So You Want to do Deep Sky Observing?
Submitted: Monday, 5th September 2011 by Faith Jordan
So you want to do deep sky observing? You’ve made a good decision, as deep sky is the most rewarding, yet challenging, aspect of amateur astronomy, there are literally thousands of objects out there to observe and it will keep you happy and busy for many years.
Planets? There are only seven of them (if you ignore the demoted Pluto and the one we’re standing on, the Earth). There’s the Moon of course, but even that can become passé after a bit. But beyond the Solar System lies a whole new realm of nebulae, remnants of dead stars, star clusters, double stars and, beyond the Milky Way, billions of distant galaxies.
However, deep sky observing can be at times frustrating as most of the objects are faint and not that easy to locate, so here’s some advice for those people who want to get into this most fascinating type of observing. This article is based on my own experiences, including a lot of trial and error, so I hope it will be of at least some use.
Start off with a reasonable sized telescope of 8 or 10 inches aperture.
If you are beyond the just-using-binoculars stage of observing, you’re going to sooner or later want a telescope. A Newtonian reflector of 8 or 10 inches aperture on an alt-az (Dobsonian) mount is ideal, simply because these are perfect apertures to get you started being not too big to handle or store (once you get to 12 inches and above, things begin to get a little awkward). An 8 inch or, better yet, a 10 inch scope will show you all the Messiers, the Herschel 400, the Herschel II (the next 400), the brighter Index Catalogue objects and a great deal more in addition.
I began with a 6 inch dobsonian reflector but found it a bit small, selling it and getting an 8 inch within a year or two as I felt I’d exhausted its possibilities (in truth I probably hadn’t at that time, but that was inexperience). An 8 inch may not sound much larger but you get 77% more light gathering power with it over a 6 inch. As for anything less than 6 inches, such as the little 4.5 inch reflectors, unless you are only a casual looker at bright deep sky objects such as the brightest Messiers, or you want a grab-and-go scope in addition to a bigger one, don’t bother. Aperture rules in deep sky observing, the bigger the scope you can afford and move around, the better.
That said, however, and at the risk of sounding contradictory, someone just starting out in deep sky observing really should not rush out and get the biggest light bucket money can buy. For beginners ‘not too small but not too big either’ is the key to successfully starting out in deep sky observing. I’ve heard of people literally only in the hobby a few months buying themselves 16, 18 or 20 inch Dobsonians; in most cases this is plain old naivety and inexperience, although sometimes there are people with more money than sense and just have to start off with a bigger scope than everyone else. It’s overkill and like learning to drive in a powerful sports car or, probably more accurately in the case of a giant Dob, a tank and will inevitably lead to frustration due to the sheer size of these things.
When I started deep sky observing it wasn’t long before I got aperture fever, and drooled over the Coulter and Meade Starfinder ads in Sky and Telescope, but didn’t succumb to it purely as I didn’t have the money for anything larger but, more importantly, I wasn’t experienced enough – just as well, because I know now that a big, heavy 12 or 16 inch Starfinder or Coulter Dob with its massive tube would never have been used, due to its sheer bulk, weight and awkwardness.
Despite saying that ‘aperture rules’ (and it does) quite a few serious and experienced observers don’t go much larger than 12 inches, simply because they are happy with their lot and don’t want the hassle of a bigger scope. One guy I know in Texas uses an 8 inch SCT and he does some very advanced observing with it. A Dob of over 12 inches is a real handful and, for a beginner or inexperienced observer, too big to handle and use. But for experienced deep sky observers going beyond the Messiers and bright NGCs, however, big scopes are perfect for those prepared for the storage and handling issues that come with them. As the saying goes ‘your mileage may vary’.
Over the years my scopes have gone from a 6 inch Dobsonian, to an 8 inch Newtonian, to a 12 inch Dob and now an 18 inch Dob. I used an 8 inch Newtonian (my own at first, then a borrowed one for a while when I was ‘between scopes’) for about 14 years before moving up in size. I daresay in a few years time, I’ll go for something even bigger than 18 inches but then I’ve been doing this stuff for 19 years, I like big scopes and I am prepared for the handling and storage issues they bring.
