Janssen Near the Edge - LUNAR IMAGING with Celestron Beta Tester Richard (Rik) Hill
February 27, 2017
Libration is the term that describes the apparent wobble of the moon during the course of a lunar day. This allows the observer to see about 9% more of the moon than would otherwise be available. It is usually denoted as the lunar latitude and longitude of the center of the visible disk. Most lunar observers will concentrate on the limb of the moon that is tipped towards us showing more of the "backside" of the moon. But the other limb can offer some very interesting opportunities as well. In this image we have one of those where Janssen, the large 196km diameter largely ruined crater with the beautiful system of rimae contained within. Normally this is seen as a more round feature, farther from the limb but in this image it is about as close to the limb as it can be.
The crater to the immediate right of Janssen is Fabricius (80km) with the odd mountain chain in a sideways square "U" shape open to the left, on its floor. Below Janssen are two craters Steinheil (70km) overlapping the lower Watt (68km). To the left of these are another, larger pair of craters. The upper one with a nice central peak is Valcq (92km) and the lower is Rosenberger (99km).
In the very cusp or tip of this image can be seen a strongly foreshortened crater, Schomberger (88km) and down along the limb from that is a larger crater, half filled with shadow, Boussingault (134km).
These are 70-76 deg. lunar latitude. Were this libration the reverse of this night, all these would be well seen.
Selection and stacking was done with AviStack2. Further processing was done with GIMP and IrfanView with assembly of the montage done with iMerge.
Celestron Product used: Skyris 445M
