THE GALFA-HI SURVEY: DATA RELEASE 1

Abstract

We present the Galactic Arecibo L-Band Feed Array HI (GALFA-HI) survey, and\nits first full data release (DR1). GALFA-HI is a high resolution (~ 4'), large\narea (13000 deg^2), high spectral resolution (0.18 km/s), wide band (-700 <\nv_LSR < +700 km/s) survey of the Galactic interstellar medium in the 21-cm line\nhyperfine transition of neutral hydrogen conducted at Arecibo Observatory.\nTypical noise levels are 80 mK RMS in an integrated 1 km/s channel. GALFA-HI is\na dramatic step forward in high-resolution, large-area Galactic HI surveys, and\nwe compare GALFA-HI to past, present, and future Galactic HI surveys. We\ndescribe in detail new techniques we have developed to reduce these data in the\npresence of fixed pattern noise, gain variation, and inconsistent beam shapes,\nand we show how we have largely mitigated these effects. We present our first\nfull data release, covering 7520 square degrees of sky and representing 3046\nhours of integration time, and discuss the details of these data.\n