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1

Expected Performance of Adaptive Optics in Large Aperture Solar Telescopes  

NASA Astrophysics Data System (ADS)

Solar adaptive optics has become an indispensable tool for high resolution solar observations. New generation solar telescopes, such as the 4 m aperture Advanced Technology Solar Telescope, introduce a new set of challenges to solar adaptive optics correction. Larger aperture sizes are more susceptible to the effects on AO correction performance of the extended field-of-view of the cross-correlating Shack-Hartmann wavefront sensor. Observations at large zenith angles further enhance these field-of-view effects and can introduce more performance reductions due to atmospheric dispersion. We study the expected correction performance of solar adaptive optics systems in large aperture solar telescopes using an end-to-end adaptive optics simulation package.

Marino, J.; Rimmele, T. R.

2012-12-01

2

The one meter aperture solar telescope in China  

NASA Astrophysics Data System (ADS)

One meter aperture solar telescope developed by Yunnan Astronomical Observatory, Chinese Academy of Sciences has seen its first light. The telescope is located by the Fushine Lake in southwest China. We expect that the telescope will play an important role for studying unresolved problems in solar magnetism by providing the community with high spatial and spectral resolution data according to its science definition. In this talk, I will introduce the telescope itself, its focal plane instrumentation and some observational results. The observational condition of the site will be included.

Ji, H.; Liu, Z.

2012-12-01

3

Design of large aperture solar optical telescope for the SOLAR-C mission  

NASA Astrophysics Data System (ADS)

A large aperture optical telescope is planned for the next Japanese solar mission SOLAR-C as one of major three observing instruments. The optical telescope is designed to provide high-angular-resolution investigation of lower atmosphere from the photosphere to the uppermost chromosphere with enhanced spectroscopic and spectro-polarimetric capability covering a wide wavelength region from 280 nm to 1100 nm. The opto-mechanical and -thermal performance of the telescope is crucial to attain high-quality solar observations and we present a study of optical and structural design of the large aperture space solar telescope, together with conceptual design of its accompanying focal plane instruments: wide-band and narrow-band filtergraphs and a spectro-polarimeter for high spatial and temporal observations in the solar photospheric and chromospheric lines useful for sounding physical condition of dynamical phenomena.

Suematsu, Y.; Katsukawa, Y.; Hara, H.; Shimizu, T.; Ichimoto, K.

2012-09-01

4

Instrument Design of the Large Aperture Solar UV Visible and IR Observing Telescope (SUVIT) for the SOLAR-C Mission  

NASA Astrophysics Data System (ADS)

We present an instrumental design of one major solar observation payload planned for the SOLAR-C mission: the Solar Ultra-violet Visible and near IR observing Telescope (SUVIT). The SUVIT is designed to provide high-angular-resolution investigation of the lower solar atmosphere, from the photosphere to the uppermost chromosphere, with enhanced spectroscopic and spectro-polarimetric capability in wide wavelength regions from 280 nm (Mg II h&k lines) to 1100 nm (He I 1083 nm line) with 1.5 m class aperture and filtergraphic and spectrographic instruments.

Suematsu, Y.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.; Takeyama, N.

2012-12-01

5

Science and Instrument Design of 1.5-m Aperture Solar Optical Telescope for the SOLAR-C Mission  

NASA Astrophysics Data System (ADS)

We present science cases and a design of one of major instruments for SOLAR-C mission; 1.5-m-class aperture solar ultra-violet visible and near IR observing Telescope (SUVIT). The SOLAR-C mission aims at fully understanding dynamism and magnetic nature of the solar atmosphere by observing small-scale plasma processes and structures. The SUVIT is designed to provide high-angular-resolution investigation of lower atmosphere from the photosphere to the uppermost chromosphere with enhanced spectroscopic and spectro-polarimetric capability covering a wide wavelength region from 280 nm (Mg II h&k) to 1100 nm (He I 1083 nm), using focal plane instruments: wide-band and narrow-band filtergraphs and a spectrograph for high-precision spectro-polarimetry in the solar photospheric and chromospheric lines. We will discuss about instrument design to realize the science cases.

Suematsu, Y.; Katsukawa, Y.; Ichimoto, K.; Shimizu, T.

2012-12-01

6

TELESCOPES: Astronomers Overcome 'Aperture Envy'.  

PubMed

Many users of small telescopes are disturbed by the trend of shutting down smaller instruments in order to help fund bigger and bolder ground-based telescopes. Small telescopes can thrive in the shadow of giant new observatories, they say--but only if they are adapted to specialized projects. Telescopes with apertures of 2 meters or less have unique abilities to monitor broad swaths of the sky and stare at the same objects night after night, sometimes for years; various teams are turning small telescopes into robots, creating networks that span the globe and devoting them to survey projects that big telescopes don't have a prayer of tackling. PMID:17832960

Irion, R

2000-07-01

7

Large aperture Fresnel telescopes/011  

SciTech Connect

At Livermore we`ve spent the last two years examining an alternative approach towards very large aperture (VLA) telescopes, one based upon transmissive Fresnel lenses rather than on mirrors. Fresnel lenses are attractive for VLA telescopes because they are launchable (lightweight, packagable, and deployable) and because they virtually eliminate the traditional, very tight, surface shape requirements faced by reflecting telescopes. Their (potentially severe) optical drawback, a very narrow spectral bandwidth, can be eliminated by use of a second (much smaller) chromatically-correcting Fresnel element. This enables Fresnel VLA telescopes to provide either single band ({Delta}{lambda}/{lambda} {approximately} 0.1), multiple band, or continuous spectral coverage. Building and fielding such large Fresnel lenses will present a significant challenge, but one which appears, with effort, to be solvable.

Hyde, R.A., LLNL

1998-07-16

8

Large aperture diffractive space telescope  

DOEpatents

A large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary objective lens functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass "aiming" at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The objective lens includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the objective lens, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets which may be either earth bound or celestial.

Hyde, Roderick A. (Livermore, CA)

2001-01-01

9

The European Solar Telescope  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) is a project to design, build and operate an European Solar 4-meter class telescope to be located in the Canary Islands, with the participation of institutions from fifteen European countries gathered around the consortium EAST (European Association for Solar Telescopes). The project main objective up to the present has been the development of the conceptual design study (DS) of a large aperture Solar Telescope. The study has demonstrated the scientific, technical and financial feasibility of EST. The DS has been possible thanks to the co-financing allocated specifically by the EU and the combined efforts of all the participant institutions. Different existing alternatives have been analysed for all telescope systems and subsystems, and decisions have been taken on the ones that are most compatible with the scientific goals and the technical strategies. The present status of some subsystems is reviewed in this paper.

Collados, M.; Bettonvil, F.; Cavaller, L.; Ermolli, I.; Gelly, B.; Pérez, A.; Socas-Navarro, H.; Soltau, D.; Volkmer, R.; EST Team

10

The European Solar Telescope  

NASA Astrophysics Data System (ADS)

In this presentation I will describe the current status of the European Solar Telescope (EST) project. The EST design has a 4-m aperture to achieve both a large photon collection and very high spatial resolution. It includes a multi-conjugate adaptive system integrated in the light path for diffraction-limited imaging. The optical train is optimized to minimize instrumental polarization and to keep it nearly constant as the telescope tracks the sky. A suite of visible and infrared instruments are planned with a light distribution system that accomodates full interoperability and simultaneous usage. The science drivers emphasize combined observations at multiple heights in the atmosphere to build a connected view of solar magnetism from the photosphere to the corona.

Socas-Navarro, H.

2012-12-01

11

Electromagnetic formation flight for sparse aperture telescopes  

Microsoft Academic Search

The use of propellant to maintain the relative orientation of multiple spacecraft in a sparse aperture telescope such as NASA's Terrestrial Planet Finder (TPF) poses several issues. These include fuel depletion, optical contamination, plume impingement, thermal emission, and vibration excitation. An alternative is to eliminate the need for propellant, except for orbit transfer, and replace it with electromagnetic control. Relative

D. W. Miller; R. J. Sedwick; E. M. C. Kong; S. Schweighart

2002-01-01

12

Mirror seeing control of large infrared solar telescope  

Microsoft Academic Search

To obtain high resolution infrared image, both low photon efficiency and long wavelength of infrared light requires enough large aperture telescope, but large aperture vacuum windows can hardly achieve high optical quality, so open structure becomes the only viable choice for large infrared solar telescope. In addition to the effects of atmospheric turbulence, open solar telescopes suffer from the heating

Haiying Zhang; Xinnan Li; Xiaohui Meng; Houkun Ni

2010-01-01

13

Science with Large Solar Telescopes  

NASA Astrophysics Data System (ADS)

With several large aperture optical/IR telescopes coming on-line, and scheduled for the near future, solar physics is on the verge of a quantum leap in observational capabilities. An efficient use of such facilities will require new and innovative approaches to both observatory operations and data handling. This two-days long Special Session will discuss the science expected with large solar telescopes, and start addressing the strategies necessary to optimize their scientific return. Cutting edge solar science as derived from state of the art observations and numerical simulations will be presented, and discussions will be held on the role of large facilities in satisfying the demanding requirements of spatial and temporal resolution, stray-light, and spectro-polarimetric accuracy. Building on the experience of recently commissioned telescopes, we will then discuss critical issues for the development of future facilities including operational issues peculiar to large telecopes, and strategies for their best use.

