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H.E.S.S. discovers VHE emission from the Fermi LAT source PKS 0447-439

ATEL # 2350; M. Raue, B. Behera, A. Charbonnier, B. Giebels, M. Hauser, K. Kosack, M. Punch, H.-S. Zechlin for the H.E.S.S. collaboration
on 16 Dec 2009; 20:35 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Martin Raue (

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Variables

The High Energy Stereoscopic System (H.E.S.S.) collaboration reports the discovery of very-high energy (VHE; E>100 GeV) gamma-ray emission from the source 0FGL J0449.7-4348, one of the brightest extragalactic source from the Fermi bright source list (Abdo et al. 2009, ApJ 700, 597). 0FGL J0449.7-4348 has been associated with PKS 0447-439 (RA: 04h49m24.7s DEC: -43d50'09'', J2000), which has been associated with a BL Lac object located at a redshift of z ~ 0.2 (Perlman et al. 1998, ApJ 115, 1253). Note that PKS 0447-439 has also been associated with a Seyfert 1 galaxy located at a redshift of z=0.107 (Craig & Fruscione 1997, AJ, 114, 4). VHE emission from this source has been detected in 12h of observations recorded with the H.E.S.S. imaging atmospheric Cherenkov telescope array between November 10 and December 16, 2009. The significance of the signal - derived from a preliminary on-site analysis - exceeds 5 standard deviations. Observations in the last 24h (night from Dec 15 to 16) show indications for an increased VHE flux level, therefore further observations of the source at VHE and at other wavelengths are encouraged. H.E.S.S. is an array of four imaging atmospheric Cherenkov telescopes for the detection of gamma-ray sources above 100 GeV located in the Khomas highlands in Namibia. It was constructed and is operated by researchers from Germany, France, UK, South Africa, Poland, the Czech and Irish republics, Austria, Sweden, Armenia, and the host country, Namibia.

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