The performance of the Apache Point Observatory 3.5 m telescope

The Astrophysical Research Consortium 3.5 m telescope facility on Apache Point (2800 m above sea level) near the National Solar Observatory in southern New Mexico is nearing completion. The telescope mount has been installed and testing and fabrication of remaining subassemblies are underway. Thef/1.75 lightweight honeycomb primary mirror was cast April 1988 by the Steward Observatory Mirror Laboratory and is currently being figured.The 3.5 m optical telescope is an altitude over azimuth mechanical structure with Ritchey-Chrétien optics. The lightweight (1800 kg) mirror leads to a mount weighting only 41000 kg; readily available rolling element bearings are used to achieve the necessary performance at low cost and without the heat dissipation of externally pressurized types. Drive torques are applied by DC servo-driven capstans. These are coupled by friction to large diameter drive disks on each axis. No gears are used. Position feedback comes from low cost incremental encoders, also capstan coupled.We have recently completed a series of measurements of the telescope mount. These measurements show that the telescope is very stiff; the lowest natural frequencies are about 7.2 Hz. Initial tracking performance is good and the mount shows high resistance to wind-induced vibration. Our experience during acceptance testing suggests that routine power spectral analysis of drive motor torque and other parameters could be an important tool in the early detection of failures.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.     

The NST: First results and some lessons for ATST and EST

In January 2009, first light observations with the NST (New Solar Telescope) in Big Bear Solar Observatory (BBSO) were made. NST has a 1.7 m primary with a 1.6 m clear aperture. First observational results in TiO and Hα are shown and discussed. The NST primary mirror is the most aspheric telescope mirror deployed to date. The NST is early in its commissioning, and the plans for this phase will be sketched. Lessons learned in building and implementing the NST are germane for the ATST and EST telescopes and will be discussed. The NST has an off‐axis Gregorian configuration consisting of a parabolic primary, heat‐stop, elliptical secondary and diagonal flats. The focal ratio of the primary mirror is f/2.4. The working wavelength range covers from 0.4 to 1.7 µm in the Coudé Lab beneath the telescope and all wavelengths including the far infrared at the Nasmyth focus on the dome floor (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

超轻量镜面系统的研制

空间望远镜的研制一直要求系统的轻量化,美国宇航局（NASA）最近研制的韦伯太空望远镜,其主镜系统面密度相对于哈勃空间望远镜已大幅减轻。在韦伯望远镜主镜系统的研制过程中,NASA开展了一系列关于超轻量镜面系统的验证计划,多家机构拿出多个方案参与竞标。本文选取几个比较典型的方案,介绍这些镜面系统的设计思想、结构、材料、加工以及相关测试结果,期望能对国内相关方面的工作提供参考。     

Scientific instrumentation for the 1.6 m New Solar Telescope in Big Bear

The NST (New Solar Telescope), a 1.6 m clear aperture, off‐axis telescope, is in its commissioning phase at Big Bear Solar Observatory (BBSO). It will be the most capable, largest aperture solar telescope in the US until the 4 m ATST (Advanced Technology Solar Telescope) comes on‐line late in the next decade. The NST will be outfitted with state‐of‐the‐art scientific instruments at the Nasmyth focus on the telescope floor and in the Coudé Lab beneath the telescope. At the Nasmyth focus, several filtergraphs already in routine operation have offered high spatial resolution photometry in TiO 706 nm, Hα 656 nm, G‐band 430 nm and the near infrared (NIR), with the aid of a correlation tracker and image reconstruction system. Also, a Cryogenic Infrared Spectrograph (CYRA) is being developed to supply high signal‐to‐noise‐ratio spectrometry and polarimetry spanning 1.0 to 5.0 μm. The Coudé Lab instrumentation will include Adaptive Optics (AO), InfraRed Imaging Magnetograph (IRIM), Visible Imaging Magnetograph (VIM), and Fast Imaging Solar Spectrograph (FISS). A 308 sub‐aperture (349‐actuator deformable mirror) AO system will enable nearly diffraction limited observations over the NST's principal operating wavelengths from 0.4 μm through 1.7 μm. IRIM and VIM are Fabry‐Pérot based narrow‐band tunable filters, which provide high resolution two‐dimensional spectroscopic and polarimetric imaging in the NIR and visible respectively. FISS is a collaboration between BBSO and Seoul National University focussing on chromosphere dynamics. This paper reports the up‐to‐date progress on these instruments including an overview of each instrument and details of the current state of design, integration, calibration and setup/testing on the NST (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

