Investigating the Jet Stream

but test everything; hold fast what is good.

                                                                           1 Thessalonians 5:21


My Local Weather


Jet Stream Data

Introduction:  One of the statements that is oft quoted by observers, particularly in the UK, is that the meteorological phenomenon known as the Jet Stream seriously affects the quality of high resolution telescopic targets. I have decided to investigate these claims to determine to what extent they are true or not, as the case may be.

Method: For simplicity, I will confine my studies to just four double stars that have long been considered reasonably tricky targets for telescopists. To begin with, my targets will include systems of varying difficulty, ranging from 2.5″ to 1.5″ separation, and the aim is to establish whether or not I can resolve the components at high magnification. These systems include *:

Epsilon 1 & 2 Lyrae

Epsilon Bootis

Delta Cygni

Pi Aquilae

* These systems were chosen for their easy location in my current skies, but may be subject to change as the season(s) progress.

Viewers are warmy welcomed to conduct their own set of observations to compare and contrast results in due course.

Instrument Choice & Magnifications Employed:

The 130mm f/5 Newtonian telescope used in the present investigation.


A high-performance 130mm (5.1″) f/5 Newtonian reflector was employed to investigate the effects of this phenomenon, as this is an aperture regularly quoted as being sensitive to the vagaries of the atmosphere. Magnifications employed were 260x or 354x (they can however be resolved with less power). The instrument at all times was adequately acclimated to ambient temperatures and care was taken to ensure good collimation of the optical train. No cooling fans used on any of my instruments.


Date: August 17 2018

Time: 21:20 to 21:35 UT

Location of Jet Stream: Currently over Scotland

Conditions: Mild, 14C, very breezy, mostly cloudy with occasional clear spells, frequent light drizzle.

Observations: Power employed at the telescope 354x

Epsilon 1 & 2 Lyrae: all four components cleanly resolved.

Delta Cygni: Faint companion clearly observed during calmer moments

Epsilon Bootis: Both components clearly resolved during calmer moments.

Pi Aquilae: Slightly mushier view, but both components resolved momentarily during calmer spells.

Truth seeking.


Date: August 19 2018

Time: 20:30 – 21:50 UT

Location of Jet Stream: Currently over Scotland.

Conditions: Mild, 13C, mostly cloudy and damp all day but a clear spell occurred during the times stated above, no wind, heavy dew at end of vigil.

Observations: Seeing excellent this evening (Antoniadi I-II); textbook perfect images of all four test systems at 354x and 260x.

Nota bene: A 12″ f/5 Newtonian was also fielded to test collimation techniques and I was greeted with a magnificent split of Lambda Cygni (0.94″) at 663X. Little in the way of turbulence experienced even at these ultra-high powers. Did not test this system on the 130mm f/5.

Clouded up again shortly before 11pm local time, when the vigil was ended.

Date: August 22 2018

Time: 23:30-40 UT

Location of Jet Stream: Currently over Scotland

Conditions: Very mild (15C), breezy, predominantly cloudy with some heavy rain showers interspersed by some brief, patchy clearings.

Observations: Just two test systems examined tonight owing to extremely limited accessibility; Epsilon 1 & 2 Lyrae and Delta Cygni. Both resolved well at 260x.



To be continued………


De Fideli.

An Observing Report from the English Lake District.

Plotina: a 130mm f/5 Newtonian that just goes on debunking myths promulgated by armchair astronomers, poodle pushers and fake theorists.


August 15 2018


Preamble: No doubt you’ve heard one or more of these statements before;

” My skies are never good enough to get steady views”

” The bleedin’ jetstream always gets the better of me.”

“The British Isles suck when it comes to doing visual astronomy.”

” Climate change is making our skies more cloudy, making small refractors more profitable to use.”

” It’s been cloudy for weeks and months on end.”

” My refractor cuts through the seeing like nothing else!”

What do they all have in common?

Lies, more damn lies, or gross distortions of the truth!

You see, I’ve been doing my homework, testing out a modest 130mm f/5 Newtonian reflector all over the British Isles, and finding that many places are plenty good enough for doing high-resolution planetary, lunar and double star observing. And from dark places, low-power, deep sky observing is also very much worthwhile.

Don’t believe me?

Do I sound like I care?

Stick this in your proverbial pipe and smoke it: if only you got off your big, fat, wicked, lazy butt and did some real testing you’d soon come to a knowledge of the truth!

Moi? I’ve observed with the same telescope from no less than five counties in Southern Ireland, the windswept Isle of Skye in Northwest Scotland, Aviemore in the heart of the Scottish Highlands, and rural Aberdeenshire in Northeast Scotland, Wigtown in Southwest Scotland, Seahouses in Northeast England and even in the heart of the large cities of Glasgow and Edinburgh. Most recently, I tested a site in southern Lakeland, Cumbria, the subject of the present observing report.

Thus far this year, I have logged 78 separate sessions under the stars (not all perfectly clear and not all long sessions), either at home here in my rural site just north of the Scottish Central Belt, or while on holiday, and no doubt there were still more nights when I was unable to observe or it cleared too late or some such to conduct any more observations. That’s 78 out of 226 nights, or just shy of 35 per cent! So, more frequently than one in every three nights proved profitable. But I suspect the figure is nearer 40 per cent.

