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Fermi LAT detection of a GeV flare from PMN J2250-2806

ATEL # 1989; E. Koerding (CEA Saclay/Paris Diderot); on behalf of the Fermi Large Area Telescope Collaboration
on 27 Mar 2009; 8:45 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Gino Tosti (

Subjects: Request for Observations, AGN

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 J2250-2806 (RA: 22h50m44.45s Dec: -28h06m35.3s, J2000, Healey et al. 2008, ApJS, 175, 97.) since Mar. 22, 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 Mar. 25, 2009 was in a high state with a gamma-ray flux (E>100MeV) of 1.36+-0.25 x 10^-6 ph cm^-2 s^-1, which represents an increase of more than a factor of 40 with respect to the source flux level in the past months. 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 E. Koerding (

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.

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