Fermi LAT detection of a GeV flare from blazar S5 0836+71 (4C 71.07)

ATel #3260; Stefano Ciprini (ASI Science Data Center, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 6 Apr 2011; 14:59 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)

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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 S5 0836+71, also known as 4C 71.07, 1ES 0836+710, 3EG J0845+7049, 1FGL J0842.2+7054 (Abdo et al. 2010, ApJS, 188, 405) with VLBI coordinates, (J2000.0), R.A.: 08h 41m 24.3652s, Dec.: +70d 53m 42.173s (Johnston et al. 1995, AJ, 110, 880). This optically bright and MeV-peaked gamma-ray blazar (detected by INTEGRAL, COMPTEL and EGRET, Pian et al. 2005, A&A, 429, 427; Collmar 2006, ASP Conf. Ser. 350; 120, Hartman et al. 1999, ApJS, 123, 79) has redshift z=2.218 (McIntosh et al. 1999, ApJ, 514, 40), presents an intervening system placed at z = 0.914 and an intrinsic absorbing environment surrounding the peculiarly-structured jet (Hutchison et al., 2001, MNRAS, 321, 525; Foschini et al. 2006, A&A, 453, 829; Perucho & Lobanov 2007, A&A, 469, L23).

Preliminary analysis indicates that S5 0836+71 on 2011, April 3 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.2 +/- 0.3) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 15 times greater than the average flux reported in the first Fermi-LAT catalog (1FGL, Abdo et al. 2010, ApJS, 188, 405) and representing the first firm detection on a daily timescale since the start of the LAT all-sky survey.

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 K. Sokolovsky (ksokolov@mpifr-bonn.mpg.de) and D.J. 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.