The Bell Laboratories H I survey

Abstract

The sky north of ô = —40° was observed in the 21 cm line of atomic hydrogen with the FWHM = 2° beam of the 20 foot horn reflector at AT&T Bell Laboratories, Crawford Hill. The survey covers a velocity range of654 km s-1 centered on the Galactic standard of rest, with 5.3 km s_1 wide filters. Calibration and reduction of the observa- tions are described. The survey is presented as a series of images of the sky, each covering a 10 km s-1 wide velocity range. This survey is distinguished by its sensitivity to low surface brightness features (TAæ 50 mK) and relative freedom from sidelobe contamination. High-velocity clouds are extracted and cataloged automatically. At the resolution of the survey, the lowest H i column density in the sky is 5.7 X 1019 cm-2.