Contents
1. Why sketch?
2. Equipment
3. Drawing techniques
4. Preparing the final version
5. Reproducing & displaying

1. Why sketch?

A DRAWING OF A DEEP-SKY OBJECT makes a personal record of what was seen by the observer, and so is satisfying as an end in itself. However, drawing also forces the observer to look for more detail and, in time, this will develop a trained eye that will be useful in all types of observing. (Macdonald, 1993). Tom Polakis says: “Drawing what you see through a telescope is a good way to document subtle details. By comparing renditions made on different nights, you can look for changes due to sky conditions or your growing ability as an observer.”

Roger Clark writes: “It’s often said that a picture is worth a thousand words. Composing a thousand words takes much time and though and still may leave the reader with the wrong mental image. So when it comes to accurate recording of scientific data, there’s often no substitute for a picture.
In past centuries a scientist was necessarily a draftsman. Nowadays scientists in almost all fields rely on photography to record images, and the pencil and sketchpad no longer rank as essential scientific tools. Visual astronomy, however, remains an exception.”

Michael Sweetman of Tucson, Arizona, wrote in Astronomy’s Letters column: “I’ve been drawing objects since I began observing, and I draw every time I go to the telescope. I approach my drawings as scientific illustrations. When you’re preparing for a drawing, proper eyepiece and magnification selection are important . . . Too little power and the delineation of details can’t be made out, too much power, and contrast and form in extended objects like nebulae are lost. A realistic drawing also requires proper paper selection and drawing technique, refined from hours of experience at the telescope and practice away from the telescope. . . . As with most endeavours, skill and hard work produce quality results.”

2. Equipment

EQUIPMENT FOR SKETCHING If good observations are to be made, it is essential that the observer is comfortable and relaxed. An observing chair of some sort should be used at the eyepiece. A clipboard is handy for holding the rest of your drawing equipment, including your red observing light -- I use a red mini-reading-lamp, with the bulb replaced by two super-bright LED’s, to throw an even light over the sketching area.

THE DRAWING PAPER should be illuminated by a dim red light, since a white light will destroy too much of the observer’s night vision which is so essential for visual deep-sky observing. Macdonald (1993) suggests using an A5-sized hardcover sketch book, the paper of which should be high-quality cartridge paper. I use 80g bond laser-printer paper, cut in half into an A5 size. Before the page is divided, a checklist and circle is laserprinted. The circle on the sketch pad represents your field of view in the eyepiece. Macdonald suggests a 50mm diameter circle; Mitchell 75-100mm; I prefer 60mm.

YOU’LL NEED A PEN to plot stars. Mitchell (1995) is of the opinion that “a pencil works better than a pen because a pen cannot convey gradations of brightness.” While a normal ball-point or fountain pen certainly won’t work, a fine-point felt-tip pen (we call them koki-pens) is perfect. They make exquisitely small dots with their tiny fibre tips. For brighter stars, slightly more pressure on the pen produces a larger blob. For really bright stars, either use a thicker tipped pen, or colour in a little circle. Of course, bright stars remain point sources, so don’t draw them as large disks; rather as bloated spots.

A SOFT-LEADED PENCIL or charcoal stick (sold at art supply shops) and an eraser is also on your shopping list. Only one type of pencil is used at the eyepiece, says Macdonald; different grades of pencil may be used to enhance the drawings indoors later on. He writes that the “ideal sketching pencil is the Ebony pencil (#6325) made by Eberhard Faber. It is coarse and soft enough to let you use just about any sketching technique you want.”

FINALLY, YOU’LL NEED A “SMUDGE STICK” or cottonwool earbuds to smudge portions of the drawing. This creates the impression of haziness and testifies to the fact that there are few straight edges and neat boundaries to deep-sky objects.

"As with most endeavours, skill and hard work produce quality results."

"Good drawings do not require special artistic talent or experience, but they do demand close attention, much time at the telescope, much time redrawing . . . and honesty in not recording details remembered from photographs but not positively seen"
--- Roger N Clark

3. Drawing techniques

BEFORE YOU PUT PENCIL TO PAPER, study the object intently. Try different eyepieces to see the most detail; use various filters to enhance contrast. Use averted vision to pick out the fainter detail, letting the overall impression build up in your mind. David Coleman (1994), commenting on sketching Mars, notes “I began each drawing session by not drawing the planet! It was important for me to spend a quiet 15 or 20 minutes carefully observing. It takes practice and patience to train your eye to pick up faint detail, so try not to rush right into drawing.”

Every time I sketch, I’m impressed by how much detail I would have missed had I just looked at the object for a short while and noted a description. Fainter stars and subtle detail is revealed through extended observing. Studying the object with intense concentration and averted vision, says Mitchell, reveals more and more detail.
When you do start sketching, draw only what you see.

