is a bowl-shaped lunar impact crater
with a slightly raised rim. It is located on the floor of the walled plain Ptolemaeus
, about 30 kilometers
northeast of the crater mid-point. In the past this crater was identified as Ptolemaeus A, before being named by the IAU
Just to the north on the lava-flooded floor of Ptolemaeus is a relatively prominent "ghost" crater: the discernible buried rim of a pre-existing crater. The diameter of this ghost crater is nearly double that of Ammonius, and is currently identified as Ptolemaeus B.