Swift/BAT reports new flaring activity from Mrk 421
ATel #2292; 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), T. Sakamoto (CRESTT/GSFC/UMBC), G. Skinner (CRESST/GSFC/UMD), M. Stamatikos (OSU/GSFC), J. Tueller (GSFC), T. Ukwatta (GSFC/GWU)
on 11 Nov 2009; 18:20 UT
Credential Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
As part of its hard X-ray transient monitor program, the Burst Alert Telescope
on Swift has detected a brightening of the blazar Markarian 421. The source
began brightening around 11-Oct-2009 (MJD 55115) when it had an average daily
rate of 0.0036 ± 0.0007 counts/s/cm^2, corresponding to ~15 mCrab in the 15-50
keV band. Over the past two days, it has brightened more rapidly, and is up to
0.019 ± 0.005 counts/s/cm^2 (~85 mCrab) on 10-Nov-2009 (MJD 55145). This
activity suggests that Mrk 421 is in a flaring state, with intensities similar
to recent outbursts in March 2008 (Krimm et al, ATel #1449) and June 2006
(Lichti et al, ATel #840 #848). Normally Mrk 421 is barely detectable in the BAT
one-day averages at 6 mcrab.
Examination of the RXTE All-Sky Monitor light curves also show an increase in
the 2-10 keV band beginning around the same time. The count rate was up to 3.4
± 0.4 counts/sec on MJD 55140.
Swift/BAT Hard X-ray Transient light curve for Mrk 421