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Fermi LAT detection of a GeV flare from blazar PKS 1424-41

ATel #2583; D. Donato (NASA/GSFC), on behalf of the Fermi Large Area Telescope Collaboration
on 23 Apr 2010; 18:15 UT
Distributed as an Instant Email Notice Request For Observations
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

Subjects: Gamma Ray, >GeV, AGN, Transient

Referred to by ATel #: 2613, 3329, 4494, 4714

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope has observed an increasing gamma-ray flux from a source positionally coincident with the FSRQ PKS 1424-41 (1FGL J1428.2-4204; RA=14h27m56.3s, DEC= -42d06'19.4", J2000, Johnston et al. 1995, AJ, 110, 880). This strong radio source is a highly optically polarized quasar with a redshift of 1.522 (White et al. 1988, ApJ, 327, 561) and its milli-arcsecond scale jet shows no relativistic motion (Piner et al. 2007, AJ, 133, 2357).

Preliminary analysis indicates that on April 21, 2010, the source was in a high state, with a gamma-ray flux (E>100MeV) of (1.0 +/- 0.2)*10^-6 photons/cm^2/s (statistical uncertainty only), representing more than an order of magnitude increase over its average flux during the first 11 months of Fermi observations (arXiv:1002.2280) and approximately doubling the intensity of a previously reported flare (Atel #2104).

Since Fermi operates in an all-sky scanning mode, regular monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. The Fermi LAT contact person for this source 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.