INTEGRAL detects a new outburst of MXB 0656-072
ATel #1281; I. Kreykenbohm (IAA Tuebingen/ISDC), S. E. Shaw (University of Southampton/ISDC), Valentina Bianchin (INAF/IASF-Bologna), R. Diehl (MPE Garching), S. Brandt (DNSC Copenhagen), M. Mas-Hesse (LAEFF, Madrid), A. Parmar (ISOC Madrid), W. Hermsen (SRON, Utrecht), R. Krivonos (IKI Moscow/MPA Garching)
on 15 Nov 2007; 14:32 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Nami Mowlavi (Nami.Mowlavi@obs.unige.ch)
Subjects: X-ray, Gamma Ray, Request for Observations, Binary, Neutron Star, Transient, Pulsar
The recurrent X-ray transient pulsar "MXB 0656-072" (also known as XTE
J0658-073, ATELs 197, 199, 200, 202, McBride et al. 2006) has begun
another outburst about four years after the previous outburst in
October 2003. On November 10 (MJD 54414.9, begin of Integral
revolution 620) the source was first detected in ISGRI with a count
rate of 6.9 +/- 0.8 counts per second between 20 and 40 keV
(corresponding to 40 mCrab). The source was clearly detected in a
single science window (SCW-ID 062000020010) with a detection
significance of 9 sigma. Since then the source was observed repeatedly
in 20 mostly non-consecutive science windows until the end of the
revolution. The observed count rate was between 4 and 12 counts per
second (20 to 70 mCrab) and the source was detected with a
significance between 6 and 16 sigma. The source was not detected above
40 keV. JEM-X clearly detected the source when the source was in its field
of view with up to 2.6 counts per second (3 to 10 keV) and with a
significance up to 22 sigma.
Preliminary spectral analysis of the ISGRI data shows that the
spectrum of the source is very soft with a spectral index of 4.3 +/-
0.3. Temporal analysis shows that the source is strongly pulsating
with a period of 160.0 seconds. The single peaked pulse profile
exhibits a large pulsed fraction of 50%.
Although the source was detected more frequently towards the end of
the revolution, the average flux did not increase significantly, it is
therefore very hard to predict the evolution of this outburst. Further
observations are therefore strongly encouraged.
Plots are available at http://isdc.unige.ch/~kreyken/mxb0656
