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THE ASTRONOMER Electronic Circular No 2473      2008 Aug 13 16.11UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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POSSIBLE RECURRENT NOVA IN MESSIER 31
M. Henze, V. Burwitz, W. Pietsch (Max-Planck-Institut fuer 
extraterrestrische Physik, MPE, D. Hatzidimitriou, P. Reig, N. Primak, 
G. Papamastorakis (University of Crete) report on Astronomer's Telegram 
1654 their discovery of a possible recurrent nova in Messier 31.

The discovery was made on CCD images, obtained on 2008 August 9, with 
the 1.3m Ritchey Chretien f/7.5 telescope at Skinakas Observatory, 
Crete, Greece.

The candidate is visible in images taken on 2008 August 09.96 and one 
image taken on 2008 August 09.98. The R magnitude is 16.4. The position 
obtained for the nova candidate is:
RA 00h 42m 52.38s DEC 41 16' 12.9" (J2000, >accuracy of 0.3"), which is 
1'31" east and 3" north of the core of Messier 31.

This position is just 0.4" away from the position of nova M31N 1997-10f 
according to the M 31 nova catalogue of Pietsch et al. (2007, A&A, 465, 
375; see http://www.mpe.mpg.de/~m31novae/opt/m31/index.php.

Since Pietsch et al. (2007) give position errors for M31N 1997-10f of 
0.2" in RA and 0.1" in Dec, respectively, the positions of both objects 
are consistent within the errors. Therefore, we classify this object as 
a recurrent nova candidate. The time lag between the two observed 
outbursts is 10.77 years. Note, that Shafter & Irby (2001) discuss M31N 
1997-10f as a possible recurrent counterpart of nova M31N 1926-07c 
(Hubble, 1929, ApJ, 69, 103; time lag of 71.3 years) using an error box 
with dimensions of 0.24' x 0.20'. However, according to the M31 nova 
catalog of Pietsch et al. (2007) the positions of both novae are 32" 
away from each other so that due the high density of observed novae 
close to the core of M 31 and the relatively loose selection criteria of 
Shafter and Irby (2001) their interpretation might not be true. In this 
Telegram, we give much stronger evidence that M31N 1997-10f actually is 
a recurrent nova and we encourage observers to perform spectroscopy for 
one of these rare objects.

All magnitudes given are obtained from a photometric solution using
R magnitudes of the Local Group Survey M 31 catalogue (Massey et al. 
2006, AJ, 131, 2478). Both candidates are not visible on Skinakas images 
of 2008 August 07.97 and before (limiting R magnitude of ~ 18.0 close to 
the core of M 31). There is no entry in VizieR/CDS for both objects 
(except, of course, of the possible recurrent nova candidate discussed 
above) and no minor planet could be found on this positions using the 
MPC/IAU Minor Planet Checker.

Guy M Hurst