The Cichus – Weiss Region

Cichus is a well-defined crater some 25 miles in diameter situated at the southern end of the mountain barrier dividing the Palus Epidemiarum from the Mare Nubium. The surrounding walls of the crater are lofty and of the order of 8000–9000 ft above the depressed interior on which faint details can be seen under a higher light, but nothing resembling a marked central elevation. Crater A, 7 miles diameter, on the crest of the western wall of Cichus is very bright at sunrise and has a characteristic hooked aspect when seen around colongitude 20°.5.

The object of the 1983 February 21 observation was to examine the eastern section of the Hesiodus rille with particular attention to where it encounters the barrier running north from Cichus and to determine, if possible, whether its course could be traced in the interstices of the mountain range as the shadows lifted.

The region embracing the ruined formation Weiss to the NE of Cichus was also found to be one of absorbing interest and prompted the inclusion of this area in the drawing. Weiss's inner west wall showed, in addition to terracing, a banded appearance and, as the illumination proceeded, the narrow defile of a rille which runs approximately parallel to the larger Hesiodus rille, could be discerned by its penetration of the barrier.