How do these data resonate with the above statements?

They don’t, do they?

Get yer logbooks oot……lemme see yer logbooks.


Sheer dumb luck?

Don’t give me that either!

I don’t believe in sheer dumb luck. Nor do I spend my precious time haunting telescope forums, you know, drooling over this instrument or that.

Nope; I’m an observer!

So I just go observing lol. You know, actually looking through my telescope; it’s not so hard is it?

Anyone with a deep enough interest in such things would quickly draw the same conclusions, at least on the British Isles.

Do I believe these findings are unique to Britannia et Hibernia?

Hell no!

Why should they be?

Surely, most of these observations were conducted during warmer, more settled spells, like in Summer?

Nope, computer says no! Check my logbooks!

Good spells occur in all weathers, from freezing cold nights to sweltering hot ones!

Have these data any historical precedents?

Absolutely yes!

See my up-and-coming book, Chronicling the Golden Age of Astronomy, for a full disclosure.

If you take the time to examine the frequency of key historical figures who loved the night sky, you’d find fairly similar results in the literature.

How do I know?

I’ve studied those historical cases.

Phew! Quite a rant there!

But better a rebuke than faint praise eh?

Now, shall we get down to business?



Plotina; the author’s ultra-portable 130mm f/5 Newtonian sampling the skies from the southern Lake District, Cumbria, England.


A 5.1″ f/5 Newtonian was transported in its custom aluminium case to a site in Southern Lakeland, Cumbria (Latitude: 54.5 degrees North) to establish whether conditions were good enough to resolve a number of test double stars and to more generally assess the seeing and transparency at this location. The success of this modest ultra-portable instrument at various sites within the UK and Ireland has been truly remarkable, so much so that this author has totally abandoned more traditional instruments such as Maksutovs and refractors in favour of this small Newtonian to pursue all areas of grab ‘n’ go amateur astronomy. As explained in a number of previous blogs, the telescope sports a significantly greater aperture (130mm) than your run-of-the-mill grab ‘n’ go telescopes. Possessing a high quality optical flat resulting in a modest 27 per cent (linear) central obstruction, it is significantly smaller than all commercial catadioptrics and sports very high reflectivity coatings that produce bright, crisp images, very comparable to an equivalent sized refracting telescope. In addition, its relatively low mass and open-tubed optics ensures that it cools more rapidly than a similar-sized refractor or catadioptric.

During the trip, just one evening turned out clear, namely the night of Friday, August 10-11 2018.


Mostly clear with some patchy cloud. Temperatures were cool (12C), with a brisk south-westerly breeze, which continued to gust for several hours, abating almost entirely by local midnight. Transparency proved very good and although there was some light pollution owing to neighboring mobile homes, the sky was good and dark. Indeed, I judged the site a little darker than at my rural observing site in Scotland, with the northern Milky Way seen more prominently, snaking its way from northeast to southwest. The northern and eastern sky was especially dark, prominently revealing the majestic constellations of Cassiopeia, Andromeda, Pegasus, while high overhead lay Cygnus and Lyra. The site had a good view of the southern sky, with Aquila and Delphinus situated very close to the meridian. Two bright planets graced the southern sky low down, a dull yellow Saturn and further east, brilliant red Mars.


The telescope was precisely collimated using a good quality Chesire eyepiece and left to cool for about 20 minutes, with the open tube pointing straight into the prevailing (south-westerly) winds at the site. A working magnification of 260x was adopted to examine a number of test double stars. This was achieved by coupling a 7.5mm Parks Gold eyepiece and Meade 3x achromatic Barlow lens.

For widefield sweeping, a 25mm Celestron X-Cel LX  was used, deliverng a power of 26x in a  2.3 degree true field. Higher power deep sky views were enjoyed with a 5.5mm Meade ultra-wide angle ocular which yields a power of 118x in a 0.7 degree true field. Mars and Saturn were observed at a power of 177x (using an 11mm eyepiece and 3x Barlow), which proved more than adequate, as both orbs were situated very low down in the southern sky around local midnight.

The test double stars were chosen for their easy accessibility as well as being progressively more difficult;

Epsilon 1 & 2 Lyrae

Epsiion Bootis

Delta Cygni

Mu Cygni

Pi Aquilae

Lambda Cygni (examined at 354x using a 5.5mm eyepiece coupled to a 3x achromatic Barlow).

Double Star Results:

The first five test systems produced text-book perfect splits at 260x, the components being very cleanly resolved, and the individual stars presenting as perfectly round Airy disks with a single but rather subdued diffraction ring. The sub-arcsecond pair, Lambda Cygni, revealed its near-equal magnitude components as ‘kissing’ at 354x. You can’t do that with a 4-inch refractor; see here for just one example.

Additionally, the wonderful triple star system, Iota Cassiopeia, was examined later in the vigil, when the constellation had risen higher in the northeastern sky. I was rewarded with a perfectly resolved rendering of all three components at 260x using the 130mm f/5 Newtonian.


