Field Drawing

Perhaps the most enjoyable way of permanently recording a double star observation is to make a field drawing, together with a short written description of the object under study. Sketching trains the eye to notice fine detail and the results can be both personally rewarding and scientifically useful.

Before starting to sketch, it is necessary to prepare some blank circles to represent the field of view. These may be drawn using a pen and template or on a com-puter/wordprocessor. A field diameter of 6 cm enables six circles to fit on a sheet of A4 paper, allowing sufficient space for captions and notes. For those

Figure 3.3. An example of a field drawing. 27 Hydrae (7 x 50 binoculars).

observers who do not own a printer, it may be convenient to produce a page of blank circles which can be photocopied as required.

Other items needed for field drawing are a medium grade black pencil, eraser, sketch-board and a red torch. Especially useful is the "clip-on" design of torch, which can be attached to the drawing board, allowing the observer to sketch more easily.

The next three steps involve finding a light-free observational position, securing the binoculars to a mounting and choosing a suitable double star. Celestial objects near the meridian (due south in the northern hemisphere and due north in the southern hemisphere) are easy to follow because their altitude does not vary much as they cross that part of the sky. After locating the double and before sketching, it may be worth panning the binoculars slightly in altitude and azimuth to obtain the most interesting field of view.

One method of creating a sketch is to begin by drawing the components of the double and the brightest field stars that are visible. Fainter ones can then be added, using the principal stars as reference points. The larger the pencil dot, the brighter the star it represents.

An alternative technique involves dividing the field of view into four equal segments or quadrants and

Figure 3.3. An example of a field drawing. 27 Hydrae (7 x 50 binoculars).

drawing all the stars visible in each section. This approach is, however, probably better suited to telescopic observation, where the field can be accurately divided using an eyepiece fitted with cross-hairs.

The pencil sketch can be overwritten with black ink, if desired, and supplemented by a brief caption. A concise field description could also be included, either with the diagram or, if preferred, in a separate notebook or on a database. An example of a completed field drawing is shown in Figure 3.3. This diagram has been reproduced from the publication A Visual Atlas of Double Stars3 which contains observational details of more than 300 double stars suitable for both binoculars and telescopes.

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