focus; a great initial sign that the optics were of potentially high quality.

After dark, more cloud encroached, but I waited for the odd sucker hole and was rewarded by a clear spot corresponding to Auriga, then high in the eastern sky. Relocating the instrument in a dark spot in the garden, I centred the bright star, Capella, using my multi-coated 32mm SkyWatcher Plossl in the field (yielding a true field of 2.5 degrees!) and was delighted to observe (with my eye glasses on)  a beautifully sharp vista, with pinpoint stars across most of the field. Then, I investigated the high power view of Capella at 244x and after refocusing, was thrilled to see a tight white Airy disk with diffraction rings a shade more prominent than what I have observed in my work horse telescope, a larger 8″ f/6 Dobsonian. This could be explained by the larger central obstruction of the Heritage telescope (~29 per cent by aperture) as compared with 22 per cent for the larger 8 inch.

On a whim, I moved the instrument north-eastward from Capella and centred the star, theta Aurigae. Focusing as accurately as I could, I was able to steadily hold its very faint companion at 244x, some 4 arc seconds away from the primary. Very encouraging to say the least!

It wasn’t long before the skies completely clouded over, and the drizzle came back, ending my first light vigil under the stars. Needless to say, the instrument performed surprisingly well under admittedly dodgy observing conditions.

More testing in the pipeline though.

Thursday, February 4, 2016


Having collimated the telescope in situ and placed a makeshift light shround around the upper telescope assembly (UTA), I am happy to reaffirm that the telescope delivers tack sharp images of distant willow tree branches at 244x.

Friday, February 5, 2016

The Heritage 130P has a parabolic primary mirror, that is, it is figured into the shape of a parabola. Why is a parabolic shape responsible for such sharp images in a Newtonian reflector? It’s an interesting question, yet many amateurs accept it as a given. But we can do considerably better than that. We can analyse the properties of the parabola, one of the conic sections beloved to the mathematicians of classical antiquity, and thereby gain a deeper appreciation of why this shape, over all others, is chosen by opticians in the fashioning of high quality primary mirrors. Our analysis will borrow from the approach of the great French mathematician, Rene Descartes (1596-1650), who developed a way of investigating geometry using algebra.

A parabola is the set of all points which are equidistant from a given point called the focus and a given line known as the directrix.

The image below outlines the basic features of a parabola drawn on a x-y axis.

The Parabola

The Parabola










Let the focus be the point S( a,0) and the directrix be the line x=-a, as shown in the diagram. Consider any point on the parabola, P(x,y).

Thus, by definition, the length of SP = length of PM

So [(x-a)^2 + y^2]^0.5 = x + a

Therefore, (x-a)^2 + y^2 = (x+a)^2

Thus, x^2 -2ax +a^2 + y^2 = x^2 + 2ax + a^2

From which y^2 = 4ax ( Eq 1)

This is the standard form of the equation of a parabola.

Consider next the parametric equations x = at^2 and y = 2at.

Substituting the expression for x into equation 1 we obtain;

y^2 = 4a^2t^2 = 4a(at^2) = 4ax

So, x = at^2 and y = 2at represents the parametric coordinates of any point on the parabola y^2 = 4ax.

We can use this to derive two more equations that will enable us to arrive at the result we want. Consider the diagram drawn below.

The parabola with the point P defined parametrically.

The parabola with the point P defined parametrically.









y^2 = 4ax

Differentiating implicitly with respect to x we obtain;

2yf'(x) =4a

so f'(x) = 2a/y, which is the gradient of the tangent at any point.

Now since y = 2at, the gradient becomes 2a/2at = 1/t

And so the equation of the tangent to the parabola at the point P is given by:

y – 2at = 1/t(x-at^2)

Multiplying across by t  gives;

ty – 2at^2 = x-at^2

or  x – ty + at^2 =0 ( Eq 2)

Also, the gradient of the normal at P = -t and so the equation of the normal will be:

y – 2at = -t(x-at^2)

or tx + y – 2at – at^3 = 0 ( Eq 3)

Now we are ready to obtain further information from the parabola under discussion.

Let the tangent at P intersect the x-axis at R and the y-axis at U, and let the normal to the parabola at P intersect the x-axis at V, as shown in the diagram below:

parabola 3

The coordinates of R are obtained by setting y = 0 in equation 2

x – ty + at^2 =0 and so if y = 0 then x = -at^2 and so the coordinates of R are (-at^2, 0)

The coordinates of U are obtained from setting x = 0  into equation 2, from which it is easily shown that y = at i.e. U(0, at).

The x-coordinate of V can be obtained by setting y = 0 in equation 3;

tx + y – 2at – at^3 = 0 and when y = 0 we obtain:

t(x- 2a – at^2) =0,and since t cannot equal zero we have

x = 2a + at^2 and so the coordinates of V are given by (2a + at, 0).

From these results it is possible to verify the following:

(i)  U is the midpoint of PR

(ii)  length of SR = length of SV = length of SP

(iii) US is parallel with PV and that PU is perpendicular with SU

I will leave these as exercises for the interested reader.

Now, to the meat of the analysis. Consider a line PZ drawn parallel to the axis of the parabola as shown in the diagram below:

parabola 4



Since  length SP = length SV so too must angle SPV = angle SVP

But angle SVP = angle VPZ since PZ is parallel with RV

So angle SPV = angle VPZ

But ZPV is the angle of incidence of a ray of light incident upon a reflective parabolic surface and so the law of reflection requires that the angle of reflection be the same i.e. angle VPS.

But since P is independent of S, the result implies that any ray of light parallel to the axis will be reflected through the focus, S.

This is the reason why parabolic mirrors work so well, as they completely avoid a phenomenon known as spherical aberration, which can can plague other kinds of optical designs.

That’s enough math for one evening eh.

After a day of more or less constant rain, the sky appears to be clearing up and so I’ll get some more time under the starry heavens using my little parabolic Newtonian.

Thank goodness for small mercies!

Saturday, February 6 2016

Time: 00:05h

The telescope was collimated perfectly before use and left to cool in a dry, unheated shed. Initially, I had intended to use my Baader zoom and dedicated 2.25x Barlow to observe Jupiter, now 31 degrees above the horizon. To my chagrin, I discovered that this combination failed to reach focus. Due to the constant interruptions from clouds and with the rain never far away, I did not want to retract the UTA enough to get it to focus. Instead I chose a 7.5mm Parks Gold ocular and 2.25x Barlow yielding 195x.

Though the helical focuser is a bit fiddly and takes some getting used to, I am happy to report that the Jupiter images were wonderful in this telescope, with lots of nice detail showing up under moderate scrutiny. The planet’s enormous equatorial belts were seen in their faithful colours and many shades of tan were observed. A Baader Neodymium filter took away a little bit of glare surrounding the planet, helping to bring out more subtle details. Although I felt 195x was a little too high, and would have been happier with 160x, I was most impressed by what this inexpensive Newtonian was delivering.

Jupiter as seen through the Skywatcher Heritage 130P Dobsonian at midnight of February 6.

Jupiter as seen through the Skywatcher Heritage 130P Dobsonian at midnight of February 6.

Turning then to some brighter stars appearing from behind the clouds, I was equally impressed by how well the instrument focused them down to tight round Airy disks at the highest powers pressed into service (244x). The telescope seems quite immune to atmospheric turbulence as judged by the calmness of the images. Returning to a 32mm Plossl, I enjoyed a spell binding few minutes drinking up the famous Double Cluster (Caldwell 14) in Perseus. The 20x delivered by this eyepiece provided a very generous field of view, allowing both star clusters to be easily framed in a most beautiful portal.

This is certainly not a toy telescope! It is impressively powerful with high quality optics. Indeed my initial impressions were very similar to this assessment made by Ralph Bell back in 2009.

Monday, February 8 2016

Time: 18:30-45 UT

I enjoyed another brief vigil under the stars with the Heritage 130P Newtonian.  Charging the telescope with a 32mm Plossl (20x), I first visited the Pleiades, now high in the southern sky. Its constituent stellar components focused to fine points of light, pure white as the driven snow, with excellent contrast. Though I did not do a side by side comparison with my 80mm f/5 shorttube refractor, I was immediately aware of the Heritage’s significant advantages in light gathering power, with many more fainter members coming through at a glance. Then, I moved the instrument southwards, where majestic Orion was just about to culminate. The view of M42, the Great Nebula, was a sight for sore eyes. Cranking up the magnification to 81x with my Baader Zoom, I enjoyed a sumptuous field of view dominated by the emission nebula and Trapezium stars at its heart. The hinterland of the nebula was jewel encrusted with brilliant white stars set against a jet black sky.

Before packing up, I examined three higher resolution targets; first Rigel, just a few degrees to the southwest of M42. Using a power of 108 diameters, I was delighted to see the faint companion to this brilliant giant star cleanly and steadily. Then I swung the telescope over to Cassiopeia, now high in the northwestern sky. First I centred eta Cassiopieae and keeping the power at 108x I was able to easily split this pair, consisting of a beautiful yellow primary of magnitude +3.5 and its ochre companion some 13 arc seconds away, shining considerably more faintly at magnitude 7.4. Finally, I moved the Heritage 130P over to iota Cassiopeiae and could make out two of the three components of this system at a glance at 108x. The third member remained somewhat more elusive though, so I attached the Baader 2.25x Barlow yielding a higher magnification of 244x, refocused, and was overjoyed to see all three components clearly and precisely!

The Heritage 130P enjoying a dry afternoon.

The Heritage 130P enjoying a dry afternoon.

The imminent arrival of another student meant that I had to end the short vigil there, but it was very rewarding nonetheless. The telescope has great potential as a deep sky instrument and appears to be no slouch on moderately difficult double stars.

Tuesday, February 9 2016

Time: 19:00-30 UT

After a cool but crisp day, I continued my Newtonian education by fielding two telescopes; the Heritage 130P and a high quality 90mm f/5.5 ED doublet on loan for a a magazine review. Both instruments were given plenty of time to thermally acclimate and placed in the darkest spot in my garden to minimise stray light flooding into the open tubed reflector.

The multicoated objective of the f/5 ED90 'scope.

The multi-coated objective of the f/5.5 ED90 refractor.

The sky after sunset was clear but the stars were corruscating fairly wildly. Transparency was excellent though, so I decided to assess the seeing conditions some more by turning the 130P on Castor, now quite high in the eastern sky. Charging the telescope with a power of 195x, both the A and B components were resolved but there was quite a bit of turbulence which made the stars bloat significantly from their calmer appearances under better seeing conditions.  Comparing the same target in the ED90 charged with a power of 188x, both components were also resolved but there was still noticeable turbulence. It was not quite as unsettled in the refractor though, a consequence I suppose of its smaller aperture. This demonstrated to me that poor seeing can (though thankfully rarely at my location) adversely affect small telescopes. I judged the image in the refractor to be slightly more aesthetically pleasing under these conditions.

The reader will also note that the refractor comes equipped with a state-of-the-art 11:1 dual speed micro-focuser and so was considerably easier to focus finely than with the comparatively crude helical focuser on the Heritage 130P. This may also have contributed to my conclusions regarding Castor A & B. Accurately focusing f/5-ish instruments is never a walk in the park.

Turning to M42 once again, I compared and contrasted the images in both telescopes matching their image scales as best I could (~100x). Both telescopes delivered good images but the superior light gathering power of the reflector gave it a distinct edge. More nebulosity was seen and the stellar images were noticeably brighter in the reflector. This was despite the fact that the refractor had superior contrast, with a blacker sky background.

I am hoping that conditions will improve by the time Jupiter rises in the sky in a few hours from now.

22:45 UT

The sky has completely clouded out and the forecast predicts that it won’t clear again until the wee small hours. I am very tired though, so will leave further testing for another night.

Thursday, February 11 2016

Time: 00:50h

I fielded the same two instruments tonight as last night; the 130P reflector and the ED90 refractor. I finally found a good eyepiece to optimise the 130P’s capabilities on Jupiter; a 4mm Plossl delivering a power of 165x.The ED90 was charged with a power of 150 diameters.

Seeing was only marginally improved over last night (Antoniadi III-IV) but it was nonetheless a good test of what both instruments could deliver on Jupiter under these sub-par conditions (we have a north westerly air flow here which almost invariably brings more turbulent conditions but with excellent transparency).

I fitted a Baader Neodymium filter (with very high light transmission and virtually no colour shift, more a moon and skyglow filter than anything else)  to the 130P to reduce the glare a little.

Comparing the images in both telescopes over a period of about half an hour, I gathered my thoughts.

Both showed some nice details in the equatorial belts. The ED90 image revealed hints of more subtle details at higher and lower latitudes but in the end I felt the 130P showed that little bit more. In particular, it was easier to see those details at temperate latitudes, as well as the more delicate polar shadings. One very striking difference was the colour of the Jovian disk presented in the telescopes. The ED90 was noticeably yellower in overall hue – a consequence of its imperfect achromaticity in comparison to the perfectly achromatic reflector. The latter presented a brighter disk in its true colour; much more creamy white than yellow. The Neodymium filter showed that the colour in the ED90 remained the same but with a little more light loss.

In retrospect, this should not have come as a surprise; while the refractor has a low dispersion element, which improves colour correction, it still can’t deliver perfectly achromatic images. Yes, it’s a sizeable improvement over the traditional achromat but still not perfect. Only a reflector image – which brings all wavelengths of light to the same focus – could really reveal this. In addition, a brighter image can also help the eye see finer details. You need light to see such details.

That being said, I do know the ED90 is capable of showing more on better evenings ( data not communicated) but so must the 130P, as they were both compared under the same conditions. I am eager to conduct further tests in this capacity as soon as the seeing conditions return to normal.

This was an instructive vigil. The 130P should  give very decent images of Jove when the seeing is fair to good.


SkyWatcher has also brought to market a related telescope called the 130PD-S, which, as far as I can tell, features the exact same optics as those possessed by the Heritage 130P but retails for about £30 more. The optics are housed in a closed tube and the spider vanes are akin to what is seen on a traditional Newtonian. It also features a low profile 2-inch dual speed focuser for precise focusing and the secure mating of a CCD camera to the instrument. The 130P-DS has proven a huge hit with astro-imagers who have used it to good effect to capture stunning views of the night sky. Featured on this link is a plethora of deep sky objects captured by this modest telescope, but the reader will also take note of the lunar and planetary images captured by the same instrument.

Although not a visual assessment, I hope you will agree that the unlying camera shows just how good the optics are in these telescopes.

Friday, February 12 2016

Time 00:01UT

The seeing was vastly improved tonight, frosty but no wind. I only had time for one target; Jupiter. Like last night I fielded the same telescopes and employed the same magnifications etc.

Both telescopes served up some excellent images, but this time there was a clear winner – the 130P.

Though the image flitted somewhat between perfect focus and slightly out of focus in both telescopes, both instruments revealed excellent details in the equatorial and temperate belts. Details in the more prominent NEB were more finely resolved in the Newtonian than in the ED90. But what clinched it for me was the sighting of the Great Red Spot (GRS) near the western limb of the planet (at 00:01UT) that was picked off in the 130P but was not seen clearly in the ED90.

As always, I would be very grateful if someone could repeat these observations if you have the 130P and a good 90mm refractor.

The 130P is turning out to be a fabulous little telescope and I am overjoyed to have made its acquaintance!

19:30 UT

I have noticed that the price of the ED90 has been bumped up by £48 in the short time since I acquired it for review. It now retails for £868?! I don’t know why this was done (it was £820 just last week, remember?), but I can tell you I do not consider these telescopes good value for money and do not understand some people’s obsession with them. Under good conditions the Heritage 130P will outperform it and for 1/6th of the price. And if the classical achromat is the prince of telescopes, Newtonians are the ruling monarchs.

I would like to keep this telescope and learn how best to maximise its potential. I have bestowed a name on her; Plotina.

