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Swift/BAT detects a strong outburst from GRO J1008-57

ATel #1298; H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (CRESST/GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. Markwardt (CRESST/GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), K. Pottschmidt (CRESST/GSFC/UMBC), T. Sakamoto (CRESTT/GSFC/UMBC), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC) on behalf of the Swift-BAT team
on 21 Nov 2007; 22:39 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Hans A. Krimm (krimm@milkyway.gsfc.nasa.gov)

Subjects: X-ray, Request for Observations, Binary, Transient, Pulsar

Referred to by ATel #: 1304, 1619, 1995, 4759, 7490

The Swift/BAT hard X-ray transient monitor reports a particularly intense outburst of the accreting X-ray pulsar GRB J1008-57. The source has been above 100 mcrab (0.023 cts/cm^2/sec) in the 15-50 keV energy range since 17-Nov-2007 and in the most recent daily average (21-Nov-2007; MJD 54425) it had risen above 400 mcrab (0.010 +/- 0.02 cts/cm^2/sec). This source is normally not detectable in the BAT except during its periodic outbursts on a 250 day cycle (Schrader et al., 1999, ApJ, 512, 920). The last time the source was detectable was in March 2007, confirming this periodicity. We note that this outburst is much larger than previous outbursts seen in Swift or reported by INTEGRAL (ATel #647). We encourage persistent monitoring of this source at all wavelengths.

Swift BAT transient monitor observations of GRO J1008-57