Photometric Calibration of the First 1.5 Years of the Pan-STARRS1 Survey

TL;DR

This paper details a highly precise photometric calibration method for the Pan-STARRS1 survey, achieving sub-10 millimagnitude accuracy across five optical bands over a large sky area.

Contribution

It introduces a calibration technique that simultaneously accounts for system throughput, atmospheric transparency, and detector flat field, improving photometric precision.

Findings

Achieved <10 mmag relative precision in three bands

Achieved ~10 mmag precision in two bands

Demonstrated potential for <1% photometry over large sky areas

Abstract

We present a precise photometric calibration of the first 1.5 years of science imaging from the Pan-STARRS1 survey (PS1), an ongoing optical survey of the entire sky north of declination -30 degrees in five bands. Building on the techniques employed by Padmanabhan et al. (2008) in the Sloan Digital Sky Survey (SDSS), we use repeat PS1 observations of stars to perform the relative calibration of PS1 in each of its five bands, solving simultaneously for the system throughput, the atmospheric transparency, and the large-scale detector flat field. Both internal consistency tests and comparison against the SDSS indicate that we achieve relative precision of <10 mmag in g, r, and i_P1, and ~10 mmag in z and y_P1. The spatial structure of the differences with the SDSS indicates that errors in both the PS1 and SDSS photometric calibration contribute similarly to the differences. The analysis suggests that both the PS1 system and the Haleakala site will enable <1% photometry over much of the sky.