PhotoObj pairs from different runs (times) that probably are the same object.

SDSS primary and secondary objects of type STAR, GALAXY, and UNKNOWN within 1 arcsec of one another and from different runs (so two different observations) Table also holds type, mode and distance information. See also MatchHead Table.

Index TypeKey or Field List
primary keyobjID, matchObjID
foreign keyPhotoObjAll(objID)