h.e.s.s. phases i and ii
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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??
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