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1.
New challenges for adaptive optics: extremely large telescopes 总被引:1,自引:0,他引:1
M. Le Louarn N. Hubin M. Sarazin A. Tokovinin 《Monthly notices of the Royal Astronomical Society》2000,317(3):535-544
The performance of an adaptive optics (AO) system on a 100-m diameter ground-based telescope working in the visible range of the spectrum is computed using an analytical approach. The target Strehl ratio of 60 per cent is achieved at 0.5 μm with a limiting magnitude of the AO guide source near R magnitude~10, at the cost of an extremely low sky coverage. To alleviate this problem, the concept of tomographic wavefront sensing in a wider field of view using either natural guide stars (NGS) or laser guide stars (LGS) is investigated. These methods use three or four reference sources and up to three deformable mirrors, which increase up to 8-fold the corrected field size (up to 60 arcsec at 0.5 μm). Operation with multiple NGS is limited to the infrared (in the J band this approach yields a sky coverage of 50 per cent with a Strehl ratio of 0.2). The option of open-loop wavefront correction in the visible using several bright NGS is discussed. The LGS approach involves the use of a faint ( R ~22) NGS for low-order correction, which results in a sky coverage of 40 per cent at the Galactic poles in the visible. 相似文献
2.
Anita Enmark Thomas Berkefeld Oskar von der Lühe Torben Andersen 《Experimental Astronomy》2006,21(2):87-99
A simulation model of the adaptive optics of the German Vacuum Tower Telescope (VTT), Observatorio del Teide, Tenerife, is
presented. The model uses modules from the integrated model of the Euro50 extremely large telescope, and includes submodels
of a Shack-Hartmann wavefront sensor, a de-formable mirror, a tip-tilt mirror, high-voltage amplifier low-pass filters, a
reconstructor and a controller. We investigate the impact on the closed loop bandwidth of changes in controller configuration
and certain system parameters, such as low pass filter bandwidth and camera integration and readout time. Control strategies
were tested on simple models before implementation on the full VTT model. Using the models, different control strategies are
compared. 相似文献
3.
Peter Cogan 《Astrophysics and Space Science》2005,297(1-4):275-281
The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is the next-generation ground-based gamma-ray observatory
that is being built in southern Arizona by a collaboration of 10 institutions in Canada, Ireland, the UK and the USA. VERITAS
is designed to operate in the range from 50 GeV to 50 TeV with optimal sensitivity near 200 GeV; it will effectively overlap
with the next generation of space-based gamma-ray telescopes. The first phase of VERITAS, consisting of four telescopes of
12 m aperture, will be operational by the time of the GLAST launch in 2007. Eventually, the array will be expanded to include
the full array of seven telescopes on a filled hexagonal grid of side 80 m. A prototype VERITAS telescope with a reduced number
of mirrors and signal channels has been built. Its design and performance is described here. The prototype is scheduled to
be upgraded to a full 499 pixel camera with 350 mirrors during the autumn of 2004.
The VERITAS collaboration consists of universities and institutions from Ireland, UK, USA and Canada. See for a full listing. 相似文献
4.
We have used the ESO Very Large Telescope (VLT) to perform as trometric observations of Near Earth Asteroids (NEAs) having
remote collision possibilities with the Earth. The observations were made for those objects which became too faint to be observed
elsewhere. Using the 4 hours allocated in the semester April–September 2003, 5 faint NEAs were observed. As a result, no NEA
that could impact the Earth was lost. 相似文献
5.
Ground Layer Adaptive Optics (GLAO) is a recently developed technique extensively applied to ground-based telescopes, which mainly compensates for the wavefront errors induced by ground-layer turbulence to get an appropriate point spread function in a wide field of view. The compensation results mainly depend on the turbulence distribution. The atmospheric turbulence at Dome A in the Antarctic is mainly distributed below 15 meters, which is an ideal site for applications of GLAO. The GLAO system has been simulated for the Kunlun Dark Universe Survey Telescope, which will be set up at Dome A, and uses a rotating mirror to generate several laser guide stars and a wavefront sensor with a wide field of view to sequentially measure the wavefronts from different laser guide stars. The system is simulated on a computer and parameters of the system are given, which provide detailed information about the design of a practical GLAO system. 相似文献
6.
