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ATEL # 1742; H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), W. Baumgartner (CRESST/GSFC/UMBC), J. Cummings (CRESST/GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (CRESST/GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (CRESTT/GSFC/UMBC), G. Sato (GSFC/ISAS), G. Skinner (CRESST/GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on 26 Sep 2008; 0:41 UT
Password Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
Subjects: X-ray, Binaries, Pulsars, Transients
The Swift/BAT hard X-ray transient monitor reports increased activity in the 15-50 keV band for the symbiotic X-ray binary 4U 1954+31, which likely contains a pulsar with a 5-hour period (Corbet et al, ApJ 675, 1424, 2008). Starting on about 2008-08-09 (MJD 54687), the source has been steadily increasing in intensity from an undetectable level (one-sigma upper limit of 0.002 cts/cm2/sec or 8 mcrab) up to a current level of 0.013 ± 0.002 cts/cm2/sec (58 mcrab) on 2008-09-25. This is the highest sustained rate seen in the BAT monitor since the end of a period of high activity that lasted from early 2005 through September 2005. Until the current activity, 4U 1954+31 has been undetectable in the BAT monitor.
Scaled Map Transient Analysis for 4U 1954+31