August 31, 2013

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Lonely Twins

image by Ramón García Durán, Barcelona, Spain

The Moon has a number of craters that always seem to be thought of as pairs, including Aristoteles and Eudoxus, Aristillus and Autolycus, Agrippa and Godin, Sabine and Ritter, and of course, the most famous pair of all Atlas and Hercules. The latter two are in Ramón's large mosaic that I clipped this small area from, but I skipped past them on purpose to look at a less visited pair and its surroundings. Franklin (59 km) and Cepheus (39 km) are smaller versions of A & H, with Franklin being remarkably similar to Atlas. Both are floor-fractured craters (you can see some of the rilles on Franklin's floor) and both overlap an older shallower crater. Like Atlas, Franklin also has a pronounced glacis (an elevated outer rim for those of you not familiar with 18th century crater nomenclature) that is well seen where it overrides the unfortunate crater to the south. Cepheus is somewhat similar to Hercules in being smaller, somewhat older and having a crater cutting into its rim. Limbward of F & C are five named craters that almost no one can identify at the telescope: Oersted, Chevallier, Schuckburgh, Hooke (a favorite scientist of mine, maligned by Newton) and Berzelius. Finally, in the bottom, center of the image are 4-6 rough-textured mounds, but I can't see any easy explanation for their existence. Usually such mountains are pieces of the rims of degraded basins and these are near a proposed rim of the putative Procellarum Basin, but I am unimpressed.

Chuck Wood

Technical Details
2013-08-24 / 02:01 U.T. (average). Lunation: 17.26. Seeing: 6-10 Trans: 5/5 Altitude: 54.4º. Barcelona, Spain.
Newton 200 mm. f/5 (f/15 with Barlow X3) + Camera: DMK 41 (a friend lent me, thanks, Zequi :) + IR filter.
12 videos (mosaic); Image processing: AutoStakkert! 2 / Astra Image / Photoshop.

Related Links
21st Century Atlas chart 9.

Yesterday's LPOD: Land of Lakes

Tomorrow's LPOD: Thrice Battered


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