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Fermi LAT detection of increasing gamma-ray activity of blazar PKS 1222+216

ATel #2021; F. Longo (INFN Trieste), M. Giroletti (INAF/IRA Bologna), G. Iafrate (INAF/OA Trieste); on behalf of the Fermi Large Area Telescope Collaboration
on 17 Apr 2009; 22:29 UT
Credential Certification: Francesco Longo (francesco.longo@ts.infn.it)

Subjects: Gamma Ray, >GeV, AGN, Transient

Referred to by ATel #: 2348, 2349, 2641, 2687, 6207

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed an increasing gamma-ray flux from a source positionally consistent with PKS 1222+216 (RA: 12h24m54.4s, DEC: +21d22m46s, J2000, z=0.43) associated with the EGRET source 3EG J1224+2118. Preliminary analysis indicates that the source on Apr 16, 2009 was in a high state with a gamma-ray flux (E>100MeV) of 4.6+/-1.6 (statistical only) *10^-7 ph cm^-2 s^-1, which represents an increase of a factor of 10 with respect to the average source flux level measured in the first 6 months of Fermi operations. Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is Giulia Iafrate (iafrate@oats.inaf.it). The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.