THE FIRST STEP IN SKETCHING is to plot the positions of the brightest stars in the field of view. These stars serve as markers that keep the drawing’s proportion correct. Start by plotting a prominent star in accurate relation to the field of view circle. Now plot a second one at the appropriate distance, and angle. Work from the outside, inwards. Examine the field, and pay close attention to other stars that make distinctive triangles with the two already drawn. Select a star that makes a recognisable shape, and add it in. Continue in this was by making triangles, or extended lines, or even rectangles, with new stars. In this way, a framework is erected within which fainter stars may be filled in.

Drawing in the bright skeleton of stars should be done quickly. Spend more time imprinting the image in the mind than staring at your sketchpad. “While dividing attention between the eyepiece and sketchpad, preserve as much night vision as possible by keeping your red light subdued. Limit exposure to light by spending most of your time studying the object, and then draw bits of remembered detail in short bursts.” Once you’ve selected a spot to position a star, see if there are other triangles in which it is also involved, that can confirm its position.

If your initial framework is not accurate, rather start again. If, as you get on, you plot a star in the wrong place, make sure you correct it. Because I use a pen to plot stars, it’s not a simple matter of erasing. Instead, I place the tip of the pen on the offending star, and draw a short (<1mm) tick away from it. When the drawing is retouched indoors, there stars are removed. A note in the margin can also draw attention to any alterations as needed.

Continue plotting the fainter stars, in relation to the brighter ones, until you’ve added all the stars you can see.

WITH THE STARS IN PLACE, sketch the major details of the object, capturing the general shape. Mitchell says: “This later serves as a template when it comes tome to fill in any subtle detail in the object’s shape.” I advise that you do this very lightly; often, as you continue observing the object, this overall impression changes, especially on complex objects. This again emphasises that prolonged observing shows detail not seen in the initial scrutiny.

With the basics recorded, refine the sketch by adding details: the glittering of stars resolved in globulars, dark dust lanes in galaxies, and so on. Each type of object has a slightly different approach.

OPEN CLUSTERS ARE MY FAVOURITE sketching target. Accurate placement of stars is vital, as is the faithful rendering of their brightnesses. Slowly build up the image, working from the outside inwards, using triangles and lines to position the stars. If there are an overwhelming number of stars, slightly defocus the eyepiece, which hides the fainter clutter. Then refocus to fill in the fainter members.

Open clusters, by the way, respond well to moonlight. While the brightened night sky drowns out fainter deepsky objects, star clusters can be seen reasonably well. Take advantage of a clear but moonlit light to prepare sketches of open clusters. Fainter stellar members can be added in on a dark night.

GLOBULAR CLUSTERS CAN BE A REAL CHALLENGE, especially for larger telescopes. Start by drawing the core dark, and the outer regions in successively fainter layers of pencil -- say two or three separate layers. This should give a zoned or tree-ring appearance to the sketch, but this is eliminated by careful smudging, either with a smudge stick or an earbud. This creates a realistic nebulous effect, if you make sure the edges fade naturally with on discernible edge. Be careful that you don’t inadvertently increase the size of the object with too much smudging; rather start out slightly smaller and build up the correct size with repeated pencilling and smudging. The shading should as accurately as possible reflect the brightness profile of the object; does it brighten suddenly or gradually; is the brightening slight or marked? To round off the drawing, add stars that are involved in, or very close to, the cluster. The resolved stars should be added in from the cluster edge, working inwards. Of course, in the case of a well resolved, rich globular cluster (say Omega Centauri in a 15-inch) it’s not a good idea to accurately plot every star; simply create the general impression. Mitchell cautions, however, that you shouldn’t “get carried away and resort to madly peppering the cluster with stars at random.”

GALAXIES ARE DRAWN IN MUCH the same way as globular clusters, starting with the darker central area (e.g. an elongated bar), working outward. Successive smudging defines the outer reaches of the galaxy, while an eraser is used to indicate obscuring dust lanes.

PLANETARY NEBULAE NEED A DIFFERENT APPROACH. Many planetaries have well-defined disks that don’t need smudging. Whether its small and bright, or large and faint. first sketch in the outline of the disk. Then fill in the centre so that the nebula becomes a smooth disk. Some planetaries, however, are diffuse, and their disks need to be slightly smudged.

DIFFUSE NEBULAE ARE PROBABLY THE MOST DIFFICULT. They are often so faint that smudged pencil creates too strong an image. Macdonald suggests you rub your forefinger or cotton bud with the pencil until it is coated with a fine layer of lead. I prefer to rub the pencil a number of times on a scrap part of the paper. When it is well-coated with lead, I then load a cotton bud by drawing it over this “lead palette”. Use this coated cotton bud to draw the shape of the nebula. Brighter portions may be enhanced by smudging with the finger.

DARK NEBULAE CAN BE CAPTURED with the same approach, although some of them have well-defined borders and are thus more like planetary nebulae. Since some of these nebulae are extremely large, a rich-field telescope, or large binoculars, show them better. Such a wide field, however, often includes a great number of brighter stars, needing a longer time to sketch accurately. I prefer preparing the star-field beforehand, by printing out on an A4 sheet an unlabelled starmap, down to say 8th magnitude. At the eyepiece, the dark nebulae are then filled in on this framework; the idea, after all, is to sketch the nebula, not the background stars.

