[vsnet-alert 10432] outburst of a recurrent nova in M31!

[Taichi Kato]

  FWD: outburst of a recurrent nova in M31!

The Astronomer's Telegram                   http://www.astronomerstelegram.org 
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ATEL #1654							     ATEL #1654

Title:		Two new, bright optical nova candidates in M 31 including
		one possible recurrent nova 
Author:	M. Henze, V. Burwitz, W. Pietsch (Max-Planck-Institut fuer
		extraterrestrische Physik, MPE), D. Hatzidimitriou, P. Reig, N. Primak,
		G. Papamastorakis (University of Crete)
Queries:	burwitz at mpe.mpg.de
Posted:	11 Aug 2008;  14:54  UT
Subjects:	Optical, Novae

We report the discovery of two new, bright possible novae in M 31 on 
dithered stacked R filter CCD images, obtained on 2008 August 09, with
the 1.3m Ritchey Chretien f/7.5 telescope at Skinakas Observatory, 
Crete, Greece, using an Andor DZ436-BV CCD Camera (with a Marconi 2k
x    2k chip with 13.5 sq. pixels).

The first object is visible in two different pointings of four images
taken on 2008 August 09.96    and three images taken on 2008 August
09.97, respectively. The R    magnitude is 16.8. The position obtained
for the nova candidate is RA =    00h42m44.99s, Dec = 41d17'07.7" (J2000,
accuracy of 0.3"), which is 8"    east and 58" north of the core of M 31.

The second candidate is visible in two different pointings of    four
images taken on 2008 August    09.96 and one image taken on 2008 August
09.98, respectively. The R    magnitude is 16.4. The position obtained
for the nova candidate is RA =    00h42m52.38s, Dec = 41d16'12.9" (J2000,
accuracy of 0.3"), which is    1'31" east and 3" north of the core of M
31. 

This position is just 0.4"    away from the position of nova M31N 1997-10f
(Shafter & Irby 2001, ApJ,    563, 749) according to the M 31 nova catalog
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    (see http://scully.harvard.edu/~cgi/CheckMP).

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