Despite enjoying just one clear night at this site during our short vacation, I achieved what I have come to view as fairly typical results for many locations in the British Isles. The telescope was able to deliver excellent high-resolution results on these test double stars. As stated earlier, I do not especially attribute these results to serendipity. Indeed, I have come to expect such results when conditions are reasonable at many sites within the UK and Ireland. Such results can easily be achieved by other observers using the same (read modest) equipment with just a little attention to detail; adequate acclimation and close attention to accurate collimation, which can be executed perfectly in under a minute. I would encourage others to test these claims so that these results become as widely known as possible.

Newtonian telescopes will continue to be my instruments of choice to observe such systems in the future, so as to help dispel a particualrly virulent myth that has arisen within the amateur community; a myth born out of ignorance and old fashioned laziness. Such a myth is plainly false and will allow many more observers to pursue such targets with unpretentious instruments that are very reasonably priced.

Observing the Planets:

Although certainly not a dedicated planetary observer, I have come to appreciate the very good views of Jupiter in recent apparitions using the 130mm f/5 Newtonian. During this vigil, my family and I enjoyed very nice, crisp images of Saturn with the telescope at 177x. Despite its low altitude in the southern sky, the planet revealed its glorious white rings with the Cassini Division being plainly seen. Some atmopsheric banding was also observed but, being much farther away, these features are much more subdued than on mighty Jupiter.

Mars was examined at the same power. This was actually the very first time the planet was observed telescopically during the present apparition. The view served up by the telescope was shockingly good and to be honest, not at all anticipated owing to its even lower altitude near the southern horizon. First off, I was amazed at how large the planet looked at 177x (a rather low power for a 5.1″ telescope on such a target generally). Though the image was roiling in the perturbed atmosphere near the local horizon, I was able to make out some dark markings on the planet as well as a rather subdued southern polar ice cap. I was aware that the planet had recently experienced a planet-wide dust storm that all but occluded many of the surface features but I was pleased to see that, while much dust was still present in the atmosphere, it was clearly settling out at the time the observations were made. Mars was a big hit with the family; its large size and great brightness to the naked eye being a lively topic of conversation with my wife and sons.

Into the Deep Sky:

Plotina is a step above the rest of the grab ‘n’ go herd with regard to deep sky observing. It’s highly efficient 5.1″ primary mirror collects enough light to put it in a different league to 90 and 100mm refractors.

How do I know?

I’ve done extensive tests with a 90mm Apo (shown below) and my notes show that double stars hard to see with a four inch refractor are easier to see and resolve in the 130mm reflector. It’s not rocket science!

Faster, cheaper, better: The author’s 130mm f/5 modified Newtonian( Plotina) enjoying crisp, bright terrestrial views and in a completely different league to a 90mm f/5.5 ED apochromat(left).

With the glorious return of true darkness to northern British skies, my first port of call was the endlessly glorious Double Cluster in Perseus. This is where the 25mm Celestron X-Cel LX eyepiece really shone through for me. I don’t know if you’ve ever held on to an eyepiece because of how well it frames a deep sky object, but this ocular delivered an absolutely beautiful, expansive view of the famous open clusters. It’s very comfortable 60 degree AFOV delivers a true field of 2.3 degrees at 26x, centring the clusters perfectly in the middle of the field and showing just enough of the rich stellar hinterland to render the experience particularly memorable. The perfect achromatism of the Newtonian delivers the pure colours of the white, yellow, blue and ruby coloured suns decorating these wonders of nature, each of which are located over 7,000 light years away. I stared at these clusters for a full 10 minutes before dragging my eyeball away!

Next, I pointed the telescope into the heart of Cygnus and drank up the sumptious views of the northern Milky Way, moving the instrument slowly from field to field in awe of the sheer number of stars this wonderful 5.1-inch pulled in. Sometimes deep sky observing is not about seeking out any particular object; for me, it often involves just sweeping the telescope through an interesting swathe of sky, sitting back and enjoying the visual sensations that bring joy to the eye-brain.

My telescopic sojourns eventually took me into Vulpecula, where I quickly chanced upon Brocchi’s Cluster (Collinder 399), otherwise known as the Coathanger, owing to its extraordinary configuation of half a dozen stars arranged just like its common name suggests and spanning over 1.5 degrees of sky, which was easily handled by the 25mm Celestron ocular.

Skies were good and dark enough to observe a number of planetary nebulae in Vulpecula, Lyra and Hercules and for these, I switched out the 25mm ocular for the 5.5mm Meade Ultrawide angle delivering 118x in a fine 0.7 degree true field. Easy to pick up in my 6 x 30mm finder as an 8th magnitude smudge, the 5.1-inch Newtonian delivered an awesome view of M27, the famous Dumbbell Nebula, its enormous size occupying a space fully a quarter the size of the full Moon. I find such structures haunting in the telescope and a kind of shiver went down my spine as I studied its enormous bi-lobed morphology alone in the dark (the wife and kids having now retired for the night). Moving west into Hercules nextdoor, I sought a spot about 4 degrees northeast of the fairly bright star, Beta Herculis. With the generous, wide field of the 5.5mm I didn’t have to switch out for a lower power eyepiece to find the lovely 9th magnitude planetary, NGC 6210. The telescope made light work of picking up its distinctive oval shape and its soft bluish hue. Finally I ventured east again into Lyra, where the telescope made light work of picking up the endlessly interesting M57, the famous Ring Nebula, easily located smack bang in the middle between Beta and Gamma Lyrae. At 188x, this planetary looks big and bright with its inner and brighter outer structures showing up well. It’s amazing that this luminous smoke ring in the August sky is estimated to be a full light year in diameter!

