Fermi LAT detection of a possible gamma-ray flaring from FSRQ PKS 0221+067
ATel #16544; Federica Giacchino (INFN & SSDC) on behalf of the Fermi Large Area Telescope Collaboration
on 20 Mar 2024; 19:00 UT
Credential Certification: Federica Giacchino (federica.giacchino@roma2.infn.it)
Subjects: Gamma Ray, >GeV, Blazar, Quasar
The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed for the first time gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar PKS 0221+067, also known as 4FGL J0224.2+0700 in the fourth Fermi catalog (The Fermi-LAT collaboration 2020, ApJS, 247, 33) with VLBI coordinates (J2000.0), R.A: 36.0577 deg, Dec.: +7.0126 deg (The Fermi-LAT collaboration 2020, ApJS, 247, 33). This blazar has redshift z=0.511 (Lister et al., 2018, ApJS, 234, 12).
Preliminary analysis indicates that 2024 March 19, PKS 0221+067 was in a never-before detected high flux state with a daily average gamma-ray flux (E>100MeV) of (0.5 +/- 0.2) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 73 times greater than the average flux reported in the 4FGL catalog. The corresponding photon index is 2.1+/- 0.3 and is harder than the 4FGL value of 2.5 +/- 0.1 within the uncertainties.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. The gamma-ray light curve of PKS 0221+067 may be found in Fermi LAT Light Curve Repository at https://fermi.gsfc.nasa.gov/ssc/data/access/lat/LightCurveRepository/source.html?source_name=4FGL_J0224.2+0700. For this source the Fermi LAT contact person is Federica Giacchino (federica.giacchino@roma2.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.
