Supernova 1999gn in M61

Alessandro Dimai, Cortina, Italy, reports his discovery of an apparent supernova (mag 16.0) on an arm of the host galaxy (NGC 4303 = M61), found on a CCD frame taken on Dec. 17.22 UT with a 0.50-m telescope. He reported the new object as being 35" east and 25" south of the galaxy nucleus; the new star is not present in J. Wray's Color Atlas of Galaxies. W. Li, University of California at Berkeley, reports that an image taken on Dec. 18.5 with the Katzman Automatic Imaging Telescope (KAIT) shows SN 1999gn at mag about 15.5. Li measured a position for SN 1999gn: R.A. = 12h21m57s.02, Decl. = +4o27'45".6 (equinox 2000.0), which is 31".7 east and 39".8 south of the nucleus of M61. A KAIT image taken on Nov. 26.5 showed nothing at the position of the new star (limiting mag about 19.0). Previous supernovae in M61 were 1926A, 1961I, and 1964F.