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Fermi LAT detection of strong gamma-ray activity from the FSRQ 3C 454.3

ATel #9190; Roopesh Ojha (NASA/GSFC/UMBC) on behalf of the Fermi Large Area Telescope Collaboration
on 25 Jun 2016; 13:00 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Gamma Ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 9192, 9723

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed strongly increasing gamma-ray flux from the FSRQ 3C 454.3. Preliminary analysis indicates that during the past two weeks the source flux increased by about an order of magnitude, compared to its flux in recent months. It reached a peak daily averaged emission on 2016 June 23 with a gamma-ray flux (E > 100 MeV) of (13.7 +/- 0.5)x10^-6 photons cm^-2 s^-1 and photon index of 2.07+/-0.03 (errors are statistical only) which is harder than its typical photon index of about 2.4. A six-hour flux of (18.3+/-1.3)x10^-6 photons cm^-2 s^-1 was observed during 2016 June 23 06:00:00 - 2016 June 23 12:00:00.

Recent gamma-ray activity exhibited by 3C 454.3 was reported by the AGILE Collaboration (ATel #9186, ATel #9176, ATel #9157). Increased optical activity and microvariability have also been reported (ATel #9178, ATel #9150).

The last gamma-ray flare of 3C 454.3 announced by Fermi was on 2014 June 15 (ATel #6236) with a gamma-ray six-hour flux reaching (19 +/- 2)x10^-6 photons cm^-2 s^-1.

All values reported are calculated above 100 MeV and errors are statistical only. Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. The blazar 3C 454.3 is a "LAT Monitored Source" (http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/3C454.3_86400.png), and consequently, a quick look estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available. The Fermi LAT contact persons are Greg Madejski (madejski@stanford.edu) and Benoit Lott (lott@cenbg.in2p3.fr). Further multiwavelength observations of the source are strongly 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.