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Swift/BAT reports new flaring activity from Mrk 421

ATEL # 1449; 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 30 Mar 2008; 21:13 UT
Password Certification: Hans A. Krimm (

Subjects: X-ray, Request for Observations, AGN

The Swift/BAT hard X-ray transient monitor reports a new episode of flaring activity from the blazar Mrk 421. This object has been rising in flux in the 15-50 keV band starting on March 17, 2008 (MJD 54542) when it reached 22 mcrab (~0.005 0.0006 cts/sec/cm^2). On March 30, 2008 it had an episode from about 01:53 UT to 06:44 UT in which the flux reached as high as 110 mcrab (0.025 0.003 cts/sec/cm^2). Normally Mrk 421 is barely detectable in the BAT one-day averages at 6 mcrab.

This is the brightest outburst since June 2006 (Lichti et al, ATel #840,#848) when the flux in the BAT reached similar levels for several weeks.

Swift/BAT Hard X-ray Transient Monitor for Mrk 421

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R. E. Rutledge , Editor
ATEL Mirror v1.0 Updates