Cauzzi, G.; Tritschler, A.; Deng, Y.

2012-12-01

14

Aperture Increase Options for the Dutch Open Telescope  

NASA Astrophysics Data System (ADS)

This paper is an invitation to the international community to participate in the usage and a substantial upgrade of the Dutch Open Telescope on La Palma (DOT, http://dot.astro.uu.nl). We first give a brief overview of the approach, design, and current science capabilities of the DOT. It became a successful 0.2-arcsec-resolution solar movie producer through its combination of (i) an excellent site, (ii) effective wind flushing through the fully open design and construction of both the 45-cm telescope and the 15-m support tower, (iii) special designs which produce extraordinary pointing stability of the tower, equatorial mount, and telescope, (iv) simple and excellent optics with minimum wavefront distortion, and (v) large-volume speckle reconstruction including narrow-band processing. The DOT's multi-camera multi-wavelength speckle imaging system samples the solar photosphere and chromosphere simultaneously in various optical continua, the G band, Ca II H (tunable throughout the blue wing), and H? (tunable throughout the line). The resulting DOT data sets are all public. The DOT database (http://dotdb.phys.uu.nl/DOT) now contains many tomographic image sequences with 0.2-0.3 arcsec resolution and up to multi-hour duration. You are welcome to pull them over for analysis. The main part of this contribution outlines DOT upgrade designs implementing larger aperture. The motivation for aperture increase is the recognition that optical solar physics needs the substantially larger telescope apertures that became useful with the advent of adaptive optics and viable through the DOT's open principle, both for photospheric polarimetry at high resolution and high sensitivity and for chromospheric fine-structure diagnosis at high cadence and full spectral sampling. Our upgrade designs for the DOT are presented in an incremental sequence of five options of which the simplest (Option I) achieves 1.4 m aperture using the present tower, mount, fold-away canopy, and multi-wavelength speckle imaging and processing systems. The most advanced (Option V) offers unblocked 2.5 m aperture in an off-axis design with a large canopy, a wide 30-m high support tower, and image transfer to a groundbased optics lab for advanced instrumentation. All five designs employ adaptive optics. The important advantages of fully open, wind-transparent and wind-flushed structure, polarimetric constancy, and absence of primary-image rotation remain. All designs are relatively cheap through re-using as much of the existing DOT hardware as possible. Realization of an upgrade requires external partnership(s). This report about DOT upgrade options therefore serves also as initial documentation for potential partners.

Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Rutten, R. J.

2007-05-01

15

Imaging Fourier transform spectroscopy with multi-aperture telescopes  

Microsoft Academic Search

Fourier spectroscopy can be performed with multi-aperture telescopes by adjusting the optical path difference between apertures. Expressions are given for the measured intensity and the recovered spectrum for a general multi-aperture system. The transfer function of a multi-aperture spectrometer is strikingly different than for a conventional Michelson imaging spectrometer. ©2003 Optical Society of America OCIS codes: (300.6300) Spectroscopy, Fourier transforms;

Samuel T. Thurman; James R. Fienup; R. L. Kendrick

16

The Space Solar Telescope  

NASA Astrophysics Data System (ADS)

(On behalf of the SST group) The Space Solar Telescope (SST) is a Chinese space project, which was first proposed in the mid of 1990s. The main purpose is to observe the basic structures and understand the instrinsic properties of solar magnetic field with a 1m optical telescope equiped with a two-dimensional real-time spectrograph and high-accuracy polarimeter. In addition, through coordinated, wide spectral coverage, highly resolving and continuous observations, it can study the evolution of multi-scale transients and various phenomena in the solar atmosphere, investigate the heating mechanism of the chromosphere and the corona, and study the mechanism of the energy build-up and release in solar flares and CMEs. Recently, along with the progress of STEREO, Hinode, SDO and other space projects, the scientific objectives and payloads of SST have been updated. In this presentation, we will briefly introduced the updated payloads and relevant progress.

Deng, Y.

2012-12-01

17

BLAST: The Balloon-Borne Large Aperture Submillimeter Telescope.  

National Technical Information Service (NTIS)

BLAST is the Balloon-borne Large-Aperture Sub-millimeter Telescope. It will fly from a Long Duration Balloon (LDB) platform from Antarctica. The telescope design incorporates a 2 m primary mirror with large-format bolometer arrays operating at 250, 350 an...

M. Devlin P. Ade J. Bock S. Dicker M. Griffin J. Gunderson M. Halpern P. Hargrave D. Hughes J. Klein

2004-01-01

18

SolarB Solar Optical Telescope (SOT)  

NASA Astrophysics Data System (ADS)

The SolarB Solar Optical Telescope (SOT) will be the largest telescope with highest performance ever to observe the Sun at visible wavelengths from space. The telescope itself (Optical Telescope Assembly, OTA) along with its focal plane package (FPP), is optimized for measurement of the vector magnetic field and associated dynamics in the solar photosphere and chromosphere. FPP observations are controlled using commands from the sequence tables in Mission Data Processor (MDP). This paper describes scientific capabilities of the instrument.

Shimizu, T.

2004-12-01

19

Introduction to the Chinese Giant Solar Telescope  

NASA Astrophysics Data System (ADS)

In order to detect the fine structures of solar magnetic field and dynamic field, an 8 meter solar telescope has been proposed by Chinese solar community. Due to the advantages of ring structure in polarization detection and thermal control, the current design of CGST (Chinese Giant Solar Telescope) is an 8 meter ring solar telescope. The spatial resolution of CGST is equivalent to an 8 meter diameter telescope, and the light-gathering power equivalent to a 5 meter full aperture telescope. The integrated simulation of optical system and imaging ability such as optical design, MCAO, active maintenance of primary mirror were carried out in this paper. Mechanical system was analyzed by finite element method too. The results of simulation and analysis showed that the current design could meet the demand of most science cases not only in infrared band but also in near infrared band and even in visible band. CGST was proposed by all solar observatories in Chinese Academy of Sciences and several overseas scientists. It is supported by CAS (Chinese Academy of Sciences) and NSFC (National Natural Science Foundation of China) as a long term astronomical project.

Liu, Z.; Deng, Y.; Ji, H.

2012-12-01

20

Introduction to the Chinese Giant Solar Telescope  

NASA Astrophysics Data System (ADS)

In order to detect the fine structures of solar magnetic field and dynamic field, an 8 meter solar telescope has been proposed by Chinese solar community. Due to the advantages of ring structure in polarization detection and thermal control, the current design of CGST (Chinese Giant Solar Telescope) is an 8 meter ring solar telescope. The spatial resolution of CGST is equivalent to an 8 meter diameter telescope, and the light-gathering power equivalent to a 5 meter full aperture telescope. The integrated simulation of optical system and imaging ability such as optical design, MCAO, active maintenance of primary mirror were carried out in this paper. Mechanical system was analyzed by finite element method too. The results of simulation and analysis showed that the current design could meet the demand of most science cases not only in infrared band but also in near infrared band and even in visible band. CGST was proposed by all solar observatories in Chinese Academy of Sciences and several overseas scientists. It is supported by CAS and NSFC (National Natural Science Foundation of China) as a long term astronomical project.

Liu, Zhong; Deng, Yuanyong; Jin, Zhenyu; Ji, Haisheng

2012-09-01

21

National Large Solar Telescope of India  

NASA Astrophysics Data System (ADS)

The National Large Solar Telescope NLST will be a state-of-the-art 2-m class telescope for carrying out high-resolution studies of the solar atmosphere. Sites in the Himalayan region at altitudes greater than 4000-m that have extremely low water vapor content and are unaffected by monsoons are under evaluation. This project is led by the Indian Institute of Astrophysics and has national and international partners. Its geographical location will fill the longitudinal gap between Japan and Europe and is expected to be the largest solar telescope with an aperture larger than 1.5 m till ATST and EST come into operation. NLST is an on-axis alt-azimuth Gregorian multi-purpose open telescope with the provision of carrying out night time stellar observations using a spectrograph at the final focus. The telescope utilizes an innovative design with low number of reflections to achieve a high throughput and low polarization. High order adaptive optics is integrated into the design that works with a modest Fried parameter of 7-cm to give diffraction limited performance. The telescope will be equipped with a suite of post-focus instruments including a high-resolution spectrograph and a polarimeter.

Hasan, S. S.

22

Photoreadout statistics analysis during space objects image acquisition in large aperture telescope  

NASA Astrophysics Data System (ADS)

The prospects for image recovery of space objects, observed in the visible range through the turbulent atmosphere by using large aperture telescope, were discussed and evaluated. A "dual" adaptation was introduced: at first - hardware adaptation, using reflected solar radiation from the space object or laser star, then algorithmic. We considered two scenarios for observation. The criterion of image quality was chosen to be potentially full compensation of phase distortion. The characteristics of photoreadout statistics for the various scenarios were analyzed.

Shumilov, Yu. P.; Bakut, P. A.; Vygon, V. G.; Grishin, E. A.; Shargorodskii, V. D.