After another beautiful, crisp day, the firmament was glorious after sunset, with a gorgeous crescent Moon adorning the western sky. I set up Plotina at the side of the house and trained her on our life-sustaining satellite. She cools super quick, faster perhaps than the ED refractor that now sits in its case. The view of Luna at 20x was simply breathtaking, with razor sharp crater fields and the most wonderful earthshine from its dark side. Cranking up the power to 165x, the image remained razor sharp with excellent contrast and without a trace of chromatic aberration.
After that, I headed over to eta Orionis, a fairly tricky double star and was rewarded by a good clean split of the A and B components, the primary shining about a magnitude brighter than the secondary (3.8 and 4.8, respectively) and separated by a mere 1.7 arc seconds. Because of its f/5 relative aperture, it is very important to examine such high resolution targets at the centre of the field. This can be achieved by placing the system at the eastern edge of the field and letting it drift into the centre. The procedure is repeated several times until one is certain that the duplicity has been unveiled.

Some haar moved in a short time ago but hopefully it will clear later. I hope to field my most powerful telescope, Octavius, to continue my study of the Giant Planet.

Saturday, February 13 2016


My luck ran night overnight, as instead of clear skies, we got a fall of snow.

The final step in keeping anything in my family is to get my wife’s approval. For that, I had to get all my facts together to make a convincing case lol:

The optical tube assembly weighs just 3.2 kilos

The little lazy Susan weighs 2.8 kilos

The telescope can be collapsed to half its length.

The tube assembly can be used with a variety of other mounts.

The telescope is easy to tweak; involving a couple of minutes with a laser collimator.

The telescope is easy to carry about using one hand, so even when I’m feeling lazy it will not overtax me.

The telescope cools rapidly, so no waiting around or extensive pre-planning involved. Just set it out 15 or 20 minutes before use and you’re cooking with gas.

Because the tube is open, the optics can be accessed to remove dust and other grime easily.

The telescope gathers a very decent amount of light to go that little deeper than my short-tube refractor; very good for deep sky viewing.

The telescope takes high magnification well; images remain sharp and well defined up 244x (higher powers not yet tested) when conditions are average to good, so will perform well on lunar, planetary and double star targets.

The telescope can be improved in a number of ways; for example, the mirrors could be re-coated to give both higher reflectivity and increased durability, the secondary size re-assessed, ways could be found to refine the helical focuser, a permanent light shroud can be installed  etc. Any amount of tomfoolery is permissible!

The instrument exudes charm and is popular with the kids.

The entire package cost only £129.

I think these points will be enough to win her over. Fingers crossed eh!

16:00 UT

Improving the Focuser:

As mentioned earlier, the focuser on the Heritage 130P is of the simple, helical variety. One simply twists it one way or another to attain a good focus. But in the field at night, it can be a little frustrating to focus precisely, especially when using high magnifications. Manhandling the focuser almost always causes the telescope to move a little, necessitating re-centering of the object under study.

Fortunately, I was able to find a very simple solution; about six inches of string!

A new improved focuser!

A new improved focuser!


The string is tied in a single knot around the focuser, gripping the top thread, and leaving two overhanging ends which can be pulled in either direction causing the focuser to move inward or outward, as desired. This enables both course and fine focusing with much less vibration or annoying image shift. I tested it out during the day on a variety of targets at various distances from about 40 yards to infinity and it worked really well! This will allow more quality time observing and more precise focusing from moment to moment.

I’m well happy with the improvement!

Sunday, February 14 2016


St. Valentine’s Day and the first Sunday of Lent.

Last night I fielded Plotina just before midnight. After snowing for much of the day, the late evening sky cleared up to reveal the hosts of the second heaven. Seeing was very good but bitterly cold(-4C), but I was rewarded by quite an extraordinary view of Jupiter and its magnificent satellite system. I watched the planet for about 40 minutes, beginning at 23:50UT and ending at about 00:35UT.

This instrument continues to humble me in many ways. The optics are unreasonably excellent in this telescope; something I was not really prepared for, but hand on heart, it has thus far given me the finest views of Jupiter in any small telescope that has passed through these parts. I made a quick sketch depicting the planet’s appearance at 23:50UT (CM II 217 degrees), when it was 33 degrees above the horizon. The Great Red Spot (GRS) was plainly seen in the eastern hemisphere of the planet. The magnification employed was 165x and a Baader Neodymium filter threaded to the 4mm Plossl.

Jupiter as it appeared though the Heritage 130P shortly before midnight on February 13, 2016. North is at the bottom and west is to the left.

Jupiter as it appeared though the Heritage 130P shortly before midnight on February 13, 2016. North is at the bottom and west is to the left.










Indeed, I was able to use this telescope to establish the most accurate longitude of the GRS during this apparition. The GRS was observed transiting the centre of the planet at 00:32 UT where the system II longitude was 243 degrees. Not bad eh?

In the immortal words of Alexander Pope;

Nature and nature’s laws lay hid in night;
God said “Let Newton be” and all was light.

Monday, February 15 2016


I subjected the 130P to a high magnification test on the first quarter Moon, at an ambient temperature of -1C. I am very happy to confirm that it handled 244x without flinching, with the craters, mountain ranges, maria and valleys  remaining tack sharp and colour free throughout. This is about as high as one would like to go with this telescope in the vast majority of applications and a testament to the quality of the underlying optics.

I would warmly encourage other individuals to test each and every one of the claims I have made about this telescope. Test everything; hold fast to that which is good.

Sound Biblical advice that!

23:15 UT

Way hay! I found me an online thread about the same telescope;  Enter the One Sky Newtonian from Astronomy Without Borders .

100,000+ hits ……..Crikey!

Seems like I don’t need to say anymore, eh.

Watcha think?

Tuesday, February 16 2016


What a thread! The things they say about this telescope warms my heart.

That thread has saved me months of blogging; Laudate Dominum!

Gary Seronik of S&T also found the telescope a joy to use; see here.

And yet another independent review can be read here.

Here my story ends.

Thank you for viewing.

Post Scriptum: 

Thursday, February 18, 2016


Having just acquired the latest issue(March 2016) of Astronomy Now (pp 63), I read with interest that the current longitude (system II) of the GRS is 238 degrees. That’s just 5 degrees shy of my best estimate made with the 130P shortly after midnight on Sunday February 14 (see above). I’m thrilled to bits to have gotten so close with this nifty little travel Newtonian.

Monday March 14, 2016

I have found that the Televue bandmate planetary filter is a great match for the 130P whilst studying Jupiter.This filter will be used in all future observations of the planet with this telescope.

The Televue Bandmate Planetary Filter.

The Televue Bandmate Planetary Filter.

The primary and secondary mirrors of the Heritage 130P have been despatched to Orion Optics UK. Both mirrors will be re-coated with Hilux enhanced aluminium reflectivity coatings and a slightly smaller secondary (35mm @27% linear obstruction) is to replace the original flat.

Will report back on progress.

Tuesday, March 22 2016

The mirrors arrived back from Orion Optics UK this afternoon and I immediately set to work putting it all back together again.

Out came the matt black paint to darken the periphery of the new secondary mirror to further reduce stray light and increase contrast.

The primary mirror has been rocaoted with 97 per cent reflectivity Hilux coating. The smaller secondary ( also Hilux coated) is seen in the middle beside the original secondary.

The primary mirror has been re-coated with 97 per cent reflectivity Hilux. The smaller secondary ( also Hilux coated) is seen in the middle beside the original secondary.








Applying a coat of matt black paint tot he periphery of the new mirrors cuts down on unnecessary stray light entering the optical train.

Applying a coat of matt black paint to the periphery of the new secondary mirror cuts down on unnecessary stray light entering the optical train.











Side view of the recoated 130mm primary mirror.

Side view of the recoated 130mm primary mirror.














The primary mirror had to be re-spotted at its centre but this can easily be done by placing the mirror shiny side down on a sheet of paper and tracing round its circumference. Next, the 130mm diameter circle was carefully cut out and folded first in half, and then once again into quarters. When the paper is unfolded the centre is marked by the intersection of the two crease lines. A scalpel (lol!)was used to excise a very small hole at the centre of the unfolded paper and then it was placed over the mirror, being secured in position with some cellotape. Finally, a doughnut shaped sticker was placed on the spot exposed by the hole. Job done!

Marking the centre of the mirror for collimation purposes.

Marking the centre of the mirror for collimation purposes.









The optics were then rehoused in the tube, collimated using an inexpensive laser collimator (SkyWatcher) and briefly tested with an eyepiece. Everything looked dandy!The telescope should now deliver brighter, more contrasty images on all celestial targets. And those special coatings will last at least a quarter of a century!

Surely now Plotina will be as durable as any high quality refractor nay?

All I have to do is wait for a decent clear spell to see how well she performs under the starry heaven.

Plotina pining for a clear sky.

Plotina pining for a clear sky.










Wednesday, March 23, 2016

Jupiter as it appeared in the modified Heritage 130P travel Newtonian on the evening of March 23, 2016.

Jupiter as it appeared in the modified Heritage 130P travel Newtonian on the evening of March 23, 2016.

Beginning about 20:30 UT this evening, I took advantage of a clear spell after a few hours of light rain. Jupiter was about 34 degrees above the horizon and rising, and I continued observations through to 21:15 UT before more cloud rolled in. I captured some beautiful detail on the Jovian disk, including the appearance of the GRS at the planet’s eastern limb. As the minutes passed, the view of Jupiter got ever better as it gained in altitude. The 130mm f/5 performed flawlessly. The planet was brighter, crisper and cleaner than I had ever seen it before with this instrument under these conditions (Ant II). To say that I’m pleased with the modifications would be an understatement, but we’ll leave it at that.

I heartily recommend this telescope to my amateur friends across the world.

Wishing you all a very blessed Easter.

March 31, 2016

23:50 UT

I enjoyed a half hour with the Heritage 130P this evening after I had observed Jupiter. After spending some time in Leo hunting down some spring galaxies, I started looking at some double stars. Gamma Leonis was easy, Castor A and B just as easy, iota Cassiopeiae triple lovely and all three components resolved. Mizar & Alcor were glorious at 150x as was Polaris A & B. Izar (epsilon Bootis), a summer favourite, was high enough in the east for me to split it. These were all seen at 183x save for Mizar & Alcor. I then decided to try a pair of stars I haven’t visited in a while; Alula Borealis and Alula Australis in Ursa Major. They are high overhead this time of year. Aiming is quite difficult using just the RDF but with my 32 mm Plossl delivering 20x, I was able to frame them both in the same field. Starting with the orange star Alula Borealis, I employed 183x using my most comfortable ocular; the Mark III Baader Hyperion zoom set to 8mm with its 2.25x Barlow. Although this does not show the highest contrast views (but only by a surprisingly small margin!!), I was able to see the very faint spark of its companion. The primary is magnitude 3.5 but the secondary shines at magnitude +10.1 and only 7.4″ separating them! I was chuffed to see this in such a humble little reflector. Then came the icing on the cake; I moved south to Alula Australis (Xi UMa) and could see that the star looked ‘entangled’ but I knew I needed a little more power to get a clearer view. So I ran in and fetched by 6mm orthoscopic and coupled it to the little 2.25x Barlow yielding 244x, centred and focused carefully: Voila! The pair (1.6″ split) were beautifully resolved (magnitudes 4.3 and 4.8), the components round as buttons, with a kind of diffraction halo encircling them; kind of like an ‘aura’ encasing two luminous eggs in a wafer thin handkerchief lol.

I was absolutely beside myself in admiration for what this little telescope can do! I believe Newtonians have been terribly maligned as unsuitable for high resolution work relating to double stars but I now know that this is another myth. The telescope takes very high power well under reasonable seeing conditions and totally exceeded my expectations.  I feel privileged to finally ‘know’ and  to share this personal discovery with my peers.

If no one bothers, how can one ever discover the truth? The Heritage 130P is unreasonably excellent on everything; a great little bundle of joy!

April 7, 2016

Mr. Adam Blake from Pennsylvannia USA, was kind enough to share some video footage of Jupiter he captured with his One Sky Newtonian, as seen on the evening of April 5, 2016 during a spell of good seeing. He used an inexpensive 5X GSO Barlow and standard UV/IR filter on the camera at prime focus to capture the images, which have only been very lightly processed to show the telescope’s potential. See below.

Mighty Jupiter as captured by Adam Blake using the 130mm f/5 Newtonian on the evening of April 5, 2016.

Mighty Jupiter as captured by Adam Blake using the 130mm f/5 Newtonian on the evening of April 5, 2016.












I aimed the Heritage 130P at iota Leonis, now high in the south. Using 244x I was able to quite easily resolve A-B. The primary shines with magnitude +4.06 and the secondary +6.71 with 2.1″ separating the components. I would warmly encourage others to try this system, as well as the aforementioned star systems with this telescope.

A Portable Dew Buster: Are you concerned about dew building up on the open tube of the Heritage 130P? Nae worries! I never let any heating devices within a country mile of my telescopes, just like my forebears. I bought a portable three-speed fan for about £10 that zaps dew in seconds from the secondary and primary using cold air. Now you can enjoy the telescope under the stars for as long as you like!

Laudate Dominum!










April 28, 2016


At an ambient temperature of -1C, the Skywatcher Heritage 130P worked flawlessly to bag epsilon 1 and 2 Lyrae, eta Bootis (with its 10th magnitude companion), pi Bootis ( AB:  4.9, 5.8  separation  5.4″ and  AC: 4.9,10.6, separation 127″), alpha Herculis ( AB:3.5, 5.4, separation 4.6″ and a corker, AD: 3.5, 11.1, separation 79″)

For lunar and planetary studies, I can also recommend the Baader single polarising filter to use with this adorable little telescope. Retailing for £32.00, it significantly enhances belt detail on Jupiter, reduces glare and presents the planet in its natural colours.

The superlative Baader single polarising filter.

The superlative Baader single polarising filter.











Sunday, May 15, 2016.

The view from the sandy beach at Luss, on the western shore of Loch Lomond. May 14, 2016.

The view from the sandy beach at Luss, on the western shore of Loch Lomond. May 14, 2016.











During a relaxing weekend away with a group of old friends in the picturesque and historic village of Luss, on the western bank of Loch Lomond, I took the little SkyWatcher Heritage 130P along with me, as it was so easy to transport and set up. After long sunny days outdoors, I set the instrument (on its Dob mount) up on the garden table for a look at Jupiter and the first quarter Moon, which were perfectly positioned in the evening sky.

The Skywatcher Heritage 130P on holiday.

The Skywatcher Heritage 130P on short vacation.











As this was an annual event away, the crew were expecting me to bring along a telescope, but it is usually of the short refractor variety. I got some odd looks from the gang as I extended the upper stage of the ‘strange’ reflecting telescope, but I was sure glad I made the effort; they were all mightily impressed by the images the little portable reflector served up:- and even more gobsmacked when I told them how relatively inexpensive an instrument of this quality cost to acquire!

That's it guys: form a nice orderly queue.

That’s it folks: form a nice orderly queue.










A close encounter with the first quarter Moon: Kenny's face says it all!

A close encounter with the first quarter Moon: Kenny’s face says it all!












July 21, 2016

 LightBridge Mini 130 5.1" tabletop altazimuth mini-Dob reflector by Meade Print Home Telescopes The Meade LightBridge. Image Credit: Meade Instruments.

The Meade LightBridge Mini 130 5.1″ tabletop alt-azimuth mini-Dob reflector
 Image Credit: Meade Instruments.

My collegaue at Astronomy Now, Steve Ringwood, has independently reviewed the New Meade Light Bridge 130 Mini Dob for the August 2016 issue of Astronomy Now (now in the shops) on page 108-10. Although a slightly different design to the Heritage 130P featured in this blog, the optics are essentially the same but features a solid tube and a more traditional four spider-vane secondary support for even more rigid collimation maintenance in the field. Steve found that the optics were very good indeed, being capable of powers in excess of 200x, in agreement with my findings. At $200, it is priced at the same as the One Sky Newtonian from Astronomy Without Borders, discussed above.

So more choice for the discerning amateur.

Brian Schultz, from his YouTube channel Cool Space, describes how the One Sky Newtonian can be fitted to an inexpensive go-to mount for added versatility. See here for a video clip.

August 8-9 2016

The Old Man of Storr, Isle of Skye, as seen in the opening scenes of the block buster movie, "Prometheus".

The Old Man of Storr (elevated in the distance), Isle of Skye, as seen in the opening scenes of the block buster movie, “Prometheus”.

