Triesnecker and Sinus Medii

Sinus Medii is so called because, when the Moon is in its mean position librationwise, it is in the middle of the visible face. Consequently the equator and the prime meridian pass through it and my mouseover of the first image shows where they run.
Triesnecker, at 27 Km in diameter, is a typical example of complex crater in the range of 10 to 35 Km.  For such craters, the rocks at the bottom of the inner wall are not strong enough to support the overlying rock and the walls collapse into the crater.  This results in a crater whose depth, relative to the diameter, is less than for smaller craters.  In addition, the compression of the rocks by the larger missile causes a rebound which gives rise to a central mountain.

Sadly, neither of the features of complex craters is visible in this image of Triesnecker as the Sun was too low in the lunar sky to illuminate the inside of the crater.  The features are, however, visible in the much older (and larger) craters, Pallas and Rhaeticus. The picture was taken with an Atik camera attached to my LX200 on 12th December 2006 when the Moon was 21.7 days old. Date and Time: 12 December 2006 05:44 UT Camera: Atik 1-HS Telescope: LX200 Capture: K3CCDTools. High gamma, 1/100", 12% gain, 506 frames Processing: Registax. 8 alignment points, 468 frames stacked. Wavelet 1-2 = 10, histogram 10-185

And here the same area imaged with the light coming from the east.  The sun was somewhat higher so we can see into Triesnecker.  Although the central mountain is still not visible, the terraced western wall can be made out.  There are many rilles in this area some of which stand out in this picture.  Rima Hyginus is 226 Km long and about 3 Km wide.  The Triesnecker rilles are a complex series of narrow cracks which are not well resolved here. The scale markers represent approximately 100 Km north and east. The picture was taken with an Atik camera attached to my LX200 on 26th March 2007 when the Moon was 8.4 days old. Date and Time: 26 March 2007 20:11 UT Camera: Atik 1-HS Telescope: LX200 Capture: K3CCDTools. High gamma, 1/100", 19% gain, 462 frames Processing: Registax. 12 alignment points, 417 frames stacked. Wavelet 1-2 = 10, gamma 1.2, histogram 0-200

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