K.G. Strassmeier I. Ilyin A. Jrvinen M. Weber M. Woche S. I. Barnes S.‐M. Bauer E. Beckert W. Bittner R. Bredthauer T. A. Carroll C. Denker F. Dionies I. DiVarano D. Dscher T. Fechner D. Feuerstein T. Granzer T. Hahn G. Harnisch A. Hofmann M. Lesser J. Paschke S. Pankratow V. Plank D. Plüschke E. Popow D. Sablowski J. Storm 《Astronomische Nachrichten》2015,336(4):324-361
PEPSI is the bench‐mounted, two‐arm, fibre‐fed and stabilized Potsdam Echelle Polarimetric and Spectroscopic Instrument for the 2×8.4 m Large Binocular Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270 000 can cover the entire optical/red wavelength range from 383 to 907 nm in three exposures. Two 10.3k×10.3k CCDs with 9‐µm pixels and peak quantum efficiencies of 94–96 % record a total of 92 échelle orders. We introduce a new variant of a wave‐guide image slicer with 3, 5, and 7 slices and peak efficiencies between 92–96 %. A total of six cross dispersers cover the six wavelength settings of the spectrograph, two of them always simultaneously. These are made of a VPH‐grating sandwiched by two prisms. The peak efficiency of the system, including the telescope, is 15 % at 650 nm, and still 11 % and 10 % at 390 nm and 900 nm, respectively. In combination with the 110 m2 light‐collecting capability of the LBT, we expect a limiting magnitude of ≈20th mag in V in the low‐resolution mode. The R = 120 000 mode can also be used with two, dual‐beam Stokes IQUV polarimeters. The 270 000‐mode is made possible with the 7‐slice image slicer and a 100‐µm fibre through a projected sky aperture of 0.74″, comparable to the median seeing of the LBT site. The 43 000‐mode with 12‐pixel sampling per resolution element is our bad seeing or faint‐object mode. Any of the three resolution modes can either be used with sky fibers for simultaneous sky exposures or with light from a stabilized Fabry‐Pérot étalon for ultra‐precise radial velocities. CCD‐image processing is performed with the dedicated data‐reduction and analysis package PEPSI‐S4S. Its full error propagation through all image‐processing steps allows an adaptive selection of parameters by using statistical inferences and robust estimators. A solar feed makes use of PEPSI during day time and a 500‐m feed from the 1.8 m VATT can be used when the LBT is busy otherwise. In this paper, we present the basic instrument design, its realization, and its characteristics. Some pre‐commissioning first‐light spectra shall demonstrate the basic functionality. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
S.N. Kemp S.J. Chan J.E. Beckman P.L. Hammersley 《Astrophysics and Space Science》2001,276(2-4):675-682
Images are presented of some of the galaxies in the sample of the BARS `International Time Project' in the near-infrared JHK
s bands, obtained with the Infra-Red Camera at the 1.5 m Carlos Sánchez Telescope, Teide Observatory, between 1996 and 1998.
We discuss the scientific importance of imaging galaxies in the near-infrared bands and recent and future developments concerning
the Infra-Red Camera.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
本文介绍1.26米红外望远镜出厂后的主要误差,用谐波分析法分离望远镜的各项主要误差(2~m显示误差,4~m17~5短周期跟踪误差以及长周期跟踪误差等),讨论误差产生原因,计算由这些原因引起的误差理论值,并与实测值进行比较,分析其对望远镜使用精度的影响,叙述消除误差的方法及实际效果。 相似文献
9.
E. Hatziminaoglou P. Cassata G. Rodighiero I. Pérez-Fournon A. Franceschini A. Hernán-Caballero F. M. Montenegro-Montes A. Afonso-Luis T. Jarrett G. Stacey C. Lonsdale F. Fang S. Oliver M. Rowan-Robinson D. Shupe H. E. Smith J. Surace C. K. Xu E. A. González-Solares 《Monthly notices of the Royal Astronomical Society》2005,364(1):47-58
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《天文和天体物理学研究(英文版)》2020,(6)
The Large Optical/infrared Telescope(LOT) is a ground-based 12 m diameter optical/infrared telescope which is proposed to be built in the western part of China in the next decade.Based on satellite remote sensing data,along with geographical,logistical and political considerations,three candidate sites were chosen for ground-based astronomical performance monitoring.These sites include:Ali in Tibet,Daocheng in Sichuan and Muztagh-ata in Xinjiang.Up until now,all three sites have continuously collected data for two years.In this paper,we will introduce this site testing campaign,and present its monitoring results obtained during the period between March 2017 and March 2019. 相似文献
12.
《天文和天体物理学研究(英文版)》2020,(6)
The Large Optical/infrared Telescope of China is a 12 meter diameter ground-based optical/infrared telescope which is proposed to be constructed in the western part of China in favor of its arid climate,and clear,dark nights.A site testing campaign was initiated between November 2016 and March2019 in order to investigate long term astronomical weather conditions in the western part of China,specifically,at three sites:Ali in Tibet,Daocheng in Sichuan and Muztagh-ata in Xinjiang.This is the first attempt to evaluate long term performances of three candidate sites with uniformly calibrated instruments and data collecting/processing methods for a two-year span in China.In this special issue,we present nine papers that describe the whole site testing campaign,including preparation,data collecting/processing methods,instrument set up at three candidate sites as well as detailed statistics for the measurement results from March 2017 to March 2019. 相似文献
13.