Our family ventured to the remote Isle of Skye, a place of outstanding natural beauty, for our summer vacation. My trusty 130mm f/5 Heritage Newtonian travelled with us. Though the weather was mostly damp and windy, I did enjoy a bout of observing with the instrument during brief clear spells on the evenings of August 8 and 9. The sky is truly glorious at this location, presenting some of the darkest and most transparent skies in all of Europe. And the (not so) little 130mm did not disappoint, serving up jaw-dropping views of the northern Milky Way high overhead, once the crescent Moon fell out of the sky. Deep sky objects were a joy to behold, including M31,Caldwell 14, M57, M13 and M92. The North American Nebula in Cygnus was as plain as the nose on the your face, as were the eastern and western Veil nebulae nearby.

Plotina ready for action on the remote island of Skye.

Plotina ready for action on the remote island of Skye.

I can also report that high resolution targets – including a batch of close test double stars – presented very well indeed. Images of systems such as Izar, delta Cygni etc, were calm and well resolved at high powers (243x), showing that this island has good seeing conditions for such work. Scotland has many such places(as I continue to discover) if one is intrepid enough to find them out!

September 30, 2016

My experiments with the Skywwatcher  Heritage130P continue apace. A while back a kindly gentleman from the USA alerted me to a potential issue with the instrument; the loss of precise collimation as the instrument is pointed to different parts of the sky. In a series of experiments conducted over the last six weeks or so, I discovered that while tightening the shaft that holds the secondary mirror in place seems to solve this problem for lightweight eyepieces, it doesn’t always hold collimation for heavier oculars such as the rather bulky, Baader Hyperion zoom.

As a consequence, I have reassessed the suite of oculars I use with the instrument and have switched entirely to smaller, more lightweight units. Below is an image of my current experimental set up; a 32mm Plossl, delivering a power of 20x and a 2.5 degree true field. Using the tiny, screw-on 2.25x Baader Barlow, I can couple the 32mm ocular to give a power of 45x and a true field of ~1.1 degrees – just large enough to frame the entire Double Cluster in the field!

For higher power work, I use a Parks Gold 7.5mm delivering 87x, a 6mm Baader classic orthoscopic yielding 108x, and a 4mm Revelation Plossl (fully multicoated) giving 163x. Finally, using the 2.25x Barlow I can achieve 243x and even 366x when mated with the 6mm and 4mm oculars, respectively. I also have an old 1.6x screw-on Barlow made by UK Astro Engineering, which gives me still more options to play with.The Barlows will increase the eye relief of the short focal length of the short focal length eyepieces too.

Plotina with a suite of lightweight oculars and low profile Barlows.

Plotina with a suite of lightweight oculars and low profile Barlows.

















Over the winter I hope to fine tune this set up some more, but I am very happy with the range of powers available to me and the relatively low cost of its operation.

I also intend purchasing some Bob’s Knobs collimating screws to fit to the secondary assembly in order to make collimation even more easy to achieve.

I will report back later in the year to tell you how I got on!

The instrument continues to inspire in so many ways and needless to say I have grown very fond of using it.

Thursday, October 13, 2016

Plotina received her new set of Bob’s Knobs secondary screws to make fine adjustments to collimation easier. I consider these to be a quality acquisition going forward.

Bob's knobs for easier adjustment of the secondary mirror.

Bob’s knobs for easier adjustment of the secondary mirror.

















Monday, October 17, 2016

Upon further investigation, I have been able to tighten up the stalk holding the secondary mirror in place by inserting a small washer, as shown below.

A simple washer tightens up the secondary support.

A simple washer tightens up the secondary support.

















This increased rigidity allows the instrument to maintain precise collimation even after moving the telescope wildly in altitude and azimuth. This was verified using a laser collimator. The telescope can now use larger oculars once again, including the Baader zoom.

Monday & Tuesday, October 18 and 19, 2016

A break in the wet autumnal weather over the last two nights has allowed me to conduct further tests with the SkyWatcher 130mm f/5 Newtonian. I fielded a 90mm apochromat (retained for further testing) side by side with the instrument and studied how both performed on a variety of high resolution targets located in different parts of the sky.

Test instruments: a 130mm f/5 Newtonian (left) and a 90mm apochromatic refractor (right).

Test instruments: a 130mm f/5 Newtonian (left) and a 90mm apochromatic refractor (right).

Yesterday evening, shortly before midnight, I compared and contrasted both instruments in respect of their ability to maintain crisp, bright images of a waning gibbous Moon. Once our satellite achieved a decent altitude, I cranked up the magnifications on both instruments and examined the cratered terrain along the day-night terminator. Both instruments performed well but the larger aperture of the Newtonian allowed me to employ significantly higher magnifications (in excess of 300x) before the image became unsatisfactorily dim for my liking. The 90mm refractor, in contrast, maxed out about 200x.

Tonight, with better seeing but in colder(+4C) and hazier conditions, I ran the two telescopes to a variety of double star targets at various altitudes; gamma Delphini, theta Aurigae, Iota Cassiopeiae and delta Cygni; these systems were deliberately chosen so as to test how the 130mm Newtonian would hold collimation as it was adjusted in altitude and azimuth. My results show that the insertion of the washer in the stalk supporting the secondary mirror (described above) worked perfectly well, the stellar images remaining crisp, round and tiny. In every case, the Newtonian produced brighter, more convincing splits of these systems under equivalent magnification regimes – 200 to 250x.

These results show that the Newtonian is a wonderful, cost-effective and versatile instrument for all celestial targets and is noticeably superior to a much more expensive 90mm refractor, which quickly runs out of both light and resolving power in comparison.

I continue to highly recommend this instrument to those who are looking for excellent performance on a limited budget.

Nothing more to say really.

Thanks for following this blog.

Best wishes,


Update: February 15 2017

My colleague at Astronomy Now, Ade Ashford, is helping to change culture by writing an excellent four page article on how to tune up the SkyWatcher Explorer 130PDS, mentioned in the blog above, and essentially the same telescope optically as the Heritage 130P (but with a closed tube) for better visual and photographic use. You can read this VERY interesting article in the March 2017 issue (page 98 through 102), out now.

De Fideli.

Changing Culture Part IV: The Ultimate Grab ‘n’ Go ‘Scope?

Monday, December 19, 2016

Ich bin ein beginner!

As described in a previous blog, I have come to learn the many virtues of the powerful yet relatively inexpensive SkyWatcher Heritage 130P, a 5.1 inch f/5 tabletop Newtonian. I described various modifications I made to the telescope in order to optimise its performance. These included replacing the existing secondary with a smaller unit, giving a secondary obstruction of just 27 per cent. Both the primary and secondary mirrors were also treated with Orion Optics’ HiLux super high reflecting coating, providing brighter, more contrasty views of celestial targets. I also described some modifications which involved tightening up the secondary stalk holding the secondary mirror in place, which helped maintain precise collimation while the telescope was being slewed to different parts of the sky.

I can report that the telescope is still performing excellently, so much so that I now question the wisdom of using a small aperture refractor (or catadioptric) for grab ‘n’ go excursions. As explained in my blog, this telescope is very lightweight, fits on a variety of ergonomic mounts owing to the included Vixen style mounting plate, and cools super quick due to its relatively small, thin primary mirror and open tube configuration. But on the evening of December 19, I learned yet more of its secrets.

The night was cold (near zero Celsius) but the sky remained steadfastly clear from sunset to near sunrise the next day. I felt rather tired that evening, having gone through several hours of maths teaching, but I still wanted to venture out under the wintry sky before the waning gibbous Moon got up. So I turned to the 130P, mounting it on a lightweight Vixen II Porta altazimuth to get some observing in. Seeing conditions were not fantastic but perfectly adequate for most targets. The instrument was precisely collimated using an inexpensive laser collimator, as described previously, and made even easier since I installed some Bob’s Knobs secondary adjustment screws. This operation takes only a couple of minutes to execute accurately and I was then ready to reach for my Baader Hyperion zoom, an eyepiece I have grown very fond of owing to its excellent quality for its modest price. Indeed, it really is only slightly inferior to high quality oculars of fixed focal lengths. Thankfully, this is now being openly acknowledged by many amateurs on the forums. See this interesting link comparing this zoom to a much more expensive Leica zoom covering more or less the same focal length range.

The truly remarkable Mark III 8 to 24mm Baader Hyperion zoom and the light weight, low profile 2.25x Baader Barlow lens.

















In previous excursions, I reported that the zoom was rather heavy and I was concerned that it might be throwing off the collimation as the telescope was aimed at targets of varying altitude. But I can report that the addition of a single washer to the stalk holding the secondary mirror greatly increased the rigidity of the system and I felt I could chance using this large (and bulky) eyepiece as my only portal on the Universe on this frosty evening. So, how did it perform? In a word; magnificently!

The Skywatcher 130P outfitted with the Baader Hyperion zoom. Note the extended distance of eye placement from the optical train.

















But to elaborate, I discovered that the zoom keeps one’s body a few inches further back, away from the optical train, and more effectively attenuates the thermal heat plumes issuing from my body. An open tube like the Heritage 130P is significantly more sensitive to thermals introduced into the optical train, especially on cold nights like that experienced on the evening of December 19. I was actually quite shocked at how calm the images appeared in the eyepiece, examing as I did, several fairly tricky double and multiple stars, including some of my seasonal favourites, like beta Monocerotis (at a fairly low altitude), and much higher up: theta Aurigae, iota Cassiopeiae and (the less challenging) Castor A & B. All were well resolved. The native zoom provides a very useful range of magnifications from 27 to 81x, and can be further extended to a greater range of powers up to 182x (and thereby further extending the distance from the optical train). The images of all these systems were remarkably calm!

Close up of the zoom housed securely in the eyepiece holder of the instrument.

Furthermore, comparing the views through the zoom and a much lower profile 7.5mm Parks Gold ocular and Barlow, I could see that the images remained calmer for longer using the zoom. The images were quite simply less affected by anthropogenic turbulence. This is going to make a very significant difference while conducting high resolution work with this telescope during the many cold nights we experience here in Scotland. Nor did the zoom cause any miscollimation issues throughout the vigil. The stars always focused down to small, tight and round seeing disks.

Moving back to the native zoom, I visited M31, riding high in the winter sky, followed by the beautiful trio of Messier star clusters adorning the heart of Auriga (M36, M37 & M38), and from there I visited to my favourite Messier open cluster, M35, in Northern Gemini. I experienced nothing but pure joy experimenting with the right magnifications to frame these clusters using the zoom and the Barlow. I especially like the way the zoom ‘opens up’ at the lower focal length settings (to a very generous 72 degrees indeed) allowing one to soak up the beautiful hinterland around the Auriga clusters.

From there, I panned the telescope down to M42, the Great Nebula in Orion, which had, by now, all but reached meridian passage, and I ‘dialled in’ the optimum viewing magnification (about 150x as it turned out), drinking up the beautiful, crisp nebulosity surrounding the theta Orionis complex (Trapezium).

My adventure under the winter sky was a wonderful experience and only ended once I saw the vault of light emerging in the eastern sky from a rising Moon. The telescope is well able to handle this extraordinary eyepiece, enabling me to effortlessly cruise from low to high power. As I already reported, it is significantly more powerful than a 90mm apochromatic refractor (tested extensively along side the 130P over several months). It can do things no 127mm Maksutov can do, especially on low power, wide field targets, and its smaller central obstruction ensures crisper lunar and planetary views.

This grab ‘n’ go system will take your short, backyard excursions to new heights, thanks to its very generous aperture. Can I recommend this telescope and zoom eyepiece combination highly enough?



Neil English is the author of several books on amateur telescopes.

Please check out this ongoing thread on a related telescope, The One Sky Newtonian, which is still going from strength to strength.

De Fideli.

The Pioneers of Parsonstown.

Birr Castle, Co. Offaly, Ireland, as it appears today.

Birr Castle, Co. Offaly, Ireland, as it appears today.

Dedicated to the memory of Peter Grego (1966-2016).

The picturesque, rural town of Birr in the County of Offaly, lies at the geographic centre of the Irish Republic. Inhabited in some capacity since the Bronze Age, a monastic settlement was established there by St. Brendan the Elder, which probably dates to the 7th century AD, and in the centuries that followed, Birr became the ancestral home of the O’ Carroll clan, the ruling Gaelic family of the northern territory of the ancient kingdom of Éile. In the aftermath of the Norman invasion of the 12th century, a castle was built there and continued to be administered by the O’Carroll’s, who were required to pay tribute to the Butlers of Ormonde, overlords of the district, whose capital was established in the neighbouring county of Kilkenny. In the aftermath of the English Plantation of Ireland in the 17th century, Birr Castle became the seat of the Parsons dynasty, the Earls of Rosse, beginning in 1620, when the civic areas were annexed to it, subsequently becoming known as Parsonstown.

From the 17th century onwards the Gaelic Irish were reduced to the status of tenants and landless peasants on their ancestral lands. Members of the O’Carroll clan were however, granted new lands in the colonies of Maryland and one family descendant, James Carroll of Carrolltown, went on to become the sole Catholic signatory of the American Declaration of Independence.

Evidence of British colonial rule can still to be seen in the elegant Georgian architecture of the modern town, with its tree-lined malls, and well-planned avenues, which still have the power to delight the eye. A railway, printing works and distillery provided employment to local families and a workhouse offered some relief to the starving peasants, a million of whom lost their lives during the famine years. A garrison of English soldiers was also established in the town. But like all Irish municipalities once administered by the iron fist of British Imperialism, the political winds of change swept rapidly through the region, as agrarian agitation by the Fenians, Land League and the Irish Parliamentary Party led to the dissolution of the landlord system, which also included the estate of the Earls of Rosse. As a symbolic act of the new order, the Gaelic Athletic Association also held the first All-Ireland Hurling Final at Birr in 1888. Remarkably, though its population was decimated in the mid-19th century owing to the ravages of the Irish potato famine (1845-52), the modern town of Birr, the inhabitants of which number about 6,000, has scarcely grown in size from its pre-famine population, making it one of the most pristine Irish heritage towns in existence.

After Birr Castle became Crown property in 1620, the Parsons family held several key offices in the administration of Ireland. William Parsons became Commissioner of Plantations and Surveyor-General of Ireland. His brother, Sir Laurence Parsons, became Attorney-General for the province of Munster and in the years that followed, the Castle was considerably enlarged and a successful glass works established which further aided the local community with employment opportunities. In the aftermath of William Parsons’ death in 1628, Birr became the epicentre of conflict between Catholics and Protestants. In 1641, a rebellion by Irish Catholics broke out. In January 1642, the castle itself was besieged by the Molloys, Coghlands and Ormonders , the factions engaging in brutal combat for five days. In some desperation, the noble incumbent, William Parsons, son of Sir Laurence, fled to the English army stationed at Dublin, and never returned. He died in 1653.

The troubles escalated during the time William’s son, Laurence, took up residence at Birr Castle after he father’s passing. This time, England was faced with the prospect of crowning a Catholic King, the Duke of York, who became James II in 1685. Laurence Parsons and his family departed for London leaving an unscrupulous heathen in charge of running the family estate at Birr, a one Colonel Heward Oxburgh, who, in 1689, seized complete control of the castle and its garrison, using it as a base for the forces loyal to William of Orange. Sir Laurence together with two of his confidants, were placed on trial by Oxburgh, accused of being traitors to King James II, the last Catholic King to rule the British Isles,  but were later granted a reprieve and rescued by William’s men.

More turmoil followed, when in 1690, the Castle was once again besieged by an army led by the Duke of Berwick, an illegitimate son of James II, who himself was not long deposed in the Glorious Revolution of 1688. During the exchange of fire, cannon balls flew through the parlour window, leaving marks in the walls of the north flanker which can still be seen to this day. Lady Parsons was even forced to relinquish the lead cistern she used for salting beef so that it could be melted down for bullets. Eventually though, the besieging army was finally repulsed, and the Parsons family returned to relative peace thereafter. The bloody events of the 17th century marked a watershed in the history of the castle, as well as the family who made it their home. A new dynasty of Parsons were to emerge from the ashes.

Throughout the 18th century, Birr castle became a popular haunt for some of the must cultivated individuals in Europe. Sir William Parsons, the 2nd baronet(in the new regime), was a close friend of the gifted composer, Georg Frideric Handel, who gave him an engraved walking stick in appreciation of the patronage which led to his magnum opus – Messiah – being first performed in Dublin. His grandson, another Sir William, the 4th baronet, began an ambitious project of landscaping the grounds of Birr Castle. Transforming bog land into an ornate lake, he planted beech trees and demolished the last of the ancient towers of the original fortress so as to complete the sweeping view of the demesne.

