The Spring sky offers many delightful sights for the backyard observer. While the nights are shorter, the temperatures are generally milder and more conducive to observing for prolonged lengths of time. In this project I have selected what I have come to discover is a first-rate grab ‘n’ go telescope(which can be tested!!!); a customised 130mm f/5 Newtonian reflector. It has a very well-figured SkyWatcher primary mirror with state-of-the-art and durable high reflectivity coatings, an upgraded secondary mirror(with the same high reflectivity coatings) with a modest 26.9 per cent central obstruction. The tube is lined with cork and overlaid with flocking material to provide excellent contrast and good thermal stability, ideally suited to high resolution work. The primary and secondary mirrors have easy to adjust hand screws to achieve ultra-precise collimation in seconds. It cools very quickly, and provides gorgeous, high-contrast images at magnifications from 26x to over 500x when conditions allow. It proved very cost-effective too; typically a small fraction of what I had already spent on similarly sized telescopes in the past. The instrument sits stably on my Vixen Porta II alt-azimuth mount, equipped with slow motion controls on both axes, and which allows me to move the telescope very smoothly and precisely, even at ultra-high powers. I can lift the telescope and tripod with one hand and whisk it into the garden where I let it acclimate for about 20 to 30 minutes (the latter if high resolution targets are being imaged) prior to use.
This choice of grab ‘n’ go didn’t come naturally though. For a decade, I was caught up in the pretentious and materialistic world of tiny, high-quality refractors costing an arm and a leg. Yes, I’ve had my fair share of ‘poodles’;
A Televue 76,
A 90mm ED
And a few other smaller 60-63mm apochromats to boot.
Only through extensive field experience did I learn that they all had their limitations. The 3- and 4 inch refractors ran out of light too quickly and didn’t have enough resolving power for my particular interest in close double stars. And while the 5-inch refractors certainly delivered more light and better resolving power, I quickly grew tired of adjusting their pivot points on a large and heavy mount on the fly, and straining to attain a comfortable observing position whilst observing objects at high altitudes.
Above all else, I learned that if you’re not comfortable observing, you won’t stick at it for very long!
Enter the modified 130mm f/5, pictured above. Its lighweight, quick cool down time and with optical performance more closely aligned with a 5-inch than a 4-inch refractor, quickly won my admiration. It was another one of those sweet experiences one ocassionally stumbles upon in life. I just found it hard to fault.
But it was the sheer ease of use, the comfortable positioning of my body in all sky orientations, that finally convinced me to give up on similar sized refractors. Nowadays, the largest refractor I have any interest in is a humble 80mm f/5 achromat; the subject of my next book. Furthermore, the fact that none of my former associates (mostly refractor nuts and “fair weathered” friends, who turned on me because I refused to become a “poodle pusher”), were willing to test and publicly report just how good a 130mm f/5 Newtonian could be, revealed to me all too loud and clear that they were in denial about its capabilities. Their reticence all too easily demonstrated the true level of their experience; which didn’t amount to very much, in retrospect!
Sorry to burst your hideous bubble boys, but you’re just not credible!
In this article, I want to share with you some of the wonderful sights that grace the vernal heavens and which are accessible to an amateur equipped with a 4- or 5-inch telescope. The observations I will report are from a fairly dark, rural sky, which enjoys excellent transparency, owing to the frequent weather systems that sweep up particulates very effectively, as they move in off the Irish Sea. What’s more, they are fairly easy to find and are a joy to study from the comfort of my back garden.
Object 1: Messier 3
Let’s begin our journey with a visit to Messier 3, a bright(magnitude +6) globular cluster on the border between Bootes and Canes Venatici. To find it, imagine an invisible line between the bright orange star Arcturus and Cor Caroli(itself a rather fetching double star for small telescopes). Almost exactly half way between these stars, binoculars will pick up a fuzzy star about half the size of the full Moon in an otherwise unremarkable patch of sky. Keen eyed individuals from the darkest sites will likely detect it with their eyes, but so far it has eluded this author’s visual acuity.
Charged with a power of 87x (Parks Gold 7.5mm), M 3 is an arresting sight, with a bright, rather condensed core surrounded by a distinctly more ragged periphery. If conditions permit, crank up the power to 135x(an old 4.8mm T1 Nagler) and you will be able to resolve quite a few of its outlying stars. Indeed, I find that more stellar members can be seen in M 3 than in the more celebrated M 13, even though the latter is brighter and slightly larger. Averted vision will help you see many more stellar members. Spare a thought for the prodigious distance of M 3; 27,000 light years from the solar system. At this distance, this magnificent bauble of starlight spans a diameter of about 180 light years, inside of which some half a million suns reside. M 3 was discovered by the great visual observer, Charles Messier, who first observed this globular cluster on the faithful evening of May 3, 1764.
