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Fermi LAT observations of increasing gamma-ray activity of blazar 3C279

ATel #2886; A. Cannon (University College Dublin, NASA/GSFC), on behalf of the Fermi Large Area Telescope Collaboration
on 29 Sep 2010; 22:54 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

Subjects: Gamma Ray, >GeV, Blazar

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed over 27th and 28th September 2010, a sharp increase in gamma-ray activity from the blazar 3C279.

Preliminary analysis indicates that the source rapidly reached a daily flux (E>100MeV) of (3.9+/-1.4) x10^-6 ph cm^-2 s^-1 on the 27th (errors are statistical only), more than a factor of 4 greater than reported in the Fermi-LAT 1st year catalog (1FGL J1256.2-0547, Abdo et al. 2010, ApJS 188, 405). This intense gamma-ray flare follows a slowly increasing trend during the course of the last month. The source was detected again on the 28th with a daily flux (E>100MeV) of (2.0+/-0.1) x10^-6 ph cm^-2 s^-1.

This well-known blazar, classified as a flat spectrum radio quasar (FSRQ), has a redshift of 0.536 (Marziani et al. ApJS, 1996, 104, 37). Increased gamma-ray activity from this source was previously reported in Atel #2154 (August 2009) and Atel #1864 (December 2008).

The Fermi-LAT contact people for this source are Greg Madejski (madejski@slac.stanford.edu) and Masaaki Hayashida (mahaya@slac.stanford.edu). 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 strongly encourage multiwavelength observations.

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.