2010CBET.2289....1M

L. A. G. Monard, Pretoria, South Africa, reports his discovery of an apparent supernova (mag 16.0 ± 0.2) on three images taken during dawn twilight on May 23.169 UT. The new object is located at R.A. = 0:55:04.86, Decl. = -37:41:43.7 (equinox 2000.0), which is 135" east and 41" south of the galaxy core of NGC 300. Nothing is visible at this position on the Digitized Sky Survey (limiting red mag 20.5) or on Monard's images prior to May 6 (limiting mag around 18.5). Additional magnitudes of 2010da reported by Monard: May 6.12, [15.5; 24.139, 15.9 (unfiltered); 24.141, V = 16.1; 24.142, R = 15.9; 24.144, I = 15.8; 24.145, B = 16.2.