Electronic Telegram No. 2576
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


APPARENT NOVA IN M81:  M81N 2010-12a
     Kamil Hornoch, Astronomical Institute, Ondrejov; and Peter Garnavich and
James Pagnini, University of Notre Dame, report their discovery of an apparent
nova in the galaxy M81 on a co-added 2970-s unfiltered CCD frame taken by
Hornoch on Dec. 5.147 UT with the 0.65-m telescope at Ondrejov and on a
co-added 580-s R-band CCD frame taken by Garnavich and Pagnini with the Vatt4k
imager on the 1.83-m Vatican Advanced Technology Telescope on Dec. 5.515 UT.
The new object, designated M81N 2010-12a, is visible on single 200-s and 60-s
images used for the co-added 1.83-m R-band image, as well as on S-Vilnius-band
CCD frames taken by Garnavich and Pagnini on Dec. 5.534 with the same
instrumentation.  M81N 2010-12a is about 0.6 mag brighter in S-Vilnius-filtered
images than are other field stars with the same R-band magnitude due to its
H_alpha emission, which also suggest that it is nova.  M81N 2010-12a 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 8.4-m Large
Binocular Telescope (Prieto et al., 2008, Ap.J. 673, 59) down to limiting
magnitudes as faint as Sloan r' = 23.0, R = 23.1, V = 23.5, and H-alpha = 22.1.
     M81N 2010-12a is located at R.A. = 9h55m48s.63, Decl. = +69o03'11".6
(equinox 2000.0), which is 82".9 east and 43".5 south of the center of M81.
Available magnitudes measured by Hornoch:  2010 June 11.164 UT, [22.9 (P.
Garnavich, C. Littlefield, N. Paul, and S. Bouzid, 1.83-m Vatican Advanced
Technology Telescope + R filter); Nov. 14.192, [22.3 (Hornoch, 0.65-m telescope
at Ondrejov; unfiltered, using R-band magnitudes from comparison stars); Dec.
5.147, 20.9 +/- 0.3 (Hornoch); 5.515, R = 21.3 +/- 0.15 (Garnavich and Pagnini,
1.83-m Vatican Advanced Technology Telescope).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 December 9                  (CBET 2576)              Daniel W. E. Green