Fermi LAT detection of a GeV flare from blazar S5 1803+78
ATel #3322; Luis C. Reyes (KICP - The University of Chicago) on behalf of the Fermi LAT Collaboration
on 4 May 2011; 04:11 UT
Credential Certification: Luis C. Reyes (lcreyes@uchicago.edu)
Subjects: Gamma Ray, >GeV, Blazar, Transient
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with S5 1803+78 (1FGL J1800.4+7827) with coordinates RA: 18h00m45.7s, Dec: +78d28m04s (J2000). The source has a measured redshift of z=0.68 (Stickel, M., Fried, J.W., & Kuehr, H. 1993, A&AS, 98, 393). Preliminary analysis indicates that the source on May 2, 2011 was in a high state with a gamma-ray flux (E>100MeV) of (1.1 +/- 0.2) e-6 ph cm-2 s-1. This is the highest measured flux for the source since the beginning of the Fermi mission and constitutes a factor of ~20 increase with respect to the average flux F(E>100 MeV) reported in the First Fermi catalog of (6.24 +/- 0.70)e-8 ph cm-2 s-1(Abdo et al. 2010, ApJS, 188, 405).
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 multi-wavelength follow-up observations. For this source the Fermi LAT contact person is Luis C. Reyes (lcreyes@uchicago.edu).
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.
