2010CBET.2487....1H

Kamil Hornoch, Astronomical Institute, Ondrejov, reports his discovery of a possible nova in M31 on a co-added 990-s R-band CCD frame taken on Oct. 6.932 UT with the 0.65-m telescope at Ondrejov. The new object, designated M31N 2010-10b, is well visible on the co-added frame and faintly visible also on single images used for the co-added frame, but it is not present on numerous archival images taken at Lelekovice and Ondrejov. The object is visible also on four pre-discovery Ondrejov R-band CCD images taken between Aug. 19.055 and Sept. 20.777. Available magnitudes for M31N 2010-10b, measured by Hornoch: July 10.200, [22.0 (J. Corral-Santana and J. Casares, 2.54-m Isaac Newton Telescope + Sloan r' filter); Aug. 19.055, R = 20.0 ± 0.3 (Hornoch and P. Hornochova, 0.65-m telescope at Ondrejov); 25.097, R = 19.6 ± 0.25 (Hornoch and Hornochova); Sept. 14.128, R = 19.4 ± 0.2 (Hornoch and Hornochova); 20.777, R = 19.5 ± 0.2 (Hornoch and Hornochova); Oct. 6.932, R = 18.9 ± 0.15 (Hornoch, 0.65-m telescope at Ondrejov); 7.767, R = 18.9 ± 0.15 (Hornoch and M. Wolf, 0.65-m telescope at Ondrejov). M31N 2010-10b is located at R.A. = 0:42:41.51, Decl. = +41:03:27.3 (equinox 2000.0), which is 32" west and 761" south of the center of M31.