Sir William also devoted much of his time to the Volunteer movement, which sprang up towards the end of the eighteenth century, ostensibly to defend Ireland from the threat of French invasion, but effectively to force the English government to give concessions to the Irish Parliament. His son, Sir Lawrence, 5th baronet, became well-known as a patriot statesman, whose friend and colleague, the Irish revolutionary, Theobald Wolfe Tone(1763-98), referred to him as ‘one of the very very few honest men in the Irish House of Commons’. This personal integrity led him not only to oppose the Union with all his strength, but also to expose the bribery the British used to push it through. Evidently disgusted with the passing of the Act of Union in 1800, Sir Laurence retired from politics at the beginning of the 19th century, though he later accepted the post of Joint Postmaster General and attended the laying of the foundation stones of Dublin’s magnificent General Post Office build during his term of office. He devoted the autumn years of his life to literature.

The ornate Georgian facade of Dublin's General Post Office, famous for the staging of the 1916 Easter Rising which led to Irish independence from Britain. Image credit: Kaihsu Tai.

The ornate Georgian facade of Dublin’s General Post Office, famous for the staging of the 1916 Easter Rising, which led to Irish independence from Britain. Image credit: Kaihsu Tai.

Sir Laurence, the second Earl of Rosse, had three sons, the eldest of whom, William (also known as Lord Oxmantown), succeeded his father as third baronet upon his death in 1841. Unlike his father before him, the third Earl had a penchant for all things scientific, especially astronomy, and we learn of his first forays in the art of telescope making as early as 1827. The illustrious career of Sir William Herschel (1738-1822) proved to be a huge influence on the young William Parsons (1800-67), inspiring him to read mathematics at Trinity College, Dublin, where he graduated with a first class honours degree in 1822. And although he resolved to embark on a scientific career, his baronial status required that he take part in public life. To that end, he entered Parliament for King’s County (later renamed Offaly) in 1823, where he enjoyed a reasonably successful career, which he brought to an end in 1834. Two years later he married Mary Wilmer-Field, who hailed from Heaton, Yorkshire. The marriage was a long and happy one, and together they had four sons, all of whom displayed considerable intellect in adult life. Lady Mary was also a gracious host for all the scientists who were to work at Birr, and took an active interest in the work of her husband. The couple took up residence at Birr castle after William’s parents retired to Brighton, England, in search of milder climes. As master of his own baronial home, William was free to pursue his scientific career.

William Parsons ( Lord Oxmantown), Third Earl of Rosse ( 1800-67).

William Parsons ( Lord Oxmantown), Third Earl of Rosse ( 1800-67). Image credit: Wiki Commons.

William Parsons lived in a singularly interesting time for telescopic astronomy. Refracting telescopes were justifiably popular, especially after the innovations heralded by the genius of Joseph von Fraunhofer(1787-1826) in Germany, who had brought high quality achromatic refractors to market astride state-of-the-art clock-driven mounts that gracefully tracked celestial objects as they moved across the sky. But Parsons was a scientist, and he was compelled to pursue reflectors rather than refractors owing to the very limited aperture of the latter. He wanted to see the nebulae of Messier and Herschel better than anyone before him. Perhaps he had seen too many of his astronomical acquaintances follow the fashions of the time; which almost invariably involved double star mensuration with small aperture refractors. Indeed, according to the late Sir Patrick Moore, he completely abandoned the refractor early in his astronomical career. Parsons had clearly decided to go after bigger fish, and was convinced that mirrors were the way to go. And to that end, he set about grinding his own.

Like many astronomers of his day, Lord Oxmantown had to learn the noble art of casting and grinding mirrors to the required geometrical shape from scratch. He was vociferous about making the details of the construction of fine optical wares public knowledge, condemning the often secretive culture of telescope makers who came before him. As was the custom in those days before silver-on-glass reflectors, he had to use speculum metal mirrors consisting of an alloy of copper and tin as the reflective surface (discussed in much greater detail in this author’s up-and-coming book). To this end, he employed his considerable inventiveness to construct a steam-powered grinding machine with a power output of 2 horse power (~1.5KW). The mirror blank, placed in a vat of water to prevent its over-heating and expansion, was rotated slowly by the contrivance whilst the polishing ‘tool’ was made to move to and fro across the metal surface by a couple of cranks placed at right angles to each other. By considerable trial and error, Oxmantown was able to construct a series of increasingly large specula, first a 15-inch and then a larger 24-inch, both of which proved to be of very high quality.

Unlike Herschel before him, who had dispensed with the use of a secondary flat mirror in order to conserve the amount of light reaching his eye, and which gave rise to the tilted mirror of the Herschelian design, Lord Oxmantown returned to the closed-tube Newtonian configuration, finding out by experiment, that it reduced turbulence on account of the observer being located at a large enough distance from the mouth of the open tube. He also showed that tilting the mirror in the Herschelian fashion introduced unwanted aberrations to the images that were much less manifest in the Newtonian design. His mounting strategy, however, was quintessentially Herschelian in form, with all its attendant weaknesses.

After many false starts and setbacks, he managed to cast and figure a fine 36-inch speculum with a focal length of 27 feet (f/9 relative aperture) in 1839. The mirror was an alloy of 126.4 parts copper with 58.9 parts tin which produced a fine, white metal. The optical flat mirror was tested by comparing a distant object in daylight, first with a fine achromatic telescope and then using the same telescope that had formed an image after its reflection in the mirror. Any distortions would have been readily seen and adjustments accordingly made.  After mounting the optics, Oxmantown’s friend, the distinguished mathematician (a pioneer in vector algebra), William Rowan Hamilton(1805-1865), whom he became acquainted with during his time at Trinity College, was the first to turn it on celestial targets, and later pronounced it as excellent. Lord Oxmantown also invited the distinguished astronomers, Sir James South (of double star fame) and Thomas Romney Robinson, to his estate at Birr Castle in order that they might test the telescope and pronounce assessments of its quality. Having just spent a considerable amount of time performing similar tests on the 13.3-inch (with an objective by Cauchoix) refractor at Markree Castle, Co. Sligo, first dedicated in 1834, the gentlemen astronomers stayed at Birr between October 29 and November 8 1840. The guest astronomers were duly impressed with Lord Oxmantown’s newly erected 36-inch, pronouncing it “the most powerful telescope that has ever been constructed,” and declaring it superior even to the late Sir William Herschel’s 48-inch behemoth. On all objects studies, which included, the Moon, double stars, open stellar clusters and nebulae, the 36-inch showed its optical excellence. Indeed, according to Robinson (who became the first Director of Armagh Observatory in 1823):

“It [was] scarcely possible to preserve the necessary sobriety of language, of speaking of the Moon’s appearance with this instrument, which discovers a multitude of new objects at every point of its surface.”

The venerable 36-inch reflector designed and built by Lord Rosse on a quintessentially Herschelian type alt-azimuth mounting.

The venerable 36-inch reflector designed and built by Lord Rosse on a quintessentially Herschelian type alt-azimuth mounting.

Robinson observed lunar features at a power of 900 diameters with the 36-inch reflector that were scarcely seen again for another 60 years, including the appearance of “two black parallel stripes in the bottom of Aristarchus,” which are now known to be depressions, and a series of “extremely minute craters” on the ridges of the crater Ptolemaeus.

Robinson also observed M31 in Andromeda and the Great Nebula in Orion (M42) in the hope that the great telescope at Birr might resolve them into stars. Examination of the Dumbbell Nebula (M 27) in Vulpecula and the Ring Nebula (M57) in Lyra showed that they remained wholly nebulous in the 36-inch.  Alas, while he detected the tell-tale signs of individual stars on the edges of M31, the results were at best ambiguous and only served to strengthen his conviction that these objects were fundamentally non-stellar in origin. Star clusters such as M13 and M92 in Hercules were reportedly breathtaking at high powers though the same instrument.

Lord Oxmantown was satisfied that he had indeed created a first-rate telescope that would contribute to scientific knowledge, and in the spirit of the age, warmly welcomed the finest observers across Europe to use the telescope for their researches:

Although the instrument and the laboratory where it was constructed are in the centre of Ireland,” he wrote, “the facilities of communication are such that those who desire further information can easily obtain it on the spot, and from their own estimate of the performance of the instrument”.

His invitation was enthusiastically accepted, and in due course, distinguished scientists and observers of the ilk of Sir John Herschel, George Johnstone Stoney, William Lassell, Otto Struve, George Bidell Airy, Franz Friedrich Brünnow and George Gabriel Stokes, all enjoyed time at the great telescopes designed by Lord Rosse.

Yet, as soon as the 36-inch was completed, Oxmantown had made plans for an even greater instrument that would remove the still pervasive ambiguity concerning the nature of the celestial nebulae:

“I think that a speculum of 6 feet aperture could be made to bear a magnifying power more than sufficient to render the whole pencil of light, and that in favourable states of the atmosphere it would act efficiently, without having recourse to the expedient, which Newton pointed out at the last resort, that of observing from the vantage of a high mountain…… an instrument even of the gigantic dimensions I have proposed might, I think, be commenced and completed within one year.”

In making the 72-inch reflector a reality, Oxmantown was faced with a daunting task. A mirror twice as large would have four times the area of the smaller 36-inch and would be much more difficult to successfully cast, grind and polish. Its much greater weight would make it considerably more challenging to mount stably as well. As Robinson later pointed out in a paper presented in 1845; it was not possible to melt down the appropriate quantities of copper and tin in the crucible used to create the 36-inch speculum. Indeed, three such crucibles would be called for, each 24 feet in diameter and weighing half a ton apiece. Oxmantown had to construct a giant chimney-shaped furnace to accommodate the three crucibles. To achieve the necessary temperatures to create the liquid alloy, 2000 cubic feet of turf cut from a local peat bog had to be combusted for ten hours before the melt was ready. It must have been quite an apparition to catch sight of the thick yellow smoke billowing upwards from the giant furnace, its eerie yellow and orange glow being clearly visible for miles around. The cylindrical metal blank, weighing in at a whopping 4 tons, was successfully cast, but an accident of some unknown nature occurred one month into figuring the giant metal slab with the result that a large crack rendered it useless. Undeterred, a plan was made to recast the same metal, and this time it was accomplished, though it was slightly thinner than the original, weighing a half ton less. The subsequent grinding and polishing phases also went well, and by April 13 1842, the mirror was completed.

Lord Rosse had to tread very carefully in considering the mounting for this giant telescope. The tube would be 58 feet long and as a result, it would not be possible to mount it in the way the 36-inch telescope was. If a Herschelian type mount were to be employed, the slightest breeze would set the giant telescope- which would  weigh over 150 tons when completed – swinging wildly from side to side, not only making observations impossible, but putting the lives of the observers and workmen operating the instrument in jeopardy. After much deliberation and consultation, Oxmantown settled on a mounting system set between two massive walls. These would be 70 feet long and 50 feet high, running parallel with the north-south line, so that celestial objects could only be examined as they crossed the local meridian. Indeed, for an object located on the celestial equator, the total viewing time would be restricted to an hour at most. But at least the great telescope would be able to view its target when it was highest in the sky and so less affected by atmospheric turbulence.

Construction started on the Parsons demesne at the end of 1842 and continued right the way through 1843 and 1844. A cast iron joint – similar to a modern universal joint – occupied the base of the mount, and upon it was bolted an 8 foot wooden box that would carry the giant mirror. Around this was placed the telescope tubing, fashioned from inch-thick staves, and held in position by a series of iron clamp rings. The tube tapered down to 7 feet at its extremities, making it a rather odd, cigar shape. Movement in declination was undertaken via a series of thick metal cables fastened to the top of the telescope, and maneuvered by a system of elaborate pulleys. Right ascension (to and fro) motion was accomplished with a manually-operated steering wheel. In addition to these course movements in both right ascension and declination, provision was made to allow fine adjustments in both axes to centre the object under study. Oxmantown also had the presence of mind to install finely meshed screens under the telescope, so as to protect workers from the accidental fall of eyepieces and other items of equipment. The financial outlay of the Leviathan was very considerable: £12,000 in the currency of the day!

The 72-inch aperture 'Leviathan of Parsonstown' c. 1860. Image credit: Wiki Commons

The 72-inch aperture ‘Leviathan of Parsonstown’ c. 1860. Image credit: Wiki Commons

Observing with the great telescope was never a solitary affair. Indeed, its operation always required a well-trained team of operators, who had to follow verbal instructions from the astronomer assigned to it on any night. Nor was the telescope ever fitted with a finder telescope! Instead, Oxmantown employed a low power, wide field ocular of his own design, with a magnification of 216 and possessing a generous true field of 31 arc minutes (so just large enough to show the full Moon) to centre objects to be studied. And while he had intended to install a clock drive to move the instrument in right ascension, in the end, this never came to fruition, neither under the Third Earl’s watch or that of his son, the Fourth Earl. After undertaking a series of mechanical trials over the winter of 1844, the instrument was deemed ready for operation in February 1845, when both Robinson and South were once again invited to Birr Castle to provide an assessment of its efficacy.

Alas, the weather didn’t cooperate and opportunities to test the Leviathan were few and far between. First light came for an hour or so on the evening of February 15, when the telescope was turned on Castor, a famous double star in the constellation of Gemini. To the delight of all in attendance, the system was easily and cleanly split, the components appearing more brilliant than any other telescope in existence. Next, the great light bucket was directed at M67, a small open cluster situated across the border into Cancer. Robinson and South reported that the faint stars in the cluster were magnificently rendered. Then the clouds rolled in again. And with further inclemencies in the weather occurring over the next  couple of weeks, it was decided to remove the primary mirror for further polishing – no mean task in itself as it required the combined effort of 25 or 30 workmen!

The working telescopes at Birr:, based on a portrait by Henrietta Crompton. Image credit: Wiki Commons.

While it is unquestionably the case that the 72 inch Leviathan of Parsonstown was very unwieldy by modern standards, Sir James South reported that he could uncap the telescope, have its position adjusted by the assistants on both axes and have a star centred for observing in about eight minutes! Second light occurred on March 4, where a spell of settled weather made observations possible up until March 13. No opportunities were missed to turn the great telescope on a suite of double stars, open clusters and nebulae that hugged the meridian at that time. It was over this period that Robinson and South declared the instrument optically excellent and capable of doing first class astronomical research. Shortly thereafter, the telescope was officially inaugurated by Dean Peacock, head of the (Protestant) Church of Ireland, who is said to have walked through the giant tube, inspecting it from one end to the other whilst donning a top hat with a raised umbrella above his head. In the milder months that followed, the Leviathan was turned on the nebula listed as number 51 in Messier’s famous catalogue (see the author’s previous chapter on Charles Messier), located in the Canes Venatici, was examined and its spiral structure clearly seen; a momentous discovery for sure, but one that was overshadowed by more terrible events.

A sketch of the Whirlpool Galaxy ( M51), as drawn by Lord Rosse in 1845 using the 72-inch Leviathan. Imahe credit: Wiki Commons.

A sketch of the Whirlpool Galaxy ( M51), as drawn by Lord Rosse in 1845 using the 72-inch Leviathan. Image credit: Wiki Commons.













The summer of 1845 marked an atrocious turning point in the history of this small nation. By now, the potato famine was palpably showing its devastating effects (with 50 per cent of the crop having being infected with blight), and the peasants who worked the land throughout the county were beginning to starve. Lord Rosse was by now a peer in the British House of Lords, and still served as Lord Lieutenant and Colonel of Militia of Kings County. Admirably though, he put the needs of his countrymen first and after consulting with the British Prime Minister, Sir Robert Peel, and his panel of appointed scientific experts, provisions were made to import cheaply purchased maize and cornmeal from the New World, which helped somewhat but could not fully ameliorate the human disaster.

