Lunar hour

A lunar hour was a unit of time measurement employed by the Federation as late as 2266.

While en route to planet Zarta, a USS Enterprise bridge officer gave the estimated time of arrival as "two lunar hours one galaxy minute." (TOS comic: "Invasion of the City Builders")

A lunar hour is typically the time it takes a moon to complete one rotation in respect to its parent planet's star. However, no moon-star system has been defined as the basis for a lunar hour.