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Increased VHE activity from PKS 1510-089 detected with H.E.S.S.

ATel #9102; Mathieu de Naurois, for the H. E.S. S. collaboration
on 31 May 2016; 13:07 UT
Credential Certification: Jean-Philippe Lenain (jlenain@in2p3.fr)

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

Referred to by ATel #: 9105, 9513, 9520

H.E.S.S. observations of the flat spectrum radio quasar PKS 1510-089 (z=0.36) have been carried out during the last few days. The observations were taken under good weather conditions with the four 12m telescopes array for a total of ~5 hours. A preliminary on-site analysis shows a rising flux (> 240 GeV) from May 29 through May 31, the time averaged significance increasing from ~5 sigmas/√h (May 29-30) to ~15 sigmas/√h (May 30-31). A preliminary on-site calibration and analysis of the data acquired during the night May 29-30 reveals a flux of ~8% Crab above 240 GeV and a soft photon index of ~4.

Optical R-band observations with the Automatic Telescope for Optical Monitoring (ATOM) showed an increase in apparent magnitude from 16.0 on May 26 to 15.1 on May 30. During the night of May 30-31, the source showed variability with a minimum flux of 15.311 ± 0.007 magnitudes and a maximum of 15.084 ± 0.008 magnitudes over a time-period of 2 hours.

Further observations are planned in the coming days and 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 located in the Khomas Highlands 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.

H.E.S.S. - The High Energy Stereoscopic System