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Fermi LAT detection of a GeV flare from 3C 446

ATel #3675; K. V. Sokolovsky (ASC Lebedev/SAI MSU) and F. K. Schinzel (MPIfR) on behalf of the Fermi Large Area Telescope Collaboration
on 10 Oct 2011; 17:56 UT
Credential Certification: Kirill Sokolovsky (kirx@scan.sai.msu.ru)

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

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed a short gamma-ray flare from a source positionally consistent with 3C 446 (22:25:47.2593 -04:57:01.391, J2000, Fey et al. 2004, AJ, 127, 3587) a flat spectrum radio quasar at z=1.404 (Perez, Penston & Moles 1989, MNRAS, 239, 55).

Preliminary analysis indicates that the source on 2011 October 08 was in a high state with a gamma-ray flux (E>100MeV) of (1.5 +/-0.4)x10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This is about 30 times higher than the average flux level observed during the first two years of Fermi mission (2FGL J2225.6-0454, Abdo et al. 2011, submitted to ApJ, arXiv:11081435). On October 09, the source was again below the detection limit in a 24h integration.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multiwavelength observations to confirm the identification of the flaring GeV source and study its activity in detail. For this source the Fermi LAT contact person is David Thompson (David.J.Thompson@nasa.gov).

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.