Having studied the bright and comparitively huge globular clusters, M13 and M92 at home in Scotland with my 12″ f/5 Dob, I was impressed at how well they presented themselves in the little 5.1-inch lightcup at 118x. I was in for a bit of shock though when I eventually tracked down M56 in Lyra, located roughly half way between Albireo and Gamma Lyrae. In the 5.5mm eyepiece, this globular was considerably smaller and fainter, looking more like a nebula than anything else. When I cranked up the power to 177x, the view was little improved; just a bright but unresolved core with a smattering of faint stars hovering like little fireflies around it. The view in my 8-inch Dob is far better but still rather lacklustre. I find my 12-inch Dob to do proper justice to this cluster and its gorgeous hinterland of Milky Way stars.

I ended my vigil in the wee small hours of Saturday morning, August 11, with a ceremonial visit to M31 and its satellite galaxies, now riding about one third of the way up the eastern sky. To be honest, galaxies never do much for me and I don’t really understand why folk in possession of larger instruments want to look at them in very small telescopes. Some say it’s heroic and admirable to do that kind of thing but I think it’s bordering on nuts. Why struggle to observe such faint fuzzies when you can more easily study them in larger telescopes? Anyway, the decent light grasp and expansive 2.3 degree field of my new Celestron LX ocular delivered a sterling view of this showpiece object of the autumn sky.

It was good to get away; our first visit to the beautiful Lake District. But all good things have to come to an end I guess.


The author did not emerge from pond scum and cannot for the life of him understand why anyone else would have such a low opinion of themselves. Such are the false fruits of evolutionary ‘science.’






De Fideli.

Sampling the Skies in Ireland with a 5.1 inch Newtonian.

Plotina: the author’s 130mm f/5 travel Newtonian enjoying the skies over Cork Habour, Cobh, County Cork, Ireland.


July 9 through 21, 2018

It could have been altogether very different.

Having access to a suite of small, portable instruments, like a fine 90mm ED refractor, a first-rate 80mm f/11 achromat, an ETX 90 and a 90mm f/10 achromat, I’m so glad I threw tradition to the wayside and brought along my 130mm f/5 Newtonian telescope on my recent trip to Ireland. As described exhaustively in several previous blogs, the latter instrument is a superior grab ‘n’ go telescope to all of the above instruments on all targets; whether in the Solar System or far beyond. Its mirrors efficiently bring light to a sharp focus and with a relatively small central obstruction (27 per cent), it behaves more like a 5 inch refractor than anything else. Yet it is very lightweight, easy to collimate accurately and, as demonstrated previously, delivers excellent images of planets, the Moon and very tight double stars down to 0.94 seconds of arc: the absolute limit imposed by its 130mm aperture. And, as will be described shortly, it’s not too shabby as a rich field/deep sky instrument either.

These findings were all  previously established in many parts of the Scottish mainland and even on some of the Western Isles, but I was especially keen to see how the telescope would fare at no less than five locations in Munster, the southern-most province of the Irish Republic. I have very fond memories from youth using much smaller instruments, but the 130mm Newtonian promised to reveal much more.

The Journey

The telescope was carried in a sturdy aluminium case in the boot of my car from my home in central Scotland down to southern Scotand, and then by ferry across to Northern Ireland, and from there, southwards to the Republic; a day’s trip.

Upon arrival, the telescope was found to be very slightly out of collimation but a laser collimator made light work of tweaking the optics in a matter of seconds.

Locations tested:

Limerick City: Ballinacurra in the southwest of the city & Caherdavin, a few miles away on the other side of the great River Shannon, in the northwest of the city.

Cobh, County Cork.

Sixmilebridge, County Clare.

Newport, County Tipperary.


Conditions: Over ten days, only two nights turned out cloudy, the rest being either fully clear or partially clear. At all locations, true darkness occurred around local midnight, remaining so for about two hours. In general, all observations were conducted on grass, as this was established to be the best surface upon which astronomical observations should be made.

Eyepieces used: Just two oculars were chosen for the trip; a Celestron X-Cel 25mm, delivering a power of 26x in a 2.3 degree true field, and a Meade Series 5000 5.5mm ultra wide angle, serving up a power of 118x in a 0.7 degree true field. Additional powers of 59x and 266x could be pressed into service by attaching a Baader 2.25x Baader shorty Barlow to the 25mm and 5.5mm eyepieces, respectively.

Telescope mounting: The 130mm f/5 is a perfect match for the Vixen Porta II Alt-azimuth mount, which travelled with me along with the telescope. High magnification targets were tracked with ease using the in-built slow motion controls.