Every increase in telescope aperture provides an improvement to the view. Seen through my 12-inch F/5 Dob at powers of 250x or above, it is a truly mesmerizing sight!
Object 2: Messier 37
Though the large and imposing constellation of Auriga is now past its best for northern viewers, it is still very well placed fairly high in the western sky immediately after sunset. Binoculars capable of delivering an 8-degree field of view can just frame the three Messier open clusters( M36, M37 and M38) running through the belly of the constellation in more or less a straight line. Messier 37 is both the grandest and eastern-most of this trio of galactic clusters, and is easily tracked down in the finder of a small, backyard telescope.
At 26x (Celestron 25mm X-Cel LX) in the 130mm reflector, the cluster presents rather like a loosely packed globular cluster about the half the size of the full Moon, in a rich stellar hinterland of the Milky Way. But as one begins to increase the magnification beyond 60x or so, the true nature of this object manifests to the eye. The impressive light gathering power and resolution of the 130mm presents a gorgeous field of faint stardust comprising some 150 members. This cluster takes magnification quite well and is very much worth a closer look with a higher power ocular. At 118x (Meade Series 5000 5.5mm UWA), M 37 is an awe-inspiring sight, with stars of mostly equal glory filling the field of view. I feel it is the near uniformity of the brightness of the stars in this cluster that renders it so visually engaging, with a distinctly orange-tinted sun at the centre of the cluster; and you’ll definitely see that distinctive hue a little better in a larger aperture ‘scope. M 37 lies about 4,500 light years away from the solar system.
Object 3: Messier 44
The constellation of Cancer is distinguished from many others in that its brightest stellar luminaries(including Epsilon Cancri at magnitude + 6.3) are actually fainter than the most celebrated Messier object within its borders. I speak of course of the magnificent M 44, more commonly known as the Beehive Cluster, which is easily tracked down with the naked eye on a dark, moonless night as a large, roughly circular third magnitude glow, approaching the meridian about 10pm local time at the beginning of April. A wonderful object for large binoculars, which pull in about 60 stars, a medium aperture telescope greatly increases the tally of stellar members that can be seen, increasing the number to well over 100. Using my 25mm Celestron X-Cel LX eyepiece delivering a true field of 2.3 angular degrees at 26x in the 130mm f/5 Newtonian, the ~ 1.5 degree wide Beehive is very well framed for study. The field explodes with the light of mostly white stars, many of which(perhaps 20 per cent?) appear to be double or multiple in nature. Higher powers will, of course, pull in still fainter members down to magnitude +12 or so, but its glory is somewhat diminished owing to the inability of the same eyepiece to capture the entire cluster within its narrower field. This rather loosely arranged galactic cluster provides clues to its more advanced age, which is estimated to be about 800 million years. M44 is located at a distance of just under 600 light years from the solar system.
Object 4: Epsilon Bootis
Contrary to received wisdom(read parroted, armchair ignorance), Newtonian reflectors make very neat double star telescopes. I have personally been astonished how well they operate on these targets, having examined a great many systems with a variety of Newtonians over the last several years. Indeed, the 130mm f/5 has rapidly become one of my favourite instruments to divine double and multiple stars, where it has resolved pairs as tight as 0.9″ under ideal conditions. What is more, it is a decidedly better instrument than the finest 4-inch refractor money can buy, its extra light gathering power and resolution coming into its own particulalrly on fainter pairs. Our next target is not especially difficult to resolve but it does present as one of the spring sky’s most beautiful binary star systems. Also known by its more common name of Izar, it is easily located with the naked eye late on spring evenings, where it can easily be made out as a magnitude +2.5 field star off to the northeast of Arcturus. Through the 130mm reflector, Izar presents as a beautiful colour-contrast double with a bright orange primary(magnitude +2.8) and fainter, magnitude + 4.8 secondary with a soft bluish hue, giving rise to its latinised nickname, Pulcherrima (the most beautiful!). Intriguingly, the secondary is actually a sun-like star in its stage of evolution, yet the eye sees it as something altogether different! I love to observe Izar regularly throughout the spring and summer months with the 130mm, usually charging it with a power of 260x (Parks Gold 7.5mm coupled to a 3x Meade Barlow lens). On the steadiest evenings the Newtonian presents the stars as lovely round Airy disks, surrounding by a faint first diffraction ring. Separated by about 3.0″, it is best seen when the system rises to a decent altitude above the eastern horizon, which in early April, is not attained until around midnight or later. If at first you don’t succeed with this system, try again on a calmer night when it’s higher in the sky.
