Fermi LAT detection of a GeV flare from blazar S5 1217+71

ATel #4885; Stefano Ciprini (ASI Science Data Center and INAF Observatory of Rome, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 13 Mar 2013; 16:46 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@asdc.asi.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 1217+71, also known as TXS 1217+713 and 2FGL J1219.2+7107 in the second Fermi LAT catalog (2FGL, Nolan et al. 2012, ApJS, 199, 31) with VLBI coordinates, (J2000.0), R.A: 185.015118 deg, Dec.: +71.091981 deg (Petrov et al. 2005, AJ, 129, 1163). This blazar has redshift z=0.451 (Stickel & Kuehr 1996, A&AS, 115, 1).

Preliminary analysis indicates that on 2013 March 11, S5 1217+71 was in a high state with a daily average gamma-ray flux (E>100MeV) of (0.6 +/- 0.2) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 90 times greater than the average flux reported in the 2FGL catalog. On 2013 March 12 the source was still in a high state with a daily average gamma-ray flux (E>100MeV) of (0.5 +/- 0.1) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This is the first high activity state observed from this source since the beginning of the Fermi mission.

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.