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The positions of DR1 sources were originally determined from the astrometric calibration of PanSTARRS using sources in common with the 2MASS catalog.  The systematic uncertainty in this calibration is not precisely known, but is likely to be close to 0.1".

However, the positions of the mean objects in the DR1 release catalog were recalibrated using Gaia DR1 positions as additional constrains in the astrometric solution.  The Gaia measurements were given very high weight, as detailed in Magnier et al. (2016).  A comparison of Gaia and PanSTARRS positions for the objects in common suggests yields a typical uncertainty residual of 5 mas (1-sigma, 2-d), with a slightly higher component in the direction of right ascension.  This comparison may not fully reflect PanSTARRS position errors, because of the correlation in the quantities that weer compared (Gaia measurements are included in the determination of individual PanSTARRS positions).

An independent test of sources with Gaia data that were not used in the recalibration suggests that the residual systematic uncertainties for recalibrated PanSTARRS positions is closer to 20 mas (1-sigma, 2-d) for sources with Gaia magnitudes between G=15 and G=18, increasing for fainter magnitudes to about 35 mas at the Gaia magnitude limit (G=21.7).  Errors are larger towards brighter magnitudes as well, possibly because saturation and proper motion effects become significant in the PanSTARRS measurements.  It is likely that systematic uncertainties of 20 mas (1-sigma, 2-d) apply to all mean objects in PanSTARRS DR1, with possibly larger uncertainties in regions with a scarcity of sources in common between Gaia and PanSTARRS.  In addition, each mean source has a statistical measurement uncertainty reported in the following fields in the ObjectThin table:

Note that the stack object astrometry has not been recalibrated with Gaia constraints, and therefore is likely to include the larger systematic uncertainty from the 2MASS calibration.

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