The Straight Wall Shows Off

 by Matt Allard, Diane Murray and Philip Steffey



In the evening of September 30, 2006, we three observed with the C-14 telescope for the first time in four months.  No bright planets were accessible after dusk but a nine day-old moon was in a clear southern sky.  As always, it was a great view at low-medium magnification (100,150X), and we had a new way to image it with less fussing than videography.  After Diane had obtained small but promising still pictures of Saturn in April with a handheld digital camera, it was obvious that the Moon and Sun would be much better objects at low power. (This camera must be used with its lens in place, so the telescope must be afocal (i.e. used with an eyepiece.)


Diane had her camera handy for the September session and promptly shot several pictures of the Moon, two of which, processed mainly for contrast, are reproduced in black & white below.  A few major impact craters are labeled.  The outstanding surface feature, visually and in the digital pictures, was the Straight Wall, a 70 mile-long fault like terrestrial escarpments.  Rising gradually from the lunar eastside ( left in the pictures), its crest is 1000 feet above the westside ground, so soon after sunrise there--phase age 8-9 days - it casts a shadow more than a mile wide.  Just before sunset at the Straight Wall--age 21-22 days--there is no sensible shadow; the crest appears as a light streak in the eastern Mare Nubium resembling an isolated crater ray segment.


For a first-time attempt, Diane’s pictures were  fine, and more of the lunar disc can be imaged by using the telescope’s focal reducer and/or wider-field eyepieces.  An eyepiece-adapter tube is planned to hold the camera and center its lens in  or around the exit pupil beam.   Beyond the ordinary Moon, we foresee applications to lunar eclipses, close Moon-planet conjunctions, the active Sun, solar eclipses, and other transient phenomena involving the Moon or Sun.








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