1. H.E.S.S. Phases I and II Paula Chadwick, Dept. of Physics University of Durham

2. 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

5. 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, Warsaw Astronomical Observatory, Jagiellonian University, Cracow

6. 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

7. 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 0.005100 hr 0.0125 hr 0.051 hr 0.120 min 0.51.5 min 130 sec

8. 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!

9. 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 2 0.5 improvement in sensitivity. Hmmm….

10. HESS II – a single, large (600 m 2 ) telescope. Lower energy in standalone mode Improved sensitivity at higher energy in coincidence mode

11. Telescope Structure Altaz mount, rotation on rails Parabolic mirror, 596 m 2, f = 36m Total weight – 560 tonnes

12. Trial Assembly Earlier this Year

14. Central Bearings and Azimuth Rail

15. Camera Design

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