The Optical system for the Large Size Telescope of the Cherenkov Telescope Array

Hayashida, M.; Noda, K.; Teshima, M.; Almeida, U. Barres de; Chikawa, M.; Cho, N.; Fukami, Satoshi; Gadola, A.; Hanabata, Y.; Horns, D.; Jablonski, C.; Kagaya, Mika; Ogino, M.; Okumura, A.; Saito, Takayuki; Stadler, R.; Steiner, S.; Straumann, U.; Vollhardt, A.; Wetteskind, H.; Yamamoto, Takahiro; Yoshida, Tatsuo

doi:10.22323/1.236.0927

Cited by 6 publications

(11 citation statements)

References 2 publications

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“…One such method would be to take advantage of the active mirror control (AMC) system present in all CTA telescopes. In the case of the LSTs, for example, the AMC system allows for real-time changes to the alignment of individual mirrors to correct for the deformations in the LST dish and camera support due to wind and gravitational loads [22]. During a UAV flight, the AMC system can quickly and easily change the focus of the LSTs and slightly de-focus the calibration light spot such that it falls on a group of seven pixels, instead of just one.…”

Section: Cross-calibrationmentioning

confidence: 99%

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

Brown

2018

Astroparticle Physics

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Recent advances in unmanned aerial vehicle (UAV) technology have made UAVs an attractive possibility as an airborne calibration platform for astronomical facilities. This is especially true for arrays of telescopes spread over a large area such as the Cherenkov Telescope Array (CTA). In this paper, the feasibility of using UAVs to calibrate CTA is investigated. Assuming a UAV at 1km altitude above CTA, operating on astronomically clear nights with stratified, low atmospheric dust content, appropriate thermal protection for the calibration light source and an onboard photodiode to monitor its absolute light intensity, intercalibration of CTA's telescopes of the same size class is found to be achievable with a 6 − 8% uncertainty. For cross-calibration of different telescope size classes, a systematic uncertainty of 8 − 10% is found to be achievable. Importantly, equipping the UAV with a multi-wavelength calibration light source affords us the ability to monitor the wavelength-dependent degradation of CTA telescopes' optical system, allowing us to not only maintain this 6 − 10% uncertainty after the first few years of telescope deployment, but also to accurately account for the effect of multi-wavelength degradation on the cross-calibration of CTA by other techniques, namely with images of air showers and local muons. A UAV-based system thus provides CTA with several independent and complementary methods of cross-calibrating the optical throughput of individual telescopes. Furthermore, housing environmental sensors on the UAV system allows us to not only minimise the systematic uncertainty associated with the atmospheric transmission of the calibration signal, it also allows us to map the dust content above CTA as well as monitor the temperature, humidity and pressure profiles of the first kilometre of atmosphere above CTA with each UAV flight. either single or dual mirror optics configuration, will extend the high-energy reach of CTA, predominantly observing γ-rays with energies from a few TeV up to 100 TeV and beyond. To allow all-sky coverage, the CTA observatory will consist of two arrays, one in each hemisphere. The northern array is intended to contain approximately 20 telescopes (LSTs and MSTs) spread over about 1 km 2 , while the southern array is intended to contain ∼ 100 telescopes (LSTs, MSTs and SSTs) spread over an area of approximately four square kilometres. More than two thirds of the southern array telescopes are foreseen to be SSTs. Furthermore, the enrichment of the southern array is envisaged with the addition of medium-sized dualmirror Schwarzschild-Couder Telescopes (SCTs; [9]), which have the advantage of a better angular resolution, smaller point spread function and a larger field of view compared to the traditional single-mirror Cherenkov telescopes.CTA will herald a new era for ground-based γ-ray astronomy, with the emphasis shifting from source discovery, to population studies and precision measurements. This change in emphasis requires a reduction in the systematic uncertainties of the ob...

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Section: Cross-calibrationmentioning

confidence: 99%

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

Brown

2018

Astroparticle Physics

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“…151 cm The Optical System of the LST is an active optics system that includes a large parabolic reflector equipped with an Active Mirror Control system (find more details in [4]) and a flat focal surface.…”

Section: Optical Systemmentioning

confidence: 99%

“…This should take about 1.5 months. After that the Telescope will be placed in vertical position 4 and CSS (previously assembled on site) mounted on the dish. In the meanwhile the camera access tower must be ready.…”

Section: Status On Site and Plansmentioning

confidence: 99%

Large size telescope report

Mazin¹,

Cortina²,

Teshima³

2017

AIP Conference Proceedings

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Abstract. The Cherenkov Telescope Array (CTA) observatory will be deployed over two sites in the two hemispheres. Both sites will be equipped with four Large Size Telescopes (LSTs), which are crucial to achieve the science goals of CTA in the 20-200 GeV energy range. Each LST is equipped with a primary tessellated mirror dish of 23 m diameter, supported by a structure made mainly of carbon fibre reinforced plastic tubes and aluminum joints. This solution guarantees light weight (around 100 tons), essential for fast repositioning to any position in the sky in <20 seconds. The camera is composed of 1855 photomultiplier tubes and embeds the control, readout and trigger electronics. The detailed design is now complete and production of the first LST, which will serve as a prototype for the remaining seven, is ongoing. The installation of the first LST at the Roque de los Muchachos Observatory on the Canary island of La Palma (Spain) started in July 2016. In this paper we will outline the technical solutions adopted to fulfill the design requirements, present results of element prototyping and describe the installation and operation plans.

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“…The Optical System of the LST is an active optics system that includes a large parabolic re-flector equipped with an Active Mirror Control system (find more details in [4]) and a flat focal surface. The optical reflector is composed of 198 hexagonal mirrors each with an area of 2 m 2 .…”

Section: Optical Systemmentioning

confidence: 99%

Status of the Cherenkov Telescope Array Large Size Telescopes

Cortina¹,

Teshima²

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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and the LST team for the CTA consortium † The Cherenkov Telescope Array (CTA) observatory, will be deployed over two sites in the two hemispheres. Both sites will be equipped with four Large Size Telescopes (LSTs), which are crucial to achieve the science goals of CTA in the 20-200 GeV energy range. Each LST is equipped with a primary tessellated mirror dish of 23 m diameter, supported by a structure made mainly of carbon fibre reinforced plastic tubes and aluminum joints. This solution guarantees light weight (around 100 tons), essential for fast repositioning to any position in the sky in <20 seconds. The camera is composed of 1855 PMTs and embeds the control, readout and trigger electronics. The detailed design is now complete and production of the first LST, which will serve as a prototype for the remaining seven, is well underway. In 2016 the first LST will be installed at the Roque de los Muchachos Observatory on the Canary island of La Palma (Spain). In this talk we will outline the technical solutions adopted to fulfill the design requirements, present results of element prototyping and describe the installation and operation plans.

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The Optical system for the Large Size Telescope of the Cherenkov Telescope Array

Cited by 6 publications

References 2 publications

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

On the prospects of cross-calibrating the Cherenkov Telescope Array with an airborne calibration platform

Large size telescope report

Status of the Cherenkov Telescope Array Large Size Telescopes

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