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Swift follow-up of the gamma-ray flaring blazar PKS 0235-618

ATEL # 2673; F. D'Ammando (INAF - IASF Palermo), K. V. Sokolovsky (MPIfR/ASC Lebedev), S. Cutini (ASI-Science Data Center) on behalf of the Fermi Large Area Telescope Collaboration and L. Vetere (PSU)
on 13 Jun 2010; 17:33 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Filippo D'Ammando (

Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, Request for Observations, AGN, Quasars

Following the gamma-ray flare of PKS 0235-618 detected by Fermi LAT on June 10, 2010 (ATel #2669, Cutini 2010), we performed a Swift target of opportunity observation on June 11.

Swift/XRT observations started on 2010-06-11 at 21:48:35 UT and ended on 2010-06-12 at 04:51:24 UT. Data were taken in Photon Counting mode for a total exposure of 6 ksec. The XRT spectrum of PKS 0235-618 can be fit in the 0.3-10 keV range with an absorbed power law model with a column density consistent with the Galactic one in the direction of the source (n_H = 2.54 x10^20 cm^-2, Kalberla et al. 2005, A&A, 440, 775) and a photon index Gamma = 1.43 +/- 0.08. The corresponding unabsorbed 0.3-10 keV flux is (8.1 +/- 0.6) x10^-12 erg cm-2 s-1. Compared to the previous ROSAT observations of PKS 0235-618, in which the observed 0.1-2.4 keV flux was about 2.0 x10^-12 erg cm-2 s-1 (Brinkmann et al. 1994, A&A, 281, 355), the XRT flux in the same energy range is about two times higher.

Simultaneous Swift/UVOT observations found PKS 0235-618 about one magnitude brighter in B-band (B = 16.94 +/- 0.02) compared to the historical state reported in the USNO-A2.0 catalog (Monet et al. 1998).

In consideration of the ongoing activity of this source, confirmed also by the Swift observation, we strongly encourage further multiwavelength observations. For this source the Fermi LAT contact person is S. Cutini (

We thank the Swift team for their rapid scheduling of these observations.

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R. E. Rutledge , Editor
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