Celestial chambers (or celestial temples) are areas on Galactica and other battlestars where navigational readings were taken hundreds of yahren prior to the destruction of the Colonies.
Apollo finds an unused celestial temple housed near one of Galactica's engines. Being the only known celestial temple in existence, Apollo repairs it.
Celestial temples were mostly removed from battlestars in the Colonial service, as their use was superseded by advanced technologies.
Celestial temples are comprised of transparent tylinium and had shutters that could close when not in use (TOS: "The Hand of God").
Notes
- The celestial chamber is reminiscent of a 17th century Earth seafarer's navigational tool called a sextant. Sextants, too, are all but obsolete as technology developed, but are popular collectors' items.