Fermi LAT detection of a GeV flare from PKS 1622-29

ATel #6327; S. Buson (INFN & Univ. of Padova) on behalf of the Fermi LAT Collaboration
on 19 Jul 2014; 17:52 UT
Credential Certification: Sara Buson (buson@pd.infn.it)

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The Large Area Telescope (LAT), on board the Fermi Gamma-Ray Space Telescope, has observed gamma-ray flaring activity from a source positionally consistent with the blazar PKS 1622-29 (J2000, RA = 16h26m06.0208s, Dec = -29d51m26.970s, Johnston, et al. 1995 AJ, 110, 880; z=0.815, Wright & Otrupcek 1990, Parkes Catalogue), also known as PKS B 1622-297 and 2FGL J1626.1-2948 in the second Fermi LAT catalog (2FGL Nolan et al. 2012, ApJS, 199, 31).

Preliminary analysis indicates that on 2014 July 18, the source was in a high state with a daily average gamma-ray flux (E>100MeV) of (1.2 +/- 0.2) x 10^-6 photons cm^-2 s^-1 (statistical uncertainty only), about 23 times greater than the average flux reported in the 2FGL catalog. Previous gamma-ray activity on daily scale was observed by the Fermi LAT in 2010 (see ATel#2531). Although PKS 1622-29 showed remarkable activity during the EGRET observations (Mattox et al. 1997, ApJ 476, 692), generally, the source remained quiescent at gamma rays since the launches of AGILE and Fermi, being only sporadically detected by the LAT (see Fermi LAT public light curve at http://fermi.gsfc.nasa.gov/FTP/glast/data/lat/catalogs/asp/current/lightcurves/PKSB1622-297_86400.png ).

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. The Fermi LAT contact person for this source is Sara Buson (buson@pd.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.