During the deferi patrol mission there was a breen capital ship sitting in the back in sensor but out of combat range. Naturally being the curious type I attacked it after finishing the mission part. It had an active squadren of fighters (Scorps) that respawned 2 more times before it didnt exist any longer. It had a gravity well also. I was wondering if any others seen this spawn?
There is an accolade for Destroying the three Breen Capital Ships. It is called "Captial Punishment". There is a ship in each of the areas where you help the Defari. I have only seen the one at outpost three. I am not sure what the spawning rate is, but I wish they would increase it to 1 chance in three that it will appear, even if that particular ship has been defeated by the player.
Your best chance at these is to catch the server as it comes up from an update. I haven't seen anything posting a spawn rate but they seem to be active post update quite a bit, which is when I got mine done