The Pan-STARRS 1 Photometric Reference Ladder, Release 12.0

Abstract

As of 2012 Jan 21, the Pan-STARRS1 (3\pi) Survey has observed the 3/4 of the sky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in 5 filters, (g_{\rm P1},r_{\rm P1},i_{\rm P1},z_{\rm P1},y_{\rm P1}). Now at the end of the second year of the mission, we are in a position to make an initial public release of a portion of this unprecedented dataset. This article describes the PS1 Photometric Ladder, Release 12.01 This is the first of a series of data releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in RA and at 4 intervals in declination. We will release updates with increased area coverage (more rungs) from the latest dataset until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of (\sim 1000) objects per square degree in the rungs of the ladder. Saturation occurs at (g_{\rm P1}, r_{\rm P1}, i_{\rm P1} \sim 13.5; z_{\rm P1} \sim 13.0;) and (y_{\rm P1} \sim 12.0). Photometry is provided for stars down to (g_{\rm P1}, r_{\rm P1}, i_{\rm P1} \sim 19.1) in the AB system. This data release depends on the rigid `Ubercal' photometric calibration using only the photometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7, 12.4) millimags in ((g_{\rm P1},r_{\rm P1},i_{\rm P1},z_{\rm P1},y_{\rm P1})). Areas covered only with lower quality nights are also included, and have been tied to the Ubercal solution via relative photometry; photometric accuracy of the non-photometric regions is lower and should be used with caution.