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Amendment to ATel 1859: CXOM31 J004245.9+411036 is Previously Reported XMMU J004245.9+411036

ATEL # 1870; J.L. Galache, M.R. Garcia, M.A.P. Torres, S.S. Murray (CfA), D. Steeghs (U. of Warwick/CfA) and B.F. Williams (U. of Washington)
on 8 Dec 2008; 19:19 UT
Password Certification: Jose Luis Galache (

Subjects: Binaries, Black Holes, Neutron Stars, Pulsars, Transients

The object CXOM31 J004245.9+411036, reported as a new X-ray source in ATel #1859 from M31 Chandra observations, is the previously reported XMMU J004245.9+411036 (Pietsch et al. 2008, ATel #1647). We thank W. Pietsch and M. Henze for kindly bringing this clerical error to our attention.

This transient source has been observed by various space telescopes since its discovery. We present a table with known observations and the X-ray luminosity in the 0.5-5 keV range. All spectra were fit with an absorbed power law and we also present the slope reported.

Date (UT) Lx (1e37 erg/s) Γ Satellite (Ref.)
2008-05-26.30 2.7 2.4* Swift (ATel #1671)
2008-05-31.47 3.5 1.7* CXO (ATel #1658)
2008-07-15.70 1.4 2.4 CXO (ATel #1658)
2008-07-18.26 4.2 2.4 XMM (ATel #1647)
2008-08-21.31 5.4 2.4* Swift (ATel #1674)
2008-10-21.63 6.1 2.4* Swift (ATel #1806)
2008-09-01.32 3.1 2.6 CXO
2008-10-13.15 0.3 2.4* CXO
2008-11-27.72 3.6 1.8 CXO (ATel #1859)

*: Slope was fixed at this value and was not a free parameter in the fit.

Based on its transient nature and the soft spectrum reported in most of the observations, we suggest XMMU J004245.9+411036 might be a black hole transient.

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R. E. Rutledge , Editor
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