2.4m天文望远镜光学系统的设计及副镜检验的几种可能方案

详细说明了 2 .4m天文望远镜分别采用主镜焦比f/1 .5和f/3时光学系统的设计 :针对主镜焦比为f/3的凸非球面副镜 ,阐述了运用 4种不同检验方案的设计结果 ;重点介绍了计算全息法。并对几种方案作了比较     

Automatic guide for the Raduga astronomical spectrograph

An automatic mirror guide has been designed and made for the Raduga fiber-optic echelle spectrograph. The new device was built into one of the parts of the spectrograph and allows the work of observers to be facilitated significantly. The automatic guide efficiently removes stellar image oscillations at frequencies of 0–2 Hz, which compensates almost completely for errors in setting the polar axis of a telescope and in its clockwork drive. The guide can be used on any telescope with a focal length of more than 5 m and has operated on two different telescopes. Over two observing seasons, several hundred stellar spectra were taken with the Raduga spectrograph using the automatic guide.     

Interferometry with the Large Binocular Telescope

The Large Binocular Telescope (LBT) will be the largest single telescope in the world when it is completed in 2005. The unique structure of the telescope incorporates two, 8.4 meter diameter primary mirrors on a 14.4 meter center-to-center mounting. This configuration provides the equivalent collecting area of a 12 meter telescope, and when combined coherently, the two optical paths offer very interesting possibilities for interferometry. Two initial interferometric instruments are planned for the LBT. A group based at the University of Arizona is constructing LBTI, a pupil-plane, nulling beam combiner operating in the thermal infrared N band. This instrument will search for and measure zodiacal light in candidate stellar systems for the Terrestrial Planet Finder (TPF) and Darwin missions. Expansion ports can accomodate additional instruments. A second group, based in Heidelberg, Arcetri, and Köln, is building LINC-NIRVANA, a near-infrared Fizeau-mode beam combiner. This type of observation preserves phase information and allows true imagery over a wide field of view. Using state-of-the-art detector arrays, coupled with advanced adaptive optics, LINC-NIRVANA will deliver the sensitivity of a 12 m telescope and the spatial resolution of a 23 m telescope, over a field of view up to 2 arc minutes square.     

The optical reflector system for the CANGAROO-II imaging atmospheric Cherenkov telescope

A new imaging atmospheric Cherenkov telescope with a light-weight reflector has been constructed. Light, robust, and durable mirror facets of containing carbon fiber reinforced plastic laminates were developed for the telescope. The reflector has a parabolic shape (f/1.1) with a 30 m² surface area, which consists of 60 spherical mirror facets. The image size of each mirror facet is 0°.08 (FWHM) on average. The attitude of each facet can be adjusted by stepping motors. After the first in situ adjustment, a point image of about 0°.14 (FWHM) over 3° field of view was obtained. The effect of gravitational load on the optical system was confirmed to be negligible at the focal plane. The telescope has been in operation with an energy threshold for γ-rays of 300 GeV since May 1999.     

Mirror matter in the solar system: new evidence for mirror matter from Eros

Mirror matter is an entirely new form of matter predicted to exist if mirror symmetry is a fundamental symmetry of nature. Mirror matter has the right broad properties to explain the inferred dark matter of the Universe and might also be responsible for a variety of other puzzles in particle physics, astrophysics, meteoritics and planetary science. It is known that mirror matter can interact with ordinary matter non-gravitationally via photon-mirror photon kinetic mixing. The strength of this possibly fundamental interaction depends on the (theoretically) free parameter ε. We consider various proposed manifestations of mirror matter in our solar system examining in particular how the physics changes for different possible values of ε. We find new evidence for mirror matter in the solar system coming from the observed sharp reduction in crater rates (for craters less than about 100 m in diameter) on the asteroid 433 Eros. We also re-examine various existing ideas including the mirror matter explanation for the anomalous meteorite events, anomalous slow-down of Pioneer spacecraft etc.     

