The Full Disk Drawing

In making a full disk drawing, the process should be completed in a series of logical steps.First, use a preprinted observing form that has Jupiter's oblate outline already recorded (Fig. 9.1). There is no scientific value in practicing to draw the perfect disk, and your observing time can be better spent drawing details anyway. The B.A.A and A.L.P.O. have observing forms that anyone can obtain and use. Forms can be reproduced onto heavier drawing paper that will hold up better under nighttime dewing and the inevitable erasures. These forms also provide a place to record data about the observation such as time, weather, seeing and transparency, telescope, eyepieces, filters used, and observing location. All of this information is important to give credibility to the observation. A selection of good artist pencils in various grades of lead are also helpful, as will be a good paper stump for smearing, and a good artist's or architect's eraser for erasing cleanly.

To begin the drawing, you should first observe the planet for several minutes, noting the features that are present. Be patient, use different magnifications and different filters, and see how the planet is going to perform for you. By all means, get into a comfortable viewing position (Fig. 9.2). Prepare yourself for an adventure!

Because Jupiter rotates so rapidly upon its axis, it is obvious in just 20 min that features are moving across the disk as the planet rotates! Therefore, it is imperative that a drawing of Jupiter be completed in 20 min or less. This task seems daunting, but it can be done. If a drawing takes more than 20 min, the placement of features can be skewed and inaccurate.

With form in hand begin the drawing by first sketching in the positions of the north and south equatorial belts. Accurately placing these belts on the drawing is critical and can be a little tricky. Poor placement can adversely affect the subsequent placement of other features during the remainder of the drawing. Bertrand Peek commented on this critical placement of the belts and wrote, "...for it is essential that in making a drawing the conspicuous markings should be used as fiducial points, to which the fainter detail can be related. The author (Peek) confesses that

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System I

System II


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