Letau was the innermost moon that surrounded the world of Cardassia Prime.

It was home to a high security prison facility that was once run by Gul Skrain Dukat. After his appointment to Bajor as Prefect of that world, he was noted to have made visits to the moon on numerous occasions when he returned home. (DS9 novel: Night of the Wolves)

Cardassia system
Cardassia I • Cardassia II • Cardassia III • Cardassia IV • Cardassia V • Cardassia VI (Blind Moon • Letau) • Cardassia VII • Cardassia VIII