| | 1 | I've been investigating the PS1 astrometry and stumbled across some odd features. When comparing PS1 to the SDSS, there was a ~.1 arcsecond systematic offset in the astrometry. I then compared PS1 to 2MASS, and recovered the same ~.1 arcsecond offset. This is particularly troubling as the PS1 astrometry is tied to 2MASS via the synthetic catalog, which is based on 2MASS data combined with USNO data as available. |
| | 2 | |
| | 3 | I then compared 2MASS to the synthetic catalog matched references, which I expected to be themselves 2MASS objects. The result was the following: |
| | 4 | |
| | 5 | [[Image(PS1_2MASS_astrometry_fig)]] |
| | 6 | |
| | 7 | More later, but the synthetic catalog is actually a combination of 2MASS positions and USNO positions, which could be the cause. |