Object 5: Messier 81 & 82
On April evenings, Ursa Major lies very high in the sky and is ideal for observing objects within its borders. Our next target is a pair of bright Messier galaxies easily tracked down by following an imaginary line from Phecda (Gamma Ursae Majoris) through Dubhe(Alpha Ursae Majoris) and extending this line about the same distance again. Use your finder to look for a 7th magnitude smudge. If you find it hard to track down with your finder, try using a 10 x 50 binocular. The 5.1″ Newtonian charged with a power of 26x frames both galaxies very well within the same field, where I can easily make out a round, softly glowing smudge with a noticeably brighter centre. This is the celebrated spiral galaxy M81. Just half an angular degree to the north you’ll see a cigar shaped smudge about twice as long as it is broad and about a magnitude fainter; the irregular galaxy M82. For a better view, I like to crank up the power to 59x using an Explore Scientific 11mm (82 degree AFOV), which considerably darkens the sky allowing me to study both galaxies better in the spacious 1.35 degree true field. With averted vision, I can just trace out the faint spiral arms of M81, but in many ways I think M82 looks more interesting, as its smaller size makes its surface brightness that little bit higher than M81. M 82 appears distinctly mottled to my eye owing to prominent dust lanes coursing through its mid-section. It is also actively birthing stars. Both galaxies lie about 12 million light years away.
Object 6: Messier 51 & NGC 5195
Our next port of call doesn’t lie too far away from M81 & M82. Easily spotted in 10 x 50 binoculars as a 8th magnitude glow, Messier 51( the Whirlpool Galaxy) is easily tracked down about 3.5 degrees to the southwest of Eta Ursae Majoris, the end star of the Plough handle, and just across the border in Canes Venatici. Easily discernible as distinctly non-stellar at 26x in my 5.1″ f/5 Newtonian two distinct glows can be seen at a glance in the low power field. To get a better view though, crank the power up to beyond a 100x or so to increase the image scale and darken the background sky. At 118x in my 5.5mm Meade Ultrawide angle eyepiece, the view is quite compelling. Hints of the spiral nature of M51 can just be made out in this small telescope as can its smaller companion galaxy, NGC 5195. With good dark adaptation and averted vision, you may just be able to make out the famous luminous bridge ‘connecting’ the two. I find that the sky needs to be very transparent and still to glimpse this structure. It also helps being so high in the sky at this time of year where the effects of the atmopshere are less severe. Failing that, if you place M51 just outside the field of the view, examining NGC 5195 for signs of a slight increase in brightness in the space separating the two galaxies. Of course, M51 and NGC 5195 are much better seen in larger instruments such as my 12″ telescope, but it’s always good to visit this historically significant face-on spiral, as it was first delineated using the great 72 inch Leviathan of Parsonstown back in 1845 by visual means. Astronomers reckon NGC 5195 brushed past M51 about 100 million years ago and is now ‘behind’ it. Both galaxies lie about 26 million light years away.
Object 7: Messier 67
Our next object, the rich open cluster, M67, is often overlooked on account of the greater splendour of Cancer’s most illustrious object, M44. To find it, move your telescope a little under two angular degrees west of Alpha Cancri(Acubens). Easily visible in binoculars as a rougly elliptically shaped misty patch about the size of the full Moon, my 130mm Newtonian at 59x resolves this pretty cluster into a mound of several dozen faint stars quite similar to M37 at first glance, the brightest of which shine at the 10th magnitude of glory. Cranking up the magnification to 118x allows you to pick off many more members bringing the stellar tally upwards of 100. The faintest members of this 300+ strong cluster are not resolved in this small telescope but rather presents the illusion of nebulosity wreathing its way throughout its 25′-wide frame. To my eye, the stars are arranged in curious swirls with an overall shape quite reminscent of ‘incandescent seahorse’ set adrift in a vast ocean of space. The cluster is believed to be quite advanced in age; 3 to 5 billion years by most astronomers’ reckoning, and lies at a distance of about 2,600 light years from us.
To be continued…………