Raptor 3
From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
Raptor 3 was a Raptor deployed to scout the planet Kobol. It was destroyed by collision with a Cylon Raider almost immediately upon entering orbit.
Since the same craft is referred to as both Raptor 2 and Raptor 275, it is unknown of this is meant to be the same craft as Raptor 312.