Fermi-LAT detection of enhanced gamma-ray activity from Changing-Look blazar OQ 334 (B2 1420+32)

ATel #15793; S. J. Kang (Liupanshui Normal University) and B. Lyu (Peking University)
on 6 Dec 2022; 16:16 UT
Credential Certification: Bing Lyu (lyubing@pku.edu.cn)

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The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray emission from a source positionally consistent with the Changing-Look blazar OQ 334 (also known as B2 1420+32, and 4FGL J1422.5+3223, http://ned.ipac.caltech.edu/ , http://simbad.cds.unistra.fr/simbad/sim-fbasic ) with radio coordinates (J2000) R.A.= 215.62657165527344deg, Dec.=32.386234283447266deg for the counterpart associated source in the third release of the fourth Fermi-LAT catalog (4FGL-DR3, Abdollahi et al. 2022, ApJS, 260, 53), and with a redshift z=0.681889 (The Fermi-LAT collaboration arXiv:2209.12070) and a redshift z=0.6819 (Hewett & Wild 2010, MNRAS, 405, 2302).

Preliminary analysis indicates that this source was found to be in an enhanced flux state (gamma-ray emission) from October, 2022. The highest LAT daily flux was observed about on November 8, 2022, (ISO:2022-11-08 05:56:40, MJD:59891.247692) with a daily averaged gamma-ray flux (E>100MeV) of (1.59+/-0.10) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only). This corresponds to a flux increase of a factor of about 22 relative to the average flux reported in the third release of the fourth Fermi-LAT catalog (4FGL-DR3, Abdollahi et al. 2022, ApJS, 260, 53). The corresponding photon index is 2.17 +/-0.13, which remains consistent with the 4FGL-DR3 value of 2.21+/-0.016.

Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Preliminary Fermi-LAT light curves can be accessed via the Monitored Source List at (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/OQ_334) and via the Fermi-LAT Light-Curve Repository at (https://fermi.gsfc.nasa.gov/ssc/data/access/lat/lcr/source.html?source_name=4FGL_J1422.3+3223) The multifrequency observations of this source are encouraged.

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.