Characteristics of the H.E.S.S. telescopes

H.E.S.S. II H.E.S.S. I
Mount
Mount type Alt-Az mount Alt-Az mount
Azimuth drive system 12 wheels in 6 bogies on 36 m diameter rail;
4 wheels driven by servo motors, plus backup motors;
peak positioning speed 200 degr./minute;
range 560 degr. 		Friction drive using separate circular rail, with servo motor and backup motor;
peak positioning speed 100 degr./minute;
range 540 degr.
Height of elevation axis 24 m 10 m
Elevation drive system Toothed ring on either side of the dish;
2 drive units with 2 motors each, plus backup motors;
peak positioning speed 100 degr./minute;
range –125 degr. +90 degr. from vertical 		Friction drive using circular rail, with servo motor and backup motor;
peak positioning speed 100 degr./minute;
range -125 degr. +90 degr. from vertical
Dish
Dimensions 32.6 m by 24.3 m; equivalent to 28 m circular dish 12.0 m; hexagonal
Shape of reflector Parabolic Davies-Cotton
Focal length 36 m 15 m
Total mirror area 614 m2 108 m2
Mirror facets 875 hexagonal facets of 90 cm (flat-to-flat) size;
quartz-coated aluminized glass;
weight per facet approx. 25 kg 		382 round facets of 60 cm size;
quartz-coated aluminized glass;
weight per facet approx. 15 kg
Facet alignment Each facet equipped with 2 actuators with 2 μm positioning step size Each facet equipped with 2 actuators with 3 μm positioning step size
Focal plane instrumentation (Camera)
Photo sensors 2048 1-1/4’ photo multipliers 960 1-1/4’ photo multipliers
Packaging 128 drawers of 16 PMTs each, drawer includes digitization, trigger, slow control, high voltage generation 60 drawers of 16 PMTs each, drawer includes digitization, trigger, slow control, high voltage generation
Pixel size 42 mm (hexagonal, flat-to-flat), equivalent to 0.067 degr. 42 mm (hexagonal, flat-to-flat), equivalent to 0.16 degr.
Sensitive area / field of view approx. 200 cm Ø, equivalent to 3.2 degr. on the sky approx. 130 cm Ø, equivalent to 5.0 degr. on the sky
Signal recording 1 GHz signal sampling ;
2 gain channels for each pixel for large dynamic range;
records signal amplitude, timing, and shape 		1 GHz signal sampling ;
2 gain channels for each pixel for large dynamic range;
records signal amplitude
Effective exposure time 16 nano-seconds 16 nano-seconds
Image recording rate 3600 images/second 500 images/second
Power consumption 8 kW 9 kW
Dimensions of camera body 227 cm wide x 240 cm high x 184 cm deep 160 cm wide x 160 cm high x 150 cm deep
Camera weight ~3.0 tons ~1.0 ton
Camera support Quadrupod Quadrupod
Weight of complete telescope 580 tons (incl. mirrors, camera) 60 tons (incl. mirrors, camera)