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Fermi LAT detection of renewed GeV gamma-ray activity from blazar PKS 1622-253

ATel #3424; Stefano Ciprini (ASI Science Data Center, & INAF Roma Observatory, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 11 Jun 2011; 17:20 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@pg.infn.it)

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

Referred to by ATel #: 5452

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 PKS 1622-253, also known as TXS 1622-253, OS -237.8, 2EG J1626-2452, 3EG J1626-2519 and 1FGL J1625.7-2524 (Abdo et al. 2010, ApJS, 188, 405) with VLBI coordinates, (J2000.0), RA: 16h25m46.9s, Dec: -25d27'38", (Johnston et al. 1995, AJ, 110, 880) and redshift z=0.786 (di Serego Alighieri et al. 1994, MNRAS, 269, 998). 

Preliminary analysis indicates that PKS 1622-253 on 2011, June 7 reached a daily gamma-ray flux (E>100MeV) of (2.0 +/- 0.3) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 19 times greater than the average flux reported in the first Fermi-LAT catalog (1FGL, Abdo et al. 2010, ApJS, 188, 405) and representing a renewed and active phase after October 2009 (ATel#2231) . The source was observed in high gamma-ray state from 2011, June 4 with a daily flux (E > 100 MeV) of (1.1+/-0.3) 10^-6 photons cm^-2 s^-1, and is continuing to be bright at least up to 2011, June 10 with a daily flux (E > 100 MeV) of (1.7+/-0.3) 10^-6 photons cm^-2 s^-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 Luis C. Reyes (lcreyes@uchicago.edu).

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.