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

ATel #6236; S. Buson (INFN & Univ. of Padova), on behalf of the Fermi LAT Collaboration
on 15 Jun 2014; 19:58 UT
Credential Certification: Sara Buson (buson@pd.infn.it)

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Blazar

Referred to by ATel #: 6237, 6246, 6266, 9190

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 week the source flux increased by more than a factor of 10 compared to its flux in recent months. It reached a daily peak emission on 2014 June 14 with a gamma-ray flux (E> 100 MeV) of (14 +/- 2)x10^-6 photons cm^-2 s^-1 and photon index of 2.06+/-0.04 (errors are statistical only). A six-hour flux of (16+/-2)x10^-6 photons cm^-2 s^-1 was observed during 2014 June 14 00:00:00 - 2014 June 14 06:00:00.

Preliminary analysis of the six-hour periods from 2014 June 15 06:00:00 to 2014 June 15 12:00:00 indicates the flare is still ongoing with an observed flux of (19+/-2)x10^-6 photons cm^-2 s^-1.

Recent gamma-ray activity exhibited by 3C 454.3 was reported by the AGILE Collaboration during the past month (see ATel #6182, ATel #6217 and ATel #6234). A correlated brightening in the optical and NIR bands was reported on 2014 June 14 (Atel #6232) and on 2014 June 9 (ATel #6213), respectively.

The most-recent previous gamma-ray flare of 3C 454.3 announced by Fermi was on 2010 November (ATel #3041, ATel #3064) with a gamma-ray six-hour flux reaching (56 +/- 4)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 (http://fermi.gsfc.nasa.gov/ssc/data/access/). 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.