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Fermi LAT detection of a GeV flare from blazar OG 050 (TXS 0529+075)

ATel #3750; Stefano Ciprini (ASI Science Data Center and INAF Observatory of Rome, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 8 Nov 2011; 22:04 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)

Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 3773

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar OG 050, also known as TXS 0529+075 and 2FGL J0532.7+0733 (Abdo et al. 2011, ApJS, submitted, arXiv:1108.1435) with VLBI coordinates, (J2000.0), R.A.: 05h 32m 38.9984s, Dec. +07d 32m 43.345s  (Beasley et al. 2002, ApJS, 141, 13).

This blazar with moderate optical brightness (R magnitude is about 17.5) is placed at z=1.254 (Sowards-Emmerd et al. 2005, ApJ, 626, 95), and has a radio and X-ray jet that is monitored by the MOJAVE program (Cooper et al. 2007, ApJS, 171, 376).

Preliminary analysis indicates that on 2011 November 7, OG 050 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.1 +/- 0.3) x 10^-6 photons cm^-2 s^-1 and a 6-hour bin (12:00-18:00 UTC) peak flux (E>100MeV) of (2.0 +/- 0.6) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 24 times greater than the average flux reported in the second Fermi LAT catalog (2FGL). 

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 encourage multiwavelength observations. For this source the Fermi LAT contact persons are S. Cutini (sara.cutini@asdc.asi.it) and S. Ciprini (stefano.ciprini@asdc.asi.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.