If I find an asteroid in SDSS is there anywhere I can find out if it is already known about? Or if not report it, I was going to post on Asteroid Zoo but that seems to have been shut down? I tried Aladin and nothing came up.
Sorry to take so long to reply to you Ptd.
There are at least four releases of the "Sloan Digital Sky Survey Moving Object Catalog"; here is a link to release #4 (here is a link to the AAS presentation where it was first made public). I've never tried to use it, but it looks reasonably straight-forward (for a large, publicly available dataset).
I think the team who produced this catalog likely did a very thorough job of identifying moving objects in SDSS (other than airplanes, meteors, and such 😉), up to at least DR7 (and I'm not sure how much new SDSS photometry there is in later releases; certainly a lot of new spectroscopy). So I think a good 0-th level assumption would be that anything you come across in an SDSS image and which looks obviously like an asteroid is in the MOC.
If you're interested in following up on anything you find, other than by checking the MOC, I'd recommend first checking to see if the asteroid is obvious in the relevant DR7 Navigate field. If it is, may be worth leaving it to follow up another day.
As all SDSS asteroid observations were reported to the Minor Planet Center (MPC), I guess you could also try to find whether an asteroid you came across was indeed reported ... but I don't know how you'd go about doing that 😦
Hope this helps, and happy hunting! 😃