 The second MAGIC telescope | |
| Alternative names | MAGIC |
|---|---|
| Location(s) | La Palma,Atlantic Ocean, international waters |
| Coordinates | 28°45′43″N17°53′24″W / 28.761944444444°N 17.89°W /28.761944444444; -17.89 |
| Altitude | 2,200 m (7,200 ft) |
| Wavelength | Gamma rays (indirectly) |
| Built | 2004 |
| First light | 2004, 2009 |
| Diameter | 17 m (55 ft 9 in) |
| Collecting area | 236 m2 (2,540 sq ft) |
| Focal length | f/D 1.03 |
| Mounting | metal structure |
| Website | magic |
  Location of MAGIC | |
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MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescopes, later renamed toMAGICFlorian Goebel Telescopes) is a system of twoImaging Atmospheric Cherenkov telescopes situated at theRoque de los Muchachos Observatory onLa Palma, one of theCanary Islands, at about 2,200 m (7,200 ft) above sea level. MAGIC detects particle showers released bygamma rays, using theCherenkov radiation, i.e., faintlight radiated by the charged particles in the showers. With a diameter of 56 ft (17 m) for the reflecting surface, it was the largest in the world before the construction ofH.E.S.S. II.
The first telescope was built in 2004 and operated for five years in standalone mode. A second MAGIC telescope (MAGIC-II), at a distance of 279 ft (85 m) from the first one, started taking data in July 2009. Together they integrate the MAGIC telescope stereoscopic system.[1]
MAGIC is sensitive to cosmicgamma rays withphoton energies between50 GeV (later lowered to25 GeV) and30 TeV due to its large mirror; other ground-based gamma-ray telescopes typically observe gamma energies above200–300 GeV.Gamma-ray astronomy also utilizes satellite-based detectors, which can detect gamma-rays in the energy range from keV up to several GeV.[citation needed]
The goals of the telescope are to detect and study primarily photons coming from:
MAGIC has found pulsed gamma-rays at energies higher than25 GeV coming from theCrab Pulsar. The presence of such high energies indicates that the gamma-ray source is far out in the pulsar'smagnetosphere, in contradiction with many models.[4]
In 2006 MAGIC detected very high energy cosmic rays from thequasar3C 279, which is 5 billion light years from Earth. This doubles the previous record distance from which very high energy cosmic rays have been detected. The signal indicated that the universe is more transparent than previously thought based on data from optical and infrared telescopes.[5]
MAGIC did not observe cosmic rays resulting from dark matter decays in thedwarf galaxyDraco.[6] This strengthens the known constraints on dark matter models.
A much more controversial observation is an energy dependence in the speed of light of cosmic rays coming from a short burst of theblazarMarkarian 501 on July 9, 2005. Photons with energies between1.2 and 10 TeV arrived 4 minutes after those in a band between0.25 and 0.6 TeV. The average delay was30±12 ms/GeV of energy of the photon. If the relation between the space velocity of a photon andits energy is linear, then this translates into the fractional difference in the speed of light being equal to minus the photon's energy divided by2×1017 GeV. The researchers have suggested that the delay could be explained by the presence ofquantum foam, the irregular structure of which might slow down photons by minuscule amounts only detectable at cosmic distances such as in the case of the blazar.[7][8]
Each telescope has the following specifications:
Each mirror of the reflector is a sandwich of an aluminumhoneycomb, 0.20 in (5 mm) plate of AlMgSi alloy, covered with a thin layer ofquartz to protect the mirror surface from aging. The mirrors have spherical shape with a curvature corresponding to the position of the plate in theparaboloid reflector. Thereflectivity of the mirrors is around 90%. The focal spot has a size of roughly half a pixel size (<0.05°).
Directing the telescope to different elevation angles causes the reflector to deviate from its ideal shape due to the gravity. To counteract this deformation, the telescope is equipped with anActive Mirror Control system. Four mirrors are mounted on each panel, which is equipped withactuators that can adjust its orientation in the frame.
The signal from the detector is transmitted over 531 ft (162 m) of optical fibers. The signal is digitized and stored in a32 kB ring buffer. The readout of the ring buffer results in a dead time of20 μs, which corresponds to about 2% dead time at the design trigger rate of1 kHz. The readout is controlled by anFPGA (Xilinx) chip on a PCI (MicroEnable) card. The data is saved to aRAID0 disk system[why?] at a rate up to20 MB/s, which results in up to800 GB raw data per night.[9]
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Physicists from over twenty institutions in Germany, Spain, Italy, Switzerland, Croatia, Finland, Poland, India, Bulgaria and Armenia collaborate in using MAGIC; the largest groups are at