View source for MAGIC (telescope)

{{Short description|Very-high-energy photon telescope in the Canary Islands, Spain}}
{{About|the telescope|other uses|Magic (disambiguation)}}
{{Infobox Telescope
| locmapin= Spain Canary Islands
| wavelength = [[Gamma ray]]s (indirectly)
| built = 2004
| focal_length = f/D 1.03
| mounting = metal structure
}}
'''MAGIC''' ('''Major Atmospheric Gamma Imaging Cherenkov Telescopes''', later renamed to '''MAGIC [[Florian Goebel]] Telescopes''') is a system of two [[IACT|Imaging Atmospheric Cherenkov telescope]]s situated at the [[Roque de los Muchachos Observatory]] on [[La Palma]], one of the [[Canary Islands]], at about 2200 m above sea level. MAGIC detects particle showers released by [[gamma rays]], using the [[Cherenkov radiation]], i.e., faint
light radiated by the charged particles in the showers. With a diameter of 17 meters for the reflecting surface, it was the largest in the world before the construction of [[High Energy Stereoscopic System|H.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 85 m from the first one, started taking data in July 2009. Together they integrate the MAGIC telescope stereoscopic system.<ref>"Technical status of the MAGIC telescopes", MAGIC collaboration, Proc. International Cosmic Rays Conference 2009, arXiv:0907.1211</ref>

MAGIC is sensitive to cosmic [[gamma ray]]s with [[photon energy|photon energies]] between 50&nbsp;[[GeV]] (later lowered to 25&nbsp;GeV) and 30&nbsp;[[TeV]] due to its large mirror; other ground-based gamma-ray telescopes typically observe gamma energies above 200–300&nbsp;GeV. [[Gamma-ray astronomy]] also utilizes satellite-based detectors, which can detect gamma-rays in the energy range from keV up to several GeV.

==Aims==
The goals of the telescope are to detect and study primarily photons coming from:
*Accretion of [[black holes]] in [[active galactic nuclei]]
*[[Supernova remnant]]s, due to their interest as sources of [[cosmic rays]].
*Other galactic sources such as [[pulsar wind nebula]]e or [[X-ray binaries]].<ref>{{Cite journal | doi = 10.1126/science.1128177| title = Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303| journal = Science| volume = 312| issue = 5781| pages = 1771–3| year = 2006| last1 = Albert | first1 = J.| pmid=16709745|arxiv = astro-ph/0605549 |bibcode = 2006Sci...312.1771A | s2cid = 20981239}}</ref><ref>{{Cite journal | doi = 10.1086/521145| title = Very High Energy Gamma-Ray Radiation from the Stellar Mass Black Hole Binary Cygnus X-1| journal = The Astrophysical Journal| volume = 665| pages = L51–L54| year = 2007| last1 = Albert | first1 = J.| last2 = Aliu | first2 = E.| last3 = Anderhub | first3 = H.| last4 = Antoranz | first4 = P.| last5 = Armada | first5 = A.| last6 = Baixeras | first6 = C.| last7 = Barrio | first7 = J. A.| last8 = Bartko | first8 = H.| last9 = Bastieri | first9 = D.| last10 = Becker | first10 = J. K.| last11 = Bednarek | first11 = W.| last12 = Berger | first12 = K.| last13 = Bigongiari | first13 = C.| last14 = Biland | first14 = A.| last15 = Bock | first15 = R. K.| last16 = Bordas | first16 = P.| last17 = Bosch-Ramon | first17 = V.| last18 = Bretz | first18 = T.| last19 = Britvitch | first19 = I.| last20 = Camara | first20 = M.| last21 = Carmona | first21 = E.| last22 = Chilingarian | first22 = A.| last23 = Coarasa | first23 = J. A.| last24 = Commichau | first24 = S.| last25 = Contreras | first25 = J. L.| last26 = Cortina | first26 = J.| last27 = Costado | first27 = M. T.| last28 = Curtef | first28 = V.| last29 = Danielyan | first29 = V.| last30 = Dazzi | first30 = F.| issue = 1| display-authors = 29 | bibcode=2007ApJ...665L..51A|arxiv = 0706.1505 | hdl = 2445/150806| s2cid = 15302221| url = http://eprints.ucm.es/23791/1/MirandaJM72libre.pdf}}</ref>
*Unidentified [[EGRET]] or [[Fermi Gamma-ray Space Telescope|Fermi]] sources
*[[Gamma ray burst]]s
*Annihilation of [[dark matter]]

