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Fermi LAT detection of a GeV flare from new gamma-ray blazar PKS 1118-056

ATEL # 1932; Luis C. Reyes (KICP - University of Chicago) and Stephane Corbel (University Paris Diderot & CEA Saclay) on behalf of the Fermi Large Area Telescope Collaboration
on 18 Feb 2009; 21:14 UT
Password Certification: Gino Tosti (

Subjects: Gamma Ray, >GeV, Transients

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 1118-056 (RA: 11h21m25.1s , Dec: -05d53m56s , J2000). Preliminary analysis indicates that the source on Feb 17 was in a high state with a gamma-ray flux (E>100MeV) of (0.4 +/- 0.1) x 10-6 ph cm-2 s-1, which represents a ten-fold increase in flux with respect to the average preliminary flux observed during the first 6 months of data of the Fermi mission (~0.04 x 10-6 ph cm-2 s-1)

PKS 1118-056 (z=1.297; M.J. Drinkwater et al. 1997, MNRAS, 284, 85) is classified as a giga-hertz peaked (GPS) radio source. Radio sources of this type are unusual among the bright gamma-ray AGN identified in the first 3-months of Fermi-LAT operation (Abdo et al., preprint, astro-ph/0902.1559). In consideration of the recent activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is C.C. Cheung (e-mail: Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue.

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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