H I observations of the high-velocity system in NGC 1275

Abstract

An attempt to detect H I emission from the high-velocity system in the Seyfert galaxy NGC 1275 (Perseus A) is presented. The data were obtained with the Westerbork Synthesis Radio Telescope using a special calibration procedure to achieve high spectral dynamic range. The new upper limit of 2.4 x 10 to the 9th solar masses for the total H I mass in this system makes it unlikely that it is a very late-type galaxy, but the limit is still not low enough to exclude galaxies of type Sc or earlier. A tentative detection of a new weak broad absorption feature is reported, and the implications of an observed 30 percent increase in the intensity of the strong absorption feature are discussed.