[ Previous | Next | ADS ]

Fermi LAT detection of a gamma-ray flare from the high-redshift blazar PKS 2123-463

ATel #3808; M. Orienti (Univ. Bologna; INAF-IRA Bologna), F. D'Ammando (INAF-IRA Bologna) on behalf of the Fermi Large Area Telescope Collaboration
on 16 Dec 2011; 08:51 UT
Credential Certification: Filippo D'Ammando (filippo.dammando@iasf-roma.inaf.it)

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

Referred to by ATel #: 3814, 3815

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 PKS 2123-463 (also known as 1FGL J2126.1-4603, Abdo et al. 2010, ApJS, 188, 405, and 2FGL J2125.0-4632, Abdo et al. 2011, submitted to ApJS, arXiv:1108.1435; RA: 21h26m30.7042s, Dec:-46d05m47.892s, J2000, Fey et al. 2006, AJ, 132, 1944). The redshift was reported to be z = 1.67 (Wright & Otrupcek 1990, Parkes Catalog 1990), although the measurement has been questioned (Jackson et al. 2002, A&A, 386, 97).

Preliminary analysis indicates that the source on December 14, 2011 was in a high state with a gamma-ray flux (E > 100 MeV) of (1.1 +/- 0.2) x10^-6 photons cm^-2 s^-1 (errors are statistical only), representing an increase of a factor of 60 with respect to the average source flux observed in the first two years of Fermi mission (Abdo et al. 2011, submitted to ApJS, arXiv:1108.1435).

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage further multiwavelength observations. For this source the Fermi LAT contact person is M. Orienti (orienti@ira.inaf.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.