| 9 | 11 | The STS astrometry showed offsets in the positions of stars in about half of the chips, with mean offsets of about 0.8 pixels. Gene first characterized this, and showed that changing the stars used for the astrometry from the brightest non-saturated stars to fainter stars improved the agreement for the majority of stars, although it created a trend of bright stars having larger position offsets, as shown in the following figures (x is the reference catalog magnitude, y is the shift in RA in arcseconds). |
