Electronic Telegram No. 2180 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Room 209; Dept. of Earth and Planetary Sciences; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbat@iau.org; cbatiau@eps.harvard.edu URL http://www.cfa.harvard.edu/iau/cbat.html APPARENT NOVA IN M81: M81N 2010-01c K. Hornoch, Astronomical Institute, Ondrejov; P. Kubanek, Image Processing Laboratory, Universidad de Valencia; N. Morales, J. L. Ortiz, J. Gorosabel, and M. Jelinek, Instituto de Astrofisica de Andalucia, Consejo Superior de Investigaciones Cientificas; and G. Jozsa and P. Serra, Netherlands Foundation Research in Astronomy, of the HALOGAS (Hydrogen Accretion in LOcal GAlaxieS) survey team, report the discovery of another apparent nova in the galaxy M81 (cf. CBET 2170) from a co-added 6480-s R-band CCD frame taken by Kubanek, Morales, Ortiz, Gorosabel, and Jelinek with the 1.23-m telescope at Calar Alto on Jan. 30.974 UT, and on a co-added 1200-s narrow-band H-alpha CCD frame taken by Jozsa and Serra with the 2.5-m Isaac Newton Telescope (+ WFC) at La Palma on Feb. 4.125. The new object, designated M81N 2010-01c, is located at R.A. = 9h55m23s.59, Decl. = +69o05'54".6 (equinox 2000.0), which is 51".3 west and 119".5 north of the center of M81. M81N 2010-01c is not present on numerous archive images from the 2.54-m Isaac Newton Telescope, the 4.2-m William Herschel Telescope, the 4-m Mayall telescope, and the 8.2-m Subaru telescope, down to limiting magnitudes as faint as Sloan r' = 23.3, R = 23.4, V = 23.8, and H-alpha = 21.6. Available R, Sloan r', and H-alpha magnitudes for nova M81N 2010-01c, measured by Hornoch: Jan. 14.394, [22.7 (J. Prieto and R. Khan, 2.4-m Hiltner telescope + RETROCAM + Sloan r' filter); 21.292, [23.1 (J. A. L. Aguerri, Instituto de Astrofisica de Canarias, and R. Sanchez-Janssen, European Southern Observatory, 2.6-m Nordic Optical Telescope + ALFOSC + Sloan r' filter); 28.961, R = 20.8 +/- 0.3 (Kubanek, Morales, Ortiz, Gorosabel, and Jelinek, 1.23-m telescope at Calar Alto); 30.974, R = 21.0 +/- 0.2 (Kubanek, Morales, Ortiz, Gorosabel, and Jelinek); 31.090, R = 21.3 +/- 0.3 (Kubanek, Morales, Ortiz, Gorosabel, and Jelinek); Feb. 3.190, R = 21.9: (Kubanek, Morales, Ortiz, Gorosabel, and Jelinek); 4.125, [H-alpha] = 20.0 +/- 0.15 (Jozsa and Serra, 2.5-m Isaac Newton Telescope). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 February 21 (CBET 2180) Daniel W. E. Green