101 spiral galaxies: neutral hydrogen distribution

This is a first report on a survey of the H I distributions in a large sample of spiral galaxies, using the 21-cm spectral-line system at Arecibo Observatory. One hundred and thirty galaxies have been observed, and 101 have been detected and roughly mapped in H I. The data have been used to determine systemic velocity, H I content, gravitational mass, and an approximate measure of the diameter of the H I distribution. There is a very high detection rate for galaxies brighter than 13.6 mag, and/or later than Hubble type Sab. Evidence is presented to show that the velocity widths of weak profiles measured at Green Bank are often overestimated because of noise. Our primary result is that there is a large scatter in H I diameters within each Hubble type. We find a weak suggestion that Sc galaxies have smaller H I diameters, on the average, than Sb galaxies. In addition, many Sb galaxies exhibit a highly asymmetric H I distribution. There appears to be no correlation between optical luminosity and H I extent