2013-05-01

23

The large European solar telescope  

NASA Astrophysics Data System (ADS)

The design of the Large European Solar Telescope (LEST) is described. The telescope is a Gregorian system and the optical system is to be used for active and adaptive optics. The mirrors and alignment system for LEST are examined. The high precision tracking of the telescope is achieved by combining low and high frequency response systems. The LEST is placed on a tower to reduce ground turbulence and has an alt-azimuth mount. The three components of the dome, which support the telescope tube, the telescope tube design, and the mirror support system are analyzed. Instrument stations and auxiliary telescope facilities are located underground. The LEST can be operated with the astronomer observing at the site, with the astronomer present in a control station, or with the staff performing an astronomer's written instructions. Diagrams of the LEST's optical system and telescope tube, mounting, and dome structure are provided.

Engvold, O.

24

Advanced Technology Solar Telescope Construction: Progress Report  

NASA Astrophysics Data System (ADS)

The 4m Advance Technology Solar Telescope (ATST) on Haleakala will be the most powerful solar telescope and the world’s leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun’s output. The ATST will provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona at infrared wavelengths. With its 4 m aperture, ATST will resolve magnetic features at their intrinsic scales. A high order adaptive optics system delivers a corrected beam to the initial set of five state-of-the-art, facility class instrumentation located in the coude laboratory facility. Photopheric and chromospheric magnetometry is part of the key mission of four of these instruments. Coronal magnetometry and spectroscopy will be performed by two of these instruments at infrared wavelengths. The ATST project has transitioned from design and development to its construction phase. Site construction is expected to begin in April 2012. The project has awarded design and fabrication contracts for major telescope subsystems. A robust instrument program has been established and all instruments have passed preliminary design reviews or critical design reviews. A brief overview of the science goals and observational requirements of the ATST will be given, followed by a summary of the project status of the telescope and discussion of the approach to integrating instruments into the facility. The National Science Foundation (NSF) through the National Solar Observatory (NSO) funds the ATST Project. The NSO is operated under a cooperative agreement between the Association of Universities for Research in Astronomy, Inc. (AURA) and NSF.

Rimmele, Thomas R.; McMullin, J.; Keil, S.; Goode, P.; Knoelker, M.; Kuhn, J.; Rosner, R.; ATST Team

2012-05-01

25

Teaching and Research in Astronomy using Small Aperture Optical Telescopes  

NASA Astrophysics Data System (ADS)

Small aperture (<1m, typically 20-50cm) optical telescopes with adequate back-end instrumentation (photometer, CCD camera and CCD spectrograph etc) can be used for spreading the joy and excitement of observational astronomy among postgraduate and research students in Colleges/. On the basis of over a decade's experience in observing with small optical telescopes it has been amply demonstrated that such a facility, which any University department can hope to procure and maintain, can be effectively used for teaching as well quality research. The Physics Department of Pt Ravishankar Shukla University at Raipur, India offers Astronomy & Astrophysics (A&A) as one of the specialization as a part of M Sc program in Physics. A set of observational exercises has been incorporated with a view to provide training in observations, analysis and interpretation of the astronomical data to the students. Observing facilities available in the department include 8"-14" aperture telescopes (CGE series from Celestron) equipped with the new-state-of-the-art backend instrumentation like Photometer, CCD Camera and also a CCD spectrograph. Observing facility of this kind is ideally suited for continuous monitoring of a variety of variable stars, and thus can provide valuable data for understanding the physics of stellar variability. This is especially true for a class of variable stars known as chromospherically active stars. The stars belonging to this class have variable light curves, and the most puzzling feature is that their light curves change year after year in a rather queerer way. A large fraction of these active stars are bright ones and, hence, the importance of small aperture telescope for collecting the much needed photometric data. For over a decade the research activity using 14" optical telescope is focused on photometric monitoring of well known as well suspected active stars. This together with spectroscopic data using observing facility at Indian Observatories has led to identification of new chromosperically active stars. The talk is aimed at sharing our experiences quoting examples with professional colleagues on the usage of small optical telescopes for teaching and research in Colleges/Universities.

Pandey, S. K.

2006-08-01

26

The Advanced Technology Solar Telescope: beginning construction of the world's largest solar telescope  

NASA Astrophysics Data System (ADS)

The 4m Advance Technology Solar Telescope (ATST) will be the most powerful solar telescope and the world's leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. The project has successfully passed its final design review and the Environmental Impact Study for construction of ATST on Haleakala, Maui, HI has been concluded in December of 2009. The project is now entering its construction phase. As its highest priority science driver ATST shall provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona at infrared wavelengths. With its 4 m aperture, ATST will resolve features at 0."03 at visible wavelengths and obtain 0."1 resolution at the magnetically highly sensitive near infrared wavelengths. A high order adaptive optics system delivers a corrected beam to the initial set of state-of-the-art, facility class instrumentation located in the coudé laboratory facility. The initial set of first generation instruments consists of five facility class instruments, including imagers and spectropolarimeters. The high polarimetric sensitivity and accuracy required for measurements of the illusive solar magnetic fields place strong constraints on the polarization analysis and calibration. Development and construction of a fourmeter solar telescope presents many technical challenges, including thermal control of the enclosure, telescope structure and optics and wavefront control. A brief overview of the science goals and observational requirements of the ATST will be given, followed by a summary of the design status of the telescope and its instrumentation, including design status of major subsystems, such as the telescope mount assembly, enclosure, mirror assemblies, and wavefront correction

Rimmele, T. R.; Wagner, J.; Keil, S.; Elmore, D.; Hubbard, R.; Hansen, E.; Warner, M.; Jeffers, P.; Phelps, L.; Marshall, H.; Goodrich, B.; Richards, K.; Hegwer, S.; Kneale, R.; Ditsler, J.

2010-07-01

27

ULTIMA free-flying large-aperture space telescope  

NASA Astrophysics Data System (ADS)

Project ULTIMA is an investigation into the feasibility of building ultralarge aperture visible/mid-LR space telescopes. A promising concept found by the study is a freely flying spherical primary mirror, 20 m or more in diameter, located at the L1 or L2 Earth-sun libration point. The primary would be passively cooled to 45 K. There would be no metering structure. Instead, using a combination of alignment and steering mirrors, reaction wheels, and microthrusters, the aspherical secondary mirror, active tertiary mirror, and focal plane instruments would be precisely stationed in the correct position above the primary. The primary advanced composition would be either a membrane or ultralight segmented technology. Preliminary findings show that a 20-30-m telescope may be feasible for imaging in the 1-20-micron regime.

Campbell, Jonathan W.; Taylor, Charles R.

1997-01-01

28

Performance Impacts for Actuator Misalignments and Failures in Large-Aperture Adaptive-Optic Telescopes.  

National Technical Information Service (NTIS)

Large-aperture telescopes require adaptive optics in order to compensate for atmospheric turbulence which would otherwise negate the resolution advantages of using large apertures. This investigation analyzes the impacts of misalignments and failures, in ...

T. D. Hogan

1993-01-01

29

Infrared observations of the solar system in support of Large-Aperture Infrared Telescope (LARITS): Calibration. Appendices. Final technical report, 1 July 1985-28 February 1989  

SciTech Connect

An infrared (I.R.) optics package designed for a I.R. detector calibration survey will be used in conjunction with the 90 inch telescope at the University of Wyoming, or as a portable, stand along unit. An important part of this instrument package is a mechanical light beam chopper which rotates with a fixed phase relation with respect to a wobbling secondary mirror in the telescope. A control circuit synchronizes the chopper to an external signal when used at the Wyoming site, or generates an internal reference frequency when used as a portable system. The portable system consists of a small equatorial telescope mount to support the same I.R. instrumentation package, which is used without additional optics. An automated positioning and tracking system encorporates a personal computer to control the environment of the telescope mount via stepper motors attached to the drive axis. The computer is also used to record all data on floppy disc for both fixed and portable systems.

Shorthill, R.W.

1990-04-01

30

The Advanced Technology Solar Telescope: Science Drivers and Construction Status  

NASA Astrophysics Data System (ADS)

The 4-meter Advance Technology Solar Telescope (ATST) currently under construction on the 3000 meter peak of Haleakala on Maui, Hawaii will be the world's most powerful solar telescope and the leading ground-based resource for studying solar magnetism. The solar atmosphere is permeated by a 'magnetic carpet' that constantly reweaves itself to control solar irradiance and its effects on Earth's climate, the solar wind, and space weather phenomena such as flares and coronal mass ejections. Precise measurement of solar magnetic fields requires a large-aperture solar telescope capable of resolving a few tens of kilometers on the solar surface. With its 4 meter aperture, the ATST will for the first time resolve magnetic structure at the intrinsic scales of plasma convection and turbulence. The ATST's ability to perform accurate and precise spectroscopic and polarimetric measurements of magnetic fields in all layers of the solar atmosphere, including accurate mapping of the elusive coronal magnetic fields, will be transformative in advancing our understanding of the magnetic solar atmosphere. The ATST will utilize the Sun as an important astro- and plasma-physics "laboratory" demonstrating key aspects of omnipresent cosmic magnetic fields. The ATST construction effort is led by the US National Solar Observatory. State-of-the-art instrumentation will be constructed by US and international partner institutions. The technical challenges the ATST is facing are numerous and include the design of the off-axis main telescope, the development of a high order adaptive optics system that delivers a corrected beam to the instrument laboratory, effective handling of the solar heat load on optical and structural elements, and minimizing scattered light to enable observations of the faint corona. The ATST project has transitioned from design and development to its construction phase. The project has awarded design and fabrication contracts for major telescope subsystems. Site construction has commenced following the successful conclusion of the site permitting process. Science goals and construction status of telescope and instrument systems will be discussed.

