Data Reduction Frequently Asked Questions

How good is HAWK-I astrometry?


The new HAWK-I pipeline ( astrometrically calibrates its science exposures using 2MASS stars in the field. The astrometric solutions are generally good to 250 milli-arcseconds, with no discernible systematic residuals, however, individual images can be slightly worse. 


Figure 1: the astrometric quality of the HAWK-I reprocessed tiles as measured by comparing the HAWK-I source lists with the 2MASS catalogue.  The standard deviation of the Δα*cos(δ) and Δδ distribution is 0.2 arcsec. This is close to the accuracies of the 2MASS point source catalogue.