Fermi LAT detection of a GeV gamma-ray flare from blazar CGRaBS J0809+5341 (87GB 080551.6+535010)

ATel #10905; Dario Gasparrini (ASI SSDC & INFN Perugia, Italy) on behalf of the Fermi LAT Collaboration
on 29 Oct 2017; 10:03 UT
Credential Certification: Dario Gasparrini (dario.gasparrini@asdc.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 CGRaBS J0809+5341 (also known as 87GB 080551.6+535010, BZQ J0809+5341 and 3FGL J0809.5+5342) with radio coordinates (J2000) R.A.: 122.4238862 deg, Dec.: 53.6903033 deg (Petrov et al. 2011, AJ, 142, 89). This blazar has a redshift z = 2.133 (Healey et al. 2008, ApJS, 175, 97).

Preliminary analysis indicates that on 2017 October 26, CGRaBS J0809+5341 was in a high state with a daily averaged gamma-ray flux (E>100 MeV) of (0.23+/-0.15) X 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 20 times greater than its four-year average flux reported in the third Fermi-LAT source catalog (3FGL, Acero et al. 2015, ApJS, 218, 23).

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. The source will be inserted in the "LAT Monitored Sources" table at FSSC ( https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ ) and consequently preliminary estimations of the daily and weekly gamma-ray flux observed by Fermi LAT will be publicly available. For this source the Fermi LAT contact person is D. Gasparrini (dario.gasparrini@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.