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Fermi LAT detection of increasing gamma-ray emission from blazar B2 1504+37

ATel #6760; Y. Tachibana (Tokyo Tech), Y. Tanaka (Hiroshima University) on behalf of the Fermi Large Area Telescope Collaboration
on 27 Nov 2014; 09:04 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@fisica.unipg.it)

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

The Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar B2 1504+37 (also known as 2FGL J1506.0+3729, Nolan et al. 2012, ApJS, 199, 31) with radio coordinates RA: 15h 06m 09.52995s, Dec: +37d 30m 51.1330s, (J2000, Lanyi et al. 2010, AJ, 139, 1695) at redshift z=0.674 (Charlot et al. 2010, AJ, 139, 1713).

Preliminary analysis indicates that the source brightened in gamma rays with a daily flux (E > 100 MeV) on 2014 November 25 of (1.3 +/- 0.2) x10^-6 ph cm^-2 s^-1 (errors are statistical only) about 50 times greater than the average flux reported in the second Fermi-LAT catalog. The flux is the highest since Fermi started science operations in August 2008, and a slight brightening started one week ago.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source is being added to the "LAT Monitored Sources" and a preliminary estimate of the daily gamma-ray flux observed by Fermi LAT will be publicly available (Monitored Source List Light Curves). In consideration of the ongoing activity of this source we encourage multiwavelength observations. For this source the Fermi LAT contact person is Y. Tachibana (tachibana@hp.phys.titech.ac.jp).

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.