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Increased Gamma-ray Activity from the FSRQ PKS 1424-41

ATel #4494; Roopesh Ojha (NASA/GSFC), Michael Dutka (Catholic U.) on behalf of the Fermi Large Area Telescope Collaboration
on 17 Oct 2012; 15:26 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

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

Referred to by ATel #: 4714

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope has observed increased gamma-ray emission from a source positionally coincident with the flat spectrum radio quasar PKS 1424-41 (1424-418; 2FGL J1428.0-4206, Nolan et al. 2012, ApJS, 199, 31). PKS 1424-41 has the coordinates RA=14h27m56.3s, DEC= -42d06'19.4", J2000, (Johnston et al. 1995, AJ, 110, 880). At a redshift of 1.522 (White et al. 1988, ApJ, 327, 561), PKS 1424-418 is a bright, compact radio source (Ojha et al. 2010, 519, A45) and a highly optically polarized quasar (Impey & Tapia 1998, ApJ, 333, 666).

Preliminary analysis indicates that, except for October 5, PKS 1424-41 has been significantly detected every day from October 1 to October 14, 2012 with daily average gamma-ray flux (E>100MeV) in the range (0.6-1.2) x 10^-6 photons/cm^2/s before rising to a daily average flux of (1.4 +/- 0.2) x 10^-6 photons/cm^2/s (statistical uncertainty only) on October 15, 2012. This is more than 8 times greater than its average flux reported in the second Fermi LAT catalog (2FGL, Nolan et al. 2012, ApJS, 199, 31) and brighter than previous flares observed on April 23, 2010 (Atel #2583) and on May 8, 2011 (Atel #3329).

This source is one of the "LAT Monitored Sources" and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available at http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/PKS1424-41_86400.png

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Multiwavelength observations during the ongoing activity of this source are strongly encouraged. The Fermi LAT contact person is F. Longo (francesco.longo@ts.infn.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.