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Swift UVOT UVW1 filter detection of a transient in the M 31 central area

ATel #3061; W. Pietsch, M. Henze, F. Haberl, V. Burwitz (Max Planck Institut f. extraterr. Physik Garching MPE, Germany)
on 1 Dec 2010; 13:36 UT
Credential Certification: Wolfgang Pietsch (wnp@mpe.mpg.de)

Subjects: Ultra-Violet, Nova, Transient

Referred to by ATel #: 3066, 3068, 5256, 5384, 5528, 5669

Analyzing Swift UVOT UVW1 filter (181-321nm) observations of the central area of M 31 we detected a new bright transient at RA = 00h42m31.60s, Dec =+41d09'51.5" (J2000, accuracy of 0.5"), which is 144" west and 377" south of the core of M 31. Light curve information is given in the table below. Many UV transients in M 31 have been identified with optical novae in M 31. There is no report of a recent detection of an optical nova or a historical nova (see http://www.mpe.mpg.de/~m31novae/opt/m31/M31_table.html ) for the position of the transient. However, for several novae in M 31 UV emission has been detected preceding the optical detection (see e.g. ATels #2713 and #2727).

ObsID              Date             exposure      UVW1
[UT] [s] [mag]
00031861009 2010-11-21.03 8312 >21.1
00031861010 2010-11-23.05 7820 20.8+-0.4
00031861011 2010-11-28.00 15889 18.8+-0.1
00031861012 2010-11-30.14 10884 18.2+-0.1

All magnitudes are on the UVOT photometric system (Poole et al. 2008, MNRAS, 383, 627). Magnitudes have not been corrected for extinction.

We would like to thank the Swift Team for making these observations possible, in particular N. Gehrels, the duty scientists as well as the science planners.