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Swift detection of a bright X-ray flare from OJ 287

ATEL # 2267; F. D'Ammando (Univ. Tor Vergata, INAF-IASF Roma), N. Gehrels (NASA/GSFC), E. Hoversten (PSU), P. Romano, S. Vercellone (INAF-IASF Palermo)
on 26 Oct 2009; 22:59 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Pat Romano (

Subjects: X-ray, AGN

Following the optical and gamma-ray flare of the blazar OJ 287 on October 22, 2009 (Ciprini et al. 2009, ATel #2256), we performed a Swift target of opportunity observation. We report on the analysis of the Swift data obtained on October 25. The spectrum of the Swift/XRT observation can be fit (0.3-10 keV) with an absorbed power law model with a column density consistent with the Galactic one in the direction of the source (n_H = 2.56e20 cm^-2, Kalberla et al. 2005) and a photon index of 1.74+/-0.06. The corresponding unabsorbed 0.3-10 keV (2.0-10 keV) flux is 1.5e-11 (8.7e-12) erg cm^-2 s^-1. This flux is a factor of 2.5 higher than that previously observed by Suzaku/XIS during November 2007 in a flaring state (Seta et al. 2009), confirming the very high activity of the source.

Swift will continue monitoring OJ 287 during this week with two more observations. We thank the Swift Team for making this observation possible.

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