It was not until January of 1848 that Lord Rosse would resume active research with the great telescope. But when it was uncapped after a three year hiatus, the mirrors were found to have tarnished owing to the excessively damp weather that characterised the worst of the famine years. And though a second mirror had by then been successfully cast, it had not been polished to the required degree. But by February 16 both specula were ready for action and by month’s end, astronomical observations were in full swing once again. Indeed the great telescope remained in active service for many years thereafter. The magnificent instrument became the centrepiece of international attention, and tourists flocked to see it from all around the world. And it was all the more remarkable that its creator did it all off his own back, with no financial assistance from governments or monarchs, quite unlike the situation with Sir William Herschel (discussed in another chapter of the book).

According to research conducted by the late Sir Patrick Moore, the defining power of the Leviathan was called into question by a number of individuals, mostly casual observers, but affirmed by those who had been given the opportunity to observe with it on a regular basis. One such tyro is reported to have remarked:

They showed me something which they said was Saturn, and I believed them….

But the reader should note that such a monstrous telescope, with such a large aperture as it possessed, was much more sensitive to atmospheric turbulence than instruments of much smaller aperture, particularly the equatorially mounted classical refractors, which by now were adorning the observatories across Europe and North America.

Consider, if you will, the remarks of the distinguised Irish physicist and astronomer, George Johnstone Stoney (1826–1911), himself a native of the town of Birr, whose reputation as an observer was unquestioned and who carried out careful tests on the 72 inch instrument over an extended period of time (four years to be precise, over the period 1848-52):

The test usually applied was the performance of the mirror on the star of the 8th or 9th magnitude, magnification 750. Such stars are bright in the great telescope. They are usually seen as balls of light, like small peas, violently boiling in consequence of the atmospheric disturbance. If the night is good there will be moments now and then when the atmospheric disturbance will abruptly seem to cease for a fraction of a second, and the star is seen for an instance as the telescope really presents it. It is by the opportunities of such moments  that the performance of the telescope must be judged. With the best of your father’s* mirrors that I saw, the appearance at such opportunities was that of the light shining through a minute needle hole in a card placed in front of a flame. I think any practical astronomer will agree with me in the opinion that mirrors of 6 feet in diameter that bore the test bordered very closely indeed on theoretical perfection.

* Stoney is referring here to the third Earl of Rosse, but the communication was to his son, who succeeded to the title of fourth Earl by the time the scientific correspondence was published on April 2 1878.

As King Solomon of old knew, there is really nothing new under the Sun. Then, as now, casual observations are not likely to reveal any great truth but rather have the greater potential to disseminate untruth.

Indeed Moore, in his book, The Astronomy of Birr Castle, provides still more evidence that the mirrors made by the third Earl of Rosse were of high quality. In February of 1848, shortly after the Leviathan was dedicated, Romney Robinson described a fine night in which Jupiter presented with a ” remarkable appearance… full of faint striae running nearly parallel to them, and seemingly belonging to the brighter zones on each side.” And in 1889, a series of published drawings of Jupiter made by a later assistant of Lord Rosse, Dr. Otto Boeddicker between 1881 and 1886, show that they compared well with modern instruments of the same size, according to the noted planetary observer, Stanley Williams, who conducted such a study in 1935.

Still more evidence of its optical quality can be gleaned from a discussion of the telescope in Henry C. King’s classic tome, The History of the Telescope, where he notes that the Leviathan was capable of resolving very tight double stars. On one occasion, Robinson, South and Lord Oxmantown managed a clean split of gamma 2 Andromedae with a power of 828 diameters and a then separation of 0.5″.

Such testimonies show that while the telescopes of Lord Rosse were not ‘planetary’ instruments in the traditional sense (for they were seldom employed in this arena), they were more than capable of doing first rate science.

The enormous light gathering power of the Leviathan added to the tally of spiral nebulae. Indeed, by the end of 1850, a total of 14 such structures were positively identified by Lord Rosse and his astronomical assistants. These included M33, M31, M77, M95 and M99. It was even possible for Lord Rosse to begin to subclassify these spiral nebulae into a variety of classes, including barred, diffuse and irregulars. He also suspected that many of the elliptical and lenticular nebulae the surveys showed up must be spiral also but that they were seen ‘edge on’ rather than ‘face on’. The spiral nature also strongly suggested to him that their complex shapes could only be maintained by motion, although he recognised that making any such measurements was hopelessly beyond his means, as they were so far away.

One enduring mystery concerning the discovery of the spiral nebulae pertains to why the  keen eye of Sir William Herschel was unable to detect them as such. It is most certainly true that the brighter spiral nebulae should have been visible in his largest telescope; the celebrated 40 foot reflector outfitted with a 49.5 inch primary speculum. One explanation, advanced by this author, may lie in Hercshel’s decision to adopt his off axis (Herschelian) design, which, as we have learned, introduced some aberrations to the images which reduced the instrument’s defining power enough to render the faint and delicate spiral arms all but invisible. Evidence in support of this comes from Herschel’s failure to detect the E and F stars of the theta Orionis complex,  as well as the fact that he almost invariably employed low powers with this instrument (much of his fine planetary work was conducted with a much smaller instrument; a conventional long focus Newtonian of 6.3 inch aperture) Yet another possibility is that Herschel may have observed such objects when his mirrors were in a more advanced state of tarnishing. In a work published by William F. Denning, we are made aware that slight tarnishing (of a silver substrate) could often be useful in improving planetary images, acting in much the same way as a modern neutral density filter, which can reduce glare and improve contrast. But this would not be the case with deep sky objects, where even slight tarnishing will apprecibaly reduce the so called “space penetrating power,” as Herschel referred to it, helping to explain why he did not see the spiral structures which were so obvious to Lord Rosse and his assistants. That said, without some form of reconstructive experimentation, we shall probably never know the precise reasons for this anomaly.

One of the most important questions still to be resolved(excuse the pun) was the nature of nebulae in general. Sir John Herschel (discussed at length in another chapter) had formed the opinion that all nebulae would eventually be resolved into stars, but Lord Rosse was more open minded about this. Telescopic scrutiny of many objects with the Leviathan, including M1 (the Crab Nebula, as coined by Lord Rosse himself), M27, M56 and M97 did not show stellar constituents, so the jury was still out concerning this question. But there was always nagging doubts that the mirror might not have been gathering the amount of light it was capable of due to rapid tarnishing in the humid, southern Irish climate. Concerning this possibility, Lord Rosse wrote:

We have had perhaps two or three specula as perfect as the first one; but the mass of observations has been made with specula considerably inferior to it, and, I am sorry to say, very often not as bright  as they should have been…..While the telescope was in constant use in all weathers, it would have been a hopeless task to attempt to keep in a state fit for the resolution of nebulae, and the attempt was not made. I may, perhaps, mention that with the 3 feet speculum in fine order I have often detected resolvability when there was no trace of it with the 6 feet speculum in its ordinary working state.

That said, Lord Rosse’s caution concerning the universality of stellar nebulae was vindicated just over two decades later, when in 1864 William Huggins employed spectroscopy to show that some nebulae were distinctly different from those of stars.

As discussed previously, Lord Rosse did not employ a finder with the telescope, relying instead on the 31 arc minute field in the ‘low power’ setting.  Oculars of various focal length were placed on an elegant sliding mechanism so that the observer could move from low to high power with little or no delay. The Leviathan was also fitted with a micrometer, the proper operation of which was a necessity for making the elaborate drawings of deep sky objects with their correct scale.

Records show that the instrument could be used about 60 nights per year, but in retrospect, it seems rather odd that Lord Rosse would choose to erect the great telescope so close to the Bog of Allen (from which the turf was derived to power the furnaces for the molten optical metal), which encouraged fog banks to form on still evenings, further reducing its utility. But at least it served to warn later generations of giant telescope makers to pay closer attention to the observing site before committing to some ambitious project. Indeed, nearly all later telescopes of grand esate were erected upon sites that were carefully field tested prior to the commencement of any building.

The great telescope and the opulent milieu in which it was erected became a Jerusalem of learning for two generations of astronomers, many of whom made their astronomical debuts observing with the great telescope. In 1852, Oxmantown hosted a meeting of the British Lunar Committee in the grounds of Birr Castle. As a general rule, Lord Rosse employed many young observers (no doubt owing to their enthusiasm for astronomical work and keen vision), who served at the telescope for a number of years before moving on to other observatories in order to further their careers. For example, Robinson served as the first Director of Armagh Observatory (a post he held until he was 90!), and a young Sir Robert Stawell Ball, who served as an astronomical assistant at Parsonstown between 1865 and 1867, as well as an academic tutor to Lord Rosse’s children, would be a future Astronomer Royal for Ireland (based at Dunsink Observatory, Dublin, between 1874 and 1892), before being appointed to the prestigious position of Lowdean Professor of Astronomy at Cambridge University in 1893. Of Lord Rosse, Sir Robert graciously observed, “personally and socially, [he] endeared himself to all with whom he came in contact.”

The distinguished Irish astronomer, Sir Robert Stawell Ball (1840 –1913), one of the great popularisers of astronomy during the Victorian Period. Image credit: Wiki Commons.

Lord Oxmantown, the third Earl, maintained an active role as an observer until failing health in the early 1860’s forced him to give up routine astronomical work, entrusting all research to the assistants whom he assiduously trained. In the summer of 1867, on the advice of his physicians, the ageing peer retired to the seaside residence of Monkstown, overlooking Dublin Bay, in the hope that the fresh, maritime air would improve his condition. But it was to no avail. He passed away peacefully on October 31 of the same year.

It was at about the same time that Lord Rosse’s eldest son (1840–1908), the fourth Earl, began to take on more of an active role in his father’s work. Born and raised in Birr, he was educated at Trinity College, Dublin, and Oxford University, before returning to Ireland to serve in various high profile roles in the administration of Ireland. Though largely considered to be overshadowed by the achievements of his father, Lawrence Parsons embraced the new technologies that were coming to the fore, having first experimented with a newly erected 18 inch reflector of ten feet focus, which was ingeniously powered by a water wheel in 1866. In the years that followed, the fourth Earl managed to construct partially successful clock drives for both the 36 inch and 72 inch telescopes.

The provision of crude clock drives on the two great telescopes enabled more sophisticated science to be performed and, in this capacity, crude spectroscopic analyses of a variety of deep sky objects was carried out. Much of this important work was carried out by a young Dane, John Louis Emil Dreyer (1852–1926), who had put down roots by marrying a lassie from County Limerick, serving as assistant astronomer at Birr between 1874 and 1878.  All the spectra obtained on the spiral nebulae were shown to be stellar in character, while all those obtained from the planetary nebulae showed quite distinctive line spectra, further advancing the notion that there were fundamental differences in the nature of nebulae.

Dreyer used the Leviathan to add a considerable number of newly discovered nebulae to the tally already discovered by his illustrious predecessors (particularly Messier and the Herschels). Many of these new objects were recorded in a catalogue compiled by the fourth Earl covering the three decades between 1848 and 1878. Another notable discovery was made by the English astronomer, Ralph Copeland (1837–1905), who served as assistant astronomer at Birr between 1871 and 1876, used the enormous light gathering power of the Leviathan to discover 35 new NGC objects, most famous of which is a grouping of seven large galaxies in Leo – Copeland’s Septet as it is known today, that include NGC 3745, 3746, 3748, 3750, 3751, 3753, and 3754.

Lawrence Parsons, the fourth Earl of Rosse (1840 –1908). Image credit: Wiki Commons.

The fourth Earl of Rosse is perhaps best known for his work in determining the surface temperature of the sunlit face of the Moon. For decades, astronomers such as Piazzi Smyth and Macedonio Melloni ( inventor of the first infrared thermopile in 1831, which transduced thermal energy into electrical energy) had wondered whether the Moon would have an equable temperature like the Earth, and to this end had carried out the first crude experiments in its determination with results which turned out to be mostly inconclusive.

Determining the temperature of the Moon is far from trivial however, as a moment’s reflection (excuse the pun once again) will reveal. Lord Rosse correctly concluded that the contribution of thermal energy from lunar vulcanism was negligible. That leaves two principal sources of heat. First, there will be that which is reflected. This will be largely independent of the temperature of the moon’s surface, but rather will depend only upon its power of reflection (its albedo). The second contributor to lunar heat is that which she emits as a consequence of her natural heat which is mainly, but not entirely, due to solar irradiance. The amount of this heat will depend upon the temperature of the Moon’s surface and its radiating power. Though the thermopile could not readily distinguish between these two sources of heat, Lord Rosse realised that they would vary differently in accordance with the development of the lunar phase, with the former increasing steadily from thin crescent and reaching a maximum at full Moon, whilst the latter ought to lag behind the former, as a consequence of the time it takes for the surface to heat up (in much the same way as daytime summer temperatures reach their maximum several hours after noon). Thus, this ‘dark’ (infrared) heat ought to be at its maximum after full Moon.

Lord Rosse begun such measurements using the 36 inch reflector in 1868 and the careful work continued for several years. His first estimates showed that the lunar surface temperature near the equator could reach 500 degrees Fahrenheit (260C), but with subsequent refinements made by his fellow physicists, he later revised this down to just over 200 degrees Fahrenheit (or about the boiling point of water at sea level). The latter measure agrees well with the modern accepted maximum value of 253 Fahrenheit.

Of course, the temperatures arrived at by Lord Rosse referred to the equator, in the middle of a long lunar day. Naturally, the further away from the equator one moves, the cooler the surface becomes. He peformed similar experiments during a lunar eclipse, when its surface is cut off from all direct sunlight. Indeed, he was able to monitor a rapid drop in lunar surface temperature as a ‘wave of cold’ moved across its surface. Indeed, he was able to record enormous temperature swings in the course of an hour. This provided further proof that the Moon is an airless world, incapable of holding onto heat as it moves from direct sunlight into darkness.

By the 1880s, the Leviathan was most definitely showing its age and many astronomers felt that its best days were well behind it. Indeed, from the late 19th century onwards the 72 inch was mostly used in sporadic observations of interesting objects. For example, on the night of September 17 1877, Lord Rosse was able to confirm the existence of the tiny Martian satellites, Deimos and Phobos, discovered by Professor Asaph Hall, just a few short months before using the great Washington refractor. The last and longest serving assistant assigned to the Leviathan was the aforementioned Dr. Boeddicker, who concerned himself with detailed visual observations of the northernly Milky Way, which culminated with an extraordinarily detailed drawing of the vast stellar archipleagos within its confines, taking him no less than five years to complete, beginning in 1885 and coming to an end in 1890. Doubtless, it was a work of outstanding artistic beauty but alas, photography was now all the rage, and as a consequence, its significance was of questionable scientific value. And while the venerable 36 inch was now equatorially mounted with a smootly operating clock drive, and even in the hope that it might be used as an astrograph, the declining relevance of the antiquated Leviathan weighed heavy on the fourth Earl’s mind:

Can the pencil of the draughtsman be any longer profitably employed upon nebulae as seen through the 6 foot reflector when photography, to say the least the least, follows so closely on his heels?

The metal mirrors making up the telescopes of the Rosse estate were possibly as good as they could be, but new technology made them living dinosaurs. In particular, the advent of much lighter silver on glass mirrors rendered the construction of large, observatory class reflectors much more easy to fashion, owing to their vastly reduced mass and higher reflectivity. In addition, glass substrates, with their lower thermal coefficients of expansion (and, to a lesser degree, their higher specific heat capacities) than the old speculum metals rendered them considerably less sensitive to small changes in temperature, allowing more stable images to be maintained in the course of a night’s work.

Lord Rosse passed away on August 30 1908 and with him all work with the Leviathan of Parsonstown ceased. With his brothers becoming the executors of his estate, the great telescope was dismantled  because of growing concerns that it had become a working concern. In 1912, the 6 foot mirror was removed and despatched to the Science Museuem in London for preservation. The 36 inch was also left idle. Dr. Boeddicker, remained in the employ of the fifth Earl, though not it seems, in a scientific capacity. He was entrusted with gathering together the historical archives of the family. And when the First World War broke out in 1914, Boeddicker, a native of Germany, was considered an enemy of the state (which was still under British rule) and was forced to return to his own country. He died aged 84 in 1937, under Hitler’s Third Reich.

The next decade of Irish history proved very turbulent, with the result that the Rosse family had to leave the castle for extended periods of time. By the time the political climate settled down in the late 1920s, the great infrastructures that once boasted the largest telescopes on the face of God’s Earth were in a very sad state of delapidation, though according to Sir Charles Parson, the 36 inch was ‘nearly intact’ as late as 1927. That said, it’s whereabouts today is unknown.

