Tau Quadrant is a solar system adjacent to Otarsis Quadrant.
Lieutenant Brie detects and reports an unknown blip from Tau. Lieutenant Starbuck initially believes the blip to be Doctor Salik's medical shuttle, but is subsequently proven wrong as the blip is actually a Cylon [[Raider (TOS)|.
Before the Raider is neutralized, it sends off a warning to the listening post, thus beginning the Battle of Otarsis Quadrant (Lost Planet of the Gods, Part I)