White, Lubow & Shiao (2022) improved the algorithm by utilizing Gaia EDR3 and correcting for the effects of DCR in declination. generally vary with color and declination in a way consistent with the effects of atmospheric differential chromatic refraction (DCR). Paper 2: Corrections for Differential Chromatic RefractionĪfter the correction procedure from Paper 1, the remaining declination positional residuals at a given decl. Residuals are shown before (blue) and after (red) the Gaia correction. the declination errors increase with zenith angle in proportion to the air mass of the observations and depend on the colors of the stars.įigure 2: Median PS1/Gaia DR2 position residuals in mas (left) and proper-motion residuals in mas/yr (right) as a function of PS1 i-band PSF magnitude for PS1 reference objects. The residual errors in declination are systematically larger than those in R.A. The residuals for the corrected positions are smallest for objects with the most point-like morphologies and with intermediate magnitudes of about 17 mag (see Fig. Systematic errors are improved by even larger factors since the remaining residuals are dominated by random measurement errors.
A spatially adaptive correction algorithm using nearby PS1 objects that are also in the Gaia catalog reduces PS1/Gaia residuals by 33% in position (median value of 13.5 mas reduced to 9.0 mas) and by 24% in proper motion (median value of 6.3 mas yr -1 reduced to 4.8 mas yr -1). A cross-match between Gaia and PS1 revealed residuals that are correlated on a scale of about 1 arcmin (see Fig. They also computed proper motions for these PS1 objects. Lubow, White & Shiao (2021) used the Gaia DR2 catalog to improve the astrometric accuracy of about 1.7 billion objects in PS1 DR2, including objects with detections at 3 or more epochs. Paper 1: Improvements to Pan-STARRS1 Astrometry Using Gaia However, for most users the new values are preferred. See the Astrometr圜orrection table if access is required to the positions before the Gaia EDR3 corrections.
The ObjectThin table's raMean, decMean and their associated error columns have been updated, and new columns have been added with proper motions ( pmra, pmdec) and errors along with a new flags column astrometryInfoFlags.
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