Rimmele, Thomas; Berger, Thomas; McMullin, Joseph; Keil, Stephen; Goode, Phil; Knoelker, Michael; Kuhn, Jeff; Rosner, Robert; Casini, Roberto; Lin, Haosheng; Woeger, Friedrich; von der Luehe, Oskar; Tritschler, Alexandra; Atst Team

2013-04-01

31

Advanced Technology Solar Telescope: a progress report  

Microsoft Academic Search

The four-meter Advanced Technology Solar Telescope (ATST) will be the most powerful solar telescope and the world's leading resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. Development of a four-meter solar telescope presents many technical challenges (e.g., thermal control of the enclosure, telescope structure and optics). We give

J. Wagner; T. R. Rimmele; S. Keil; J. Barr; N. Dalrymple; J. Ditsler; B. Goodrich; E. Hansen; S. Hegwer; F. Hill; R. Hubbard; L. Phelps; R. Price; K. Richards; M. Warner

2006-01-01

32

The Five-Hundred Aperture Spherical Radio Telescope (fast) Project  

NASA Astrophysics Data System (ADS)

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is a Chinese mega-science project to build the largest single dish radio telescope in the world. Its innovative engineering concept and design pave a new road to realize a huge single dish in the most effective way. FAST also represents Chinese contribution in the international efforts to build the square kilometer array (SKA). Being the most sensitive single dish radio telescope, FAST will enable astronomers to jump-start many science goals, such as surveying the neutral hydrogen in the Milky Way and other galaxies, detecting faint pulsars, looking for the first shining stars, hearing the possible signals from other civilizations, etc. The idea of sitting a large spherical dish in a karst depression is rooted in Arecibo telescope. FAST is an Arecibo-type antenna with three outstanding aspects: the karst depression used as the site, which is large to host the 500-meter telescope and deep to allow a zenith angle of 40 degrees; the active main reflector correcting for spherical aberration on the ground to achieve a full polarization and a wide band without involving complex feed systems; and the light-weight feed cabin driven by cables and servomechanism plus a parallel robot as a secondary adjustable system to move with high precision. The feasibility studies for FAST have been carried out for 14 years, supported by Chinese and world astronomical communities. Funding for FAST has been approved by the National Development and Reform Commission in July of 2007 with a capital budget ~ 700 million RMB. The project time is 5.5 years from the commencement of work in March of 2011 and the first light is expected to be in 2016. This review intends to introduce the project of FAST with emphasis on the recent progress since 2006. In this paper, the subsystems of FAST are described in modest details followed by discussions of the fundamental science goals and examples of early science projects.

Nan, Rendong; Li, Di; Jin, Chengjin; Wang, Qiming; Zhu, Lichun; Zhu, Wenbai; Zhang, Haiyan; Yue, Youling; Qian, Lei

33

The Balloon-borne Large Aperture Submillimeter Telescope: BLAST  

NASA Astrophysics Data System (ADS)

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a suborbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between three arrays, observes simultaneously in broadband (30%) spectral windows at 250, 350, and 500 ?m. The optical design is based on a 2 m diameter telescope, providing a diffraction-limited resolution of 30" at 250 ?m. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of ~30" postflight pointing reconstruction to <~5" rms is achieved. The onboard telescope control software permits autonomous execution of a preselected set of maps, with the option of manual override. In this paper we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100 hr flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in 2005 June; and a 250 hr, circumpolar flight from McMurdo Station, Antarctica, in 2006 December.

Pascale, E.; Ade, P. A. R.; Bock, J. J.; Chapin, E. L.; Chung, J.; Devlin, M. J.; Dicker, S.; Griffin, M.; Gundersen, J. O.; Halpern, M.; Hargrave, P. C.; Hughes, D. H.; Klein, J.; MacTavish, C. J.; Marsden, G.; Martin, P. G.; Martin, T. G.; Mauskopf, P.; Netterfield, C. B.; Olmi, L.; Patanchon, G.; Rex, M.; Scott, D.; Semisch, C.; Thomas, N.; Truch, M. D. P.; Tucker, C.; Tucker, G. S.; Viero, M. P.; Wiebe, D. V.

2008-07-01

34

Spacecraft conceptual design for the 8-meter Advanced Technology Large Aperture Space Telescope (ATLAST)  

NASA Astrophysics Data System (ADS)

The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8- meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David; Mosier, Gary; Stahl, H. Philip; Thomas, Dan; Thompson, Kevin S.

2010-07-01

35

Infrared observations of the solar system in support of Large-Aperture Infrared Telescope (LARITS): Calibration. Final technical report, 1 July 1985-28 February 1989  

SciTech Connect

The Purpose of this project was to improve the infrared calibration base for infrared detectors. Groundbased infrared measurements of solid-surfaced planetary bodies, such as asteroids, are being used for the calibration of spacecraft detectors. A limitation has been the relatively poor theoretical understanding of thermal emission from these objects. The goal was to: (1) develop a database of sources and, (2) improve or modify the thermal models for these sources to provide a calibration data base for spacecraft infrared detector systems. The technique consisted of five phases: (1) design and construct infrared detector system to be used with and without collecting optics, (2) acquire whole-disk infrared lunar data relative to a laboratory blackbody and tie them to Mars (Venus or Mercury) and Vega, (3) compare with thermophysical model of the mood and modify, (4) acquire infrared asteroid photometry, (5) compare the lunar disk photometry the asteroid calibrators using photometry and thermophysical models. The Si bolometer is calibrated without optics, attached to the portable telescope drive and Lunar disk measurement made. Next the bolometer is attached to the 90 inch telescope, Lunar scans are made and the remaining objects (planets, stars, asteroids) are measured.

Shorthill, R.W.

1990-05-02

36

EST: The European Solar Telescope  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) is a project for a 4 meter-class ground-based telescope, to be located in the Canary Islands. The project is promoted by the European Association for Solar Telescopes (EAST), a consortium formed by research organizations from 15 European countries. EST will be optimized for studies of magnetic coupling between the deep photosphere and upper chromosphere. The project has been approved for funds by the European Union, within the FP-7 framework, to produce the design of all systems and subsystems of the telescope during the next three years. This includes the optical and optomechanical design of the telescope itself and of the instruments and their control. MCAO will be included in the optical path in a natural way to compensate for atmospheric disturbances in an optimum way. The design of EST will strongly emphasize the use of a large number of visible and near-infrared instruments simultaneously which will influence the telescope design from the very beginning. This communication will center mainly on the scientific objectives that EST will address. Generally speaking, they involve understanding how the magnetic field emerges through the solar surface, interacts with the plasma dynamics to transfer energy between different regions, and finally releases it in the form of heat or as violent events in the solar chromosphere and corona. Among the many topics of interest, one may cite, as described in the EST Science Requirements Document: small-scale flux emergence in quiet sun regions, large-scale magnetic structures, magnetic flux cancellation processes, polar magnetic fields, magnetic topology of the photosphere and chromosphere, conversion of mechanical to magnetic energy in the photosphere, wave propagation from photosphere to chromosphere, energy dissipation in the chromosphere at small and large scales, etc. The present status and future perspectives of the project will also be outlined.

Collados, M.

2008-09-01

37

Miyun metre-wave aperture synthesis radio telescope  

NASA Astrophysics Data System (ADS)

The Miyun metre-wave aperture synthesis radiotelescope, working at frequency of 232 MHz, consists of an E-W array of 28 elements, each of 9 m aperture. 192 baselines are effected with a full coverage of the U-V plane (Fig. 2). The longest baseline is 1,164m. This instrument is designed for source survey and detection of peculiar sources in northern declinations. A set of observations completed in 2 × 12 hours gives a thermal noise limited sensititity of 0.05 Jy and a resolution of 3'8 × 3'8 csc ?. The field of view is 8° × 8°. This should enable us to complete an overall survey of the region ? >= + 30° within two years, and to carry out monitoring of selected areas. Figures 1 and 2 show the main properties and general design of the instrument and Figures 3 and 4 give some preliminary results of sky mapping. The following persons took part in the designing and making of the telescope: WANG Hong, Wang Xin-min, Wang Shou-guan, Liu Fu-you, Pu Ting-yi, Chen Hong-shen, Qiu Yu-hai, Yang Yi-pei, Pang Lei, Zhang Chun-lu, Zhang Guo-quan, Zhang Xi-zhen, Jin Tie-lin, Zheng Yi-jia, Zhao Hui-ping, Nan Ren-dong, Kang Lian-sheng, Bao Hong-qi, Wei Ming-zhi.

