Two new, bright optical nova candidates in M 31 including one possible recurrent nova
ATel #1654; M. Henze, V. Burwitz, W. Pietsch (Max-Planck-Institut fuer extraterrestrische Physik, MPE), D. Hatzidimitriou, P. Reig, N. Primak, G. Papamastorakis (University of Crete)
on 11 Aug 2008; 14:54 UT
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Referred to by ATel #: 1703
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 13.5Âµm 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 ).