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Fermi LAT detection of a GeV flare from blazar CTA 102

ATel #3320; Stefano Ciprini (ASI Science Data Center, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 3 May 2011; 17:49 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)

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

Referred to by ATel #: 4409, 6631

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the flat spectrum radio quasar CTA 102, also known as 4C 11.69, OY 150,  3EG J2232+1147, 1FGL J2232.5+1144 (Abdo et al. 2010, ApJS, 188, 405) with VLBI coordinates, (J2000.0), R.A.: 22h 32m 36.4089s, Dec. +11d 43m 50.904s (Johnston et al. 1995, AJ, 110, 880). This MeV-peaked gamma-ray blazar (detected by COMPTEL and EGRET,  Blom et al. 1995, A&A, 295, 330;  Nolan et al. 1993, ApJ, 414, 82)  has redshift z=1.037 (Schmidt 1965, ApJ, 141, 1295).

Preliminary analysis indicates that  CTA 102 on 2011, April 29 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.4 +/- 0.3) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 10 times greater than the average flux reported in the first Fermi-LAT catalog (1FGL, Abdo et al. 2010, ApJS, 188, 405) and representing the first firm detection on a daily timescale since the start of the LAT all-sky survey. The source was detected at lower confidence and similar flux level also on 2011, May 1.

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 persons is S. Cutini (sara.cutini@asdc.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.