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H.E.S.S. detection of a strong VHE activity from the blazar 3C 279

ATel #11239; Mathieu de Naurois for the H. E.S. S. collaboration
on 28 Jan 2018; 15:00 UT
Credential Certification: Jean-Philippe Lenain (jlenain@in2p3.fr)

Subjects: Gamma Ray, VHE, Request for Observations, AGN, Blazar, Quasar

Referred to by ATel #: 11246

H.E.S.S. observations of the flat spectrum radio quasar 3C 279 (redshift z=0.536, R.A.: 12h56m11.1665s, Dec: -05d47m21.523s (J2000)) have been carried out during the past 2 weeks, on the basis of the detection of flaring activity in the gamma-ray band with Fermi-LAT (ATel #11189) and AGILE (ATel #11200), as well as in the optical band (ATels #11190, #11196, #11202, #11216).

A preliminary online analysis of the data acquired with CT5 (monoscopic analysis) of previous nights indicates no detection, while during the night January 27-28 the online analysis shows an unprecedented flux with a total significance of ~11 standard deviations in 1.8 hours of observation. This could be the highest flux level of this source ever seen at very high energies (E>100 GeV). Unfortunately, further observations cannot be planned beside the upcoming night due to Moon constraints, however a multi-wavelength coverage is strongly encouraged.

H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes for the detection of VHE gamma-ray sources. H.E.S.S. is located in the Khomas Highland in Namibia. It was constructed and is operated by researchers from Armenia, Australia, Austria, the Czech Republic, France, Germany, Ireland, Poland, South Africa, Sweden, UK, and the host country, Namibia.