Swift Observations of the current outburst of XTE J1908+094
ATel #5529; H. A. Krimm (CRESST/GSFC/USRA), J. A. Kennea (PSU) and S. T. Holland (STScI)
on 30 Oct 2013; 20:09 UT
Credential Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
Subjects: Ultra-Violet, X-ray, Binary, Black Hole, Transient
The Swift observatory carried out pointed observations of the black hole candidate XTE J1908+094 for a total of 973 seconds starting at 20:16:01 2013 October 29. The source is clearly detected in the XRT with an average count rate of 11 ct/sec in the 0.3-10 keV band. The XRT data are well fitted by an absorbed power-law model (reduced chi-squared is 1.59 for 249 dof) with the following parameters:
N_H = 3.41 +/- 0.2 x 10^22 cm^-2
Gamma = 1.63 +/- 0.07
Flux (0.3-10 keV; unabsorbed) = 1.5 +/- 0.1 x 10^-9 erg/s/cm^-2
This suggests that the source is currently in the hard state.
Using the Chandra X-ray position of the source (Jonker et al., 2004, MNRAS 351, 1359 at RA(J2000) = 19:08:53.07, Dec(J2000) = +09:23: 5. 0), we see no evidence of a source in the UVOT v-band. The 3-sigma limiting magnitude is v > 20.3, which is consistent with the high absorption in this direction.
The BAT count rate continues to rise. On 2013 October 30 (MJD 56595) the count rate in the 15-50 keV band is 0.027 +/- 0.002, which corresponds to ~120 mCrab.
We also note that the position of the IR counterpart given in Chaty et al., 2006, MNRAS 365, 1387 (RA(J 2000) = 19:08:53.77; Dec(J2000)=+09:23:4.9) is not consistent with either the radio position or Chandra X-ray position given in Jonker et al., 2004: radio: RA(J2000) = 19:08:53.077, Dec(J2000) = +09:23: 4.9).
BAT hard X-ray transient monitor light curve for XTE J1908+094
