Fermi-LAT detection of renewed gamma-ray activity from the FSRQ NRAO 190 (PKS 0440-00)
ATel #17197; S. Wagner (University of Wuerzburg), on behalf of the Fermi Large Area Telescope Collaboration
on 20 May 2025; 16:49 UT
Credential Certification: Sarah Wagner (sarah.wagner@physik.uni-wuerzburg.de)
Subjects: Gamma Ray, >GeV, 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 NRAO 190 (also known as PKS 0440-00 and 4FGL J0442.6-0017, The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 70.66109 deg, Decl. = -0.29539 deg (J2000; Johnston et al., 1995, AJ, 110, 880), and redshift z=0.844 (Hewitt & Burbidge 1987, ApJS, 63, 1).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on May 19, 2025, with a daily averaged gamma-ray flux (E>100MeV) of (1.3 +/- 0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of about 20 relative to the average flux reported in the fourth release of the Fourth Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2024, arXiv:2307.12546). The corresponding photon index is 1.9 +/- 0.1, indicating a harder spectrum than the 4FGL-DR4 value of 2.45 +/- 0.02. We have previously reported flares from this source in ATels #17102 #16563, #16395, #5156 and #2049.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. A preliminary light curve for PKS 0440-00 can be accessed via the Fermi-LAT Light-Curve Repository and via the Monitored Source List.
We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact people are S. Ciprini (stefano.ciprini@pg.infn.it) and F. Longo (francesco.longo@ts.infn.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.
