Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 0202-17
ATel #15311; G. La Mura (LIP, Portugal) on behalf of the Fermi Large Area Telescope Collaboration
on 4 Apr 2022; 19:19 UT
Credential Certification: Giovanni La Mura (glamura@lip.pt)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Transient
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 0202-17, also known as 4FGL J0205.0-1700 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 31.24031 deg, Decl. = -17.02218 deg (J2000; Fey et al. 2004, AJ, 127, 3587), 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 April 3, 2022, with a daily averaged gamma-ray flux (E>100MeV) of (1.0+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of approximately 30 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 measured photon index is 2.4+/-0.2, corresponding to a harder spectrum than the 4FGL value of 2.63+/-0.03, similarly to what has been previously reported (e. g. ATel #14801).
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source is included in the "LAT Monitored Sources" and consequently, a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT will be publicly available (http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/). Further information on the light curve of this source is also available through the Fermi-LAT Light Curve repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=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 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.