Don’t get bogged down with gadgets or jump into imaging.
Too often I hear, and see on forums, people who have just got into astronomy wanting to take the plunge straight into imaging. Why? What’s the hurry? Do some visual observing first – most established imagers began as visual observers and quite a lot of them are still visual observers, getting some eyepiece time in while the CCD does its thing. By going off the deep end and bypassing visual observing in favour of taking pictures, people are missing the best bits. Far too often visual observing is unfairly and wrongly dismissed as being a positively dinosaurian relic of the past and is bypassed or ditched in favour of the CCD chip or webcam. Visual observing can be – and often is! – frustrating but imaging is on a whole higher level of aggravation and the results often leave a lot to be desired, at least when it’s me doing the imaging!
That said, for people in badly light polluted areas or those with bad eyesight, imaging or webcam observing is the most effective and sensible option. Visual observing’s no fun if you’re spending all your time hunting for stuff or not seeing it. I know that if, by some horrible turn of events I found myself living in a city again, or (heaven forbid) my eyesight deteriorated, I’d definitely invest in a WATEC, Mallincam or other camera, it beats no observing at all! But, for those in less polluted areas – and not everyone lives in inner-city ‘white zones’ – or with decent eyesight, there’s no excuse for not at least giving visual observing a go.
Keep it simple, at least at first. Learn your away around the sky by using a star chart and navigating your way to the objects by star hopping. When I began, I was itching for a ‘Go-to’ drive but, not being able to afford one was a blessing in disguise because it meant I got very familiar with the constellations, and I haven’t come to rely on gadgets. If you can’t star hop, haven’t got a chart and your Go-to system breaks or the power supply fails, you’re going to have to stop observing which would be, to say the least, frustrating and annoying.
Binoculars or a scope, a good finder, eyepieces, charts, pen and paper is literally all you need, and a lot of people – including me – find they need no more than that for the rest of their observing ‘career’.
Get a decent star atlas, a Telrad and a good finder scope.
A decent star atlas is a must, particularly for those with larger scopes. If you have a scope of 8 inches or larger, you need at least Sky Atlas 2000.0 and, for those with scopes over 12 inches, Uranometria 2000.0 and/or a charting program like MegaStar is essential, otherwise you’ll not be able to locate the objects you have on your observing list.
A decent finder, 8×50 or larger, is also a must-have. Too small a finder, such as a tiny 6×30 one, is a recipe for annoyance because it will be no good for locating deep sky objects, especially the fainter ones.
Back in the 1970s, the Telrad finder was invented. This is a 1x finder, consisting of a plastic screen onto which is projected three red concentric circles. The inner circle is half a degree in diameter (around the size of the full Moon), the second circle is two degrees, while the outer circle has a diameter of four degrees. Many publishers of star charts include clear plastic overlays with the circles printed on them, to the scale of the circles on the actual device, and MegaStar allows you to print charts off with the circles on them. Telrads are brilliant, one of the best inventions in amateur astronomy, and once they are aligned with the scope, as all finders need to be, they are very accurate and easy to use. Finding things in the sky is so much easier with one.
Make notes and/or sketches.
The idea of making notes or doing drawings is appalling to some people because it might seem like drudgery but, to others, it’s an essential part of the whole experience. I’m in the latter camp because I like looking back at what I’ve done and seen. I can open old notebooks at a particular place and that session will come right back to me, even down to the sounds I heard and the smells I’ve smelled (barking dogs, distant rock festivals and the scent of foxes in the UK, howling coyotes and cooking burgers in the USA, the thumping of kangaroos in the dark and bush fires in Australia), even after a number of years.
