Fermi-LAT detection of renewed gamma-ray activity from the blazar PKS 1716-771
ATel #15381; J. Valverde (UMBC/NASA GSFC), B. Rani (KASI, S. Korea), G. La Mura (LIP, Portugal) on behalf of the Fermi Large Area Telescope Collaboration
on 16 May 2022; 16:27 UT
Credential Certification: Giovanni La Mura (glamura@lip.pt)
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 blazar PKS 1716-771, also known as 4FGL J1723.6-7714 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 260.961855 deg, Decl. = -77.230706 deg (J2000; Petrov et al. 2011, MNRAS, 414, 2528), and without a spectroscopic redshift (see Kaur et al. 2018, ApJ, 859, 80).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on May 14, 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 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 2.00+/-0.15, and is smaller than the 4FGL value of 2.29+/-0.02, while other recent flaring activity (see ATel #15336) had a measured spectrum consistent with that of 4FGL.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J1723.6-7714). We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Teddy 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.
