H.E.S.S. Phases I and II

Paula Chadwick, Dept. of Physics

University of Durham

High Energy Stereoscopic System – H.E.S.S.

Four 13m diameter telescopes

Davies-Cotton design, 382 0.6 m diameter mirrors

FoV 5°

960-pixel cameras

Routine operations since January 2004

23°16'18'' S, 16°30'00'' E 1.8 km a.s.l

M-PIK Heidelberg; Humboldt University, Berlin; University of Hamburg; Ruhr University, Bochum; Landessternwarte Heidelberg LLR Ecole Polytechnique, LPNHE, PCC College de France, University of Grenoble, CERS Toulouse, CEA Saclay, Observatoire de Paris-Meudon, University of Montpellier II

Durham University, Leeds University

Dublin Institute for Advanced Studies

Charles University, Prague

Yerevan Physics Institute, Armenia

University of Namibia

North-Western University, South Africa

Nicolaus Copernicus Astronomical Centre, WarsawAstronomical Observatory, Jagiellonian University, Cracow

Many Different Categories of Object Observed with H.E.S.S. I

• Pulsar Wind Nebulae• Shell Supernova Remnants• Binary systems• Young star cluster(s)• Galactic centre (inc. diffuse emission)• Blazars• Radio galaxy/ies• Unidentified objects…

The beginnings of source taxonomy

Improvement in Sensitivity – The Crab Nebula

The Crab Nebula is the ‘standard candle’ in this field – it is a bright, constant source of gamma rays right up to several 10s of TeV.

Crab flux fraction

Obs. Time required

0.005 100 hr

0.01 25 hr

0.05 1 hr

0.1 20 min

0.5 1.5 min

1 30 sec

PKS2155-304 in 2006

Preliminary

In late July 2006, this AGN produced a burst that made the object on average 7 times brighter than the Crab Nebula. The burst contained over 60,000 gamma rays – c.f. 5134 gamma rays from the Crab detected over lifetime of EGRET.

WOW!

H.E.S.S. Phase II

Original idea – have an array of 16 telescopes in total….

…provides about a factor of 4 extra in area, slightly better angular resolution and a factor of 2-3 in sensitivity.

…it’s also expensive, so how about another 4 telescopes?

Factor of about 2 improvement in area, slightly better angular resolution and 20.5 improvement in sensitivity.

Hmmm….

HESS II – a single, large (600 m2) telescope.

Lower energy in standalone mode

Improved sensitivity at higher energy in coincidence mode

Telescope Structure

Altaz mount, rotation on rails

Parabolic mirror, 596 m2, f = 36m

Total weight – 560 tonnes

Trial Assembly Earlier this Year

Central Bearings and Azimuth Rail

Camera Design

Can we really let the sun set on UK involvement in VHE gamma rays??