Fermi-LAT detection of renewed gamma-ray activity from the FSRQ B2 2308+34
ATel #15149; B. Rani (Korea Astronomy and Space Science Institute), J. Valverde (UMBC/NASA GSFC), G. La Mura (LIP), on behalf of the Fermi Large Area Telescope Collaboration
on 2 Jan 2022; 01:49 UT
Credential Certification: Janeth Valverde (valverde@llr.in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed renewed gamma-ray activity from a source positionally consistent with the flat-spectrum radio quasar B2 2308+34 (R.A. = 347.7682 deg, Decl. = +34.4223 deg, J2000; z=1.817, Wills & Wills 1976, ApJS, 31,143), also known as 4FGL J2311.0+3425 (The Fermi-LAT collaboration 2020, ApJS, 247, 33).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on December 28, 30 and 31, 2021, with a consistent daily averaged gamma-ray flux (E>100MeV) of (1.1+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 14 relative to the average flux reported in the fourth Fermi-LAT source catalog data release 2 (4FGL-DR2; Ballet et al., arXiv:2005.11208). The corresponding photon index is 2.0+/-0.1, and is smaller than the 4FGL-DR2 value of 2.35+/-0.02. The GeV gamma-ray activity of B2 2308+34 was announced previously in 2013 and in 2010, by the Fermi LAT Collaboration (ATel#5477, ATel#2783).
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. The light curve for this source can be accessed via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.php?source_name=4FGL_J2311.0+3425, and via the Fermi-LAT Monitored Sources at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/B2_2308p34. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Filippo D'Ammando (dammando@ira.inaf.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.
