Are the answers right?
The overlaps between images are a rigorous test of our internal
With the CTIO 0.9-m we get to a few milli-mags.
We have done photometry of standard fields, as though they were
data,and this suggests we typically get to within 2% of the standard
Checking one catalogue against another suggests our relative positions
are good to 0.05 arcsec.
Correlations with catalogues like 2mass and SuperCosmos give RMSs of
around 0.17 arcsec, presumably driven by their accuracy.