Pan-STARRS Photometric and Astrometric Calibration

Abstract

We present the details of the photometric and astrometric calibration of the Pan-STARRS1 3 π  Survey. The photometric goals were to reduce the systematic effects introduced by the camera and detectors, and to place all of the observations onto a photometric system with consistent zero-points over the entire area surveyed, the ≈30,000 deg 2 north of δ  = −30°. Using external comparisons, we demonstrate that the resulting photometric system is consistent across the sky to between 7 and 12.4 mmag depending on the filter. For bright stars, the systematic error floor for individual measurements is ( σ g , σ r , σ i , σ z , σ y ) = (14, 14, 15, 15, 18) mmag. The astrometric calibration compensates for similar systematic effects so that positions, proper motions, and parallaxes are reliable as well. The bright-star systematic error floor for individual astrometric measurements is 16 mas. The Pan-STARRS Data Release 2 (DR2) astrometric system is tied to the Gaia DR1 coordinate frame with a systematic uncertainty of ∼5 mas.