H.E.S.S. and ATOM detect a high flux state in the blazar PKS 1510-089
ATel #12965; Mathieu de Naurois for the H. E.S. S. Collaboration
on 30 Jul 2019; 12:04 UT
Credential Certification: Michael Zacharias (mz@tp4.rub.de)
Subjects: VHE, Request for Observations, AGN, Blazar, Quasar
The High Energy Stereoscopic System (H.E.S.S.) conducted observations on
the flat spectrum radio quasar PKS 1510-089 (z=0.361) last night (July
29, 2019) as part of its regular monitoring campaign on this source.
While this source usually cannot be detected within a single night at
very-high-energy gamma-rays (E>100GeV), during observations last night
an exceptional high state was detected with a preliminary flux exceeding
10^-10 ph/cm^2/s (E>100GeV) or about 25% of the flux of the Crab Nebula
above the same energy threshold. The observations were conducted under
favorable conditions and lasted for 3h50.
A VHE gamma-ray flux like this has only been seen once before, namely in
2016 (ATel #9102, #9105). In that instance the flare lasted for only 2 nights,
and therefore follow-up observations are strongly encouraged.
The Automatic Telescope for Optical Monitoring (ATOM) measured an optical B-band flux of 13.9 at MJD 58693.80. PKS 1510-089 went on to exhibit strong variability on timescales below 10 minutes -- including a drop of 0.2 magnitudes over less than 30 minutes.
H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes
for the detection of very-high-energy gamma-ray sources and is located
in the Khomas Highlands in Namibia. It was constructed and is operated
by researchers from Armenia, Australia, Austria, France, Germany,
Ireland, Japan, the Netherlands, Poland, South Africa, Sweden, UK, and
the host country, Namibia.
ATOM is a 75cm optical telescope located at the H.E.S.S. site in Namibia. Operated by the Heidelberg State Observatory, it monitors around 300 known gamma-ray emitters.
