I am trying to use JSkyCat to mark a set of coordinates on a FITS image, and have found the dialog for choosing a catalog file to load. However, I am having trouble finding any documentation on what format it expects (and my guesses have been unsuccessful).
OK, my initial guess is the VOTable format, but after some digging I found that the format is one of .cat, table and scat. You can save any catalogue as a local file and open it in the editor and see.
Generally speaking JSkyCat should in principle take on many formats as the GaiaSkyCat or SkyCat does since it is developed from that. The software also "listens" to the Simple Application Messaging Protocol (SAMP) servers, so that's the reason that I think VOTable is its choice.
EDIT: I found some documentation at the features page for JSkyCat where it actually confirms my guess.