三孔较差视宁度监视仪及试观测报告

本文介绍了云南天文台研制的三孔较差视宁度监视仪，统计了１９９４年３月至７月期间的试观测情况，及仪器定标和数据处理结果。     

The development of the Schmidt telescope

Bernhard Schmidt (1879–1935) was born in Estonia. After a few years of studying engineering he ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, on behalf of the Hamburg Observatory, he developed a short focal length optical system with a large field of view. For this purpose, Schmidt moved his workshop to the observatory. He succeeded in inventing the “Schmidt telescope” which allows the imaging of a large field of the sky without any distortions. Schmidt's first telescope (spherical mirror diameter 0.44 m, correction plate 0.36 m diameter, aperture ratio 1:1.75, and focal length 0.625 m) has been used since 1962 at the Boyden Observatory in Bloemfontein/South Africa. Apart from his 0.36m telescope, Schmidt produced a second larger one of 0.60m aperture. Shortly after Schmidt's death, the director of the observatory published details on the invention and production of the Schmidt telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope, the “Big Schmidt” (1.26 m), Mount Palomar, USA, was completed in 1948. The 0.80 m Schmidt telescope of Hamburg Observatory, planned since 1936, finished in 1954, is now on Calar Alto/Spain (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

New Semi-Automated Photometric Telescope at the Skalnate Pleso Observatory

A semi-automated photometric telescope built at the Skalnate Pleso Observatory is described. In December 2000, the 0.3-m f/5 Zeiss astrograph was replaced by a 0.61-m f/4.3 mirror telescope equipped with a CCD camera. The observing programme is created to conform to the photometry of asteroids which are suspected to be of binary nature; photometry of NEAs and MBAs; a long-term photometry for theoretical modelling of the shape of asteroids; and photometry and astrometry of active comets and asteroids. Some results concerning the binary character of the asteroids are described in the paper.     

Image Quality Control and Alignment of a Submillimeter Balloon-Borne Segmented Telescope

PRONAOS is a balloon-borne system dedicated to astronomical observations in the submillimeter range (180µm - 1050µm) based on the use of a 2m Cassegrain telescope. The primary mirror consists of six CFRP (Carbon Fiber Reinforced Plastic) panels, each being positioned by three actuators. The rotation angles of the panels have been measured in the visible range with the help of a CCD and digital centroiding techniques that were necessary because of the light scattering on the CFRP mirror. The translation movements (along the optical axis) of the panels have been measured with an interference technique in the submillimeter range. Both visible and submillimeter measurements were also necessary to determine the alignment of the telescope - focal instrument system with the star sensor. The whole alignment process leads to a precision of ±8 for the rotation angles and ±7µm for the translation of each panel, sufficient for a qualification of the system.     

Progress of the Magellan Project

The 8 m-diameter Magellan Telescope will be located at Las Campanas Observatory, Chile. The project is a joint effort of the Carnegie Institution of Washington, the Johns Hopkins University, and the University of Arizona. Conceptual designs for the telescope, enclosure and aluminizing facility are described. A detailed site survey is underway.Paper presented at the Symposium on the JNLT and Related Engineering Development, tokyo, November 29–December 2, 1988.     

An experimental indoor phasing system based on active optics using dispersed Hartmann sensing technology in the visible waveband

A telescope with a larger primary mirror can collect much more light and resolve objects much better than one with a smaller mirror,and so the larger version is always pursued by astronomers and astronomical technicians.Instead of using a monolithic primary mirror,more and more large telescopes,which are currently being planned or in construction,have adopted a segmented primary mirror design.Therefore,how to sense and phase such a primary mirror is a key issue for the future of extremely large optical/infr...     

