Humbolt libration - LUNAR IMAGING with Celestron Beta Tester Richard (Rik) Hill
March 6, 2017
It was a good night for observing on this part of the limb and I noticed that I did not have any good images of Mare Humboldtianum. It's not a difficult feature to find if the libration is favorable. You go to Atlas and Hercules, more move east (lunar east) to the large, 129km diameter crater Endymion, seen in the lower middle of this image with its floor streaked with rays from the Thales impact to the north, and a little further on is the Mare. Endymion is an ancient crater possibly over 4 billion years old. Notice the unnamed rille that goes from the southeast wall of Endymion to the 20km crater Endymion farther to the east. Mare Humboldtianum is just over 270 km in diameter but it sits in Humboldtianum basin that is nearly three times larger. You can see a large ray crossing the northern end of . Tracing the ray back it appears to come from the region of Mare Crisium, possibly the bright recent crater Proclus?
The large flat expanse north of the mare is Bel'Kovich (204km) and a little further on is the very clear crater Hayn (90km) with very clear central peak and a dark shadow on the southern wall. This central peak is a curious formation clearly divided into quadrants by wide valleys.
That's only hinted at in this image. The crater beyond Hayn is Bel'Kovich K (47km). Seems a shame that a crater of this size is given such an inferior name but then it is not often visible due to libration.
Each image of this two image montage was made from 400 frames of a 1200 frame AVI selected and stacked with AviStack2 and then assembled with iMerge. Further processing was done with GIMP and Irfanview.
Celestron Product used: Skyris 445M