Results on the Planets: Planetary views of Jupiter and Venus were conducted earlier in the evening. Mars was not viewed owing to its very late culmination well into the wee small hours of the morning.  The extra 4 degrees of elevation in the sky owing to the sites’ lower northerly latitude (centred around 52 degrees north), proved significant; Jupiter showed a wealth of detail using the 5.5mm Meade ultrawide angle ocular delivering 118x. Much dark banding and subtle colour differences within the bright zones could be discerned. The North Equatorial Belt (NEB) was very prominent throughout all the vigils, being noticeably darker and more disturbed morphologically than its southern counterpart. On one evening, I was able to accurately establish the CM II longitude of the Great Red Spot and the finest images of Jupiter were afforded at Newport, County Tipperary, with the telescope set up on tarmac owing to a lack of a suitable grassy surface, but the relatively high elevation of the shorttube 130mm reflector astride the Viven Porta II above the surface proved an effective dampener of thermals, even though the same day and evening were hot and sunny.

Venus showed its pretty, early gibbous phase at 118x in the telescope, despite its very low altitude at the times of observation. Some atmospheric refraction yielded some false colour but this was expected and largely unavoidable.

The Moon:

On Thursday, July 19, I shared some magical moments with my elder brother, who lives in Newport, County Tipperary. Around sunset, I set the instrument on the tarmac ouside his house and aimed it at a late crescent Moon. The view in the 5.5mm Meade delivering 118x was amazing; my brother being deeply impressed at seeing the entire lunar regolith  in razor-sharp detail, floating through the huge portal hole. At first he couldn’t help but hold the eyepiece (a natural newbie reaction), but as soon as I taught him to let go, he just relaxed and let the telescope do the work. I could tell that he was quite taken aback with this strange little telescope, where you peer through its side rather than directly along the tube. With a few minutes training, he learned how to use the slow motion controls to bring Luna back into the centre of the field.

 Double Stars:

Test double stars examined included:

Epsilon Bootis ( Izar)

Delta Cygni

Epsilon 1 & 2 Lyrae

Pi Aquilae

Such systems were chosen for their sensitivity to ambient seeing conditions and ease of location, even from an urban/suburban setting.

Results: At every location examined, the results proved very much the same: all systems were beautifully resolved at 266x, the companions being perfectly picked off from their respective primaries. One location proved to be windy (overlooking Cork Harbour in Cobh), but this turned out to be largely inconsequential to the observations made. Once the wind died down, the companions yielded easily.


Deep Sky Observations:

General appearance of the sky after sunset, as witnessed on a few evenings during the vacation. Such cloud formations augur good, stable summer air.


Naked Eye: I immediately noticed the lower elevation of the Pole Star than at home.

I recorded three bright fireball-like meteors streaking across the sky (2 on one evening, the other on a subsequent evening)  from the direction of Cassiopeia/Perseus. These were possibly early Perseid meteors, which will culminate around the middle of August.

Even from a suburban location (Caherdavin), the sky got dark enough to easily see magnitude +4.6, Iota Cassiopeiae, low in the northeast, which was not possible from my Scottish vantage owing to the encroach of twilight. From the same location, I was able to trace out the more prominent parts of the Northern Milky Way streaming through Cygnus and Cassiopeia.

The darkest skies were experienced at Cobh, which is not too surprising, but there was still a significant amount of light pollution from the adjacent harbour to the southwest of my viewing location. Still, magnitude +5.8 Messier 13 could not be seen owing to this light pollution despite its high elevation in the southwest at the times of observation.

Telescopic Impressions:

The 5.1 inch reflector set up for an observing session at Sixmilebridge, County Clare.

The 25mm Celestron X-Cel LX eyepiece proved very satisfactory with the 130mm f/5 reflector, delivering sharp, high-contrast images of star fields nearly all the way to the edge of its 2.3 degree field. I enjoyed studying the stellar hinterlands of bright stars within Cygnus, particularly Sadr and Deneb, the truly dark skies pulling out a wealth of fainter stars frankly invisible in the twilight of Scotland.

M39 in northern Cygnus was pariticularly captivating in the 25mm wide field eyepiece at Caherdavin; a rich smattering of approximately three dozen suns of the 7th magnitude of glory and fainter, arranged in a neat triangular space approximately 30′ in size. The Barlowed view with the same eyepiece at 59X was much more immersive though. M29 was dull in comparison; small wonder my guide book has nothing to say about it lol!

The 5.5mm Meade ocular was by far my most used ocular during the trip. Having become somewhat disillusioned by high-quality, small field of view oculars, such as the Vixen HR series, with their measly 40 degree fields, I very much appreciated the vastly more expansive (yet very well corrected) fields afforded by this 82 degree ocular. Such short focal length, wide-angle eyepieces are a godsend to those who enjoy manually tracking tight doubles. They are visible for longer, allowing the observer much more time to examine their morphology before having to nudge the telescope along.

