Ctesibius is a small lunar impact crater that is located near the equator, on the far side of the Moon.

[1] It lies between the larger crater Abul Wáfa to the west and the slightly smaller Heron to the east.

The outer wall of Ctesibius is wide and sharp-edged, with little erosion.

A low ridge is attached to the southern rim, and curves to the south-southeast.

Faint traces of ray material lies across the western floor and rim from Necho to the southeast.