The Arecibo L-band Feed Array Zone of Avoidance (ALFAZOA) Shallow Survey

The Arecibo L-band Feed Array Zone of Avoidance (ALFAZOA) Shallow Survey is a blind H i survey of the extragalactic sky behind the northern Milky Way conducted with the ALFA receiver on the 305 m Arecibo Radio Telescope. ALFAZOA Shallow covered 900 square degrees at full sensitivity from 30° ≤ l ≤ 75° and $| b| \,\leqslant \,10^\circ$ and an additional 460 square degrees at limited sensitivity at latitudes up to 20°. It has an rms sensitivity of 5–7 mJy and a velocity resolution of 9–20.6 km s⁻¹, and detected 403 galaxies out to a recessional velocity of 12,000 km s⁻¹, with an angular resolution of 34 and a positional accuracy between 02 and 17. The survey is complete above an integrated line flux of F_{H i} = 2.0 Jy km s⁻¹ for half the survey, and above F_{H i} = 2.8 Jy km s⁻¹ for the other half. Of the ALFAZOA H i detections, 43% have at least one possible optical/near-infrared counterpart in the literature, and an additional 16% have counterparts that only included previous H i measurements. There are fewer counterparts in regions of high extinction and for galaxies with lower H i mass. Comparing the results of the survey to the predictions of Erdoǧdu et al., and using their nomenclature, ALFAZOA confirms the position and extent in the ZOA of the C7, Cζ, Pegasus, Corona Borealis, and Delphinus structures, but not of the Cygnus void. Two new structures are identified, both connected to the C7 overdensity; one extends to  35°, and the other crosses the ZOA.