《天文和天体物理学研究(英文版)》2015,(6)
As a facility used for astronomical research, the Lijiang 2.4-m telescope of Yunnan Astronomical Observatories, requires the ability to change one auxiliary instrument with another in as short a time as possible. This arises from the need to quickly respond to scientific programs(e.g. transient observation, time domain studies) and changes in observation conditions(e.g. seeing and weather conditions). In this paper, we describe the design, construction and test of hardware and software in the rapid instrument exchange system(RIES) for the Cassegrain focal station of this telescope, which enables instruments to be quickly changed at night without much loss of observing time. Tests in the laboratory and at the telescope show that the image quality and pointing accuracy of RIES are satisfactory.With RIES, we observed the same Landolt standard stars almost at the same time with the Princeton Instruments VersA rray 1300 B Camera(PICCD) and the Yunnan Faint Object Spectrograph and Camera(YFOSC), while both were mounted at the Cassegrain focus. A quasi-simultaneous comparison shows that the image quality of the optical system inside the YFOSC is comparable with that provided by the PICCD. 相似文献
14.
Wei-Bin Wen Sheng-Zhen JinNational Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(6):599-606
The Solar Guide Telescope (SGT), an important solar attitude sensor of the SST (Space Solar Telescope, a space solar observing instrument being developed in China), can accurately produce pointing error signals of the SST for attitude control at high speed. We analyze in detail the error algorithm of the heliocentric coordinates and the edge judging of solar images. The measuring accuracy of ±0.5 arcsec of the SGT is verified by experiments on the tracking of the Sun and by testing a sun simulator. Some factors causing the pointing errors are examined. 相似文献
15.
A. Hughes L. Staveley-Smith S. Kim M. Wolleben M. Filipovi 《Monthly notices of the Royal Astronomical Society》2007,382(2):543-552
We present a mosaic image of the 1.4-GHz radio continuum emission from the Large Magellanic Cloud (LMC) observed with the Australia Telescope Compact Array (ATCA) and the Parkes Telescope. The mosaic covers with an angular resolution of 40 arcsec, corresponding to a spatial scale of ∼10 pc in the LMC. The final image is suitable for studying emission on all scales between 40 arcsec and the surveyed area. In this paper, we discuss (i) the characteristics of the LMC's diffuse and compact radio continuum emission, (ii) the fraction of the emission produced by thermal processes and the implied star formation rate in the LMC and (iii) variations in the radio spectral index across the LMC. Two non-standard reduction techniques that we used to process the ATCA visibility data may be of interest for future wide-field radio continuum surveys. The data are open to the astronomical community and should be a rich resource for studies of individual objects such as supernova remnants, H ii regions and planetary nebulae as well as extended features such as the diffuse emission from synchrotron radiation. 相似文献
16.
The Gran Telescopio CANARIAS (GTC) is a high performance 10-m class telescope whose construction has been promoted by the
IAC (Instituto de Astrofísica de Canarias). It will be installed at the Roque de los Muchachos Observatory (ORM), in the island
of La Palma. First light is planned for end-2002. The key science drivers for the project are image quality, operational efficiency
and reliability, as emphasized in the Conceptual Design Document which was finished in mid-97. The Preliminary Design is now
proceeding on all aspects of the project. The GTC Project is presently funded at the 70% level by Spain. The scientific drives
behind the GTC project are described here, as well as the current technical, managerial, and operational baseline.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The Siberian Solar Radio Telescope: the current state of the instrument,observations, and data 总被引:2,自引:0,他引:2
Grechnev V.V. Lesovoi S.V. Smolkov G. Ya. Krissinel B.B. Zandanov V.G. Altyntsev A.T. Kardapolova N.N. Sergeev R.Y. Uralov A.M. Maksimov V.P. Lubyshev B.I. 《Solar physics》2003,216(1-2):239-272
The Siberian Solar Radio Telescope (SSRT) is one of the world's largest solar radio heliographs. It commenced operation in
1983, and since then has undergone several upgrades. The operating frequency of the SSRT is 5.7 GHz. Since 1992 the instrument
has had the capability to make one-dimensional scans with a high time resolution of 56 ms and an angular resolution of 15 arc sec.
Making one of these scans now takes 14 ms. In 1996 the capability was added to make full, two-dimensional images of the solar
disk. The SSRT is now capable of obtaining images with an angular resolution of 21 arc sec every 2 min. In this paper we describe
the main features and operation of the instrument, particularly emphasizing issues pertaining to the imaging process and factors
limiting data quality. Some of the data processing and analysis techniques are discussed. We present examples of full-disk
solar images of the quiet Sun, recorded near solar activity minimum, and images of specific structures: plages, coronal bright
points, filaments and prominences, and coronal holes. We also present some observations of dynamic phenomena, such as eruptive
prominences and solar flares, which illustrate the high-time-resolution observations that can be done with this instrument.
We compare SSRT observations at 5.7 GHz, including computed `light curves', both morphologically and quantatively, with observations
made in other spectral domains, such as 17 GHz radio images, Hα filtergrams and magnetograms, extreme-ultraviolet and X-ray
observations, and dynamic radio spectra. 相似文献