Rostron said that the sighting took place around 3:15, Carpathia was about 45 minutes from picking up the first boat if his time was correct. If that was between T and C earlier, then it had to be pass very close to T and the time she foundered. Nobody saw any vessel very close, by or passing close by, at that time. What always bothered me about that tidbit from Rostron is how he left it. He never said what happened to it after that sighting. We do know that hey spotted a green flare from boat #2 fine off their port bow, almost directly ahead, about then, and they fired rockets in response, but that is all we really know about Rostron's mystery ship. There are others (which shall be unnamed) who try to insinuate that this vessel may have been the one seen from Californian at 4am, which is the time Carpathia arrived by the lifeboat.