Fermi-LAT detection of renewed gamma-ray activity from the FSRQ PKS 0402-362
ATel #15903; Stefano Ciprini (INFN Roma Tor Vergata & ASI Space Science Data Center, Roma, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 14 Feb 2023; 22:51 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 PKS 0402-362 (also known as 4FGL J0403.9-3605), with coordinates R.A. = 60.973958 deg, Decl. = -36.083864 deg (J2000; Johnston, K. J., et al. 1995, AJ, 110, 880), and redshift z = 1.417 (Peterson et al. 1976, ApJ, 207, 5).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on 2023 February 13, with a daily averaged gamma-ray flux (E>100MeV) of (3.5+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of 20 relative to the average flux reported in the fourth Fermi-LAT catalog (4FGL-DR3, Abdollahi, S., et al. for the Fermi-LAT collaboration 2022, ApJS, 260, 53). The corresponding photon index is 2.08+/-0.05, and is significantly smaller than the 4FGL-DR3 value of 2.53+/-0.01. High gamma-ray activity from this source was previously detected by Fermi-LAT and reported in ATels #2413 and #3655.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Preliminary Fermi-LAT light curves can be accessed via the Monitored Source List at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/PKS_0402-362, and via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/lcr/source.html?source_name=4FGL_J0403.9-3605. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is J. Vandenbroucke (vandenbrouck@wisc.edu).
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.
