The GALFA-H i Survey Data Release 2

We present the Galactic Arecibo L-Band Feed Array H i (GALFA-H i ) survey data release 2 (DR2). The survey covers the 21 cm hyperfine transition of Galactic H i from −650 to 650 , with 0.184 channel spacing, 4′ angular resolution, and 150 mK rms noise per 1 velocity channel. DR2 covers the entirety of the sky available from the William E. Gordon 305 m antenna at Arecibo, from decl. −1°17′ to decl. + 37°57′ across all R.A.: 4 steradians or 32% of the sky. DR2 differs in a number of ways from data release 1, which was released in 2011. DR2 is built from a largely separate set of observations from DR1, which were taken in a much more consistent mode. This consistency, coupled with more careful attention to systematics and more advanced data reduction algorithms, leads to a much higher-quality DR2 data product. We present three data sets for public use: H i data cubes, far-sidelobe stray-radiation-corrected column density maps, and results of the Rolling Hough Transform linear feature detection algorithm.