Previous
abstract 
Next
abstract
Since May of 1994, we have been using a 0.36m Celestron telescope on a DFM Engineering computerized mount to monitor 1250 nearby galaxies for supernovae. We survey up to 100 galaxies an hour, typically taking 30-second exposures, which allows us to detect supernovae as faint as 16th magnitude. To identify candidate objects, we place on the TV monitor transparent plastic overlays with the positions of known stars marked; a possible supernova is immediately apparent as an unmarked star. Our 8-bit CCD camera, which is controlled by a PC, was manufactured by Microluminetics and has a Sanyo chip with 572 by 480 pixels each measuring 13 by 15 microns; at the f/7 beam of our telescope, this corresponds to a scale of about one arc second per pixel and a field of about 10 by 8 arc minutes. The telescope is controlled by an Apple II+ microcomputer and has a pointing accuracy of 1 arc minute. Since images are automatically recorded on videotape, the system can work in an automated mode, but we prefer to have an operator (usually a Wheaton student) examine the images real-time to eliminate false alarms (about 10% of the exposures have cosmic rays that look like stars) and to allow us to report any supernova candidates as quickly as possible. On the tenth night of regular operation, June 26/27 1994, we discovered a 14th magnitude candidate in NGC 4948 and immediately notified the IAU; a spectrum taken with the ESO 1.5m telescope less than 24 hours later identified SN 1994U as a typical Ia at maximum light (IAU Circular No. 6011). We currently monitor all galaxies which are north of -15 degrees declination, brighter than magnitude 14.5, and have radial velocities less than 2000 km/s; we welcome suggestions for additional galaxies, and we would especially like to coordinate our efforts with astronomers interested in making rapid follow-up observations. A more detailed description of our program has been published in the Fall 1994 issue of CCD Astronomy. We are grateful to IBM, Research Corporation, and The American Astronomical Society Small Research Grant Program for their support.
