Intercept 1 is the callsign of the Viper initially assigned to Captain Apollo.
However, disgruntled over the fact that Serina is assigned as Apollo's wingman, Lieutenant Starbuck commandeers the ship, claiming that he and Apollo switched patrols. He launches before Apollo, Serina and Colonel Tigh are able to stop him. Intercept 2 and Intercept 3, with Apollo and Serina respectively, launch to pursue Starbuck.
Using Intercepts 2 and 3 as a means to keep a fix on Galactica, Intercept 1 exits the void to investigate the blip pursuing them, only to be captured by a patrol from Baltar's basestar as part of Baltar's plan to convince the Colonials that he comes bearing a peace proposal on behalf of the Cylon Empire (TOS: "Lost Planet of the Gods, Part II").