The 5.5mm served up excellent, immersive views of showpiece summer deep sky objects such as M13, M92 and M57, the 118x power really helping to darken the sky. The view of M13, in particular, was most impressive, even from suburban locations, comparing very nicely with my 5″ f/12 refractor from my recollections. The outer part of the globular was well resolved with dozens of stars seen directly or by using averted vision.

The same eyepiece is especially good at observing wide ‘binocular’ doubles such as Albireo, 61 Cygni, Gamma Delphini, Beta Lyrae and the incomparable 31 (Omicron) Cygni, all of which were enjoyed with the telescope at most of the sites visited.

At 23:30 UT on the evening of July 16, I aimed the telescope from suburban Limerick (Caherdavin) at Iota Cassiopeiae, then located just above the tree line of the garden. To my sheer delight, I was able to clearly see the three components of this trple system using the Meade ocular at 118x. This was a particularly impressive observation, owing to the fairly low power employed but also because of its low elevation at this site. This is a powerful testimony to the excellent stability of Irish suburban skies.

I enjoyed some special time exploring the rich treasures of the far northern constellation of Cepheus on the evening of July 16, which is drowned out by twilight in Scotland. Delta Cephei was very captivating at 118x. The primary is an old, yellow pulsating Cepheid variable( the prototype of this stellar class) with a gorgeous blue companion; a near twin of the more famous Albireo. Xi Cephei  presented beautifuly also; its blue white and yellow suns well resolved at 118x. Omicron Cephei was also briefly visited; easily resolved at 118x but better seen at 266x; its magnitude +4.9 ochre primary and much fainter (magnitude +7.3) steely grey companion being readily observed. Then, there is the incomparable Mu Cephei, an enormous red giant star, its deep sanguine hue standing out like a sore thumb against a good, dark sky was a sight for sore eyes. Mu is comely at low or high power in the 130mm reflector.

Don’t forget Saturn!

Almost forgot!

Though it was past their bedtime, I showed my boys the planet Saturn for the very first time, located well east of Jupiter and only becoming visible to the naked eye very late in the evening. Being even lower in the sky than brilliant Jove, the telescope still did a mighty good job at 118x showing them the mottled globe of the planet, with its beautiful, icy-white ring system, the Cassini Division being easily dicsernible at a glance. The view at 266x was not so good though; a simple consequence of the blurring effect of the Earth’s atmosphere at this low altitude. Still, I showed off Saturn to friends and family where ever possible. Of all the celestial objects studied, it was the Ringed Planet that received the most oohs and aaws!

Concluding Thoughts

The experience of a truly dark sky in mid-July was a joyous event for me; accustomed as I am to ferreting out things to see in twilight at home in Scotland. The small Newtonian proved to be the perfect travelling companion, its generous aperture, light weight and easy set-up all helped to make the trip memorable and worthwhile. In many ways, Ireland is a transformed nation now (it would be naive not to think so); sadly, it has sleepwalked its way into the pernicious mire of secularism, with all its attendant depravities. But at least the skies overhead are still good to go, a comforting reminder of God’s incomparable glory and omniprescence. Though I would like to have visited a site completely devoid of light pollution it was not to be on this occasion, yet conditions were near ideal during these eight days of observations (especially for high-resolution, double star work), but surely many more such evenings occur on the Emerald Isle?

And I’d do it all again in a heartbeat!


Neil English is author of a large and ambitious work; Chronicling the Golden Age of Astronomy, due out later in 2018.



De Fideli.

Observing in Twilight.

A great ‘scope to use in twilight; the author’s 130mm f/5 Newtonian which combines light weight with good optical power.

















At my northerly latitude (56 degrees north) every year from about the middle of May to the first week in August, the sky fails to get properly dark and twilight dominates the northern horizon. As a result, the glory of the summer night sky greatly diminishes, with only the brightest luminaries being visible to the naked eye. But despite these setbacks, one can still enjoy a great deal of observing. In this article, I wish to outline some of the activities I get up to during this season.

Observing in twilight makes observing faint deep sky objects very difficult, so my attention is drawn to the Moon, brighter stars and the planets. Although a telescope of any size can be used during twilight observing, I find it most productive to field a telescope that has decent aperture and so I generally reach for my larger telescopes. Arguably my most used instrument during these times is a simple 130mm f/5 Newtonian, which offers good light grasp and resolution but I am also very much at home with my larger 8 and 12 inch reflectors for more specialised work. The 130mm has the advantage of being light and ultraportable and so I can move the instrument around to get better views of low lying targets.

The bright planets are very accessible during twilight and I find it fun to observe them with a variety of instruments. Venus is generally uninspiring, showing only an intensely white partial disk, but I find Jupiter much more exciting owing to its constantly changing atmospheric features and satellite configurations. But because of its low altitude in my sky, I employ colour filters to bring out the most details on the planetary disk. This is where larger apertures have their advantages, as some filters can absorb a significant amount of light and dim the images too much. The sketch below was made during twilight using my 130mm f/5 and a Tele Vue Bandmate planetary filter, power 108x, which imparts a lively colour tone to the planet, enhancing the colour differences between the dark belts and light zones. It’s also an ideal filter for enhancing the visibility of the Great Red Spot(GRS).

