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Fermi LAT further detection of a GeV flare from low redshift source PKS 0521-36

ATel #2683; G. Iafrate (INAF - OATs, Trieste), F. Longo (INFN Trieste), F. D'Ammando (INAF - IASF Palermo) on behalf of the Fermi Large Area Telescope Collaboration
on 18 Jun 2010; 21:52 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Francesco Longo (francesco.longo@ts.infn.it)

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

Referred to by ATel #: 2689

The Large Area Telescope (LAT), on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with 1FGL J0522.8-3632, a source associated with PKS 0521-36 (RA: 05h22m57.98465s, DEC: -36d27m30.8509, J2000, Lambert et al. 2009, A&A, 493, 317) at z=0.055.

Preliminary analysis indicates that the source on June 17, 2010 was in a high state with a gamma-ray flux (E>100MeV) of (1.0 +/- 0.2) e-6 ph/cm^2/s (statistical uncertainty only), about 10 times the flux reported in the 1FGL catalogue (Abdo et al. 2010, ApJS, 188, 405).

This is the second time that Fermi is announcing activity on this source. It was already reported by Fermi at a slightly lower flux in its Gamma-ray sky blog on January 29, 2010.

This source first classified as an N galaxy, and then as a BL Lac object, showed in optical and UV strong narrow and broad emission lines typical of Seyfert 1 galaxies (Ulrich 1981, A&A, 103, L1; Scarpa et al. 1995, A&A, 303, 730). Given the doubtful classification, the low redshift and in consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is Filippo D'Ammando (filippo.dammando@ifc.inaf.it).

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.