Constraining the time of outburst of an optical nova candidate in M 31

ATel #2189; M. Henze, F. Kaduk, W. Pietsch, V. Burwitz (Max-Planck-Institut fuer extraterrestrische Physik, MPE), A. Liakos (Dept. Physics, University of Athens), D. Hatzidimitriou (Dept. of Physics, University of Crete), P. Niarchos (Dept. Physics, University of Athens)
on 4 Sep 2009; 16:51 UT
Credential Certification: Wolfgang Pietsch (wnp@mpe.mpg.de)

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We confirm a nova candidate in M 31 reported to us by K. Nishiyama and F. Kabashima and present a pre-discovery detection that allows us to tightly constrain the time of outburst for this object.

The nova candidate was discovered by Nishiyama and Kabashima (Miyaki-Argenteus observatory, Japan) on 2009 September 3.752 UT, with no object visible at its position on September 1.566 UT (private communication). We detect the object on a 10x60s stacked unfiltered CCD image obtained at the 40-cm Cassegrain telescope with a focal reducer (F/5.1) equipped with a 2184 x 1472 pixel ST-10XME CCD camera (pixel size 6.8 microns square) at the Athens University Observatory, Greece on 2009 September 2.078 UT with a magnitude of 17.8. This detection is 1.7 days before the discovery by Nishiyama and Kabashima and 0.5 days after their last upper limit, thus strongly constraining the time of outburst of the nova candidate. The position of the object is RA = 00h42m26.08s, Dec = +41d04'01.0" (J2000, accuracy 0.3"), which is 3'26" west and 12'08" south of the core of M 31. Additional photometry obtained with the Athens University camera: August 29.033 UT: < 19.0; September 3.999 UT: 17.6. There is no entry in VizieR/CDS for this object and no minor planet could be found on this position using the MPC/IAU Minor Planet Checker (see http://scully.harvard.edu/~cgi/CheckMP ).

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).