Jupiter as observed durng twilight at 22:55 to 23:05 UT on the evening of May 28 2018 using a 130mm f/5 Newtonian, magnification 108x and a Televue BPL filter.

















Twilight nights are also excellent for double star work and summer often brings prolonged periods of excellent seeing at my location. Larger apertures allow higher magnifications to be pressed into service, which also helps to darken the sky making the views more aesthetically pleasing. As in all other aspects of amateur astronomy, you can be as ambitious as you want. The most demanding systems are difficult, sub arc second pairs. As a case in point, I recently trained my 8 inch f/6 Newtonian on 78 Ursae Majoris (78UMa), conveniently located near the bright star, Alioth, in the handle of the Ploughshare. Conditions were near ideal on this evening (details provided in the sketch below) and I was able to push the magnification to 600x to splice the very faint and tight secondary star from the brighter primary.

The sub arc second pair 78 Ursae Majoris 78 as seen in twilight on the morning of May 30 2018 at 23:20UT using an 8″ f/6 Newtonian reflector (no fan).

Another system that I like to re–visit in summer twilight is Lambda Cygni (0.9″), which is easier to resolve than 78UMa, as the components are more closely matched in terms of their brightness and are slightly farther apart. Because it rises very high in my summer sky, it is ideally placed for high magnification work.

Conducting sub–arcsecond work with an undriven Dob mount is certainly not for the faint hearted but does bring its unique challenges, and I for one get a buzz out of doing this kind of work. But there are many easy and visually stunning systems that can be enjoyed at lower powers and it is to some of these that I will turn my attention to in the coming nights.

Last night (the early hours of June 2 2018) my wonderful little 130mm f/5 Newtonian was used to visit a number of easy to find and visually engaging binary and multiple star systems. During warm, settled weather, and with high pressure in charge, the twilight conditions proved near ideal for studying these fascinating objects;

Some binary systems visited in twilight using a 5.1″ f/5 Newtonian.





The celebrated Double Double in Lyra as seen through the 5.1 inch reflector at 260x.

















The very fetching Epsilon Bootis as seen in the 130mm f/5 Newtonian at 260x.



























These observations were conducted between 23:00UT and 00:00 UT.

Indeed, of all my Newtonians, it is the 130mm f/5 that provides the most aesthetically pleasing views of double stars. Colours are always faithful and images are invariably calm owing to its moderate aperture and rapid acclimation. Contrast is excellent too. It just delivers time after time after time…..

The sky as experienced 15 minutes before local midnight on the evening of June 12 2018.

















As May turns to June, the twilight becomes ever brighter, with more and more stars becoming invisible to the naked eye. But this greater sky brightness should never deter a determined observer. On the evening of June 12 2018, I set about visiting a score of  double and multiple stars with my 130mm f/5 Newtonian, as is my custom. I turned the telescope toward Polaris at 22:45 UT  and was deligted to be able to pick up the faint 8th magnitude companion to the 2nd magnitude Cepheid primary. Looking for something more challenging, I waited another half an hour to allow the sky to darken maximally but also to allow a summer favourite to gain a little altitude but still several hours away from culmination in the south. I speak of that wonderful binary system, Pi Aquilae( Aql), a pair of yellow white stars of near equal brightness and separated by about 1.5 seconds of arc.

From extensive, previous experience, I know it is possible to split this pair in smaller telescopes than the 5.1 inch reflector, particularly a suite of refractors ranging in aperture from 80mm to 102mm. But under these June conditions, the advantages of decent aperture become readily apparent; smaller telescopes simpy run out of light too quickly when the high powers needed to splice this pair are pressed into action. Locating the 6th magnitude pair at a fairly low altitude under bright June twilight  is even a challenge for the 6 x 30mm finder astride the main instrument. To my delight though, I was able to track it down and once centred, I cranked up the power to 325x ( using a 2mm Vixen HR ocular) to obtain a marvellous view of this close binary system, the components aligned roughly east to west with clear dark space between them. Adopting these powers with smaller apertures is problematical to say the least. Why strain one’s eyes when one can view it in much greater comfort using the generous aperture of this trusty 130mm grab ‘n’ go ‘scope?

I made sketeches of both Polaris A & B and Pi Aql as I recorded them at the eyepiece (see below).

Polaris A & B and the tricky, near equal magnitude pair, Pi Aql, as seen in the 130mm f/5 Newtonian reflector on the evening of June 12 2018.

















As the June solstice approaches, the twilight continues to brghten the sky, but there’s still lots to see. Beginning about 10pm local time, I began observing a pretty crescent Moon sinking into the western sky. The instrument I chose this evening was a very inexpensive but optically excellent 76mm f/9.3 Newtonian reflector, which I described at length in previous blogs such as this one. Because our natural satellite is so big and bright, a small telescope like this one is ideal for casual observing. Because the sky is still quite bright at this time, I found it helpful to employ either a neutral density or variable polarising filter to increase the contrast between the lunar regolith and the background sky.

An amazing performer in June twilight: the Orion Space Probe 3 altazimuth reflector.

