The eponymous Ravashol pulsar is Dr. Ravashol's creation, designed to be a peaceful but powerful communications device transmitting information through laser energy. Built into the side of Mount Hekla by Ravashol's Theta-class lifeforms, the device is captured during the Cylon Empire's occupation of Arcta.
In the aftermath of the Battle of Cimtar, the Cylons establish a garrison lead by Vulpa to guard the instrument, utilizing it as an offensive weapon that is capable of destroying Galactica in a single pulse, in addition to the other ships under her protection.
Otherwise undetectable by long range scans, Cadet Cree's scans record the pulsar's ramparts are fourteen metrons high and a destructive power infinite within a span of two hectars (TOS: "The Gun on Ice Planet Zero, Part I").
Captain Apollo leads a specialized band of Colonial Warriors (including prisoners) in a successful mission to destroy the emplacement, with the assistance of Ravashol and the Thetas, thus allowing the Fleet to safely pass Arcta (TOS: "The Gun on Ice Planet Zero, Part II").