Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 1203-26
ATel #16094; P. V. van Zyl (SARAO), J. Valverde (UMBC/ NASA GSFC), I Mereu (INFN Perugia) on behalf of the Fermi Large Area Telescope Collaboration
on 23 Jun 2023; 18:18 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 flat-spectrum radio quasar (FSRQ) PKS 1203-26, also known as 4FGL J1205.7-2635 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with radio coordinates R.A. = 181.388385 deg, Decl. = -26.567907 deg (J2000; Beasley et al. 2002, ApJS, 141, 13), and redshift z=0.789 (Wright et al. 1979, ApJ, 229, 73).
Preliminary analysis indicates that this source has been in a consistently elevated gamma-ray emission state since June 17, 2023, reaching a daily averaged gamma-ray flux (E>100MeV) of (0.5 +/- 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). This is the highest LAT daily flux ever observed for this source. The corresponding photon index is 2.0 +/- 0.2, indicating a harder spectrum than the 4FGL value of 2.54 +/- 0.05.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of these sources will continue. A preliminary light curve for PKS 1203-26 can be accessed via the Fermi-LAT Light-Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/lcr/source.html?source_name=4FGL_J1205.7-2635. We encourage multifrequency observations of these sources. For PKS 1203-26, the Fermi-LAT contact person is Pfesi Van Zyl (pfesi24@gmail.com).
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.
