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Fermi LAT detection of a GeV flare from PMN J2331-2148

ATel #2101; F. Longo (INFN Trieste) and G. Iafrate (INAF/OA Trieste) on behalf of the Fermi Large Area Telescope Collaboration
on 27 Jun 2009; 20:17 UT
Credential Certification: Francesco Longo (francesco.longo@ts.infn.it)

Subjects: Gamma Ray, >GeV, Request for Observations, AGN

Referred to by ATel #: 2206

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 PMN J2331-2148 (RA=23h31m04.03s, Dec=-21d48'15.3", J2000, Healey S. et al. 2007, ApJS, 171, 61) on June 26, 2009. This object is a known flat spectrum radio source (no redshift known). There is no previously reported EGRET gamma-ray detection at this location. Preliminary analysis indicates that the source on June 26, 2009 was in a high state with a gamma-ray flux (E>100MeV) of 0.82 +/- 0.26 x 10^-6 ph cm^-2 s^-1 (statistical only), which represents an increase of more than a factor of 10 with respect to the first 9 months of all-sky monitoring (Aug 2008 - Apr 2009). Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the flaring activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is F.Longo (francesco.longo@ts.infn.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.