Telescope specifications - H.E.S.S. Collaboration

Telescope structures

	H.E.S.S. II (CT5)	H.E.S.S. I (CT1-4)
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
Weight of complete telescope	580 tons (incl. mirrors, camera)	60 tons (incl. mirrors, camera)

Cherenkov Cameras

	CT5 (initial camera, until 2019)	CT5 (FlashCam, since 2019)	CT1-4 (upgraded in 2016)
Photo sensors	2048 1-1/4’ photo multipliers	1761 38 mm (1.5 inch) diameter photo multipliers	960 1-1/4’ photo multipliers
Packaging	128 drawers of 16 PMTs each, drawer includes digitization, trigger, slow control, high voltage generation	147 modules of 12 PMTs each, modules include slow control and high voltage generation. Digitization and trigger system on digital signals in readout system	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.	50 mm (hexagonal, flat-to-flat), equivalent to 0.08 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 220 cm Ø, equivalent to 3.4 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	250 MHz signal sampling 1 gain channel with controlled saturation for large dynamic range records signal amplitude, timing and baseline	1 GHz signal sampling 2 gain channels for each pixel for large dynamic range records signal amplitude
Effective exposure time	16 nano-seconds	9 nano-seconds	16 nano-seconds
Image recording rate	3600 images/second	2000-3000 images/second	500 images/second
Power consumption	8 kW	4 kW	9 kW
Dimensions of camera body	227 cm wide x 240 cm high x 184 cm deep	281 cm wide x 299 cm high x 120 cm deep	160 cm wide x 160 cm high x 150 cm deep
Camera weight	~3.0 tons	~2.2 tons	~1.0 ton