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Sketching at the Telescope


Why make sketches at the telescope?

While observing, I always make some notes for my observing log, though it is not easy to write down a detailed description of a deepsky object. No matter how elaborate your notes are, you may still leave other readers with the wrong impression. It's often said that a picture is worth a thousand words, and that goes for a drawing of a deepsky object too. A drawing will pass on an image of what the observer really saw at the eyepiece.

Another good reason to make sketches at the eyepiece is that it forces you to examine an object thoroughly while looking for details. You will take more time to look at it. This will definitely improve your observing skills.

Anyway, there maybe a dozen or more good reasons to start sketching at the telescope. Just give it a try; it's fun to do! You only need some equipment and drawing materials, and last but not least, perseverance!




Equipment and drawing-materials you may need for sketching at the telescope

  • An observing chair, or at least something to sit on; you should feel comfortable while observing and sketching; it can take one to two hours before the sketch is completed, so you have to be in a relaxed position.
  • A clipboard to hold your drawing equipment like paper, pencils, erasers etc.
  • One or two red lights; I prefer LED's which can be dimmed, and produce a nice even light.
  • What can come in very handy, is a drive on the RA of some kind, so that you don't have to adjust the telescope manually every few minutes, but this isn't a must for sketching at the eyepiece.
  • Sketching paper, preferably with pre-printed (or drawn) circles with a diameter of 2 to 2.5 inches; I use a compass to draw the circles, but you can also use a jar lid or anything else which has the right form and size.
  • A few different pencils; I use an HB pencil at the telescope; however when I return indoors I make my final version of the sketch, I use different H (Hard) and B (Blackness) pencils, as well as the HB.
  • A wedge-type eraser or a kneaded rubber eraser; I prefer the latter because it can be kneaded into any form.
  • An eraser shield;
  • A little knife to scrape of some small flakes of lead from the tip of the pencil; (you can also use a piece of charcoal instead of to pencil to get some flakes from).
  • A smudging tool, to spread the lead or charcoal flakes out over the paper and make a diffuse appearance; you also can use a finger or an ear bud as smudging tool.
  • Maybe a circle template for drawing circles can come in handy sometimes (optional).

Before you start drawing

Don't rush into drawing once you have located the object. Take your time (15 to 30 minutes) to observe the selected object carefully. Try different magnifications, using all your eyepieces. Try different filters, in combination with different eyepieces. Maybe they bring out details, you didn't notice before. Also try averted vision and see what happens. I noticed that if you take your time to study an object systematically and thoroughly, you will see more detail, and detect fainter field stars. During this phase you can also decide which magnification you will use while sketching.


Making the field sketch

Centre the field of view on a certain (bright) star, which can be used as a reference point. Divide the field of view into four imaginary quarters. Then start to record the brightest stars into the pre-printed circle. Accurately place the first bright star in relation to the field of view. Then plot down the next one at the right distance and angle of the first. Repeat this for every bright star. Try to work from the outside inwards. Always look for recognizable shapes like triangles, rectangles, doubles or strings of stars that might help you to plot the stars in the correct position to one another. Repeat these steps for every of the four imaginary quarters. Working this way, you create a sort of framework of bright stars in which the fainter stars can be filled in later. If there are to many stars in the field of view, turn the view slightly out of focus. The fainter stars will disappear, only the brighter will remain.



When the framework of brighter stars is complete, start to fill in the fainter stars using the brighter ones as reference points, until you've added all the stars that you see. When you plot a star at the wrong position, just put a little mark or cross over it, so that it can be removed later. With all the stars in place, draw the outline of the deepsky object. Then start filling in the details (use some flakes of led and a smudging tool if you want to create a diffuse look). Use the eraser to make dark lanes or patches in the deepsky object (what is bright in the eyepiece is dark on the paper and vice versa).

Before you end the session, find out which way is West. You can do this by switching of the RA drive. The direction where the stars drift out of the field of view is West. East is on the opposite side. In a Newtonian, North is 90 degrees counter clockwise from the West. In a refractor or cassegrain, using a star-diagonal, North is 90 degrees clockwise from the West. Of course South is at the opposite side of North. Mark the four directions on the circle.

Then record the date, name of the object, magnification, filters used and the field of view on the sketching paper.






Making a final version

After the observing session, make a final version based on the field sketch(es). Do this as soon as possible. Make the corrections you noted while sketching at the telescope. Compare your drawing with your star map or atlas, and see if you made any major mistakes while plotting the stars into their position. On a next observing session you can compare the final version to the field of view, and see if it is accurate. When you are satisfied with the result, file the drawing for your archive, compare them with sketches from other deepsky-observers, or scan them to create a permanent record on your computer or your website.



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