1986-03-01

38

Fourier transform imaging spectroscopy with a multiple-aperture telescope: band-by-band image reconstruction  

Microsoft Academic Search

Fourier transform imaging spectroscopy can be performed with a segmented-aperture telescope or a multiple-telescope array using the subaperture piston control mechanisms. Spectrum recovery from intensity measurements is analyzed for a general aperture configuration. The spatial transfer functions of the recovered spectral images are shown to vanish necessarily at the DC spatial frequency. This poses an interesting image reconstruction problem as

Samuel T. Thurman; James R. Fienup

2004-01-01

39

The Balloon-borne Large Aperture Submillimeter Telescope: BLAST  

NASA Astrophysics Data System (ADS)

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a suborbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between three arrays, observes simultaneously in broadband (30%) spectral windows at 250, 350, and 500 microns. The optical design is based on a 2 m diameter telescope, providing a diffraction-limited resolution of 30" at 250 microns. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of 30"; postflight pointing reconstruction to <5" rms is achieved. The onboard telescope control software permits autonomous execution of a preselected set of maps, with the option of manual override. On this poster, we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100 hour flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in 2005 June; and a 250 hour, circumpolar flight from McMurdo Station, Antarctica in 2006 December. The BLAST collaboration acknowledges the support of NASA through grants NAG5-12785, NAG5-13301, and NNGO-6GI11G, the Canadian Space Agency (CSA), the Science and Technology Facilities Council (STFC), Canada's Natural Sciences and Engineering Research Council (NSERC), the Canada Foundation for Innovation, the Ontario Innovation Trust, the Puerto Rico Space Grant Consortium, the Fondo Institucional para la Investigacion of the University of Puerto Rico, and the National Science Foundation Office of Polar Programs.

Truch, Matthew D. P.; Ade, P. A. R.; Bock, J. J.; Chapin, E. L.; Chung, J.; Devlin, M. J.; Dicker, S.; Griffin, M.; Gundersen, J. O.; Halpern, M.; Hargrave, P. C.; Hughes, D. H.; Klein, J.; MacTavish, C. J.; Marsden, G.; Martin, P. G.; Martin, T. G.; Mauskopf, P.; Netterfield, C. B.; Olmi, L.; Pascale, E.; Patanchon, G.; Rex, M.; Scott, D.; Semisch, C.; Thomas, N. E.; Tucker, C.; Tucker, G. S.; Viero, M. P.; Wiebe, D. V.

2009-01-01

40

Infrared Observations from the New Solar Telescope at Big Bear  

NASA Astrophysics Data System (ADS)

The 1.6 m clear aperture solar telescope in Big Bear is operational and with its adaptive optics (AO) system it provides diffraction limited solar imaging and polarimetry in the near-infrared (NIR). While the AO system is being upgraded to provide diffraction limited imaging at bluer wavelengths, the instrumentation and observations are concentrated in the NIR. The New Solar Telescope (NST) operates in campaigns, making it the ideal ground-based telescope to provide complementary/supplementary data to SDO and Hinode. The NST makes photometric observations in H? (656.3 nm) and TiO (705.6 nm) among other lines. As well, the NST collects vector magnetograms in the 1565 nm lines and is beginning such observations in 1083.0 nm. Here we discuss the relevant NST instruments, including AO, and present some results that are germane to NASA solar missions.

Goode, Philip R.; Cao, Wenda

2013-10-01

41

The Advanced Technology Solar Telescope - Constructing The World's Largest Solar Telescope  

NASA Astrophysics Data System (ADS)

The 4m Advance Technology Solar Telescope (ATST) will be the most powerful solar telescope and the world's leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. The ATST shall provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona at infrared wavelengths. With its 4 m aperture, ATST will resolve features at 0.03" at visible wavelengths and obtain 0.1" resolution at the magnetically highly sensitive near infrared wavelengths. A high order adaptive optics system delivers a corrected beam to the initial set of five state-of-the-art, facility class instrumentation located in the coude laboratory facility. Coronal magnetometry and spectroscopy will be performed by two of these instruments at infrared wavelengths. In January 2010 the ATST project transitioned from design and development to the construction phase. The project has awarded contracts for major subsystems, including the 4m primary mirror, architectural and engineering services related to the Support Facilities, Enclosure construction design, Telescope Mount Assembly, and Facilities Thermal System construction design. The State of Hawai'I Board of Land and Natural Resources approved the Conservation District Use Permit submitted by the University of Hawai'I at their December 6, 2010 meeting in Honolulu, HI. A brief overview of the science goals and observational requirements of the ATST will be given, followed by a summary of the project status of the telescope and discussion of the approach to integrating instruments into the facility.

Rimmele, Thomas R.; Keil, S.; Wagner, J.; ATST Team

2011-05-01

42

Solar Multi-Conjugate Adaptive Optics at the Dunn Solar Telescope  

NASA Astrophysics Data System (ADS)

Solar adaptive optics has become an indispensable tool at ground based solar telescopes. Driven by the quest for ever higher spatial resolution observations of the Sun solar adaptive optics are now operated routinely at major ground based solar telescopes. The current high-resolution solar telescopes, such as the Dunn Solar Telescope (DST), are in the one-meter class and utilize AO for >95 % of the observing time to achieve the diffraction limit at visible and NIR wavelengths. Solar AO [1,2] has revitalized ground-based solar astronomy at existing telescopes. The development of high-order solar AO that is capable of delivering high Strehl in the visible will be absolutely essential for next generation solar telescopes, such as the 4m aperture Advanced Technology Solar Telescope (ATST), which undoubtedly will revolutionize solar astronomy [3]. Solar observations are performed over an extended field of view. The limited size of the isoplanatic patch, over which conventional adaptive optics (AO) provides diffraction limited resolution is a severe limitation. Solar science would benefit greatly from AO correction over large field of views. A single sunspot typically has a size of about 30 arcsec; large active regions often cover a field of 2-3 arcmin. Figure 1 shows an image of solar granulation and embedded magnetic g-band bright points observed near the limb of the sun. The field of view is approximately 120"x 80". This diffraction limited image was recorded at the Dunn Solar Telescope with high order adaptive optics and post-processed using speckle interferometry. Post-processing is required to achieve the uniform, diffraction limited imaging over such an extended FOV. However, speckle interferometry as well as other post facto restoration methods typically rely on short exposure imaging, which in most cases can not be deployed when quantitative spectroscopy and polarimetry is performed, i.e., long exposures are required. Multi-conjugate adaptive optics (MCAO) is a technique that provides real-time diffraction limited imaging over an extended FOV [4]. The development of MCAO for existing solar telescopes and, in particular, for the next generation large aperture solar telescopes is thus a top priority. The Sun is an ideal object for the development of MCAO since solar structure provides "multiple guide stars" in any desired configuration. It is therefore not surprising that the first successful on-the-sky MCAO experiments were performed at the Dunn Solar Telescope and at a solar telescope on the Canary Islands. However, further development is needed before operational solar MCAO can be implemented at future large aperture solar telescopes such as the ATST on Haleakala [5]. MCAO development must progress beyond these initial proof-of-concept experiments and should include laboratory experiments and on-sky demonstrations under controlled or well characterized conditions as well as quantitative performance analysis and comparison to model predictions. At the DST we recently implemented a dedicated MCAO bench with the goal of developing well-characterized, operational MCAO. The MCAO system uses 2 deformable mirrors conjugated to the telescope entrance pupil and a layer in the upper atmosphere, respectively. DM2 can be placed at conjugates ranging from 2 km to 10 km altitude. For our initial experiments we have used a staged approach in which the 97 actuator, 76 subaperture correlating Shack-Hartmann solar adaptive optics system normally operated at the DST is followed by the second DM and the tomographic wavefront sensor, which uses three "solar guide stars". We use modal reconstruction algorithms for both DMs. We have successfully and stably locked the MCAO system on artificial objects (slides), for which 1 The National Solar Observatory is operated by the Association of Universities for Research in Astronomy under a cooperative agreement with the National Science Foundation, for the benefit of the astronomical community turbulence screens are generated directly in front of the DMs, as well

Rimmele, T.; Hegwer, S.; Richards, K.; Woeger, F.

43

1.6 M SOLAR TELESCOPE IN BIG BEAR - THE NST  

Microsoft Academic Search

New Jersey Institute of Technology (NJIT), in collaboration with the University of Hawaii (UH), is upgrading Big Bear Solar Observatory (BBSO) by replacing its principal, 65 cm aperture telescope with a modern, o-axis 1.6 m clear aperture instrument from a 1.7 m blank. The new telescope oers a sig- nificant incremental improvement in ground-based infrared and high angular resolution capabilities,

PHILIP R. GOODE; CARSTEN J. DENKER; LEONID I. DIDKOVSKY; J. R. KUHN; HAIMIN WANG

44

1.6 M Solar Telescope in Big Bear -- The NST  

Microsoft Academic Search

New Jersey Institute of Technology (NJIT), in collaboration with the University of Hawaii (UH), is upgrading Big Bear Solar Observatory (BBSO) by replacing its principal, 65 cm aperture telescope with a modern, off-axis 1.6 m clear aperture instrument from a 1.7 m blank. The new telescope offers a significant incremental improvement in ground-based infrared and high angular resolution capabilities, and

Philip R. Goode; Carsten J. Denker; Leonid I. Didkovsky; J. R. Kuhn; Haimin Wang

2003-01-01

45

Design progress of the solar UV-Vis-IR telescope (SUVIT) aboard SOLAR-C  

NASA Astrophysics Data System (ADS)

We present a design progress of the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar mission SOLAR-C. SUVIT has an aperture diameter of ~1.4 m for achieving spectro-polarimetric observations with spatial and temporal resolution exceeding the Hinode Solar Optical Telescope (SOT). We have studied structural and thermal designs of the optical telescope as well as the optical interface between the telescope and the focal plane instruments. The focal plane instruments are installed into two packages, filtergraph and spectrograph packages. The spectropolarimeter is the instrument dedicated to accurate polarimetry in the three spectrum windows at 525 nm, 854 nm, and 1083 nm for observing magnetic fields at both the photospheric and chromospheric layers. We made optical design of the spectrograph accommodating the conventional slit spectrograph and the integral field unit (IFU) for two-dimensional coverage. We are running feasibility study of the IFU using fiber arrays consisting of rectangular cores.

