That's no moon... that's a space station.
Can't believe no one else said that first...
Seems to me that there shouldn't be much question as to if it's an SIVB or not. Wouldn't it be pretty easy to esablish an ephemeris for each booster?
Seems that we would know it's velocity and trajectory based on that of the rest of the vehicle when separation occured, and a "close enough" guess as to the delta-vee imposed on the booster from the actual separation process, right?
MrPex