One of the original 72 inch speculum mirrors used in the Leviathan, now housed in the Science Museum, London. Image credit: Wiki Commons.


A final twist in the story of the Leviathan occurred after a TV programme, lecture, and book by the late Sir Patrick Moore appeared on the great telescope in the 1970s. This resulted in a renewed interest in the 72-inch telescope, with the restoration of its wooden tube between 1971 and 1975, and soon it became a tourist attraction. But it was not before the 1990s that plans to actually rebuild the telescope came to fruition. In 1994, the retired structural engineer and amateur astronomer, Michael Tubridy, was commissioned to research and re-design the Rosse Leviathan. Unfortunately, the original plans were lost, and so it took a considerable amount of detective work which included re-examining the remains of the telescope, together with old observing logs and contemporary photographs taken by Mary Rosse, wife of the 3rd Earl. Reconstruction work lasted from early 1996 until the beginning of 1997. It had been planned to include a working mirror, but owing to budget constraints, this had to be left for a separate project.

A faithful rainbow appearing over the reconstructed Leviathan, in the modern  grounds of Birr Castle. Image credit: Wiki Commons.











The new mirror was installed in 1999. Unlike the speculum original, and in a historically respectful departure from modern aluminium- or silver-coated glass mirrors, the replica was cast from solid aluminium, thus acting as a compromise between authenticity and utility in astronomical observation.

The great technical achievements of the Rosse family,  their friendship to the people of Ireland, as well as to the wider international astronomical community, will not easily be erased from memory. Once the brain and glory of all that was held dear in astronomical enquiry, their telescopes continue to be remembered in the mind’s eye as emblems of the indefatiguable spirit of the human imagination; to peer farther into space than anyone had ever seen before; to bring the heavenly creation closer to the earth, as well as to understand something more of its mysteries. And we’ve been doing that ever since.

References & Links

Mollan, C., William Parsons, 3rd Earl of Rosse: Astronomy and the Castle in Nineteenth-century Ireland (Royal Dublin Society – Science and Irish Culture), Manchester University Press, 2014.

Moore, P., The Astronomy of Birr Castle, Quack Books, 1992.

King, H.C., The History of the Telescope, Dover, 1955.

Ball, R.S., The Story of the Heavens, Casell, 1893.

Denning, W. F., Telescopic Work for Starlight Evenings (1891), HardPress Publishing, 2013.

Bell, L. The Telescope (1922), HardPress Publishing, 2013.

Professor Paul Callanan of University College Cork, explains the significance of Lord Rosse’s Leviathan.

Some History of Birr, Ireland.

Links to historical works on the subject of the astronomy of Lord Rosse and Birr Castle.

More about Birr Castle for the Astronomical Tourist.


Read more about the telescopes and personalities that inspired four centuries of telescopic astronomy in my up and coming book, Astronomy Tales from the Golden Age.





De Fideli.

Cleaning Newtonian Mirrors.

I’ve noticed that one issue that seems to give folk concern about investing in a good Newtonian pertains to having to clean the optics every now and again. I’ve never really understood this mindset though. Having had my closed-tube 8-inch Newtonian for about 18 months now, and having clocked up a few hundred hours of observations with it, I felt it was time to give the mirrors a cleaning. Here’s how I do it:

The mirrors are removed from the tube.

Two fairly grimy mirrors

Two fairly grimey mirrors.

















First I make sure that all the loose dust and debris has been blown off using an air brush. Next, I run some cold tap water into a sink and add a drop or two of washing up liquid. The water we use here is very soft; indeed we are graced with some of the softest water in the British Isles, which also makes drinking tea especially pleasant! If your local water source is hard, I’d definitely recommend using de-ionised/distilled water.

Starting with the secondary mirror, I dip my fingers into the water and apply some of it onto the mirror surface with my finger tips, gently cleaning it using vertical strokes. Did you know that your finger tips are softer than any man-made cloth and are thus ideal for cleaning delicate surfaces like telescope mirrors?

Finger-tip cleaning of the mirror.

Finger-tip cleaning of the mirror.

















Next, the mirror reflective surface is rinsed under some cold, running tap water.

Rinse the secondary with some cold tap water.

Rinse the secondary with some cold tap water.

















The procedure is repeated for the primary mirror;

Gentle massaging of the mirror using the finger tips.

Gentle massaging of the mirror using the finger tips.

















Rinsing the primary mirror using cold tap water

Rinsing the primary mirror using cold tap water.

The mirrors are then supported on their sides to allow them to drain excess water, and then left to dry in a warm, kitchen environment. Stubborn water droplets nucleating on the mirrors are removed using some absorbent tissue.

Washed and drying out in the kitchen.

Washed and drying out in the kitchen.

















Finally, the mirrors are placed back in the telescope tube, making sure not to over-tighten the screws which hold the primary in place inside its cell. All that remains then is to accurately align the optical train, as described previously.

There we are! Not so difficult after all; and all done in about 40 minutes! The soft water doesn’t show up any significant spots after cleaning unlike hard water sources and now the optics are as clean as the day they were produced.

With a busy season of optical testing and planetary observing ahead, I know that my 8-inch will be operating as well as it possibly can. And that’s surely good to know!


I feel a nice, hot cuppa is in order!

De Fideli.

Further Newtonian Adventures with Double Stars.

'Plotina'; the author's ultraportable 130mm f/5 Newtonian reflector.

‘Plotina’; the author’s ultraportable 130mm f/5 Newtonian reflector.











In this department of astronomy, the names of Herschel, South, Struve, Dawes, Dembowski, Burnham, and others are honourably associated and it is notable that refracting-telescopes have accomplished nearly the whole of the work. But reflectors are little less capable, though their powers seem to have been rarely employed in this field. Mr. Tarrant has lately secured a large number of accurate measures with a 10-inch reflector by Calver, and if care is taken to secure correct adjustment of the mirrors, there is no reason why this form of instrument should not be nearly as effective as its rival.

W. F. Denning, from Telescopic Work for Starlight Evenings (1891), pp 290-291

Eye seeth afore I measureth.

Introduction: Having spent several years enjoying the views of double stars of varying degrees of difficulty with a variety of classical achromatic and apochromatic refractors of various apertures (60mm-150mm), this author has dedicated the last 15 months investigating the prowess of Newtonian reflectors in regard to their efficacy in splitting double stars. Surprisingly, a 8″ f/6 Newtonian with traditional spider vanes and a 22 per cent central obstruction was found to be noticeably superior to a first rate 5″ f/12 glass, as well as a 180mm f/15 Maksutov Cassegrain, on all targets, including double stars.

These experiences have collectively led to a deep seated scepticism concerning the traditional claims of self appointed ‘authorities’ who have tended to downplay the Newtonian reflector as a worthy double star instrument. But as the quote from Mr. Denning’s book states above, this prejudice is not derived from sustained field experience. Instead, it is cultivated by, at best, tenuous theoretical considerations. And yet theory counts for nothing if contradictions are found by experimentation, and must be revised in light of new evidences brought to the fore by active observers.

In this capacity, this author has spent several months investigating the performance of a very modest 5.1 inch (130mm) f/5 Newtonian reflector on an undriven alt-azimuth mount. The instrument was modified  in two principal ways:

  1. The original secondary mirror was replaced with a slightly smaller flat (blackened around its periphery), giving a central obstruction of 26.9 per cent, significantly lower than Schmidt and many Maksutov Cassegrains of similar aperture.
  2. Both the primary and secondary mirrors were re-coated with ultra-high reflectivity (97 per cent) coatings delivering a light throughput broadly equivalent to a refractor of similar size.

The instrument has a single stalk supporting the secondary mirror which produces greatly reduced diffraction effects compared with more traditional  Newtonians, yet was found to be sufficiently rigid to deliver very sharp and detailed views of the Moon, planets and deep sky objects.

The single stalk, rigidly supporting the secondary of the 130mm f/5 Newtonian.

The single stalk, rigidly supporting the secondary of the 130mm f/5 Newtonian.











The optical train can be accurately aligned in minutes by means of fully adjustable screws on both the primary and secondary mirrors and an inexpensive laser collimator.

The collimating screws behind the primary mirror.

The collimating screws behind the primary mirror.









Preliminary field testing has shown that the telescope provides very fine high power views of stellar targets under fair to good conditions. Even at  powers beyond 50 per inch of aperture, stars remain round, free of astigmatism and perfectly achromatic. Furthermore, the diffraction spikes attributed to Newtonians are much subdued in this instrument owing to its single vane secondary support. The diagram below shows the relative intensity of diffraction spikes manifesting from various secondary mounting configurations and the reader will note the minimal effects of a single support (seen on far left).

Comparison of diffraction spikes for various strut arrangements of a reflecting telescope – the inner circle represents the secondary mirror

Comparison of diffraction spikes for various strut arrangements of a reflecting telescope – the inner circle represents the secondary mirror.






Materials & Methods: The telescope was mounted on an ergonomic but sturdy Vixen Porta II alt-azimuth mount equipped with slow motion controls on both axes. the instrument was carefully collimated prior to the commencement of observations using a laser collimator. No cooling fans were employed. A red dot finder was used to aim the instrument and various oculars and barlows were used to resolve pairs. For fainter stellar targets, the system was centred first using a 32mm SkyWatcher Plossl which delivers 20x and an expansive 2.5 degree true field.


Date: 12.05.16

Time: 00:00-00:30 UT

Seeing: Antoniadi II-III

Epsilon Lyrae: x 271; all four components cleanly resolved, stars round, white and undistorted. No diffraction effects noted.

Pi Bootis: Easy at 150x. Components appearing white and blue-white.

Mu Bootis (Alkalurops): Wonderful triple system; fainter pair (magnitudes 7 and 7.6) separated by 2.2″ and perfectly presented at 271x. This pair has an orbital period of just 260 years!

Epsilon Bootis: Primary (magnitude 2.5) presenting in a lovely ochre hue and its fainter companion (magnitude 4.7) easily picked off at 271x.

Delta Cygni:  Magnitudes: 2.89, 6.27, separation:  2.7″

Well split at 271x, although conditions a little turbulent and not yet at an optimal altitude for observation.

Date: 13.05.16

Time: 00:00-00:30 UT

Seeing: II. Indifferent seeing at sunset (III-IV), improving as the night advanced (II).

Temperature: +7.5C

Xi UMa: beautiful clean split of this 1.6″ pair (magnitudes 4.3 and 4.8) at 271x

Epsilon Bootis: textbook perfect split @ 271x

Delta Cygni: Child’s play this evening, separation 2.7″. Companion presented as a perfectly round, steely grey orb @271x.

Beta Lyrae: remarkable multiple star system. Four white/blue white stars framed in the same field at 271x.

O^1 Cygni: a corker at 20x, but more fetching at 81x. Orange and turquoise stars, with the former showing its blue magnitude 7 companion.

Date: 15.05.16

Time: 22:30 UT

Seeing: II-III, clear, brightening moon, twilit

Temperature: +3.5C

Iota Cassiopeiae: Just one entry tonight. More challenging to locate owing to its relatively low altitude above the northern horizon and the encroach of twilight. All thee components well resolved at 271x. This is the third successful split of this attractive multiple star system with the same instrument.

Date: 21.05.16

Time: 22:10 UT

Seeing: II, partially cloudy, twilit.

Temperature: +10C

Epsilon Bootis: Another lovely split this evening @271x. Primary(magnitude +2.5) orange and the secondary a regal blue (magnitude 4.9) separated by 2.8″.

Xi Bootis: Striking yellow and orange components (magnitudes 4.7 and 7, respectively), separated by ~6.5″ and beautifully framed @ 150X.

Rho Herculis: A comely pair of blue-white stars shining at magnitudes +4.5 and +5.4. Easily resolved (4.0″)@271X.


Epsilon 1 & 2 Lyrae: textbook perfect split of all four components @271x. Subtle colour differences noted between the stars.

22:45 UT

Delta Cygni: Perfectly resolved at 271x. Magnitudes: 2.89, 6.27, separation:  2.7″

Date: 22.05.16

Time: 23:10UT

Seeing: II, very good, mostly clear, twilit, bright Moon low in south.

Temperature: +9C

Marfik(Lambda Ophiuchi): Quite hard to track down owing to an unusual amount of glare in the southern sky. System split at 271x. The components ( magnitudes 4.2 & 5.2), well resolved. Tightest system so far resolved with this instrument: 1.4″. Both stars appeared creamy white and orientated roughly northeast to southwest. Superficially, very much like Xi UMa but slightly more challenging.

No’ bad ken.

Date: 24.05.16

Time: 00:10 UT

Seeing: I-II, excellent steady atmosphere, no cloud, twilit, cool.

Temperature: +5C

Pi Aquilae: Another good target affirmatively resolved this evening. Separation 1.5″ with magnitudes of 6.3 and 6.8. Power of 271x applied. First hint of duplicity seen shortly after local midnight when the system was quite low down in the east, but much better presented at 23:45 UT when it rose a little higher.

Delta Cygni: Another textbook perfect split! This system is child’s play with this telescope, but remains a good indicator of local seeing.

I would warmly encourage others using this telescope, or its closed tubed counterpart, to confirm these findings.

Date: 28.05.16

Time: 22:45 UT

Seeing: II, good stable air for double star work, cloudless sky, twilit.

Temperature: +6C

Epsilon 1 & 2 Lyrae: beautiful easy and dazzling split of all four components @271x

Delta Cygni: Another textbook perfect split of this very unequal magnitude pair @271x

Mu Cygni: difficult to find as it is currently lower down in the east under twilit conditions. Excellent multiple star system, A-B well split @271x, colours white and yellow (+4.8/6.2 magnitudes, respectively), separation ~1.66″. Another tight, unequal magnitude pairing. C component too faint to pick off in the twilight. D component (+6.9) seen about 3′ off to the northeast.

Doing well so far don’t you think?

Ps. Interesting findings from a few guys here.

Date: 29.05.16

Time: 23:10 UT

Seeing: II, almost a carbon copy of last night. Twilit.

Temperature: +7C

Just two targets this evening.

Epsilon Bootis: a good ‘warm up’ system. The telescope showed a textbook perfect split during the finest moments at 271X. I have found that wearing a good heat-insulating jacket and hat gives noticeably better results on cooler nights, as thermal energy from the body can sometimes distort the image at least for a wee while.

From there I moved to my target system for the evening.

Sigma 1932 AaB: a very challenging system in Corona Borealis. It is located about 3.67 degrees directly west of Alphecca (alpha CrB) which is easily seen even in twilight. My 32mm SkyWatcher Plossl, which yields a field of view of 2.5 angular degrees was used, together with my star atlas, to finally track down this magnitude 7 system. After a few false starts, I eventually centred the target system, cranked up the power to 271x and, with a concentrated gaze, obtained a good split! This binary system consists of a pair of yellowish stars with equal magnitudes (7.3 and 7.4, respectively) oriented roughly east to west and separated by 1.6″.

Battle o' the weans. In the foreground a 90mm Apo, in the backgroud, a 130mm Newtonian.

Battle o’ the weans. In the foreground a 90mm Apo, in the backgroud, a 130mm Newtonian.











Date: 30.05.16

Time: 23:00-23:30 UT

Seeing: A fine and mild night, remaining very good (II), high pressure bubble stabilised over Scotland, some intermittent cloud, twilit. Midge flies back.

Temperature: +11C

Tonight, I wanted to compare and contrast two very different telescopes in respect to their ability to split a few of the tougher pairs visited thus far; a 90mm f/5.5 doublet Apo (retail price now £912 UK) and the 130mm f/5 Newtonian (~£200 UK with the modifications).

System:Delta Cygni

90mm glass; difficult split @208x

130mm speculum: much more cleanly resolved@271x

System: Pi Aquilae*

90mm glass: very dim, touching @208x

130mm speculum: cleanly resolved/brighter @271x


90mm glass: dim, elongated @208x

130mm speculum: fully resolved /brighter @271x

*Suboptimal altitude

You cannae change the laws o’ physics captain!

And ignorance of the law is no excuse.

Oh vanity of vanities!

Self-evidently, an unfair comparison: the 130mm f/5 Newtonian is clearly the superior double star instrument.

