2010CBET.2571....3H

Kamil Hornoch, Astronomical Institute, Ondrejov, reports his discovery of an apparent nova in M31 on a co-added 1260-s R-band CCD frame taken on Oct. 29.729 UT with the 0.65-m telescope at Ondrejov. The new object is well visible on the co-added frame as well as on single images used for the co- added frame, but is not present on numerous archive images taken at Lelekovice and Ondrejov. The object is visible also on a pre-discovery Ondrejov R-band CCD frame taken on Oct. 28.719. M31N 2010-10d is located at R.A. = 0:42:36.91, Decl. = +41:19:29.6 (equinox 2000.0), which is 84" west and 201" north of the center of M31. Available R-band magnitudes for M31N 2010-10d, measured by Hornoch: 2010 Oct. 22.934 UT, [20.6 (Hornoch and P. Hornochova, 0.65-m telescope at Ondrejov); 28.719, 19.8 ± 0.25 (Hornoch and M. Wolf, 0.65-m telescope at Ondrejov); 29.729, 17.85 ± 0.1 (Hornoch, 0.65-m telescope at Ondrejov); 30.725, 17.2 ± 0.1 (Hornoch and Hornochova); 30.979, 17.4 ± 0.1 (Hornoch and Hornochova); 31.761, 17.0 ± 0.1 (Hornoch and Hornochova); Nov. 3.070, 17.55 ± 0.1 (Hornoch).