The sky north of declination -40{deg} was observed in the 21cm line of atomic hydrogen with the FWHM=2{deg} beam of the 20 foot horn reflector at AT&T Bell Laboratories, Crawford Hill. The survey covers a velocity range of 654km/s centered on the Galactic standard of rest, with 5.3km/s wide filters. This survey is distinguished by its sensitivity to low surface brightness features (antenna temperature about 50mK) and relative freedom from sidelobe contamination. High-velocity clouds are extracted and catalogued automatically. The data are presented in declination zones in equatorial and polar coordinates, and as R.A. - velocity images. Introduction: Observations were made as drift scans along even declinations between -40{deg} and +90{deg} at the epoch (1981) of the observations. The horn antenna has a FWHM beam size of 2{deg} at 21cm. This large beam made it possible to cover the whole visible sky in 66 constant declination scans. The survey is undersampled in declination (one beam width sampling) and oversampled in right ascension (roughly quarter beamwidth sampling). The average rms noise of spectra taken at all declinations is 0.017K in 5.2km/s wide channels, although in some cases baseline problems make the survey unreliable at this level. The survey contains 19,248 spectra. The data are in FITS format.