Alpha Nine was the designation for a ship used by the Maquis in a joint attack of a Yridian convoy in 2370.
Kalita piloted this ship during the Maquis attack. After the convoy was revealed to be a trap, planned by Starfleet to neutralize Maquis resistance, Lieutenant Ro Laren defected to the Maquis, and Alpha Nine retreated to safety with the rest of the fleet into the DMZ. (TNG: "Preemptive Strike")
This fighter was only mentioned in dialogue.
Based on the ships present in the Maquis fleet, this vessel could be one of the following: a Federation attack fighter, Bajoran interceptor, or Bajoran raider.