Fermi-LAT detection of enhanced gamma-ray activity from the BCU MG2 J164800+2224
ATel #16227; Adithiya Dinesh, (Universidad Complutense de Madrid), on behalf of the Fermi Large Area Telescope Collaboration
on 4 Sep 2023; 08:16 UT
Credential Certification: Denis Bernard (Denis.bernard@in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
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 BCU MG2 J164800+2224, also known as 4FGL J1648.0+2221 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 252.0226 deg, Decl. = +22.3523 deg (J2000; Petrov et. al 2016, AJ, 142, 89), and redshift z=0.822 (The Sloan Digital Sky Survey 2017, ApJS, 233, 25).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on September 2, 2023, with a daily averaged gamma-ray flux (E>100MeV) of (0.43 +/- 0.13) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 39 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL). This is the highest LAT daily flux ever observed for this source. The corresponding photon index is 1.79 +/- 0.17, significantly smaller than the 4FGL value of 2.64 +/- 0.09.
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 Adithiya Dinesh (adinesh@ucm.es).
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.
