Enhanced gamma-ray activity detected by Fermi-LAT from SBS 1646+499
ATel #15565; Sara Cutini (INFN Perugia), Isabella Mereu (INFN Perugia) and Dario Gasparrini (INFN Rome 2) on behalf of Fermi-LAT Collaboration
on 22 Aug 2022; 14:27 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 enhanced gamma-ray activity from a source positionally consistent with the blazar SBS 1646+499, also known as 4FGL J1647.5+4950 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 251.8954 deg, Decl. = +49.8334 deg (J2000; Petrov et al. 2011, AJ, 142, 89), and redshift z = 0.0475 (Falco et al. 1998, ApJ, 494, 47).
Preliminary analysis indicates that on 2022 August 18 and August 19, SBS 1646+499 appeared in a flaring state with a daily gamma-ray flux (E>100MeV) of 4.8e-07 +/- 1.5e-07 and 2.4e-07 +/- 0.8e-07 photons cm^-2 s^-1 respectively (statistical uncertainty only), about 17 times and 9 times the average flux of the 4FGL catalog source.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Sara Cutini (sara.cutini@pg.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.
