Hi Andrea,
the decaps_dr1.object table now offers .ra and .dec columns in the x-match web tool. Take it for a spin!
Regarding the issue with a mydb table not being available... Can you please post a minimal code sample here, or send us a minimal notebook file (to datalab@noirlab.edu) that shows what you are trying to do, and how it fails? (It would be much easier for us to diagnose it then.)
Thank you!
Robert