Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 0035-252
ATel #17053; P. Benke (GFZ, MPIfR), G. La Mura (INAF - Astronomical Observatory of Cagliari), on behalf of the Fermi Large Area Telescope Collaboration
on 26 Feb 2025; 18:14 UT
Credential Certification: Petra Benke (pbenke@mpifr-bonn.mpg.de)
Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar, Quasar
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 0035-252, also known as 4FGL J0038.2-2459 (The Fermi-LAT collaboration 2020, ApJS, 247, 33), with coordinates R.A. = 9.56140 deg, Dec. = -24.98395 deg (J2000; Le Bail et al, 2016, AJ, 151, 79), and redshift z=0.498 (Jones et al, 2009, MNRAS, 399, 683).
Preliminary analysis indicates that this source was in an elevated gamma-ray emission state on February 24, 2025 , with a daily averaged gamma-ray flux (E>100MeV) of (1.4+/-0.3) 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 release of the fourth Fermi-LAT catalog (4FGL-DR4, Ballet et al. 2024, arXiv:2307.12546). The corresponding photon index is 2.1+/-0.1, and is consistent with the 4FGL-DR4 value of 2.23+/-0.01 within the uncertainties. The Fermi-LAT Collaboration has previously reported flaring activity from this source in ATels #11854, #10951.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. This source belongs to the "LAT Monitored Sources" and consequently, a preliminary estimation of the daily gamma-ray flux observed by Fermi-LAT will be publicly available ( https://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/PKS0035-252_86400.png ). A preliminary light curve for PKS 0035-252 can be accessed via the Fermi-LAT Light-Curve Repository. We encourage multifrequency observations of this source. For this source, the Fermi-LAT contact person is Janeth Valverde (valverde@llr.in2p3.fr).
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.
