Harold Corwin

IC 3993 is a galaxy at its catalogued position, found by Wolf on a Bruce 16-inch refractor plate, and confirmed on the print I examined. There is no problem with its identification.

However, the SDSS images from 25 April 2003 show a blue star superposed east of the nucleus by 5.1 arcseconds and 0.9 arcseconds north. The star does not appear on any of the other digitized surveys that I examined (DSS1, DSS2, or 2MASS), so may be a supernova (it is not included in the IAU supernova list, nor the possible supernova list, maintained at CfA). Fortunately, SDSS has it in all five bands, so the photometry and position are good if the object ever needs to be followed up.

See NGC 5521 for another possible supernova.

― IC Notes by Harold Corwin