Katsukawa, Y.; Ichimoto, K.; Suematsu, Y.; Hara, H.; Kano, R.; Shimizu, T.; Matsuzaki, K.

2013-09-01

46

Performance impacts for actuator misalignments and failures in large-aperture adaptive-optic telescopes  

Microsoft Academic Search

Large-aperture telescopes require adaptive optics in order to compensate for atmospheric turbulence which would otherwise negate the resolution advantages of using large apertures. This investigation analyzes the impacts of misalignments and failures, in the deformable mirror actuators, upon the performance of such systems. A numerical simulation of a standard adaptive optics system is used to generate characteristic optical transfer function

Timothy D. Hogan

1993-01-01

47

Solar System Observing Capabilities With The James Webb Space Telescope  

NASA Astrophysics Data System (ADS)

The James Webb Space Telescope (JWST) will provide breakthrough capabilities to study our Solar System. JWST is a large aperture, cryogenic, infrared-optimized space observatory under construction by NASA, ESA, and CSA for launch in 2018 into a L2 orbit. Imaging, spectroscopy, and coronography covers 0.6-29 microns. JWST is designed to observe Solar System objects having apparent rates of motion up to 0.030 arcseconds/second. This capability includes the planets, satellites, asteroids, Trans-Neptunian Objects, and comets beyond Earth’s orbit. JWST can observe solar elongation of 85 to 135 degrees, and a roll range of +/-5 degrees about the telescope’s optical axis. During the observation of a moving target, the science target is held fixed in the desired science aperture by controlling the guide star to follow the inverse of the target’s trajectory. The pointing control software uses polynomial ephemerides for the target generated using JPL’s HORIZON system. The JWST guider field of view (2.2x2.2 arcmin) is located in the telescope focal plane several arcmin from the science apertures. The instrument apertures are fixed with respect to the telescope focal plane. For targets near the ecliptic, those apertures also have a nearly-fixed orientation relative to the ecliptic. This resultsfrom the fact that the Observatory's sun-shade and solar panels must always be between the telescope and the Sun. On-board scripts autonomously control the execution of the JWST science timeline. The event-driven scripts respond to actual slew and on-board command execution, making operations more efficient. Visits are scheduled with overlapping windows to provide execution flexibility and to avoid lost time. An observing plan covering about ten days will be uplinked weekly. Updates could be more frequent if necessary (for example, to accommodate a Target of Opportunity - TOO). The event-driven operations system supports time-critical observations and TOOs. The minimum response time for TOOs is 48 hours (observation approval to execution).

Sonneborn, George; Milam, S. N.; Hines, D. C.; Stansberry, J.; Hammel, H. B.; Lunine, J. I.

2013-10-01

48

CAMERA: a compact, automated, laser adaptive optics system for small aperture telescopes  

Microsoft Academic Search

CAMERA is an autonomous laser guide star adaptive optics system designed for small aperture telescopes. This system is intended to be mounted permanently on such a telescope to provide large amounts of flexibly scheduled observing time, delivering high angular resolution imagery in the visible and near infrared. The design employs a Shack Hartmann wavefront sensor, a 12x12 actuator MEMS device

Matthew Britton; Viswa Velur; Nick Law; Philip Choi; Bryan E. Penprase

2008-01-01

49

Development of adaptive optics elements for solar telescope  

NASA Astrophysics Data System (ADS)

The devices and components of adaptive optical system ANGARA, which is developed for image correction in the Big solar vacuum telescope (BSVT) at Baykal astrophysical observatory are described. It is shown that the use of modernized adaptive system on BSVT not only reduces the turbulent atmospheric distortions of image, but also gives a possibility to improve the telescope developing new methods of solar observations. A high precision Shack-Hartmann wavefront (WF) sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640X640 ?m with an error not exceeding 4.80 arc.sec. Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourier-demodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

Lukin, V. P.; Grigor'ev, V. M.; Antoshkin, L. V.; Botugina, N. N.; Kovadlo, P. G.; Konyaev, P. A.; Kopulov, E. A.; Skomorovsky, V. I.; Trifonov, V. D.; Chuprakov, S. A.

2012-07-01

50

Effect of noise in image restoration of multi-aperture telescope  

NASA Astrophysics Data System (ADS)

Multi-aperture telescope is proposed to achieve high angular resolution without fabricating a large diameter monolithic primary mirror. Due to the array structure, the multi-aperture telescope has almost the same cut-off frequency as an equivalent diameter telescope, but decrease in the area of light collecting, which is the reason that the direct output image of multi-aperture telescope is blurred and low contrast. The additive noise level is another reason for low image quality. The Wiener filter is sensitive to noise because of the zero value out of the cut-off frequency in optical transfer function. An alternative image deblurring method is total variation (TV) blind deconvolution. The TV method is an iterative algorithm and preserves the edge information well. The most important characteristic of TV blind deconvolution is that the algorithm is still working with high noise level and produces reasonable result.

Zhou, Zhiwei; Wang, Dayong; Wang, Yunxin; Wan, Yuhong

2010-07-01

51

Hubble Space Telescope solar array damper  

Microsoft Academic Search

This paper describes the design of a solar array damper that will be built into each of two new solar arrays to be installed on the Hubble Space Telescope (HST) during Servicing Mission 3. On this mission, currently scheduled for August 2000, two 'rigid' solar array wings will replace the 'flexible' wings currently providing power for HST. In addition to

Joseph R. Maly; Scott C. Pendleton; J. Salmanoff; Garcia J. Blount; Kevin Mathews

1999-01-01

52

Planning the 8-meter Chinese Giant Solar Telescope  

NASA Astrophysics Data System (ADS)

The Chinese Giant Solar Telescope (CGST) will be a diffraction limited solar telescope optimized for the near-infrared (NIR) spectral region (0.8 - 2.5 microns). Its diffraction limit will be reached by the incorporation of Multi-Conjugate Adaptive Optics (MCAO) enhanced by image restoration techniques to achieve uniform (u.v) plane coverage over the angular spatial frequency region allowed by its 8-meter aperture. Thus it will complement the imaging capabilities of 4-meter telescopes being planned elsewhere which are optimized for the visible (VIS) spectral region (300 - 1000 nm) In the NIR spectral regions the CGST will have access to unique spectral features which will improve the diagnostics of the solar atmosphere. These include the CaII lines near 860 nm , the HeI lines near 1083 nm, the 1074 nm FeXIII coronal lines, the large Zeeman-split FeI line at 1548 nm, and (v) the H- continuum absorption minimum at 1.6 micron. Especially in sunspot umbrae the simultaneous observation of continua and lines across the NIR spectral range will cover a substantial depth range in the solar atmosphere. Of course the mid- and far- infrared regions are also available for unequalled high-angular resolution solar observations, for example, in the Hydrogen Bracket lines, CO molecular bands, and the MgI emission line at 12.3 microns. The CGST is a so-called ring telescope in which the light is captured by a 1 meter wide segmented ring or by a ring of 7 smaller off-axis aperture telescopes. The open central area of the telescope is large. The advantages of such a ring configuration is that (a) it covers all the spatial frequencies out to those corresponding to its outer diameter, (b) its circular symmetry makes it polarization neutral, (c) its large central hole helps thermal control, and (d) it provides ample space for the MCAO system and instrumentation in the Gregorian focus. Even though optimized for the NIR, we expect to use the CGST also at visible wavelengths in the so-called “Partial Adaptive Optics” (PAO) mode (Applied Optics 31,424,1992) to obtain angular resolution twice that of a 4-meter telescope if their observations indicate that higher resolution is desirable. The CGST is a Chinese solar community project.

Beckers, Jacques M.; Liu, Z.; Deng, Y.; Ji, H.

2013-07-01

53

Design of a coded aperture Compton telescope imaging system (CACTIS)  

NASA Astrophysics Data System (ADS)

We have developed a prototype of a scalable high-resolution direction and energy sensitive gamma-ray detection system that operates in both coded aperture (CA) and Compton scatter (CS) modes to obtain optimal efficiency and angular resolution over a wide energy range. The design consists of an active coded aperture constructed from 52 individual CZT planar detectors each measuring 3×3×6 mm3 arranged in a MURA pattern on a 10×10 grid, with a monolithic 20×20×5 mm3 pixelated (8×8) CZT array serving as the focal plane. The combined mode is achieved by using the aperture plane array for both Compton scattering of high-energy photons and as a coded mask for low-energy radiation. The prototype instrument was built using two RENA-3 test systems, one each for the aperture and the focal plane, stacked on top of each other at a distance of 130 mm. The test systems were modified to coordinate (synchronize) readout and provide coincidence information of events within a user-adjustable 40-1,280 ns window. The measured angular resolution of the device is <1 deg (17 mrad) in CA mode and is predicted to be approximately 3 deg (54 mrad) in CS mode. The energy resolution of the CZT detectors is approximately 5% FWHM at 120 keV. We will present details of the system design and initial results for the calibration and performance of the prototype.

