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Fermi LAT detection of increased gamma-ray activity from blazar S5 0716+71

ATel #6085; S. Buson (INFN & Univ. of Padova), on behalf of the Fermi LAT collaboration
on 21 Apr 2014; 16:58 UT
Credential Certification: Sara Buson (buson@pd.infn.it)

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

Referred to by ATel #: 6086

The Large Area Telescope (LAT), one of two instruments on-board the Fermi Gamma-ray Space Telescope, has observed an increase in gamma-ray activity from a source positionally coincident with the BL Lac object S5 0716+71 (also known as 2FGL J0721.9+7120, Nolan et al. 2012, ApJS, 199, 31; R.A.= 07h21m53.4484s, Dec.=+71d20m36.363s, J2000, Johnston et al. 1995, AJ 110, 880). Nilsson et al. (2008, A&A 487, L29) derived a photometric redshift for this source of z = 0.31+/- 0.08.

Preliminary analysis indicates that the source on 2014 April 19 was detected in a high state with an average daily flux (E>100 MeV) of (1.2+/-0.2) x10^-6 ph cm^-2 s^-1 and a hard spectrum with a photon index of 1.7 +/- 0.1 (statistical uncertainties only). The source flux started to increase several days ago, and in recent days the daily average flux (E>100 MeV) has been close to (0.9+/- 0.2) x10^-6 ph cm^-2 s^-1.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source is among the "LAT Monitored Sources" and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/). We encourage further multifrequency observations of this source. The Fermi LAT contact person for this source is D. Bastieri (bastieri@pd.infn.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.