一种新型轻量化反射镜结构及其在空间望远镜相关跟踪摆镜上的应用研究

本文提出一种新的反射镜轻量化方案。此方案在结构特征和减重比例上接近蜂窝结构,减重效果比背面开孔的镜子和拱形镜要好得多;同时又可避免蜂窝镜的制造难度。另外,本文还就此方案在空间太阳望远镜(SST)的相关跟踪摆镜上的应用进行探讨,给出了主要结构参数和镜面变形分析结果,其结果表明,此轻量化平面镜能满足SST的使用要求。     

The infrared space observatory camera

At the focal plane of the ISO 60 cm telescope, ISOCAM will take images of the sky in the wavelength range 2.5 to 17 m. It features two independent channels, containing each a 32×32 array detector. The long wavelength (4–17 m) detector, developed by LIR-LETI specifically for ISOCAM, is a Si:Ga array bonded with indium bumps to a DV readout circuit. The short wavelength (2.5–5.5 m) detector, developed by SAT, is an InSb array with a CID readout.Only one channel operates at a time. The channel selection is obtained with two field mirrors supported by a wheel. The field mirror in operation is in the focal plane of the telescope, covering the 3 arcmin field of view, and reflecting the light into one or into the other channel.In each channel, 10 or 12 discrete band pass filters and CVFs with resolution 45 are mounted on a wheel. A second wheel supports a set of lenses, which reimage the focal plane of the telescope on the array, with a pixel field of view of 1.5, 3, 6 or 12 arcsec.Two integrating spheres, illuminated through small holes by black body sources, are mounted on the selection wheel, for flat fielding and calibration purposes.The flight model of ISOCAM, fully tested and calibrated, has been, delivered to ESA and is ready to be integrated in the satellite, whose expected launch date is September 1995.     

30m环形干涉望远镜

简要介绍了云南天文台对下一代地面大型天文光学望远镜进行的初步研究，依据这些研究结果我们提出研制一个新概念的大型地面望远镜：30m环形干涉望远镜（Ringy Interferometric Telescope），它既有单口径望远镜那样的直接成像能力和分辨率，又可以进行综合孔径模式的高分辨率成像，该计划显著地不同于经典的地面大型望远镜，对其中关键技术的研究正在积极进行之中。     

A configuration for future giant telescope

A configuration for the Future Giant Telescope is proposed. It is a 30m telescope with segmented primary mirror and alt-azimuth mounting. The aspherical f/1.2 primary mirror is made up of 1095 partial annular submirrors. The optical system includes a Nasmyth system, a coude system and a wide field system. The Nasmyth system has a novel design with four mirrors and provides a ∼10 arcmin field of diffraction-limited images, a much larger field than can be obtained by the traditional Nasmyth system. Several diffraction-limited observations each over a small field, can be carried out simultaneously. By applying active optics to change the shape, tip, tilt and piston of the submirrors, thereby to effect a new aspherical surface of the primary, excellent quality images can be obtained for the coude system and the wide field system. The wide field system has a field of 25 arcmin, the focal surface is only slightly curved and the atmospheric dispersion could be corrected. The tolerances of the surface shape and position for the submirrors, and the telescope mounting and structure are also discussed. The innovations in this configuration should have a general significance for future giant telescopes.     

A simulation model for a telescope earthquake analysis: the VST primary mirror safety system

The VST (VLT Survey Telescope) is a wide field survey telescope going to be commissioned at Cerro Paranal (Chile). Due to the geological nature of the area, telescopes in Chile can be submitted to unpredictable and sometimes severe earthquake conditions. The commonly used response spectrum analysis has proven to be not suitable to evaluate the behavior of the VST telescope during an earthquake, due to the high number of devices with a nonlinear force–displacement characteristic in the primary mirror cell. Therefore, a nonlinear transient analysis based on a mixed Finite Element-Simulink approach has been carried out. A linear Finite Element (FE) model of the telescope has been developed and exported to Simulink, using a space state model representation. Then all nonlinear devices have been properly modeled and artificial accelerograms based on seismic history of the site have been applied. The paper focuses on the Simulink model, while giving an overview of the whole procedure.