Volkovskii, Alexander; Clajus, Martin; Gottesman, Stephen R.; Malik, Hans; Schwartz, Kenneth; Tumer, Evren; Tumer, Tumay; Yin, Shi

2010-08-01

54

Large-Aperture, Three Mirror Telescopes for Near-Earth  

NASA Astrophysics Data System (ADS)

In this era when Space Situational Awareness (SSA) is a national priority and optical-infrared telescopic sensor development is underway, cost-benefit analyses of competing approaches are necessary and appropriate. The DOD is presently investing in a new three-mirror telescope for SSA. At the same time, the Air Force, various universities and private research organizations are either studying or building wide-field telescopes with similar capabilities, but in most cases, at a significantly lower cost. Much of the expense for the DOD system appears driven by certain design choices which were advertised as necessary to fulfill the mission. Design details which would allow an independent analysis have not been published and no public comparison with other approaches is known to exist. Most telescope designs however, can be closely approximated from their optical configuration and imaging performance specifications. An optical designer will tell you that field curvature is one of the five monochromatic aberrations which they try to eliminate. The fact that one DOD development effort considers field curvature a design feature immediately draws attention to the project. This coupled with the paucity of published information and the very high development cost makes this program irresistible for comparison with competing approaches. This paper examines the likely design and performance of a proxy telescope intended to find NEOs, compares and contrasts that telescope with similar, but lower cost on-going projects, and examines the predictable impacts of reproducing such a telescope and placing multiple copies around the globe. The study primarily concentrates on performance measured in terms of search rate in square degrees per hour vs. object visual magnitude. Other considerations such as cost, transportability, availability of replacement components and ease of installation are also considered.

Ackermann, M.; McGraw, J.

55

The Advance Solar Telescope and Future Solar Physics  

NASA Astrophysics Data System (ADS)

The magnetic activity of the Sun, with its terrestrial outreach, is conventionally defined in terms of the larger magnetic features on the surface of the Sun, while the evolution of the large magnetic features is largely determined by their small-scale fibril structure. Unfortunately the individual fibrils can be observed only as unresolved bright blobs. Thus their frequent interactions, their internal structure, and the associated dynamical flows all remain a mystery, which prevents our constructing a definitive dynamical theory of the large-scales and of solar activity in general. The microscopic world of magnetic fibrils awaits investigation, requiring a suitable telescope system with adaptive optics at an excellent site so as to provide angular resolution of 0.1" or better on a regular basis. The telescope must be of sufficient aperture ( 4m) to carry on high resolution, high dispersion spectroscopy at rapid cadence to determine the time dependent spatial structure of the gas flows and magnetic fields on the smallest possible scales. It will be important to follow the rapid evolution of the small flux bundle, or fibril, as it first appears through the visible surface somewhere in the interior of a supergranule, and then to follow the resulting magnetic fibril as it is convected into the boundary downdrafts, and ultimately into the junctions of several boundaries. The quiet photosphere, the active photosphere, at both low and high latitudes, the umbra and penumbra of sunspots of all sizes, the ephemeral active regions, the microstructure of all classes of flares, and the microstructure of spicules, surges and prominences are obvious immediate targets for the high resolution telescope. We cannot anticipate what will be seen, but whatever it turns out to be, it will move scientific comprehension well ahead of the present limited conjectural state.

Parker, E. N.

2002-05-01

56

MCAO at the German Solar Vacuum Telescope.  

National Technical Information Service (NTIS)

We present the features of the MCAO system presently being developed for the 70cm German Solar Vacuum Tower Telescope (VTT) by the Kiepenheuer Institute for Solar Physics, Freiburg, Germany. The system will increase the isoplanatic angle from 10' to 30' i...

T. Berkefeld D. Soltau

2002-01-01

57

NLST: India's National Large Solar Telescope  

NASA Astrophysics Data System (ADS)

This article introduces the new Indian 2 m telescope which has been designed by MT Mechatronics in a detailed conceptual design study for the Indian Institute of Astrophysics, Bangalore. We describe the background of the project and the science goals which shall be addressed with this telescope. NLST is a solar telescope with high optical throughput and will be equipped with an integrated Adaptive Optics system. It is optimized for a site with the kind of seeing and wind conditions as they are expected at a lake site in the Himalayan mountains. The telescope can also be used for certain night time applications. We also give the scientific rationale for this class of telescope.

Hasan, S. S.; Soltau, D.; Kärcher, H.; Süß, M.; Berkefeld, T.

2010-06-01

58

Direct imaging with a dense aperture masking in comparison with a telescope or a hypertelelescope  

NASA Astrophysics Data System (ADS)

Dense Aperture Masking (DAM) is a new interferometric technique allowing high-angular resolution over a narrow field of view (FOV) imaged by the present class of mono-pupil telescopes equipped with adaptive optics (AO). DAM is realized by a suited afocal double lenslet array (BIGRE), remapping the entrance aperture (telescope pupil) into coherent sub-apertures (sub-pupils), and adopted as sub-pupils spatial filter and re-imager.We focus our attention on the point spread function (PSF) properties of DAM, highlighting those related to spatial sampling and filtering of the frequency coverage of the entrance pupil.We stress why the high spatial frequency sampling of the pupil and the low spatial frequency filtering of the sub-pupils are consistent with both a mono-pupil (telescope) and an array of sub-pupils (hypertelescope). We explain how DAM provides high Strehl and high-angular resolution images, first by filtering the low frequencies, which in turn are not so well corrected with a standard AO, second by preserving an object-image convolution relation over a narrow FOV. Finally, we make a comparison with the imaging properties of a telescope and a hypertelescope with the aim to show the complementary of DAM with other techniques adopted in high-contrast imaging.

Patru, Fabien; Antichi, Jacopo; Girard, Julien

2011-09-01

59

solar magnetic fiber and space solar telescope in engineering model  

NASA Astrophysics Data System (ADS)

The solar magnetic fiber and the magnetic element are the most important factor in the solar activity and solar atmosphere. Because the space resolution of measurement of solar magnetic field is much lower than that of the size of the nature solar magnetic fiber and element from the earth atmospheric turbulence. The estimate of the magnetic element nature from various indirect researches shows great difference with several orders. The research results about magnetic elements have been reviewed in the paper.Because the size of the magnetic element has been estimated for 0.1T-0.2T, the space solar magnetic field telescope with big diameter is the most basic choice. For the exploration of solar magnetic fiber and element, a Space Solar Telescope is under development in the phase C and D, there are five payloads which are: 1) MOT, 1 diameter telescope with 8 channels real time 2-D spectrograph and 8 sets CCD with 2K`2K; 2) EUV, 4 tubes of soft X-ray Telescope with 0.252 space resolution; 3) WBS, the wide Band Spectrometer with 256 channel from soft X-ray to Gamma-ray. 4) HAT, Ha and white light telescope; 5) SIRA, Solar and interplanetary Radio Spectrometer, with 100 KHZ-60 MHZ. The assembly and test will be introduced.

Ai, G.

60

ATLAST-9.2m: a large-aperture deployable space telescope  

NASA Astrophysics Data System (ADS)

We present results of a study of a deployable version of the Advanced Technology Large-Aperture Space Telescope (ATLAST), designed to operate in a Sun-Earth L2 orbit. The primary mirror of the segmented 9.2-meter aperture has 36 hexagonal 1.315 m (flat-to-flat) glass mirrors. The architecture and folding of the telescope is similar to JWST, allowing it to fit into the 6.5 m fairing of a modest upgrade to the Delta-IV Heavy version of the Evolved Expendable Launch Vehicle (EELV). We discuss the overall observatory design, optical design, instruments, stray light, wavefront sensing and control, pointing and thermal control, and in-space servicing options.

Oegerle, William R.; Feinberg, Lee D.; Purves, Lloyd R.; Hyde, T. Tupper; Thronson, Harley A.; Townsend, Jacqueline A.; Postman, Marc; Bolcar, Matthew R.; Budinoff, Jason G.; Dean, Bruce H.; Clampin, Mark C.; Ebbets, Dennis C.; Gong, Qian; Gull, Theodore R.; Howard, Joseph M.; Jones, Andrew L.; Lyon, Richard G.; Pasquale, Bert A.; Perrygo, Charles; Smith, Jeffrey S.; Thompson, Patrick L.; Woodgate, Bruce E.

2010-07-01

61

Solar System SETI Using Radio Telescope Arrays  

Microsoft Academic Search

The search for extraterrestrial intelligence must include complementary observing programs that investigate our solar system and near Earth. Solar system observing strategies involve a search for energy (e.g., artificial microwaves) or physical manifestations (e.g., exploratory robotic probes) that may be present. Artificial electromagnetic emissions from robotic probes may be detectable using existing ground-based radio-telescope observatories like Arecibo, or those undergoing

Bruce Cornet; Scot L. Stride

2003-01-01

62

Solar optical telescope primary mirror controller  

NASA Astrophysics Data System (ADS)

The development of a technique to control the articulated primary mirror (APM) of the solar optical telescope (SOT) is discussed. Program results indicate that a single, all digital controller has sufficient capability to totally handle the computational requirements for control of the SOT APM.

Brown, R. J.; Liu, D.

1980-08-01

63

Solar System Observations with Spitzer Space Telescope  

Microsoft Academic Search

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 mum, and

D. P. Cruikshank; J. A. Stansberry; J. P. Emery; J. van Cleve; Y. R. Fernández; M. W. Werner; G. H. Reike; D. E. Trilling

2006-01-01

64

The CERN Axion Solar Telescope (CAST)  

SciTech Connect

A decommissioned LHC test magnet is being prepared as the CERN Axion Solar Telescope (CAST) experiment. The magnet has a field of 9.6 Tesla and length of 10 meters. It is being mounted on a platform to track the sun over plus or minus 8 to the sixth power vertically and plus or minus 45 to the sixth power, horizontally.