The words of the prophet, Isaiah, come to mind;

For fools speak folly,
their hearts are bent on evil:
They practice ungodliness
and spread error concerning the Lord;
the hungry they leave empty
and from the thirsty they withhold water.
Scoundrels use wicked methods, they make up evil schemes
to destroy the poor with lies,
even when the plea of the needy is just.
But the noble make noble plans,
and by noble deeds they stand.

Isaiah 32:6-8

Date: 31.05.16

Time: 23:05 UT

Seeing: III; significantly more turbulent than last night. Twilit.

Temperature: +10C

This evening I had intended to concentrate my observations on one target; the very difficult sub-arc second companion to Lambda Cygni, using my best instrument; a 8-inch f/6 Newtonian, in order that I might train my eyes to see this companion (separated by 0.9″) in my smaller 130mm instrument.

Using the 130mm as a seeing gauge; I found Epsilon 1 & 2 Lyrae to be resolved well but nearby Delta Cygni was poorly resolved. This was also found to be the case in the 8-inch aperture.

Project shelved for a better night.

Date: 01.06.16

Time: 23:30 UT

No opportunities afforded this evening owing to the encroach of haar after sunset.

Let us consider some of the optical principles relevant to splitting such a tight pair.

Diffraction theory states that the position of the first bright ring (between 1st and 2nd minima) is located at a linear radius of 1.63 lambda x F where lambda (wavelength) is quoted in microns and F is the focal ratio of the scope. By dividing this quantity by the focal length we obtain the angular radius of the 1st minimum (in radians) and this yields (1.63 x lambda)/D where D is the aperture of the scope in metres.

Now, there are 57.3 angular degrees in a radian and 3600 arc seconds in each angular degree, so if we multiply the above expression by 57.3 x 3600 = 206280 and so we arrive at 206280 x (1.63 x lambda)/D.

Setting D = 0.1m for example, and lambda = 0.55 microns (green)  yields 1849300 micro arc seconds, which is 1.85”.

Or more generally, the locus of the first diffraction ring is 185/D where D is the aperture of the telescope expressed in mm.

Applying this formula to the 200mm and 130 mm reflectors, the position of the first diffraction ring is 0.9” and 1.4”, respectively. Thus, the companion to Lambda Cygni will be located on the first diffraction ring in the 8-inch instrument, and inside the ring in the case of the 130mm telescope.

The primary has a magnitude of +4.5 and the secondary, + 6.3, so there is a magnitude differential of 1.8. The significant brightness differential makes this system more difficult to crack.

The Dawes limit for a 130mm (5.1 inches) ‘scope is given by 4.57/D in inches, which is ~0.9”.

More on this here.

Date: 02.06.16

Time: 23:30 UT

Seeing: III-IV, very turbulent

Conditions clear but remaining very turbulent. A light, northeasterly air flow is likely the culprit(see my local weather; Stirling, Scotland).

My notes show that I have glimpsed the companion to the primary on a few occasions over the last few summers with my 5″ f/12 achromatic. But I have seen it much more clearly – and also on a few occasions – with the 8″ f/6 Newtonian.

Date: 06.06.16

In order to maximise my chances with Lambda Cygni, I have decided to wait until August at the earliest, when the system will be high overhead here, in a dark sky. Patience is a virtue is it not? And I can afford to be patient with this one, as it is a very slow moving binary and so will remain very challenging for a good few years to come. So no hurry.

The capabilities of the 130mm f/5 on double stars have already well exceeded my expectations. My experiences with the smaller, 90mm refractor especially, have reinforced the notion that aperture is a vital commodity when it comes to seeing objects clearly and distinctly. It pays to remember that resolution scales with aperture. That’s why it is easier to see things in the 130mm than the 90mm, irrespective of how fancy its optics and mechanics are. And this can be tested, again and again and again…..ad nauseam.

This is factual knowledge, and facts are stubborn and immutable things!

Physics pays no attention to human hubris.

Physics cares little for hubris.







Over the next few months I would like to return to the many beautiful and easy systems within reach of this remarkable telescope; even in heavy twilight.

Time: 23:00-59 UT

Temperature: +11C

Seeing: II, good, a little hazy, twilit.

I walked through the garden in the cool of the evening, after a very warm and sunny day. I set up the 130mm f/5 as usual and began to explore some of the nicer double stars of the sky.

Mizar & Alcor: A perennial favourite, high overhead this time of year, dazzlingly bright, the light from these stars fills the field and induces instant joy. Well framed at 81x in my trusty Baader mark III zoom.

Cor Caroli (Alpha CVn): Easy to find under the handle of the Ploughshare. Both components appearing white to the eye with magnitudes 2.9 & 5.6.

Alpha Herculis (Rasalgethi): A corker! At 108x, this pair presents as marmalade orange and blue-green, which orbit their common centre of gravity every 3600 years.

Albireo (Beta Cygni):  A stunning sight in the little reflector at 81x. Glorious contrast of colour; orange (magnitude 3.1) primary, blue-green secondary (5.1).

61 Cygni: historically very significant as the first star system to have its distance measured in 1838 by F.W.Bessel. Only 10.4 light years away. Both stars are cool, orange dwarfs with magnitudes 5.2 and 6.1.

Eta Cassiopeiae: A bit more challenging to locate in the strongest twilight coming from low in the northeast. Easily split at 81x, presenting as orange and red (magnitudes 3.5 & 7.5, respectively). These constitute a true binary system, with a period of about 480 years.

A quick peek at a more difficult pair:

Pi Aquilae: Once again, beautiful and easy to resolve in the 5.1” reflector at 243x. I have been observing this system for five years now, with various instruments. My notes from the end of July 2011 showed that it was very difficult with a high-quality 4” f/15 classical refractor, the twilight making it challenging. Observations made with variety of 5” refractors over the same period – and also in summer twilight –  show that it is not difficult in these sized instruments (only anomaly recorded in an optically so-so 6” f/8 speculum used for outreach also from 2011, where it was relatively poorly seen).  In the absence of a good 4” refractor at present, this provides good evidence that the 130mm reflector is indeed operating closer to the performance of a 5” glass than a 4” glass, which is very encouraging.

Before leaving the field, I spotted Saturn below the tree line in the south, so I decided to uplift the telescope on its Porta II mount and walk about a hundred yards to a grassy spot at the local primary school grounds, where I could better aim the telescope. Despite its very low altitude, it was a beautiful sight at ~150x, it glorious ring system now wide open for business. Cassini Division seen, as well as some banding on the Saturnian globe.

Vicious midge flies making any further observations uncomfortable, the vigil was aborted shortly before 1 AM local time.

Date: 08.06.16

Time: 23:00-30 UT

Seeing: II, good and stable, variable amounts of thin cloud, twilit.

Temperature: +10C

Polaris: Always a lovely system to study, even in the twilight. In the telescope at 108x, the 2nd magnitude primary (Polaris A) presents as a beautiful creamy white, the secondary a haunting bluish grey some 6 magnitudes fainter seen in the 10 o’ clock position in the 130mm Newtonian. A third companion lies much closer to Polaris A but is woefully beyond the powers of any backyard telescope to resolve. Interestingly, all three stars in this system, located about 430 light years away, are of the F spectral class, and thus should present with the same colours. This is readily seen with Polaris A but the exceeding faintness of the Polaris B hides its true colour. Polaris B orbits A at a distance of about 2400 further out than the Earth-Sun distance, taking over 400 centuries to complete a single lap.  Polaris A is a giant, pulsating star, part of a class known as Cepheids. With such stars, humans have been able to extend the plumbline of their reach into the realm of the galaxies. Stars like Polaris A have helped us gain a truer sense of the vastness of the Universe in which we miraculously inhabit. These are some of the things I like to ponder on, whilst spying the Pole Star.

16 Cygni: A fourth magnitude system a little to the northeast of the lovely red variable star R Cygni. In the 130mm f/5 at 81x, the decent light gathering power of the instrument presents the pair  in their natural colours: a yellow primary (magnitude 4) and golden secondary (magnitude 6), separated by about 40 arc seconds of sky.

Eta Lyrae: Located a few telescopic fields east of Vega, this is normally a very easy system to crack at low powers (~40x) with a magnitude 4.4 blue-white primary and 9th magnitude secondary wide away. In the twilight, I find a higher power of 108x is needed to see the faint secondary well, and is even better presented again at 150x. Much more gloriously presented from a truly dark sky.

Date: 17.06.16

Time: 22:30-59 UT

Temperature: +7.5C

Seeing: II-III, clear, twilit, bright waxing gibbous Moon culminating in the south. Evening made especially pleasant by the absence of midge flies, which don’t like temperatures below 10C.

After over a week long hiatus in the weather, which brought endless cloud and some rain, the sky finally cleared up this evening, allowing me to resume my adventures with my 130mm f/5 Newtonian.

Two reasonably challenging doubles to start with:

Epsilon Bootis: beautifully sharp and well resolved at 195x

Delta Cygni: Ditto @195x; always a joy to observe this system so well.

Iota Bootis: A wonderful low power system, located about 4 degrees northeast of Alkaid (at the tip of the handle of the Ploughshare). At 81x, the system was beautifully framed  and showed a yellowish primary(magnitude +4.8) well separated from a bluish secondary,  some three magnitudes fainter (+7.5). Very fetching colour contrast in the Newtonian!

95 Herculis: Found by panning some 10 degrees east of Delta Herculis. To my eyes, this nearly equal magnitude pairing(4.9/5.2) has a very subtle colour contrast: one appears silvery, the other creamy white. Easily resolved at 81x. Consulting my old Burnham’s Celestial Handbook Vol 2, there is an interesting discussion on the historical colour presentation of this pair, especially from some eccentric 19th century observers!

What colours do you see?

How wonderful it is to get outside on this beautiful mid-summer evening!

Date: 18.06.16

Time: 22:30 UT

Temperature: +10C

Seeing: II, some hazy cloud, bright Moon in south.

Epsilon 1 & 2 Lyrae: Textbook perfect split of all four components at 243x

Delta 1 & 2 Lyrae:  Easily found in the low power (20x) field of my 32mm SkyWatcher Plossl, just a few degrees to the east of Vega. No need for higher power with this system; lovely colour contrast – red and blue-white. Stars physically unrelated i.e an optical double.

SHJ 282: Seen in the same lower power field of Beta Lyrae, some 1 degree to its northeast. Under darker skies, it forms a wonderful sight in the 2.5 degree field of the 32mm Plossl, together with the celebrated Ring Nebula (M57). At 41x, this comely system (actually triple) looks like a copy of Albireo; an aureal primary well separated from its pale blue secondary.

Date: 27.06.16

Time: 22:45-23:10UT

Temperature: +10C

Seeing: II, very good, partially clear, beautiful noctilucent clouds in the northeast, fresh westerly breeze, nae midgees.

The weather has been quite unsettled of late, with little in the way of clear skies, but this evening I grabbed an opportunity with both hands and fielded my bonnie 130mm Newtonian.

A number of systems visited this evening including:

Delta Cygni: wonderful split and (as usual) easily resolved at 243x. Lovely round stars well separated in the twilight.

Epsilon 1 & 2 Lyrae: Textbook perfect at 243x

Epsilon Bootis: Very easy for this telescope, as I have found on many occasions now. Lovely colour contrast at 243x

Pi Aquilae: Better positioned these days. Easily split at 243x

11 Aquilae: Found by centering Zeta Aquilae in the low power (20x) field. 6th magnitude 11 Aq lies just one degree or so to its west. At powers up to 100x or so, only the white 6th magnitude primary is visible, but when the power is cranked up beyond about 150x, the much fainter 9th magnitude companion was observed wide away. Reasonable concentration is required to tease this out of the twilight. Once picked off, the greyish companion was better seen at higher powers (243x). This system is far more glorious in a fully dark sky, and I shall look forward to visiting it again in August.

All in all, a grand half hour under a Scottish summer sky. My little Newtonian reflector is most assuredly a proficient double star telescope. The unbridled joy of discovery!

Date: 29.06.16

Time: 22:45-23:20 UT

Seeing: Excellent, I-II, gentle breeze, very little cloud, twilit.

Temperature: +8.5C

After assessing the seeing in the 130mm Newtonian and judging it fine ( as evidenced by cleanly splitting Delta Cygni at 243x), I fielded my 8-inch f/6 Newtonian and turned it on Lambda Cygni, now considerably higher in the sky and applied a power of 450x. I also employed a Baader single polarising filter, which helped to reduce glare and darken the sky. I could indeed see the companion to the primary star intermittently and oriented north to south. And during the better moments I could see that it was clearly disembodied from the primary. I then turned the 130mm on the same system, employing a power of 365x with the polarising filter. Letting the image settle down as it moved across the field, I observed good elongation in the same orientation, but no separation.

This was a most exciting and encouraging vigil, the first of many more I hope.

Date: 01.07.16

Time:22:50-23:40 UT

Temperature: +7C

Seeing: II, good clear spells, some cloud, westerly gusts, cold, twilit.

After a day of heavy and frequent rain showers, I enjoyed a short clear spell around midnight.

Iota Cassiopeiae: Fairly tricky to track down in twilight, but was rewarded with a lovely clean split of this picturesque triple star system at 243x.

Eta Cassiopeiae: Picturesque colour contrast pair (A/B orange and yellow). Easy to split at powers at ~100x.

Sigma Cassiopeiaie: located a few degrees southwest of the easternmost star in the constellation ( Beta), this is a wonderful target for small telescopes. It consists of two blue-white stars separated by about 3.2″. The primary shines with magnitude 5.0 and the secondary, 7.2. Best seen at magnifications > 150x.

Delta Cephei: Beautiful and easy with the 130mm Newtonian. The stars appeared pure white and easily resolved even at low power but nicely framed at 81x. The primary is actually another Cepheid variable (described above in relation to Polaris).

Two tighter test systems visited:

Delta Cygni: good clean split at 243x

Epsilon Bootis: ditto at 243x

Date: 05.07.16

Time: 23:05-30UT

Seeing: III-IV, below average seeing, partially cloudy.

Temperature: +8C

Fairly choppy seeing this evening, as evidenced by somewhat bloated stellar seeing disks observed with the 130mm f/5 Newtonian.

Delta Cygni: barely resolved at 243x

Epsilon Bootis: split but not cleanly at 180x

Xi Bootis: yellow and orange pairing, easily resolved (6.4″) at 150x

Pi Bootis: Blue and yellow components, easily resolved (5.6″) at 150x

Zeta Coronae Borealis: Lovely yellow and blue-green components easily resolved (6″) at 150x

Mu Bootis (Alkalurops): All three components resolved easily with the 130mm Newtonian at 243x. System previously visited on May 12 last. The two seventh magnitude stars (B/C) were surprisingly well split (~2″), a consequence I suppose of their low brightness which curtails the size of their seeing disks. Fainter pairs seem less susceptible to seeing conditions.

Date: 08.07.16

Time: 22:40-23:00 UT

Temperature: +12C

Seeing: III-IV, remaining turbulent, mostly cloudy.

Further trials with the 130mm f/5 Newtonian.

Delta Cygni : unresolved at 183x

Epsilon 1&2 Lyrae: resolved at 183x

Cor Caroli: very pretty at 63x

Date: 11.07.16

Time: 22:45- 23:00 UT

Temperature: +13C

Seeing: III-IV, very turbulent mostly cloudy, a few suckerholes appearing here and there.

Two instruments fielded this evening; a 130mm f/5 Newtonian and a 90mm f/5.5 apochromatic refractor (price now hiked up to £1017?! i.e. fourth successive hike since review)

Epsilon Bootis (Izar): Companion resolved reasonably well with 130mm  reflector but very poorly (if at all) with 90mm refractor at comparable magnifications i.e.~180x. Quite revealing really!

Mission aborted owing to light drizzle.

Date: 12.07.16

Time: 22:30-23:00 UT

Seeing: III, partially clear, cool, twilit.

Temperature: +10C

The conditions were slightly improved over last night. I fielded the 130mm f/5  Newtonian again and examined the following systems. I employed a single polarising filter which does a very good job removing some glare and improving the aesthetic of the stellar images, especially in twilight.

Epsilon 1&2 Lyrae: easily split at 181x.

Epsilon Bootis: well split at 180x

Delta Cygni: good split at 180x and 243x

Low down in the east, I visited Delphinus for the first time this season.

