Fermi LAT detection of renewed GeV flaring activity from PKS 0426-380

ATel #4660; Stefano Ciprini (ASI ASDC & INAF OAR, Rome), on behalf of the Fermi Large Area Telescope Collaboration
on 20 Dec 2012; 00:30 UT
Credential Certification: Stefano Ciprini (stefano.ciprini@asdc.asi.it)

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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 BL Lac object PKS 0426-380 (also known as 2FGL J0428.6-3756, Nolan et al. 2012, ApJS, 199, 31, and RX J0428.6-3756) with radio coordinates R.A.: 67.16843 deg, Dec: -37.93877 deg, J2000 (Johnston et al. 1995, AJ, 110, 880) and redshift z=1.111 (Heidt et al. 2004, A&A, 418, 813).

Preliminary analysis indicates that on 2012 December 17 and 18, PKS 0426-380 was in a high state with an average daily gamma-ray flux (E>100MeV) of (1.0 +/- 0.2) x 10^-6 and (1.1 +/- 0.2) x 10^-6 photons cm^-2 s^-1 respectively (errors are statistical only), about 4 times greater than the average flux reported in the second Fermi LAT catalog (2FGL). Fermi already observed increased GeV activity from this blazar in 2010 January (reported in ATel#2366). PKS 0426-380 is one of the LAT Monitored Source List and consequently a preliminary, uncalibrated estimation of the daily and weekly gamma-ray flux observed by Fermi LAT is publicly available at: http://fermi.gsfc.nasa.gov/ssc/data/access/

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 person is Y. T. Tanaka (tanaka@astro.isas.jaxa.jp).

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.