GALEX and 2MASS astrometry

I spent the early morning hours learning how the GALEX and 2MASS missions do their astrometry. They are both impressive, both possibly better than any standard astrometric catalog, though both have possible remaining systematics. It is hard to tell from the documentation of either mission what systematics have been explored to date. Certainly the people working on these projects did not see themselves as producing astrometric standards, even though that is exactly what they have produced, beautifully.