Gamma Delphini: A corker at 181x! Located some 100 light years from the Solar System, the primary(magnitude +4.4) shines with a lovely marmalade orange hue, while the secondary (magnitude 5.0) shows up as lime-like. 9 arc seconds separates them.

Struve 2725: Seen in the same high power field as Gamma Delphini, this fainter system can be seen a little to the southwest of Gamma. This pair is a bit more challenging to spot, the primary and secondary having magnitudes of 7.5 and 8.4 respectively and orientated north to south. To my eye they both look white and are separated by 6″.

No’ bad innings for an average July evening, ken.

Date: 13.07.16

Time: 22:30-23:00 UT

Seeing: II-III, an improving picture, though not where I would like it to be. Partially cloudy, twilit.

Temperature: +10C

Systems visited this evening with the 130mm f/5 Newtonian (with single polarising filter) included:

Delta Cygni: well split at 181x

Iota Cassiopeiae: A beautiful, delicate triple system, well resolved at 181x but more compelling to behold at 243x

After spending about five minutes admiring the comely, sanguine Garnet Star (Mu Cephei), I move the instrument a little to its southwest until I arrived at a field of view containing two other stellar systems of interest:

Struve 2816: A magnificent triple system (actually quadruple). All three stars are arranged in a line running roughly northwest to southeast. A/B looks yellow to the eye (magnitude +5.6) with two equally bright stars (C and D), located 12″ and ~20″ away from the primary, respectively. A grand sight at 181x.

Struve: 2819: Just off to the northwest of Struve 2816, this is a fainter system requiring high powers to see well. Both stars appear white to the eye. The primary is magnitude + 7.4 and has a fainter companion (magnitude +8.5) ~13″ off to its northeast. Best seen at 243x.

Very much looking forward to darker and more stable skies coming back in a few more weeks.

Date: 18.07.16

Time: 22:20-30 UT

Seeing: sultry, clouded out, midge flies by the legion, twilit.

Temperature: +18C

Poodle versus Plotina

Lens versus Speculum.















I was hoping to get some observing done this evening, as the forecast looked reasonably promising after a long spell of very unseasonal weather (The Open at Troon sure wasn’t pretty lol). I have not been able to make any additional progress beyond what I’ve recorded but having been at this a few months now and having seen what I’ve seen, my conclusions are as follows;

The modified 130mm f/5 appears to be an excellent double star instrument! This came as a quite a surprise to me, as I was not entirely prepared for what it could deliver given its very modest cost. All of this can be tested, of course, and I’d warmly encourage you to have a go.

The instrument will comfortably outperform any 90-100mm refractor given a fair trial (proper acclimation, optical train alignment, reasonable to good seeing conditions, etc.). It is especially adept at resolving close, fainter pairs of roughly equal brightness.

Millimetre for millimetre, its performance in comparison to a refractor of equal aperture is much closer than is commonly reported (or commonly believed), though I would concede that the refractor will have an edge when pushed to the limits*.

*Valid only over the aperture ranges studied.

My conclusions are fully in agreement with the comments made by W.F. Denning (1891), reproduced above.

I will continue to monitor these and other double stars, God willing, in the coming months and years and will report back in due course.

It has been an absolute pleasure discovering the many charms of this little Newtonian. As telescopes go, there is something very endearing about their ingenious simplicity, and given half a chance, they can show you remarkable things.

As I write this, there are more encouraging signs that the prejudice traditionally attributed to Newtonians for this kind of work is being lifted and that is great to see! Just have a look at the CN Double Star forum to see some examples. I believe much of this prejudice is/has been due to the usual suspects: laziness, lack of interest, somewhat irrational, material attachment to other kinds of telescopes, and the like. You see, you don’t need a big vainglorious refractor (I should know, I’ve got one lol) to do this kind of work, and dare I say, one can actually derive a greater level of satisfaction achieving goals with these modest instruments over more traditional ones. You begin to see the hobby in a whole new light.

Thank you for following this blog.

Clear Skies!



Date: August 17, 2016

Time: 00:05h BST

Seeing: Excellent: I, excellent definition, fairly bright sky owing to very late gibbous Moon low in the south, gentle westerly breeze.

Temperature: +12C

Instruments: 203mm f/6 & 130mm f/5 Newtonians, Baader single polariser.

Observation: The 8-inch reflector easily resolved Lambda Cygni B (0.9″), clearly seen at 450x and orientated at right angles to the direction of drift (E-W). Both components presenting as perfectly round and clean white. Deeply impressive!

The 130mm f/5 showed the system as plainly and strongly elongated N-S, power employed x325. Careful attention to accurate collimation necessary. Best evidence for the appearance of duplicity thus far recorded with this instrument.

Date: August 28 2016

Time: 23:10 BST

Seeing: Excellent (I), a bonnie evening, very steady, no clouds, no Moon, cool.

Temperature: +10C

Instruments: 203mm f/6 and 130mm f/5 Newtonian reflectors, Baader single polariser.

After obtaining an excellent high power split of delta Cygni & pi Aquilae with both instruments, I turned the telescopes toward lambda Cygni. The 8-inch served up another clear split of the 0.9″ B component at 450 diameters, just like the evening of August 17. The 130mm, once again showed strong elongation (north to south orientation) at 325x and 406x, but was not split.


De Fideli.

Changing Culture III: Aperture & Resolution.

On the left, a 90mm apochromatic refractor and on the right, a 203mm f/6 reflector enjoying a bout of late evening sunshine.

On the left, a 90mm apochromatic refractor and on the right, a 203mm f/6 Newtonian reflector enjoying a spell of late evening sunshine.












One of the ABCs of telescopic optics is that resolving power scales linearly with aperture and light gathering power with the square of aperture. These are fundamental facts that are demonstrably true and have been used productively over two centuries of scientific applications. And yet, all the while, there has been a consistent drive in the last few decades within a section of the amateur community that somewhat erroneously links performance to absolute monetary value. This largely corrupt movement is most ostensibly seen in the refractor market, where amateurs are apparently willing to shell out relatively large sums of money for telescopes that, in terms of performance, are severely limited by their small apertures. This is a worrying trend indeed, and has led many astray within the hobby.

In this capacity, I decided to highlight the anomaly by devising a simple test which exposes this ‘peashooter’ mentality for what it is; a gross misrepresentation of basic optical principles.

Materials & Methods:

Two telescopes were set up in my back garden; a 90mm apochromatic refractor retailing at £1017 (tube assembly only) and a 203mm f/6 Dobsonian, with a retail price of £289, but with some basic modifications (97% reflectivity coatings and a smaller secondary giving a linear obstruction of just 22 per cent) which increased its cost to  approximately half that of the smaller telescope. The Newtonian was carefully collimated before use.

The telescopes were left out in the open air during a dry and bright evening when the temperatures had stabilised and were fully acclimated. Both instruments were kept out of direct sunlight. The refractor had an extendable dew shield to cut down on ambient glare, while the Newtonian was fitted with a flexible dew shield to serve the same purpose. To remove the complicating effects of atmospheric seeing, the telescopes were targeted on the leaves of the topmost boughs of a horse chestnut tree, located about 100 yards away.

Both telescopes were charged with approximately the same magnifications, in this case, a very high power was deliberately chosen; 320x. Next, the images of the leaves were examined visually, being especially careful to achieve the best possible focus, and the results noted.


The 203mm Newtonian images of the leaves were crisp, bright and full of high contrast detail. In comparison, the image served up by the refractor was much dimmer and a great deal of fine detail seen in the larger instrument was either ill-discerned or completely invisible in the smaller instrument. Though less dramatic, the same results were obtained when a larger refractor (127mm f/12) was compared with the 203mm f/6 Newtonian under similar conditions, with the latter delivering brighter, crisper images with finer detail.


This simple experiment, requiring nothing more than a few minutes of one’s time and no complicated formulae or optical testing devices, clearly showed the considerable benefits of larger aperture. The images served up by the Newtonian were brighter and easier to see than those served up by the smaller instrument. Resolving power and light gathering power work hand in hand; you need decent light grasp to discern fine details and vice versa.These results were largely independent of the surrounding atmospheric conditions, as the targets were located at close proximity to the telescopes and thus had to travel through a short column of air.

These experiments were repeated with larger instruments; a 127mm f/12 refractor and the same 203mm Newtonian, with the same results, that is, the smaller instrument runs out of light faster than the larger and shows less fine detail in the images served up.

These results confirm that larger aperture is superior to smaller aperture. No amount of claptrap can change the result either. Complications may arise when the same tests are performed on celestial targets, especially during bouts of turbulent atmospheric seeing, when the larger instrument will be commensurately more sensitive. In such instances, it is the environment that introduces anomalies. But when conditions are good, the benefits of larger aperture will be seen, clearly and unambiguously. Absolute monetary value has little or nothing to do with the end result, in direct contradistinction to what is claimed by those who promote small aperture refractors in an unscientific way.

See here for further reading.


De Fideli

Tales from the Golden Age: The ‘Hevelius’.

The Hevelius: a 17 foot focus singlet refracting telescope designed and built by Dr. Alan Binder. Image credit: Aland Binder.

The Hevelius: a 17 foot focus singlet refracting telescope designed and built by Dr. Alan Binder. Image credit: Aland Binder.

As discussed in a previous article, astronomers of the mid-17th century tried to improve on the optical quality of short-focus Galilean-type telescopes by grinding object glasses with ever increasing focal lengths. This strategy improved the defining power of these telescopes at the expense of convenience. The images got better because all Seidel aberrations fall off as focal length increases in a singlet object glass, but they became commensurately more difficult to use. In the hands of skilled lens makers like the brothers Huygens in Holland, and Giuseppe Campani (1635-1715) in Italy, lenses of enormous focal lengths were constructed, some in excess of 100 feet.

That said, these telescopes were used to establish an impressive array of new factual knowledge about the Universe. Christiaan Huygens (1629-95) established that Saturn was surrounded by a flat ring that nowhere touched the planet, as well as discovering Titan, its largest satellite. He also recorded the first clear marking on Mars – the Syrtis maior- celebrated ever since by observers of the Red Planet. At the Paris Observatory, G.M. Cassini (1625-1712) discovered a clear division of Saturn’s rings – the Cassini Division – as well as two other Saturnian satellites; Tethys and Dione. He also accurately recorded some of the main features of Jupiter’s belt system and accurately timed the planet’s rotation, arriving at the essentially modern value; 9h 56min. He did likewise for Mars, recording the length of its day as 24h 40 min.  And under the aegis of Cassini, the Danish astronomer, Ole Rømer (1644-1712), after conducting timings of the eclipses of the large Jovian satellites at various stages of the planet’s orbit, deduced that the speed of light was very fast (214,000 km/s or 71 per cent of the accepted modern figure), but necessarily finite.

Across the sea in England, men of the ilk of Robert Hooke (1635-1703) used similar instruments to record accurate drawings of many lunar craters and even hit on the mechanism by which they were produced – by means of impacts with the surface. And James Bradley(1693-1762) used a singlet refracting telescope to deduce that the Earth really moves in its orbit around the Sun, thereby vindicating the Copernican Principle.

Although the long focus singlet refractors were still in use well into the 18th century, it is difficult for the modern reader to ascertain how good they really were. We know of one reference dating from 1871 when a 10-foot (3.0 m) telescope by Campani was tested and found to provide good definition and a flat field, with a magnification of about 20 times.

In recent years however, there have been some valiant attempts made by curious individuals to assess the efficacy of these early telescopes. In this capacity, amateur astronomer and planetary scientist, Dr. Alan Binder, based at the Lunar Research Institute, Tucson, Arizona, made a systematic investigation  of  double  stars  brighter  than magnitude 5.5 using an entirely homemade instrument- including the object glass and eyepieces!  Calling it ‘The Hevelius’, Binder’s telescope consisted of an uncoated, plano-convex objective of 17 foot focus, having a clear aperture of just 2.8 inches. The object glass was placed inside a long wooden tube that was itself mounted on a pole. Three Huygenian eyepieces (also homemade) were employed, yielding powers of 50x, 100x and 150x.

Binder investigated its performance on a number of double star targets acknowledging that only two such systems were discovered during this era using these telescopes; Mizar, discovered by Benedetto Castelli (a former student of Galileo) in 1617 and re-discovered by Riccioli in 1643, and γ Arietis, discovered by Hooke in 1664.  Binder showed that about 175 double stars down to magnitude 5.5 could be resolved with this typical 17th century telescope and that it resolved pairs as close as 2.3”, just 50 per cent poorer than the Dawes limit (the traditional resolution limit for equally bright components used by double star observers)! Why then the discrepancy between the tally of double stars discovered by astronomers from the 17th century and Binder’s very encouraging results?

One explanation is mechanical convenience. The ‘Hevelius’ was small enough and mounted well enough to allow him to accurately point it at many stars in the sky, while those constructed by those historical astronomers were often longer and more unwieldy than Binder’s experimental set up. In their zeal to make their telescopes ‘bigger’ and ‘better’, these astronomers of old made their telescopes too cumbersome to use systematically.

The three Huygenian eyepieces used by Dr. Binder during his study. Image credit: Aland Binder.

The three Huygenian eyepieces used by Dr. Binder during his study. Image credit: Alan Binder.

Either way, Dr. Binder’s independent research indicated that a considerable amount of useful work could be done with a modest non-achromatic telescopes and that the images were not as bad as is commonly expressed in the literature. Still another possibility is that the astronomers of the day were not overly concerned with double stars, being more preoccupied with Solar System objects, and so were less likely to seek them out, unlike the decidedly different astronomical culture of later centuries, when double star astrometry formed a major part of astronomical investigation.

Close-up of the micrometer employed in the double star study using the Hevelius. Image credit: Alan Binder.

Close-up of the micrometer employed in the double star study using the Hevelius. Image credit: Alan Binder.

“Everyone I have invited to look through The Hevelius has been duly impressed by the quality of the images it serves up,“ he told me. As well as looking at an impressive suite of double stars, Binder also conducted observations of the brighter planets and some bright deep sky objects. His drawings of Mars, Jupiter and the Orion Nebula (M42) show that the telescope was quite capable indeed.

Sketches of Jupiter as seen through the Hevelius. Image credit: Alan Binder.

Sketches of Jupiter as seen through the Hevelius. Image credit: Alan Binder.

Only by undertaking this kind of ‘reconstructive astronomical history’ can we modern observers appreciate the kinds of views likely enjoyed by these early telescopists. What is clear however, is that though the non-achromatic refractor was far from ‘perfection’ in the modern sense of the word, it was nonetheless used to great effect by a number of astronomers to substantially increase our knowledge of the cosmos. Through their painstaking observations and the genius of the trained human eye, they extended the frontiers of knowledge and inspired new generations of sky gazers to take up the gauntlet.

Mars sketches made with the Hevelius. Image credit: Alan Binder.

Mars sketches made with the Hevelius. Image credit: Alan Binder.

The Orion Nebula (M42) as seen through the Hevelius. Image Credit: Alan Binder.

The Orion Nebula (M42) as seen through the Hevelius. Image Credit: Alan Binder.

How fortunate we are today in being able to make use of telescopes which, on the one hand, are vastly superior to those employed by our forebears, and on the other, are available inexpensively and far more convenient to use. Truly, we’ve never had it so good!

Dr. Neil English is currently writing a book – Tales from the Golden Age – on the history of observational astronomy over four centuries since Galileo. The author would like to thank Dr. Alan Binder for supplying the images used in this article as well as providing some commentary on the efficacy of the singlet refracting telescope.

Further Reading:

Double Star Observations with a 17th century Achromatic Telescope



De Fideli.

Changing Culture.

Octavius: instrument of change.

Octavius: instrument of change.















As  I have commented on in previous communications, an urban myth has been cultivated over the years regarding the unsuitability of Newtonian reflectors in the pursuit of double stars. In the last six months or so, there are encouraging signs that more people are bucking this trend using Newtonian optics of various f ratios and in the examination of pairs of various difficulty, including the sub-arc second realm;

Exhibit A

Exhibit B

Exhibit C

Exhibit D

Exhibit E

These are but a few examples, and I can only hope that the changes will continue so that more people can enjoy this wonderful pass-time.

De Fideli