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Fermi LAT detection of increasing gamma-ray activity from the FSRQ B3 1708+433

ATEL # 3026; A. Allafort (Stanford/KIPAC), F. D'Ammando (INAF-IASF Palermo) on behalf of the Fermi Large Area Telescope Collaboration
on 11 Nov 2010; 18:50 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Filippo D'Ammando (

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Quasars
Referred to by ATEL #: 3030

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed an increasing gamma-ray flux from a source positionally consistent with the Flat Spectrum Radio Quasar B3 1708+433, also known as CGRaBS J1709+4318 and 1FGL J1709.6+4320 (RA=17:09:41.09,Dec=+43:18:44.55,J2000; Helmboldt et al. 2007, ApJ 658, 203). The source is located at redshift z=1.027 (Healey et al. 2008, ApJS 175, 97).

The source was detected in a high state between November 9 and November 10, 2010. Preliminary analysis indicates that the source on November 9, 2010 reached a daily gamma-ray flux (E> 100 MeV) of (1.2 +/- 0.3) x10^-6 ph cm^-2 s^-1 (errors are statistical only), a factor of 30 greater than reported in the Fermi-LAT 1st year catalog (Abdo et al. 2010, ApJS 188, 405). The source also showed high gamma-ray flux level on daily intervals on October 18 and November 3, 2010 (

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. For this source the Fermi LAT contact person is A. Allafort (

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.

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