Fermi LAT detection of a GeV gamma-ray flare from blazar OQ 334 (B2 1420+32)

ATel #12277; Stefano Ciprini (1. INFN Tor Vergata, Rome; 2. ASI Space Science Data Center, Rome), on behalf of the Fermi Large Area Telescope Collaboration
on 8 Dec 2018; 20:02 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@ssdc.asi.it)

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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 flat spectrum radio quasar object OQ 334 (also known as B2 1420+32, GB2 1420+326 and 3FGL J1422.4+3227) with radio coordinates (J2000) R.A.: 215.626579deg, Dec.: 32.386233deg (Petrov & Taylor 2011, AJ, 142, 89). This blazar has a redshift z=0.6819 (Hewett & Wild 2010, MNRAS, 405, 2302).

OQ 334 (B2 1420+32) has brightened in GeV gamma rays since 2018 December 5. In particular, preliminary analysis indicates that on 2018 December 7, OQ 334 was in a high state with a daily averaged gamma-ray flux (E>100 MeV) of (1.3+/-0.2) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), almost 180 times greater than its four-year average flux reported in the third Fermi-LAT source catalog (3FGL, Acero et al. 2015, ApJS, 218, 23). The corresponding single power-law photon spectral index (E>100 MeV) of 1.8+/-0.1 (statistical uncertainty only) is smaller (i.e. harder spectrum) than the 3FGL catalog value of 2.56+/-0.21.

The peak 6-hour integrated gamma-ray flux (E>100 MeV) of (2.5+/-0.5) X 10^-6 photons cm^-2 s^-1 was reached by OQ 334 on 2018 December 7 in the interval 00:00-06:00 UT, and was about 340 times greater than the average flux reported in the 3FGL catalog.

This is the first time that an increasing gamma-ray flux trend for this source is announced with a telegram by the Fermi LAT Collaboration after more than 10 years of Fermi LAT all-sky survey observations. The source will be inserted in the "LAT Monitored Sources" table at FSSC, and consequently preliminary estimations of the daily and weekly gamma-ray flux observed by Fermi LAT will be publicly available.

Because Fermi 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 encourage multiwavelength observations. For this source the Fermi LAT contact person is S. Ciprini (stefano.ciprini@ssdc.asi.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.