Observing the Moon in June twilight is fun at all magnifications, but I have discovered this little telescope can provide razor sharp images up to about 210x. You’ll not get this information from the telescope forums though; it still seems beneath them to test it and spread the word, but I digress!

On the evening of June 18 2018, I visited a suite of summer double and multiple stars with the same instrument.

At about 11.30pm local time, the sky was dark enough to track down some pretty tight double stars, as well as a variety of easier but just as comely systems. Conditions were good enough for the little Spaceprobe reflector to nicely resolve Epsilon Bootis, Epsilon 1 & 2 Lyrae and Delta Cygni (210x in each case). My study of the Lyra Double Double in particular with this telescope shows that it is significantly better than any 60mm refractor in terms of raw resolving power. As I have reported earlier this year, the same telescope was able to resolve Xi Ursae Majoris, Porrima, Eta Orionis, and the wonderful triple system, Iota Cassiopeiae. Sadly, the latter system, which is still present low in the northern sky in June, was hopelessly lost in the summer twilight. Bootes always presents a nice playground for easy and pretty double stars, including Kappa, Pi, Xi and Nu 1 & 2 Bootis, which were all easily split at 116x.

June is also high season for the beautiful, ghostly whisps that meteorologists refer to as noctilucent clouds. These thin, high altitude formations are lit up by the Sun while still below the northern horizon, creating quite surreal visual delights to the naked eye. I took a couple of low resolution images with my iphone (shown below).

Noctilucent clouds captured outside my house at local midnight on the evening of June 18 2018.

















Another view captured at local midnight on the evening of June 18 2018.

















I shall endeavour to capture some higher resolution shots of these wonderful meteorological structures in due course.

Plotina, the author’s amazing 130mm f/5 Newtonian reflector as seen at 11.10pm on the evening of June 21 2018.

















On the June Solstice of 2018, I  walked through the garden in the cool of the evening, fetching my trusty Vixen Porta II mount to field my 130mm f/5 Newtonian. A gentle westerly breeze was blowing and the sky was resolutely clear, but I have learned on many past occasions that these conditions often bring very good seeing conditions for high resolution double star work. And my efforts were rewarded with text book perfect images of a suite of difficult double stars, some of which I have mentioned earlier in this report. I also ended my year long evaluation of a variety of eyepieces and Barlow lenses,varying quite considerably in price range. These studies have led to some firm conclusions regarding the effects of moving air upon Newtonian optics, as well as some very surprising results concerning the efficacy of certain oculars in regard to resolving double stars. Do you always get what you pay for? Most certainly not!

Insofar as artificiallly blowing air on a Newtonian mirror has been shown to scrub off the so-called boundary layer immediately above the reflective surface, my field testing over many nights shows that natural wind can also improve the images in exactly the same way. For this reason, I invariably point the telescope into any prevailing wind while the telescope cools and this works especially well for my larger Newtonian reflectors (8- and 12 inches). Furthermore, I am not aware of any historical precedent for this; the work of some notable telescopic ancestors of the ilk of W.F. Denning, T.H.E.C. Espin, T.E.R. Philips, A.S. Williams, T.W Webb and N.E. Green ( the selected work of which I will feature in my up-and-coming historical work) all of whom used Newtonian reflectors to great effect do not explicitly give mention to this result, though there is no doubt it is generally true.

The Vixen HR series of oculars; nice but totally overkill for high resolution double star work in medium and large aperture aperture Newtonian reflectors.

















On many fine evenings using a variety of Newtonian telescopes, I have compared the views through top-of-the-range eyepieces, such as the new Vixen HR series of ultra-short focal length oculars(1.4mm, 2.0mm and 2.4mm) and those derived from much more modest (but still very good) Plossls and orthoscopics coupled to decent Barlow lenses and my conclusions are that the much more expensive eyepieces do not confer any real advantages over the latter.

Ordinary eyepieces and Barlows work perfectly well with Newtonian reflectors for high-resolution double star work. Left to right; a 3x Meade achromatic Barlow, a 7.5mm Parks Gold and Baader 6mm classic orthoscopic.


















Yes, the HR series do display slighly better contrast and reduced light scatter compared to Plossls and orthoscopics but the differences were never enough to count. i.e. There was never an occasion where I could not see a tight companion in one over the other at comparable magnifications. Indeed, the HR series of eyepieces have very restrictive fields (42 degrees), even compared with the modest 50 degree fields offered up by a Plossl and/or the Baader classics (which have a larger 50 degree field) when Barlowed allow for significantly larger fields to be exploited. There is thus a distinct advantage to the using the far less expensive Plossl and orthoscopic type eyepieces over the HR series (the three of which will set the consumer back a hefty £750 UK), especially when employing a non-motorised altazimuth mount such as my Vixen Porta II.

Don’t believe the hype; binary stars are very simple, just tight little Airy disks. Save your money and use it more productively on other things.

Well, I hope you enjoyed this blog and that you don’t become discouraged observing throughout the twilight season wherever you live.

Thanks for reading.


Neil English’s new book, Tales from the Golden Age, uses history to debunk a few myths that have crept into modern amateur astronomy. Available in late 2018.



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… 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.