THE BELL-LABORATORIES H-I SURVEY

The sky north of delta = -40-degrees was observed in the 21 cm line of atomic hydrogen with the FWHM = 2-degrees beam of the 20 foot horn re flector at AT&T Bell Laboratories, Crawford Hill. The survey covers a velocity range of 654 km s-1 centered on the Galactic standard of rest , with 5.3 km s-1 wide filters. Calibration and reduction of the obser vations are described. The survey is presented as a series of images o f the sky, each covering a 10 km s-1 wide velocity range. This survey is distinguished by its sensitivity to low surface brightness features (T(A) almost-equal-to 50 mK) and relative freedom from sidelobe conta mination. High-velocity clouds are extracted and cataloged automatical ly. At the resolution of the survey, the lowest H I column density in the sky is 5.7 x 10(19) cm-2.