THE PAN-STARRS 1 PHOTOMETRIC REFERENCE LADDER, RELEASE 12.01

Abstract

As of 2012 Jan 21, the Pan-STARRS 1 3\\pi Survey has observed the 3/4 of the\nsky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in 5\nfilters, g_p1, r_p1, i_p1, z_p1, y_p1. Now at the end of the second year of the\nmission, we are in a position to make an initial public release of a portion of\nthis unprecedented dataset. This article describes the PS1 Photometric Ladder,\nRelease 12.01 This is the first of a series of data releases to be generated as\nthe survey coverage increases and the data analysis improves. The Photometric\nLadder has rungs every hour in RA and at 4 intervals in declination. We will\nrelease updates with increased area coverage (more rungs) from the latest\ndataset until the PS1 survey and the final re-reduction are completed. The\ncurrently released catalog presents photometry of \\approx 1000 objects per\nsquare degree in the rungs of the ladder. Saturation occurs at g_p1, r_p1, i_p1\n\\approx 13.5; z_p1 \\approx 13.0; and y_p1 \\approx 12.0. Photometry is provided\nfor stars down to g_p1, r_p1, i_p1 \\approx 19.1 in the AB system. This data\nrelease depends on the rigid `Ubercal' photometric calibration using only the\nphotometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7,\n12.4) millimags in (g_p1, r_p1, i_p1, z_p1, y_p1). Areas covered only with\nlower quality nights are also included, and have been tied to the Ubercal\nsolution via relative photometry; photometric accuracy of the non-photometric\nregions is lower and should be used with caution.\n