We categorize what we see in the night sky as Solar System or Deep Sky.
Solar System is self explanetary - it's what's in our own solar system. This could be the Sun, our own Moon, other planets or pieces of debris such as meteors, comets or asteroids.
Deep Sky is everything else. It could be a star cluster inside our own galaxy, or another galaxy millions of light years from our own.
Everything in the Universe wants to group together. In the beginning was (probably) an unevenly distributed soup of hydrogen and helium. It formed immense clouds called galaxies. Within the cloud smaller, denser clouds formed, called nebulae. Out of these stars formed in clusters. Some star clusters, for example the Plaiedes, still have some of this nebulosity. Depending on how they die, stars might leave behind a planetary nebula or supernova remnant. These are often some of the most difficult deep sky objects to see.
Galaxies are classified according to their shape. Most are elliptical or some sort of spiral, but can be orientated to us such that they are either face on or tilted at an angle. Some galaxies have dark lanes of dust. Then other galaxies are classified 'irregular', which can mean any shape at all. These could be galaxies not far enough along the evolutionary process to have attained a regular shape, or galaxies which have been interfered with in some way, perhaps an interaction or collision between galaxies.
Star forming nebulae fall into two categories - reflection and emission. Reflection nebulae are relatively cool and are lit by the reflected light of stars within them. Emission nebulae are so hot that the gas of the nebula is itself emitting light. These are some of the real gems of the night sky.
Star clusters can be open or globular. Open clusters are exactly as they sound. Many are big and bright enough to be seen with the unaided eye. Globular clusters are huge balls containing perhaps many thousands of stars.
Planetary nebulae are spherical shells of gas cast off by the last explosion of a very ordinary star like our Sun. Very large, super hot stars die more dramatically and cast off a cloud that in time will expand far out into space. It may well be the death throes of one star which will cause a nebula to form and collapse in on itself to form new stars.
Charles Messier was a eighteenth century astronomer working in Paris whose primary occupation was finding and predicting comets. When through his telescope he found other fuzzy things in the sky he listed them to avoid confusing them with his comets, and published that list. Together with his colleague Pierre Mechain, he listed 109 dep sky objects, all of which can be seen from Britain wih a fairly small telescope. They are known as the Messier objects and have numbers prefixed 'M'. Although they did not discover all the Messier objects, Messier and Mechain were the first to catalogue them.
Messier's work was continued by William Herschel and his son John. Working with much larger telescopes than Messier, they systematically searched the skies for 'nebulae', a term then applied to all deep sky objects. John Herschel published the 'General Catalogue of Nebulae' in 1864. It listed nearly 5100 deep sky objects, including those of the southern sky. However only 24 years later the Herschels' work was superceded when John Dreyer, working for the almost defunct Armagh Observatory, was asked by the Royal Astronomical Society to pull together all the previously published work on deep sky objects. The 'New General Catalogue of Nebulae' and its two supplementary Index Catalogues list 14755 objects. They are prefixed 'NGC' or 'IC'. Messier's objects are listed in the NGC but they are always known by their Messier numbers.
See the article 'From Messier to the NGC' for a detailed look at just how these two catalogues came to be and how our understanding of deep sky objects grew as a result.
Although a half metre diameter reflecting telescope was used for some of the photographs, a 12 inch reflector was most widely used. Still a pretty serious bit of kit by amateur standards, it is large enough to give good images while still being easy to use. The half metre is a bit of a beast! The telescope is in a dome on an equatorial mount driven in both axes, essential for photography. A simple driven equatorial camera mount was used for 'piggyback' photography.
The 35mm camera I use is a Praktica MTL. It is fully manual, an advantage for this type of photography. No battery is required to keep the shutter open, and it is simply used on the 'B' setting with a cable release. I also use a Canon OES350D digital SLR with a remote release. Instead of switching entirely to digital, I use the camera that best suits the subject. I think 35mm is still better for bright nebulae and star clusters, and for wide field piggyback constellation images. Where digital scores is in its ability to capture much fainter objects with very short exposures, eliminating that film fogging that would occur on 35mm.
Film.......Ah, film! The film varies. Initially I used 1600ASA print film, Fuji or Agfa, however I don't do my own printing and even a professional lab wasn't the answer. I switched to 400ASA slide film, initially Fuji but more recently Kodak, and even more recently ack to Fuji. The reason for these frequent switches is that the manufacturers, even of fast film, do not intend their products to be used for long exposures in the pitch dark, so I had to experiment to find a film with an acceptable colour balance. That's fine until the manufacturer 'improves' the film - its daylight properties of course. Then it's time to find another film....! The problem now is that slide film is on the way out. The switch back to Fuji was not out of choice but through being unable to obtain Kodak. For the amount I use ordering specialist film is not an option.
Both negatives and slides were scanned using a PrimeFilm slide scanner and image proccessed in Paint Shop Pro and Adobe Photoshop. The digital images were added using FitsX or Deep Sky Stacker before image processing.
The drawings were done using a variety of telescopes - 6 inch, 8 inch, 10 inch, 12 inch and half metre reflectors and a 4 inch refractor. Some were driven, some were not. Again the half metre gets the thumbs down. Fantastic for purely visual work, it can leave the observer clinging to a precarious perch, not conducive to a work of art! Whatever telescope I am using I choose the field to have some distinctive stars, preferably near the edge, which I draw first. This makes it easy to recentre things. Even a driven telescope can get knocked when you are moving from eyepiece to sketch pad and back again, juggling glasses and a torch. The one most widely used is the same 12 inch I use for most of my photography. The drawings you see here are copies of the sketches done at the telescope.
Name: Jan Wrightson
Home: South West England
Interested in astronomy for: Since childhood, with a lengthy gap betwen then and fairly recently. Why? I didn't even have a pair of binoculars and it got boring. Not even a magazine to tell me what I was missing. I rediscovered it years later through a pair of binoculars and the Moon, then magazines, the Astrofest and a holiday in Portugal.
Equipment: 6 inch Newtonian reflector on a very simple alt-az mount, 10 inch Newtonian reflector on an equatorial mount, some basic cameras, pencils and a good dark sky (usually cloudy). And lots of rain!
Preferred observing site: COAA in the Algarve region of Portugal. Dark skies, telescopes up to half metre in cosy domes in the garden, warm and dry, and no need to get up for work! I go there every year and it is where most of my observing is done. I have another site just down the road from my house. It's cheap to get to but means moving all the kit by car, freezing (and that's in Summer), then struggling awake for work next morning.
Member of: The Society for Popular Astronomy, which caters for eveyone young and old, experienced or merely interested. Bridgwater Astronomical Society, perhaps typical of the smaller astronomical societies found all over the county. We have members from all walks of life, with a variety of experience and interests. The regular membership is small, meaning that we cannot 'buy in' speakers. Volunteering to give a talk is a great way of broadening one's knowledge. We are also very happy to give talks on basic astronomy to other organisations. We have entertained (or sent to sleep) local community groups, model engineers and the WI.