Mount

• Alt-Azimuth mount running on six bogeys on a circular rail. Undercarriage and bogeys constructed in steel; space frame of 17 m diameter, carrying the segmented mirror, made from carbon fiber reinforced plastic (CRFP) tubes (rod-and-knot system by MERO, without welds);
• camera mounted on a single aluminum tubular arc, secured against transverse movements by pre-stressed steel cables;
• total moving weight in azimuth 64 tons, in altitude 20 tons; Azimuthal (altitude) movement by two (one) driving motors, each of maximally 11 kW;
• angular positions measured by 14-bit shaft encoders, and cross-checked by a starguider camera;
• re-orientation of telescope to any point in 40 seconds (average), with a maximum of 100 seconds (major improvements foreseen), used in the case of GRB follow-up observations.

Mirrors

• Active mirror surface 236 sq.m., made of 974 square elements 49.5x49.5cm, diamond-milled aluminum with quartz coating; f/D = 1.03;
• maximum deviation of individual mirrror element from ideal paraboloid < 10 micrometers; roughness (rms) 4nm; average reflectivity, focussed on a spot of 2 cm radius (wavelength 290-650 nm): 80%;
• four mirror elements (three at the four inclined edges and near the Alt-axis) mounted on 1 sq.m. panels and pre-adjusted;
• 13 kW mirror heating system to prevent dew deposition and icing of the mirror surface;
• mirror panels mounted on three points, two of which are computer-controlled actuators;
• automatic adjustment of the mirror panel orientation by an Active Mirror Control system ensures optimum focusing for each telescope orientation.

Camera

• Camera active area hexagonal with effective (maximum) diameter of 1.05 m, corresponding to a field of view (FoV) of 3.6 deg.; diameter of housing 1.5 m;
• total 576 photomultiplier tubes (PMTs), inner hexagonal area of 396 PMTs of 1" tube diameter (ET 9116A from Electron Tubes); outer pixels 180 PMTs of 1.5" diameter (ET 9117A) arranged in four concentric rings;
• PMTs of hemispherical shape, with six dynodes, low gain (x20,000 - 30,000), followed by a low-noise, high bandwidth transimpedance preamplifier;
• hexagonal light catchers ('Winston cones', made from thin aluminized Mylar foil of mean reflectivity of 85%), in front of all PMTs, corresponding to collection area of 0.1 (0.2) deg FOV for inner (outer) PMTs;
• PMTs coated with diffusely scattering lacquer (Paraloid, acrylic-based material) enriched by a wavelength shifter (P-Terphenyl), for a passive enhancement of the photon detection efficiency, also called quantum efficiency (QE);
• effective QE of 0.25 to 0.3 for all tubes, which includes effects (~25%) of light catcher and laquer / wavelength shifter enhancement (look at the QE curve with the laquer effect);
• total weight of camera: ~600 kg.

Data transmission

• Fast analog signals transmitted from camera to control house (~160 m) via optical fibres, using transimpedance and power amplifiers driving laser diode modulators (VCSELs) for transmission; dynamic range 57-60 db; bandwidth 230 MHz; these components located inside the camera housing;
• digitization in the control room: until 2006 high (*10) and low gain digitization by 300 MSamples/s 8-bit FADCs; since February 2007 single-gain digitization by 2 GSamples/s FADCs (Acquiris DC282), 16-fold multiplexing of channels, with 40 ns channel-to-channel optical delay;
• dead time for readout ~25 microsec/event.

Some performance numbers

• Maximum trigger rate > 1kHz;
• achieved up time >90 % of time with good atmospheric conditions; in average ~1100 hours/year without moon, ~1400 hours/year including moderate moonlight (with minor degradation);
• energy threshold at small zenith angle (statistical maximum of accepted energies) ~50 GeV (trigger), ~60 GeV (analyzed);
• achieved point spread function (PSF) for gammas 0.1 deg, somewhat depending on energy;
• MAGIC-I sensitivity: a Crab-like source with 50 times less intensity would be observed in 50 hours with a significance of 5 sigma;
• achieved energy resolution (from Crab analysis): +- 22 % at 150 GeV and above.