부산대학교 도서관

We use the Gaia DR2 catalog to improve the astrometric accuracy of about 1.7 billion objects in Pan-STARRS1 Data Release 2 (PS1 DR2). We also obtain proper motions for these PS1 objects. The cross match between Gaia and PS1 reveals residuals that are correlated on a scale of about 1 arcmin. We apply a spatially adaptive correction algorithm for all PS1 objects having more than two detections to reduce these residuals and align the object positions to Gaia. For point-like PS1 objects that cross match to Gaia, the algorithm 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 reduced to 4.8 mas/yr). The residuals for the corrected positions are smallest for objects with the most point-like morphologies and with intermediate magnitudes of about 17 mag. The residual errors in declination are systematically larger than those in right ascension; the declination errors increase with zenith angle in proportion to the air mass of the observations. Declination positional residuals at a given declination generally vary with color and are consistent with the effects of differential atmospheric refraction. In principle, these residuals could be reduced further by taking into account object color.
Comment: 22 pages, 31 figures