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'Re-outburst of M31 source XMMU J004215.8+411924'

ATEL # 2682; Nakisa Noorraee (DIAS, UCC), Robin Barnard (SAO), Wolfgang Pietsch (MPE), Paul Callanan (UCC) and Michael Garcia (SAO)
on 18 Jun 2010; 20:01 UT
Password Certification: Michael R. Garcia (

Subjects: X-ray, Binaries, Neutron Stars, Transients

From a 5ks Chandra ACIS-I observation of M31 on May 27 2010, we report the re-outburst of XMMU J004215.8+411924. The first outburst was discovered in August 2006, and also observed on 2006 July 31st and 2006 September 11 (Atels #881,899 and 969). The position as determined from the May 27 2010 ACIS-I observation is within 0.5'' of that determined from a July 31 2006 5ks ACIS-I observation and that determined by Voss et al 2008 (A&A 489, 707). The spectrum of new outburst can be fit with an absorbed powerlaw with photon index of 1.7, and an absorption column density of 5.7x10^21 cm^-2. Spectral parameters are entirely consistent with those found in ATEL 881. The 0.5-10 keV flux observed in the Chandra May 27 observation is 1.3x10^-12 erg cm-2, corresponding to an emitted luminosity of 1.2x10^38 erg/s assuming a 780 kpc distance to M31. Swift observations on 2010 June 6, 9, 12, 15, and 18 find the source fading with an XRT count rate of 0.011 c/s, 0.0088 c/s, 0.0061 c/s, 0.0054 c/s, and 0.0019 c/s. Assuming the same spectral parameters as found with the ACIS-I observation, and correcting for vingnetting dependent area, these XRT rates correspond to emitted luminosities of 9.8, 7.5, 5.9, 4.4, and 1.3 in units of 10^37 ergs/sec. Errors in the luminosities due to counting statistics are 10% to 20%. We thank the Swift team for carrying out these Target of Opportunity observations.

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