Electronic Telegram No. 2425
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


VARIABLE STAR M31N 2010-08a
     Regarding the report on CBET 2412 of a possible new nova in M31,
designated M31N 2010-08a, subsequent reports suggest that the object is
some sort of variable star that is readily visible on older reference images.
Koichi Nishiyama (Kurume, Japan) and Fujio Kabashima (Miyaki, Japan) note
that a star of red mag 18.8 in the USNO-B1.0 catalogue is located at R.A. =
0h43m28s.269, Decl. = +41o41'25".26 (equinox 2000.0), and they provide
the following magnitudes for this star from their own unfiltered CCD frames
taken with a Meade 200R 0.40-m f/9.8 reflector (+ SBIG STL1001E camera):
2008 Oct. 18.577 UT, 19.2; 2009 Oct. 20.528, 19.1; 2010 June 16.754, 18.0;
July 17.752, 17.8; Aug. 14.815, 18.5.
     Also, Kamil Hornoch, Astronomical Institute, Ondrejov, reports that
the following magnitudes of M31N 2010-08a were obtained from CCD frames
taken by himself using the 0.65-m telescope at Ondrejov:  Aug. 19.071 UT,
R = 18.38 +/- 0.05; 19.075, I = 16.53 +/- 0.07; 19.089, V = 19.8 +/- 0.15.
Hornoch inspected archival images taken by J. Gallagher and P. Garnavich
using the 0.91-m telescope at Kitt Peak, yielding the following R-band
magnitudes:  2006 Jan. 6.084, 19.27 +/- 0.04; 25.086, 19.42 +/- 0.06.
The variable is well visible on Digitized Sky Survey red and infrared
images but is not visible on a blue image.  Hornoch suggest that that the
object is not a nova, but very likely a red long-period variable star.
     Additional unfiltered CCD magnitudes for M31N 2010-08a:  Aug. 17.968,
18.0 (R. Ferrando); 19.984, 18.1 (Ferrando); 20.001, 18.2 (C. Segarra).


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2010 CBAT
2010 August 24                   (CBET 2425)              Daniel W. E. Green