Fermi LAT detection of renewed gamma-ray activity from the FSRQ PKS 0202-17
ATel #17640; F. Casaburo (INAF & Astronomical Observatory of Rome, INFN & Rome Tor Vergata, Sapienza University Rome,), C. Bartolini (University of Trento & INFN Bari), S. Ciprini (INFN - Rome Tor Vergata & ASI- SSDC), G. La Mura (INAF-OACa), P. Monti-Guarnieri (University of Trieste & INFN Trieste), on behalf of the Fermi Large Area Telescope Collaboration
on 31 Jan 2026; 08:46 UT
Credential Certification: Giovanni La Mura (giovanni.lamura@inaf.it)
Subjects: Gamma Ray, >GeV, Blazar, Quasar
Referred to by ATel #: 17670
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 FSRQ PKS 0202-17, also known as 4FGL J0205.0-1700 (The Fermi-LAT collaboration 2020, ApJS, 247, 1), with coordinates R.A. = 31.24031 deg, Decl. = -17.02218 deg (J2000; Fey et al. 2004, AJ, 128, 2593), and redshift z= 1.739 (Jones et al. 2009, MNRAS, 399, 683).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on January 29, 2026, with a daily averaged gamma-ray flux (E>100MeV) of (0.7+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor more than 10 relative to the average flux reported in the fourth data release of the fourth Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2023, arXiv:2307.12546). The corresponding photon index is 2.2+/-0.2, indicating a marginally harder spectrum than the one corresponding to the 4FGL-DR4 value of 2.49+/-0.02.. The Fermi-LAT Collaboration has previously reported flaring activity from this source in ATels #15311 and #14801.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source belongs to the list of LAT daily monitored sources, therefore a daily light curve can be accessed at PKS 0202-17. A preliminary light curve for PKS 0202-17 can also be accessed via the Fermi-LAT Light-Curve Repository at 4FGL J0205.0-1700. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Isabella Mereu (mereuisabella[at]gmail[dot]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.
