  SETI@home observes a 2.5 MHz bandwidth centered on 1420 MHz near the 21-cm
line using a short line feed at Arecibo which provides a 6' beam. This feed
sits on Carriage House 1. During normal astronomical observations with the new
Gregorian dome the feed scans across the sky at twice the sidereal rate. We are
using the SETI@home receiver to obtain about 4.4x10^6 HI spectra per year with
integration time of 5 seconds per spectrum. We have accumulated 2.6 years of
data covering most of the sky observable from Arecibo. This survey has much
better angular resolution than previous single dish surveys and better
sensitivity than existing or planned interferometric surveys.
