Hitchhiker's Guide to Rukl Chart 36

Cauchy Hyperbolas -- Rima and Rupes Cauchy (...Akkana)

On Rukl's chart 36, Rima and Rupes Cauchy make a striking pair of parallel slashes flanking their namesake crater in Mare Tranquilitatus; and in the photo appendix he shows a photo of this area, equally striking. I tried for many months to get a glimpse of the "hyperbolas". At 4/15/98 12:30am PDT, with the area in sunset and the terminator passing through the prominent Macrobius, Rupes Cauchy stood out as a bright line (just as Rukl says: it casts a shadow at sunrise, but appears bright at sunset), but I was unable to see any trace of Rima Cauchy.

Finally, on 3/21/99 at 7:30pm PST, I got a good view of both of them. The rille was still quite a bit less prominent than the wall, but the pair was eyecatching and obvious in a 6" Newtonian.

The strong impression they give is that the area between the hyperbolas is a plateau, raised compared to the area outside; I was unable to shake this impression although I don't believe it to be true.

Cauchy Domes (JRF <freeman _at_ netcom.com>)

Note the domes, Cauchy tau and Cauchy omega, across Rupes Cauchy from the crater itself.

Rima Cauchy I (JRF <freeman _at_ netcom.com>)

This rille passes north of Cauchy crater. It runs northwest / southeast.

Rupes Cauchy (JRF <freeman _at_ netcom.com>)

Although labeled a wall, this formation is perhaps best described as a rille that is higher on one side than on the other. It runs northwest / southeast, and passes south of Cauchy crater.

Jansen and Rima Jansen (...Akkana)

A very smoothly filled crater with a nearby rille.