FINISHING THE DRAWING As you study the field, notice at which edge of the eyepiece the stars appear to move out. Indicate this position on your sketch - this is west. East is on the opposite side, of course. To indicate north, turn the sketch so that east is pointing upward. If you are using a Newtonian, which has two mirrors, north is to the right. If you have a one-mirror system, like a refractor with a star-diagonal, north is to the left.
Don’t forget to also record the date (and time), instrument and eyepieces used, and the observing conditions which may influence the quality of the drawing. Also see the section on using an Observing Checklist for details.

"Any drawing takes considerable time, first at the telescope, then indoors . . . A very simple subject with only a couple of field stars, such as a faint, featureless galaxy, may take only 10 minutes at the telescope. Most subjects take over 30 minutes, and complicated ones like the Orion nebula (M42), several hours"
-- Roger Clark

4. Preparing the final version

SYNTHESIS Your field sketches are not supposed to be finished works of art, but rather rough drafts. For complex objects, you’ll probably have made several drawings. When you’ve completed an evenings sketching, return indoors to prepare a better rendition of your work, under normal lighting conditions. Combine the rough sketches into a composite version and make any corrections that you noted.

THE FINAL TEST When you next observe, take your sketch out to the telescope for a moment of truth. Compare it to the view in the eyepiece, looking for and noting any inaccuracies. In this way, you can ensure maximum fidelity in your final sketch. Your final sketch should readily show the casual viewer what the skilled observer was able to discern only with time and effort at the eyepiece.

5. Reproducing and displaying sketches

MACDONALD SUGGESTS REDRAWING YOUR SKETCHES if they are to be displayed or sent to other observers or observing sections. He redraws the sketch, enlarging it by representing the field of view with a 100mm circle. “This time,” he notes, “different grades of pencil are used to highlight different features. For example, a 4B (very soft) pencil is used for the cores of galaxies or very bright planetary nebulae, and an HB for faint nebulosity. It should be remembered, however, that the relevant positions and brightnesses of the stars and nebulae must be the same as in the original drawing. Otherwise, the drawing will lose its accuracy.”

I much prefer to do the reproduction digitally, by scanning in the final drawing into a computer graphics file. Open clusters can be scanned in and retouched with minimum effort. Nebulous objects require a certain amount of knowledge of graphics editing software to deal with properly. This creates a permanent record with all the benefits of a digital document. If it is necessary to make a hand-drawn copy, photocopy your original, perhaps enlarging it as necessary. Nebulae, which almost always reproduce badly, can now be touched up as discussed above.

“Most of all, practice. There’s no other way to master deep-sky observing. And don’t quit on any object, no matter how vague it may look, until you’ve given it a good, long, thorough scrutiny.”

References

Examples of exquisite sketching may be found in the numerous studies of the Orion Nebula. A good introductory article is: Ashbrook, J. (1975) “The Visual Orion Nebula” Sky & Telescope, November, 299.

Publications that may be interested in your sketches:
Deep Sky Journal; 6210 Karjala Road, Aberdeen WA 98520, USA
Betelgeuse; National Deep Sky Observers Society, 1607 Washington Blvd., Louisville, KY 40242, USA
The Deep Sky Observer; Webb Society, 12 Burton Close, Windlesham, Surrey, GU20 6Q, UK

Mort, G. (1996) “Drawing the Face of Jove” Sky & Telescope, October, 92.
Mitchell, S. (1995) “Have sketchpad, will travel” [In an era when film and CCDs greedily gobble up light from the cosmos, don’t forget to reserve a few photons for you and your trusty sketchpad] Astronomy, July, 76.
Biver, N. (1995) “Drawing the Sky” Sky & Telescope, December, 84.
Macdonald, L. T. (1994) “Sketching the Deep Sky” [You don’t need to be Michelangelo to record the sky’s greatest objects. Grab pencil and paper and head for the stars] Astronomy, January, 76.
Cicchetti, P. (1994) “Drawing Lunar Features” Sky & Telescope, November, 91.
Coleman, D. (1994) “A Personal Martian Chronicle” Sky & Telescope, December, 94.
Macdonald, L. T. (1993) “Visual Recording of Deep-Sky Objects” [Drawing deep-sky objects is both of personal reward and trains the eye to see fine details. This paper presents the author’s own techniques for drawing the deep sky] J. Br. Astron. Assoc., 103, 2, 84-86.
Matty, L. (1990) “To See Planets Better, Draw an Egg” Sky & Telescope, June, 643.
Sweetman, M. (1989) “Reader Reports: Capturing the Universe on Paper” Astronomy, August, 98.
Morel, P. (1988) “Drawing the Sun and Moon” Sky & Telescope, April, 404.
Romer, J. (1984) “Observer’s page: Cheap astronomy: the joy of sketching.” Sky & Telescope, 68(3, September), 277.