2011ApJS..194...20P

We present the Galactic Arecibo L-Band Feed Array H I (GALFA-H I) survey and its first full data release (DR1). GALFA-H I is a high-resolution (∼4'), large-area (13,000 deg2), high spectral resolution (0.18 km/s), and wide band (-700 km/s < v_LSR< +700 km/s) survey of the Galactic interstellar medium in the 21 cm line hyperfine transition of neutral hydrogen conducted at Arecibo Observatory. Typical noise levels are 80 mK rms in an integrated 1 km/s channel. GALFA-H I is a dramatic step forward in high-resolution, large-area Galactic H I surveys, and we compare GALFA-H I to past, present, and future Galactic H I surveys. We describe in detail new techniques we have developed to reduce these data in the presence of fixed pattern noise, gain variation, and inconsistent beam shapes, and we show how we have largely mitigated these effects. We present our first full data release, covering 7520 deg2 of sky and representing 3046 hr of integration time, and discuss the details of these data.