Getting Started in Astronomy
Astronomy is anything from a passive hobby to a devout passion that covers a very wide range of fields of interest that can keep anyone happily engaged for an entire lifetime but, it depends on an individual’s bias as to what interests you in particular.
Our centre has members with diverse interests. Groupings occur that pursue specific interests on their own bat from time to time, the monthly meetings help to socialise the groups. The amateur telescope making group is quite strong there are other groups that arrange/enjoy outings from time-to-time. There are near-professional members that do serious observing and contribute to the development of science.
How to get started?
- Read widely for you own enjoyment and establish a deep connection with the universe;
- Get a pair of binoculars and observe the objects in the sky with the help of a guiding book (e.g.: ASSA Sky Guide) or download a free package from the internet such as ‘Cartes Du Ciel’ or ‘Stellarium’ that will help identify the objects that are visible from a given location;
- Buy a telescope, learn how to use it, observe the objects in the sky, take photos of objects such as the Moon, planets or of deep-sky objects and then do image processing on the images to bring out detail, do formal observations and submit these to international organizations for further processing or ratification;
- Build a telescope;
You have probably thought that astronomy is usually done under very dark skies where people try to preserve their dark adaptation. Some branches of observing and imaging do not need very dark skies or much dark adaptation at all. The most obvious is lunar and planetary observing. Many observers call this “shallow space” which can become a life’s entertainment.
Our advice is to play to your strengths and interests in order to maximise your enjoyment, but also continue doing the groundwork you have started; a good foundation is important. A sound binocular observing mode will stand you in good stead. In the future we urge you to continue pursuing that and to achieve a relatively high level of skill before moving on to more expensive instrumentation.
Modern instruments indeed have a lot of embedded computing power, for go-to operation, to work in alt-az instead of equatorial mode, for imaging and so on. But you do not need a high level of expenditure to start with. Join some of our gatherings and find out why people made the instrumentation choices they did, rather than rushing off to spend money on the first thing a salesman punts. You can build or buy a modest scope, and maybe implement a tracking system that will enable imaging. Even a humble webcam can give great results. In fact, for planetary imaging, it is now possible to get better images with a webcam and a modest scope than the best professional images of just a few decades ago.
More advanced techniques involve high speed imaging of satellites or long duration images of distant galaxies. Some ‘amateurs’ have photographed the space shuttle in flight and could resolve the windows easily, others routinely look back in time for hundreds of millions of years. Of course, the more advanced your programme, the more expertise you have to develop yourself that’s part of the learning process.
If you equip a telescope or binoculars with the right filters, it is even possible to observe the vagaries and nuances of the Sun. Many of the tutors at the telescope making class will be more than happy to show you how to make a set of solar filters but please don’t observe the sun without them you could loose your sight permanently!
If your main interest is deep-sky, I suppose you are like most of us in that we have the most perverse fascination with the very things to which we are denied access! Indeed, in the city especially, light pollution is a curse, hiding most deep-sky objects. However, through digital photography it is possible to “subtract out” the light pollution and extract stunning images of deep-sky objects that would be impossible to observe visually under the same conditions. Of course, this requires a serious investment in equipment, and an even larger investment in personal time, effort and dedication. Not for the faint hearted, but achievable by those who have the drive.
If you enjoy tinkering with electronic toys and software, you would probably enjoy the challenges of imaging. You could avoid a lot of the start-up costs by teaming up with someone who is already well down that road. Perhaps you could find someone who has made the investment in equipment, but does not really have the IT skills required to bring out the best. Alternatively, you can access a lot of data on the Internet, and do real science by assisting an established programme in the data analysis process.
So there’s a lot to do. What you put in, is generally what you get out. However, astronomy is an endeavour that has the potential for you to marvel at our daily lives in a fashion very few people are privileged to experience and participate in.
“The men of experiment are like the ant, they only collect and use; the reasoners resemble spiders, who make cobwebs out of their own substance. But the bee takes the middle course: it gathers its material from the flowers of the garden and field, but transforms and digests it by a power of its own. Not unlike this is the true business of philosophy (science); for it neither relies solely or chiefly on the powers of the mind, nor does it take the matter which it gathers from natural history and mechanical experiments and lay up in the memory whole, as it finds it, but lays it up in the understanding altered and disgested. Therefore, from a closer and purer league between these two faculties, the experimental and the rational (such as has never been made), much may be hoped.”
Bacon, Francis [Francis Bacon, Novum Organum, Liberal Arts Press, Inc., New York, p 93.]
Firstly, there is no one filter that is a universal panacea. A broadband (also called and LPR or Light Pollution Rejection) filter is probably the best to start with, in that it is relatively mild and helps to delete the worst effects of artificial light. Planets and stars look weird, everything takes on a green cast and the image is considerably fainter. However, certain objects respond well, the benefit being vastly increased contrast. Of course, going to a dark site would be even better. Often called UHC (Ultra-High Contrast), narrow-band “nebula” filters let through even less wavelengths, and the cut-off is much steeper. So they basically have much more of the same effect. They therefore work even better, but on fewer objects (and are of course much worse for all other possible targets). Both of these are severe notch filters, aggressively blocking specific wavelengths and letting other key wavelengths through. If the object you wish to view does not emit in the passbands, you will see nothing. If it is a good match, then you will see more because of improved contrast. Planetary nebulae are generally good subjects for these, but it is useless to try them on galaxies, because galaxies transmit in an essentially continuous spectrum.
Another interesting filter, which is extremely good for a handful of objects only, is an OIII (oxygen three) filter, which lets through the light emitted by ionised oxygen to the exclusion of virtually everything else. So the Eta Carina nebula (for example) is stunningly rendered, but the number of suitable subjects is severely limited. Similar comments apply to the other specialised filters (e.g. Sulphur SII, hydrogen-alpha, hydrogen-beta, etc.) Apart from limiting the spectrum available, all of the filters mentioned cut out light at all wavelengths, so the image gets quite faint. You really need a large telescope (more than 8-inch diameter, preferably bigger than 10) for them to be viable.
One thing not generally realised is that these filters are not absorption filters (like a polarising or plain coloured filter) but work by destructive interference. As such, they have many coatings, each extremely thin and tightly controlled. So they are difficult to make, hence expensive and delicate. More interestingly, they are highly reflective – this means that light coming in the eyepiece end gets reflected back to your eye and the image is consequently much poorer. You need to wear a hood and use the rubber eyecup to get the most from them.
My advice on the above is to go to a star party and try other people’s filters before making a purchase. Few people have seen the Horsehead Nebula, which is a notoriously difficult object, and the right filter can reveal it in even modest instruments. That’s exciting. But do you want to pay a couple of grand for the privilege, when you can get professional images off the net, or put the money towards some other accessory?
A few more comments, just to round off the discussion…
For comets, a Swann filter is often promoted, to assist in discerning the ion tail. By comparison to the others mentioned above, this is a mild filter, but again dedicated to a particular subject.
The Moon can benefit from a neutral-density (or crossed polariser) filter, to cut the glare, but this is more for comfort than anything else. The planets can benefit by using plain coloured filters, bringing out features like the cloud belts of Jupiter, or dust storms and the polar cap of Mars. For these, my advice is to go to camera shop and get some second-hand photographic filters. Kokin make a good range of optically good plastic filters that are quite inexpensive and capable of being cut to fit your needs. Similarly, if you have a refractor that exhibits colour fringes on bright objects due to chromatic aberration, you can improve the image by introducing a “minus violet” or (less effective) “skylight” filter, again cheaply obtainable from camera outlets. These look a pale yellow in colour.