Cauchy is a small crater in the eastern parts of Mare Tranquillitatis. The crater itself is bright but rather unassuming, although it is nicely framed by about 100 km long rille to the north (Rima Cauchy) and an even longer fault to the south (Rupus Cauchy).
At the eyepiece and with excellent seeing they were both an easy catch. Unfortunately I forgot to look for the two domes that can be found to the south of the fault.
This 166 km long valley cuts straight through Montes Alpes, and connects Mare Imbrium to the southwest with Mare Frigoris to the northeast. The valley is believed to be a graben flooded with material from the adjacent mares.
Under excellent conditions a rille can be seen bisecting the valley, but not so during my observation.