While observing the moon on the last evening of August, I was looking for a target to sketch while I was enjoying the view. I wanted to pick a crater or two I had never sketched before but one that would be an interesting target. It wasnâ€™t long before the ancient crater pair of Klaporth and Casatus caught my eye and both together became my target. Klaproth and Casatus are Pre-Nectarian period impact scars on the lunar southern highlands. Klaproth is the larger and older of the two with a diameter of 119 km compared to 111 km for Casatus. It is easy to see that crater Casatus slightly overlaps the southern wall of Klaporth but both craters appeared to have taken a terrific beating over a very long time. Neither of these large walled-plain craters exhibits a central peak and both have nearly flat floors. Small craters on these floors were appearing off and on in the eyepiece during the sketch as the seeing improved for brief intervals. The rims of both craters are high above the floors. The top of the rampart of Casatus stands nearly 6 km above its floor. The light color to the floors of these craters has led lunar geologist Chuck Wood to speculate they may be the result of non-mare volcanism (see LPOD for August 5, 2006 http://www.lpod.org/?m=20060805)
I feel I spent quality time observing and attempting to capture the view of this southern highland pair.
For this sketch I used: white sketching paper 10â€x 8â€, HB, 4B, 6B graphite pencils, a blending stump and a gum eraser. After scanning, Brightness was decreased (-3) and contrast increased (+2) using Microsoft Office Picture Manager.
Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241x
Date: 9-1-2009, 3:30 - 4:45 UT
Temperature: 15Â° C (58Â° F)
clear, calm, 45% humidity
Seeing: Antoniadi III
Lunation 11.9 days
Illumination 90 %