Fermi LAT Detection of a Bright GeV Flare from VER 0521+211
ATel #5472; S. Buson (INFN/Univ. Padova) on behalf of the Fermi LAT Collaboration
on 15 Oct 2013; 17:45 UT
Credential Certification: Sara Buson (buson@pd.infn.it)
Subjects: Gamma Ray, AGN, Blazar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from a source positionally consistent with the blazar VER 0521+211 (RA=05h21m45.9658s, Dec=+21d12m51.451s, J2000; z= 0.108, Shaw et al. 2013, ApJ 764, 135).
Preliminary analysis indicates that on 2013 October 14, VER J0521+211 was detected with a daily averaged flux (E>100MeV) of (1.0 +/- 0.3) x 10^-6 photons cm^-2 s^-1 (errors are statistical only) and a daily photon index of 2.4 +/- 0.3. The observed flux is the highest ever recorded for this source and is 12 times the average flux of its gamma-ray counterpart 2FGL J0521.7+2113 (Nolan et al. 2012, ApJS, 199, 31). This source is also reported in the 1FHL catalog of LAT sources detected above 10 GeV (1FHL J0521.7+2113, Ackerman et al. 2013, ApJS, submitted, arXiv1306.6772) and was announced as a VHE emitter by VERITAS in 2009 (ATel #2309).
Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing prominent gamma-ray outburst, we strongly encourage multiwavelength observations of this object. For this source the Fermi LAT contact person is S. Buson (buson@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.