==Observations==
MAGIC has found pulsed gamma-rays at energies higher than 25&nbsp;GeV coming from the [[Crab Pulsar]].<ref>{{Cite journal | doi = 10.1126/science.1164718| title = Observation of Pulsed -Rays Above 25 GeV from the Crab Pulsar with MAGIC| journal = Science| volume = 322| issue = 5905| pages = 1221–1224| year = 2008| last1 = Aliu | first1 = E.| last2 = Anderhub | first2 = H.| last3 = Antonelli | first3 = L. A.| last4 = Antoranz | first4 = P.| last5 = Backes | first5 = M.| last6 = Baixeras | first6 = C.| last7 = Barrio | first7 = J. A.| last8 = Bartko | first8 = H.| last9 = Bastieri | first9 = D.| last10 = Becker | first10 = J. K.| last11 = Bednarek | first11 = W.| last12 = Berger | first12 = K.| last13 = Bernardini | first13 = E.| last14 = Bigongiari | first14 = C.| last15 = Biland | first15 = A.| last16 = Bock | first16 = R. K.| last17 = Bonnoli | first17 = G.| last18 = Bordas | first18 = P.| last19 = Bosch-Ramon | first19 = V.| last20 = Bretz | first20 = T.| last21 = Britvitch | first21 = I.| last22 = Camara | first22 = M.| last23 = Carmona | first23 = E.| last24 = Chilingarian | first24 = A.| last25 = Commichau | first25 = S.| last26 = Contreras | first26 = J. L.| last27 = Cortina | first27 = J.| last28 = Costado | first28 = M. T.| last29 = Covino | first29 = S.| last30 = Curtef | first30 = V.| display-authors = 29|arxiv = 0809.2998 |bibcode = 2008Sci...322.1221A | pmid=18927358| s2cid = 5387958}}</ref> The presence of such high energies indicates that the gamma-ray source is far out in the pulsar's [[magnetosphere]], in contradiction with many models.

In 2006 MAGIC detected<ref>{{Cite journal |last1=Albert |first1=J. |last2=Aliu |first2=E. |last3=Anderhub |first3=H. |last4=Antonelli |first4=L. A. |last5=Antoranz |first5=P. |last6=Backes |first6=M. |last7=Baixeras |first7=C. |last8=Barrio |first8=J. A. |last9=Bartko |first9=H. |last10=Bastieri |first10=D. |last11=Becker |first11=J. K. |display-authors=29 |date=2008-06-27 |year=2008 |title=Very-High-Energy Gamma Rays from a Distant Quasar: How Transparent is the Universe? |journal=Science |volume=320 |issue=5884 |pages=1752–4 |arxiv=0807.2822 |bibcode=2008Sci...320.1752M |doi=10.1126/science.1157087 |pmid=18583607 |last12=Bednarek |first12=W. |last13=Berger |first13=K. |last14=Bernardini |first14=E. |last15=Bigongiari |first15=C. |last16=Biland |first16=A. |last17=Bock |first17=R. K. |last18=Bonnoli |first18=G. |last19=Bordas |first19=P. |last20=Bosch-Ramon |first20=V. |last21=Bretz |first21=T. |last22=Britvitch |first22=I. |last23=Camara |first23=M. |last24=Carmona |first24=E. |last25=Chilingarian |first25=A. |last26=Commichau |first26=S. |last27=Contreras |first27=J. L. |last28=Cortina |first28=J. |last29=Costado |first29=M. T. |last30=Covino |first30=S.|s2cid=16886668 }}</ref> very high energy cosmic rays from the [[quasar]] [[3C 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.

