3 occurrences in 3 dictionaries

Reference: Athach

Hastings

Unknown town in the south of Judah.

A'thach

City in the south of Judah. 1Sa 30:30.

A'thach

(lodging place).

As the name does not occur elsewhere, it has been suggested that it is an error of the transcriber for Ether, a town in the low country of Judah.