A 21 cm survey of the Pisces-Perseus supercluster. I. The declination zone +27.5 to +33.5 degrees.

Neutral-hydrogen 21 cm line data for a sample of galaxies in the region bounded by 22 h less than R.A. less than 04h, + 27 deg 30 arcmin Dec. less than + 33 deg 30 arcmin are presented as the first installment of a survey of galaxies in the region of the Pisces-Perseus supercluster. Of the 415 galaxies observed in this strip with the Arecibo 305 m telescope, 342 have been detached in the 21 cm line; another ten have useful upper limits to their H I content. The sample includes most spiral, irregular, and dwarf galaxies larger than 1 arcmin; in selected areas, spirals to a limiting magnitude of + 15.7 have been observed. The velocity distribution of the 511 galaxies with known redshift in this zone deviates markedly from that expected for a similar sample of randomly placed objects. The region contains significant clustering in all three dimensions.