MAGIC did not observe cosmic rays resulting from dark matter decays in the [[dwarf galaxy]] [[Draco Dwarf|Draco]].<ref>{{Cite journal | last1 = Albert | first1 = J. | last2 = Aliu | first2 = E. | last3 = Anderhub | first3 = H. | last4 = Antoranz | first4 = P. | last5 = Backes | first5 = M. | last6 = Baixeras | first6 = C. | last7 = Barrio | first7 = J. A. | last8 = Bartko | first8 = H. | last9 = Bastieri | first9 = D. | last10 = Becker | first10 = J. K. | last11 = Bednarek | first11 = W. | last12 = Berger | first12 = K. | last13 = Bigongiari | first13 = C. | last14 = Biland | first14 = A. | last15 = Bock | first15 = R. K. | last16 = Bordas | first16 = P. | last17 = Bosch‐Ramon | first17 = V. | last18 = Bretz | first18 = T. | last19 = Britvitch | first19 = I. | last20 = Camara | first20 = M. | last21 = Carmona | first21 = E. | last22 = Chilingarian | first22 = A. | last23 = Commichau | first23 = S. | last24 = Contreras | first24 = J. L. | last25 = Cortina | first25 = J. | last26 = Costado | first26 = M. T. | last27 = Curtef | first27 = V. | last28 = Danielyan | first28 = V. | last29 = Dazzi | first29 = F. | last30 = De Angelis | first30 = A. | display-authors = 1 | title = Upper Limit for γ‐Ray Emission above 140 GeV from the Dwarf Spheroidal Galaxy Draco | doi = 10.1086/529135 | journal = The Astrophysical Journal | volume = 679 | pages = 428–431 | year = 2008 | issue = 1 | bibcode=2008ApJ...679..428A
|arxiv = 0711.2574 | s2cid = 15324383 }}</ref> 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 the [[blazar]] [[Markarian 501]] on July 9, 2005. Photons with energies between 1.2 and 10&nbsp;TeV arrived 4 minutes after those in a band between 0.25 and 0.6&nbsp;TeV. The average delay was 30&nbsp;±12 ms per GeV of energy of the photon. If the relation between the space velocity of a photon and [[photon energy|its energy]] is linear, then this translates into the fractional difference in the speed of light being equal to minus the photon's energy divided by 2×10<sup>17</sup> GeV. The researchers have suggested that the delay could be explained by the presence of [[quantum 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.<ref>{{Cite journal |last1=Albert |first1=J. |last2=Ellis |first2=John |last3=Mavromatos |first3=N. E. |last4=Nanopoulos |first4=D. V. |last5=Sakharov |first5=A. S. |last6=Sarkisyan |first6=E. K. G. |date=2008 |title=Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope |journal=Physics Letters B |volume=668 |issue=4 |pages=253–257 |doi=10.1016/j.physletb.2008.08.053|arxiv=0708.2889 |bibcode=2008PhLB..668..253M |s2cid=5103618 }}</ref><ref>{{Cite web |last=Lee |first=Chris |date=2007-08-23 |title=Probing quantum gravity with gamma ray bursters |url=https://arstechnica.com/science/2007/08/probing-quantum-gravity-with-gamma-ray-bursters/ |access-date=2022-08-10 |website=Ars Technica |language=en-us}}</ref>

==Technical specifications==
[[File:Magicmirror.jpg|thumb|MAGIC on a sunny day]]
[[File:Tiles of a MAGIC telescope.jpg|thumb|Individual segments of a MAGIC telescope]]
Each telescope has the following specifications:
*A collecting area 236 m<sup>2</sup> consisting of 956 50&nbsp;cm&nbsp;×&nbsp;50&nbsp;cm [[aluminium]] individual reflectors
*A lightweight [[carbon fibre]] frame
*A detector consisting of 396 separate hexagonal photomultiplier detectors in the center (diameter: 2.54&nbsp;cm) surrounded by 180 larger photomultiplier detectors (diameter: 3.81&nbsp;cm).
*Data are transferred in analogue form by [[fibre optic]] cables
*Signal digitization is done via an ADC (analog-to-digital converter) with a 2&nbsp;GHz sampling rate
*Total weight of 40,000&nbsp;kg
*Reaction time to move to any position of the sky less than 22 seconds<ref name="Cortina_2004">{{Cite journal|arxiv=astro-ph/0407475|last1= Cortina|first1= J.|title= Status and First Results of the MAGIC Telescope|journal= Astrophysics and Space Science|volume= 297|issue= 2005|pages= 245–255|author2= for the MAGIC collaboration|year= 2005|doi= 10.1007/s10509-005-7627-5|bibcode = 2005Ap&SS.297..245C |s2cid= 16311614}}</ref>

