About the ALFALFA Survey
The Arecibo Legacy Fast ALFA (ALFALFA) Survey used the seven-horn Arecibo L-band Feed Array (ALFA) to map nearly 7000 square degrees of high Galactic latitude sky accessible to the Arecibo telescope over approximately 4400 nighttime hours between 2005 and 2011.
ALFALFA was conducted as a blind survey: at each position, the entire frequency range from 1335–1435 MHz, corresponding to heliocentric velocities −2000 < cz < 18000 km/s, was searched for line emission.
The survey was designed to cover two sky regions at high Galactic latitude, one in the northern Galactic hemisphere and one in the southern hemisphere. For practical reasons, the final footprint is somewhat reduced near the survey edges, as described in Haynes et al. (2018) and Jones et al. (2018).