Fermi-LAT detection of renewed gamma-ray activity from the FSRQ PKS 0537-286
ATel #15405; J. Valverde (UMBC/NASA GSFC) and J. Forman (Florida Tech.), on behalf of the Fermi Large Area Telescope Collaboration
on 30 May 2022; 21:57 UT
Credential Certification: Janeth Valverde (valverde@llr.in2p3.fr)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar
Referred to by ATel #: 15415
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 flat-spectrum radio quasar PKS 0537-286, also known as 4FGL J0539.9-2839 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 84.976173 deg, Decl. = -28.665541 deg (J2000; Johnston et al. 1995 AJ, 110, 880), and redshift z = 3.104 (Osmer et al. 1994, ApJ, 436, 678).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on May 28, 2022, with a daily averaged gamma-ray flux (E>100MeV) of (1.6+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 40 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 2.7+/-0.2. Fermi-LAT observations for this source during previous gamma-ray flaring activity are reported in ATels #14285 and #10356.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Preliminary light curves can be accessed via the Monitored Source List at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_0537-286, and via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/lcr/source.html?source_name=4FGL_J0539.9-2839. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is C. C. Cheung (teddy.cheung@nrl.navy.mil).
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.