Each mirror of the reflector is a sandwich of an aluminum [[Honeycomb structure|honeycomb]], 5&nbsp;mm plate of AlMgSi alloy, covered with a thin layer of [[quartz]] to protect the mirror surface from aging. The mirrors have spherical shape with a curvature corresponding to the position of the plate in the [[paraboloid]] reflector. The [[reflectivity]] 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 an [[Active optics|Active Mirror Control]] system. Four mirrors are mounted on each panel, which is equipped with [[actuator]]s that can adjust its orientation in the frame.

The signal from the detector is transmitted over 162&nbsp;m of optical fibers. The signal is digitized and stored in a 32&nbsp;kB ring buffer. The readout of the ring buffer results in a dead time of 20&nbsp;μs, which corresponds to about 2% dead time at the design trigger rate of 1&nbsp;kHz. The readout is controlled by an [[FPGA]] ([[Xilinx]]) chip on a PCI (MicroEnable) card. The data is saved to a [[RAID0]] disk system at a rate up to 20&nbsp;MB/s, which results in up to 800&nbsp;GB raw data per night.<ref name="Cortina_2004"/>

==Collaborating institutions==
[[File:The MAGIC Telescope at night.jpg|thumb|During [[fog]]gy nights, the [[laser]] reference beams of MAGIC's [[Active surface|active]] control could be seen. However, they are no longer needed for operation.]]

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
*Institut de Física d'Altes Energies ([[IFAE]]), Spain
*[[Universitat Autònoma de Barcelona]], [[Spain]]
*[[Universidad Complutense de Madrid]], Spain
*Centro de Investigaciones Energéticas, MedioAmbientales y Tecnológicas ([[CIEMAT]]), Spain
*[[Instituto de Astrofísica de Andalucía]], Spain
*[[Instituto de Astrofísica de Canarias]], Spain
*ETHZ, Zürich, Switzerland
*UNIGE, Geneva, Switzerland
*Dipartimento di Fisica and INFN, [[University of Padua]], Italy
*[[Tuorla Observatory]], [[Piikkiö]], [[Finland]]
*Dipartimento di Fisica and INFN, [[University of Siena]], Italy
*Dipartimento di Fisica and INFN, [[University of Udine]], Italy
*[[Technical University of Dortmund|TU Dortmund University]], [[Germany]]
*[[University of Würzburg]], [[Germany]]
*[[Max Planck Institute for Physics]], [[Germany]]
*Institute for Particle Physics, [[Zürich]], [[Switzerland]]
*[[National Institute for Astrophysics]] (INAF), Italy
*[[Institute for Nuclear Research and Nuclear Energy]], [[Sofia]], [[Bulgaria]]
*Croatian MAGIC Consortium ([[Ruđer Bošković Institute|Institute Ruđer Bošković]], [[Zagreb]]; [[University of Split]], [[Split (city)|Split]]; [[University of Rijeka]], [[Rijeka]]), [[Croatia]]

==See also==
*[[Pavel Cherenkov]]

==References==
<references />

==External links==
{{Commons category|MAGIC}}
*[https://magic.mpp.mpg.de/ Official MAGIC Telescope webpage]
*[https://web.archive.org/web/20190902142811/http://magic.pic.es/ MAGIC Data Center]
*[https://web.archive.org/web/20141116032423/http://www.aspera-eu.org/ Aspera European network portal]
*[http://arquivo.pt/wayback/20160314152446/http://www.astroparticle.org/ Astroparticle.org: to know everything about astroparticle physics]
*[https://www.twitter.com/astroparticle Astroparticle physics news on Twitter]

{{DEFAULTSORT:Magic (Telescope)}}
[[Category:Gamma-ray telescopes]]
[[Category:Astronomical observatories in La Palma]]