The new Swift X-ray transient is likely a flare star.
ATel #4635; P. A. Evans (U. Leicester), J. P. Osborne (U. Leicester), K. L. Page (U. Leicester), R. L.C. Starling (U. Leicester)
on 10 Dec 2012; 14:35 UT
Credential Certification: Phil Evans (pae9@star.le.ac.uk)
Subjects: Star, Transient
Referred to by ATel #: 4642
In ATEL #4631 we reported the discovery of a new transient, hereafter
Swift J063933.6+054917. We stated that there were no objects catalogued
by Vizier within 8 arcsec of the X-ray position. This statement was
based on the unenhanced X-ray position, i.e. in the co-ordinate frame
determined by the star trackers onboard Swift. This turns out to be ~8
arcsec from the enhanced position given in ATEL #4631, due to an unusually
large inaccuracy in the star tracker solution.
The enhanced X-ray position corresponds to an object seen in 2MASS and
WISE, with 2MASS magnitudes J=14.0, H=13.4, K=13.2 and WISE magnitudes
W1=13.0, W2=12.9. Based on Kirkpatrick et al. (2011, ApJS, 197, 19)
we deduce a stellar type of ~M4 for this object. We thus suggest that
the transient X-ray object Swift J063933.6+054917 is a stellar flare from
this M star.
