Context. A new challenging adaptive optics (AO) system, called multi-object adaptive optics (MOAO), has been successfully demonstrated on-sky for the first time at the 4.2 m William Herschel ...Telescope, Canary Islands, Spain, at the end of September 2010. Aims. This system, called CANARY, is aimed at demonstrating the feasibility of MOAO in preparation of a future multi-object near infra-red (IR) integral field unit spectrograph to equip extremely large telescopes for analysing the morphology and dynamics of high-z galaxies. Methods. CANARY compensates for the atmospheric turbulence with a deformable mirror driven in open-loop and controlled through a tomographic reconstruction by three widely separated off-axis natural guide star (NGS) wavefront sensors, which are in open loop too. We compared the performance of conventional closed-loop AO, MOAO, and ground-layer adaptive optics (GLAO) by analysing both IR images and simultaneous wave-front measurements. Results. In H-band, Strehl ratios of 0.20 are measured with MOAO while achieving 0.25 with closed-loop AO in fairly similar seeing conditions (r0 ≈ 15 cm at 0.5 μm). As expected, MOAO has performed at an intermediate level between GLAO and closed-loop AO.
Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large ...Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory AO real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems.
The Synthetic Aperture Microwave Imaging (SAMI) diagnostic is a Mega Amp Spherical Tokamak (MAST) diagnostic based at Culham Centre for Fusion Energy. The acceleration of the SAMI diagnostic ...data-processing code by a graphics processing unit is presented, demonstrating acceleration of up to 60 times compared to the original IDL (Interactive Data Language) data-processing code. SAMI will now be capable of intershot processing allowing pseudo-real-time control so that adjustments and optimizations can be made between shots. Additionally, for the first time the analysis of many shots will be possible.
Micro-machined membrane deformable mirrors (MMDMs) are being evaluated for their suitability as wavefront correctors at cryogenic temperatures. Presented here are experimental results for the change ...in the initial mirror figure of 37-channel MMDMs from OKO Technologies upon cooling to T=78K. The changes in the influence functions are also explored. Of the sample of 3 mirrors tested, one was found to have sufficiently small initial static aberrations to be useful as a wavefront corrector at this temperature. The influence functions at T=78K were found to be similar in shape to both those at room temperature and theoretical predictions of the MMDMs surface shape. The magnitude of the surface deflection at T=78K was reduced by around 20% compared with room temperature values.
Centaurus X-3: A Source of High-Energy Gamma Rays Chadwick, P. M; Dickinson, M. R; Dipper, N. A ...
Astrophysical journal/The Astrophysical journal,
08/1998, Letnik:
503, Številka:
1
Journal Article
TeV gamma rays from PSR 1706-44 Chadwick, P.M.; Dickinson, M.R.; Dipper, N.A. ...
Astroparticle physics,
08/1998, Letnik:
9, Številka:
2
Journal Article
Recenzirano
Observations made with the University of Durham Mark 6 atmospheric C̆erenkov telescope confirm that PSR B1706-44 is a very high energy γ-ray emitter. There is no indication from our dataset that the ...very high energy γ-rays are pulsed, in contrast to the findings at < 20 GeV, which indicate that more than 80% of the flux is pulsed. The flux at
E > 300 GeV is estimated to be (3.9 ± 0.7
stat) × 10
−11 cm
−2 s
−1.
Hard X-rays from Coma cluster region BAZZANO, A; FUSCO-FEMIANO, R; UBERTINI, P ...
Astrophysical journal/The Astrophysical journal,
10/1990, Letnik:
362, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A high-energy nonthermal component in the 18-130 keV energy band was detected by balloon-borne observations of the region containing the Coma Cluster of galaxies. The emitted photon spectrum is ...well-described by a single power law of photon index -1.77 and an intensity of 8.9 x 10 to the -5th photons/sq cm/s/KeV at 50 keV. The emission supports the presence of a hard tail, and could be due to the inverse Compton mechanism of relativistic electrons permeating the cluster off the 2.7 K background radiation or the presence in the field of an active galactic nucleus. 30 refs.
TeV gamma rays from Geminga Bowden, C C G; Bradbury, S M; Chadwick, P M ...
Journal of physics. G, Nuclear and particle physics,
02/1993, Letnik:
19, Številka:
2
Journal Article
Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large ...Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory adaptive optics real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems.
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