Notes and sketches don’t fade over time but memories will and I’d hate to forget my favourite sessions and what I’ve observed over the years. It’s also fun to look back at old sketches and notes and see how they hold up against the newer ones and see how your observing’s progressed over time. Even bald, unadorned lists of objects are better than nothing, but not very valuable apart from keeping track of what you’ve seen. At the very least, make a note of the date, place, sky conditions, object name/designation and a brief description of its appearance – in time you’ll be glad you did.
Sketching’s fun and, as the old expression says ‘a picture is better than a thousand words’. Even if you can’t draw, have a go anyway. Deep sky sketching, in its simplest form, is about drawing dots and smudges and anyone can draw dots and smudges.
Use a dim red torch and not a white light.
Deep sky observing, more so than lunar or planetary observing, needs as much light as possible from the object and as little as possible in your surroundings. You are going to need to look at your charts and make notes or sketches, but white light will completely ruin your dark adaptation and make it impossible to see faint galaxies or nebulae or details in brighter objects.
Deep sky objects are generally quite faint, indeed quite a lot of them are on the very edge of visibility, and even red light, if too bright, will make it hard, if not impossible to see them. Get a specially made red flashlight, which you can buy from astronomy retailers, or adapt a normal white one by covering the front with red acetate, cellophane or even red nail varnish (if you’re female you won’t get any funny looks when you buy some, if you’re a bloke you’ll have to pretend it’s a present for your wife/girlfriend! ;) ). That way, you’ll see your charts and notes without rendering the object in the eyepiece temporarily invisible.
Get away from lights if you can.
Deep sky observing requires as dark an observing site as possible, for the same reasons mentioned above – deep sky objects are rendered invisible by extraneous light. Artificial light pollution is a real menace to deep sky observers as, not only does it make it extremely hard to see the objects, it makes it difficult, if not actually impossible, to even find them in the first place. Light pollution (badly directed light going into the sky where it is wasted) from street lamps, (in)security lights, porch lights, car park lights, lights on business premises, etc, all combine to cause skyglow which wipes out all but the brightest stars. Even light from a window is a nuisance if it is shining out onto your observing patch.
If you can’t get away from artificial lights, try and shield yourself and your telescope from them by erecting a screen, or putting bushes, trees or a building between you and them. Even better, if you can, take yourself and your scope to a darker site but this isn’t always practical, and personal safety at a remote site is an issue, but if you’ve got a friend or relative with rural property and you can stay there, or your club has a dark sky site, then you’re set.
Join your local astronomy society and the Webb Deep Sky Society.
I think that when I was a beginner, if it hadn’t been for Vectis Astronomical Society, with the experienced observers among the membership, I would not have learned as much as I did and the ‘learning curve’ would have been considerably steeper. You can get help and advice at societies and also get to try out telescopes. Some societies, if not most of them, have a ‘loaner scope’ program, where members can borrow equipment from the club. That’s a good way of trying a telescope out without making a financial commitment.
The Webb Deep Sky Society is the world’s foremost society devoted to deep sky observing. Their quarterly magazine, the Deep Sky Observer, has articles and observing ideas.
Failing the above, join a forum, such as IceInSpace or Cloudy Nights. The people you ask for advice may not be with you in person but their advice is no less valuable for that. Forum information is usually more permanent than that found on personal websites, so it’s usually easy to go back and find later.
Have a PLAN.
An observing plan is pretty important. Don’t just go out with nothing in mind and jump aimlessly from object to object, you won’t see much that way – make an observing list. If you’re a beginner start with the Messier 110 list, then go on from there…the Herschel 400…Herschel II…etc, the choice is endless.
The Astronomical League website has ‘observing clubs’ and there you’ll find some ideas for all sorts of observing programs. A definite plan of what you intend to observe before you go out will make a huge difference to what you see and the amount of observing you do.
Despite all the advice above, this is a hobby, so the best advice anyone can have is enjoy it, have fun.
A search on Amazon.com/Amazon.co.uk will find these books. Tom Clark’s book Starry, Starry Nights can be found on http://www.tomclarkbooks.com.