How to make a sketch
Observing astronomical objects through a telescope can be a thrill. Realizing you are looking at a star that exploded and left a planetary nebula or seeing a galaxy millions of light years distant or looking at an emission nebula like the Great Orion Nebula where new, hot stars are still being formed can be awe inspiring. Most amateur astronomers will want to have a record of the things they observe. One way to do that is taking notes to permanently record how a particular object looked through the eyepiece and these notes can be compared with notes taken with different telescopes or compared with other astronomers. Another way is astrophotography. Taking pictures through the telescope can be done with relatively simple cameras but for the more professionally looking images one needs rather expensive equipment.
A third way to record an observation is by sketching what one sees through the telescope. Sketches are more true to what the observer actually sees visually than photographs are and it doesn’t take budget-busting equipment either. All that is needed to start are some pencils and paper although other methods are also used such as ink. Sketching also helps to see more details than otherwise would be seen and makes one a better observer in the end as well.
It can seem daunting to the beginner to sketch what is seen in the eyepiece but keep in mind that what you are trying to do is record your observations, not create a masterpiece of art. Start by observing the object thoroughly first. Take in as much detail as you can and spending anywhere from 5 to 20 minutes on this is fine. Taking notes in addition to making a sketch is a good idea. Use a red light so you can preserve your night vision. My own method is to make a rough sketch at the telescope and take a lot of notes on the various details that are visible. Start by sketching the brightest field stars that can be seen in the eyepiece and plot successively fainter stars. When sketching an open cluster, do the same thing. Sketch the brightest stars first and go fainter as you progress. In particularly rich clusters like M11 for instance, don’t try to plot each individual faint star as that will be very hard to achieve accurately. Instead, better results are achieved by drawing the general appearance as long as the brighter and more prominent details are more or less accurately placed. For globulars that are resolved into stars, the same applies.
Nebulae and galaxies might seem more difficult to sketch but that need not be the case. When the brighter field stars are in place draw a rough outline of the object, drawing the size, shape and orientation of the object. Note the details like brighter or darker areas, bright knots, prominent stars and any sharp edges you might note. An eraser, or even a finger, can be used to realistically render nebulous areas. An area that is too bright can be made more diffuse by rubbing a finger over it.
I find it works best for me to take the sketch and accompanying notes and make a second sketch later on. The object is not to make it look better but it is easier to accurately draw details inside than it is out in the field. After you are done you are left with a black-on-white sketch, which is fine of course but for a more realistic effect you can scan the sketch into your computer and use a program like photoshop or similar software to make an inverted copy (negative) where the stars and objects are light on a black background. The software can also be used to tweak the sketch to make it more realistic but to be an accurate record of your observation, take care not to want to make it more “beautiful”!
For some examples of astronomical sketches see my website at http://mordorp.zymichost.com/Astrohomepage/htmlfiles/index2.html