Aalseth, Craig E. (BATTELLE (PACIFIC NW LAB)); Arik, E (Bogazici Universitesi); Autiero, D (European Organization for Nuclear Research); Avignone, Frank T. (UNKNOWN); Barth, K (European Organization for Nuclear Research); Bowyer, Sonya M. (BATTELLE (PACIFIC NW LAB)); Brauninger, H (Max-Planck-Institut fur Extraterrestrische Physik); Brodzinski, Ronald L. (BATTELLE (PACIFIC NW LAB)); Carmona, J. M. (Universidad de Zaragoza); Cebrian, S (Unknown); Celebi, S (Universidad de Zaragoza); Cetin, S (Bogazici Universitesi); Collar, J I. (Chicago, University Of); Creswick, R (South Carolina, Univ Of); Delbart, A (Centre d'Etudes de Saclay); Delattre, M (European Organization for Nuclear Research); DiLella, L (European Organization for Nuclear Research); De Oliveira, R (European Organization for Nuclear Research); Eleftheriadis, Ch (Aristotle University of Thessaloniki); Erdutan, N (European Organization for Nuclear Research); Fanourakis, G (National Research Center for Physical Sciences, Demokritos, Greece); Farach, H A. (South Carolina, Univ Of); Fiorini, C (Politecnico di Milano, Italy); Geralis, Th. (National Research Center for Physical Sciences, Demokritos, Greece); Giomataris, I (Centre d'Etudes de Saclay, Gif-Sur-Yvette, France); Girard, Thomas A. (VISITORS); Gninenko, S. N. (Institue for Nuclear Research, Moscow, Russia); Golubev, N. A. (Institute for Nuclear Research, Moscow, Russia); Hasinoff, M (British Columbia,University of); Hoffmann, D (Technische Universitat Darmstadt); Irastorza, I. G. (Universidad de Zaragoza); Jacoby, J (Technische Universitat Darmstadt); Jeanneau, F (Centre d'Etudes de Saclay, Gif-Sur-Yvette, France); Knopf, Michael A. (BATTELLE (PACIFIC NW LAB)); Kovzelev, A. V. (Institute for Nuclear Reserach, Moscow, Russia); Kotthaus, R (Max-Planck-Institut fur Physik, Muenchen, Germany); Krcmar, M (Ruder Boskovic Institute); Krecak, Z (Ruder Boskovic Institute, Zagreb, Croatia); Lakic, B (Ruder Boskovic Institute, Zagreb, Croatia); Liolios, A (Universidade de Li

2002-10-10

65

The influence of co-phasing error on image quality in synthesized aperture telescope  

NASA Astrophysics Data System (ADS)

In this paper, an active co-phasing and aligning synthesized aperture imaging system with three quasi-annulus-sectors segmented mirrors was analyzed. The influence of co-phasing error, especially piston error, on image quality of the synthesized aperture imaging system was studied. The relationship of the Point Spread Function (PSF) and piston errors between the adjacent segments was deduced theoretically within the coherence length of the source. According to this theoretical model, the influence of piston error on the image quality in the synthesized aperture imaging system was known that the PSF changes with the variation of piston error. And more importantly, the cycle of this change is ?/2 (? is the wavelength of the source) when a certain piston error is introduced between two adjacent segment. Additionally, simulation model of the three segmented synthesized aperture imaging system was set up by ZEMAX and simulation experiments have been carried out to verify the conclusion derived from the theory model deduced above. The results show that the simulation experiments results consistent with the theoretical conclusion deduced above. The results provide theoretical foundation for further study and actual reference of tolerance for a synthesized aperture telescope design and manufacture.

Zhang, Lifang; Zhao, Weirui; Li, Yimin

2013-08-01

66

Advanced Technology Solar Telescope: A status report  

NASA Astrophysics Data System (ADS)

Magnetic fields control the inconstant Sun. The key to understanding solar variability and its direct impact on the Earth rests with understanding all aspects of these magnetic fields. The Advanced Technology Solar Telescope (ATST) has been design specifically for magnetic remote sensing. Its collecting area, spatial resolution, scattered light, polarization properties, and wavelength performance all insure ATST will be able to observe magnetic fields at all heights in the solar atmosphere from photosphere to corona. After several years of design efforts, ATST has been approved by the U.S. National Science Foundation to begin construction with a not to exceed cost cap of approximately $298M. Work packages for major telescope components will be released for bid over the next several months. An application for a building permit has been submitted.

Keil, S. L.; Rimmele, T. R.; Wagner, J.; ATST Team

2010-06-01

67

Two-dimensional solar mapping at 5.2 CM with the Siberian Solar Radio Telescope  

NASA Astrophysics Data System (ADS)

We present 2D solar maps at 5.2 cm computed from 1D observations with the Siberian Solar Radio Telescope (SSRT), using earth rotation aperture synthesis techniques. The resolution attained with the E-W branch of the instrument is 15 by 45 arcsec for a solar declination of about 23 deg. Maps during the period of June 8 to 13, 1988 clearly show the quiet-sun background, sunspot, and plage associated emission as well as compact sources above the neutral line in some active regions. We found that the latter disappear as the gradient of the longitudinal magnetic field decreases. We also detected emission associated with active regions behind the limb, apparently from unresolved loops, extending up to about 40 arcsec. The prospects of the SSRT, as a dedicated solar instrument, are discussed.

Alissandrakis, C. E.; Lubyshev, B. I.; Smol'Kov, G. Ia.; Krissinel', B. B.; Treskov, T. A.; Miller, V. G.; Kardapolova, N. N.

1992-12-01

68

The five-hundred-meter aperture spherical radio telescope (FAST) project  

NASA Astrophysics Data System (ADS)

Five-hundred-meter Aperture Spherical radio Telescope (FAST) is a Chinese "mega-science" project to build the largest single dish radio telescope in the world. Its engineering concept and design pave a new road to realize a huge single dish in an effective way. Being the most sensitive single dish radio telescope, FAST will enable astronomers to jump-start many science goals, such as surveying the neutral hydrogen in the Milky Way and other galaxies, detecting faint pulsars, hearing the possible signals from other civilizations, etc. The feasibility studies for FAST have been carried out for 14 years, supported by Chinese and international astronomy communities. The National Development and Reform Commission approved the funding proposal of FAST in 2007 with a capital budget close to 700 million RMB. The project time is 5.5 years from the commencement of work in March of 2011 and the first light is expected in 2016.

Nan, Rendong; Li, Di

2013-04-01

69

Recent enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed at MSFC  

NASA Astrophysics Data System (ADS)

Recent incremental upgrades to the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed have enabled the demonstration of phasing (with a monochromatic source) of clusters of primary mirror segments down to the diffraction limit. PAMELA upgrades include an improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, and mechanical improvement of mirror surface figures. This report summarizes the recent PAMELA upgrades and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the PAMELA telescope in 1993 after Kaman Aerospace was unable to complete integration and testing under the limited SDIO and DARPA funding. The PAMELA is a 36-segment, half-meter aperture, adaptive telescope which utilizes a Shack-Hartmann wavefront sensor, inductive coil edge sensors, voice coil actuators, imaging CCD cameras and interferometry for figure alignment, wavefront sensing and control. MSFC originally obtained the PAMELA to supplement its research in the interactions of control systems with flexible structures. In August 1994, complete tip, tilt and piston control was successfully demonstrated using the Shack-Hartmann wavefront sensor and the inductive edge sensors.

Rakoczy, John M.; Montgomery, Edward E.; Lindner, Jeffrey L.

2000-08-01

70

Imaging M15 with a Small Aperture Telescope by Treating the Core as a Single Star  

NASA Astrophysics Data System (ADS)

The objective for this study will be to explore various time series methods using CCD photometry for use with amateur telescope observations of the dense globular cluster M15. Amateur telescopes are defined here as having an aperture of less than 40 cm, and are collecting photometric filtered observations over time. Specifically, we attempt to determine the light curve of the core of M15 as a "single star". This requires selection of comparison and check stars to perform differential photometry; i.e. subtraction of flux density measures between a nonvariable (reference star) and the variable "single star" of the M15 core as it changes in magnitudes over time. We explore the possibility of measuring the M15 periodicity as an aggregate of many standard stars as identified in the Stetson catalog for NGC7078 (2010). In this paper we'd like to propose methods and techniques for aggregating different cluster region's flux densities (luminosity) and periods.

Howe, Rodney; Iakovos-Marios, Strikis

2011-05-01

71

Ray-tracing and physical-optics analysis of the aperture efficiency in a radio telescope.  

PubMed

The performance of telescope systems working at microwave or visible-IR wavelengths is typically described in terms of different parameters according to the wavelength range. Most commercial ray-tracing packages have been specifically designed for use with visible-IR systems and thus, though very flexible and sophisticated, do not provide the appropriate parameters to fully describe microwave antennas and to compare with specifications. We demonstrate that the Strehl ratio is equal to the phase efficiency when the apodization factor is taken into account. The phase efficiency is the most critical contribution to the aperture efficiency of an antenna and the most difficult parameter to optimize during the telescope design. The equivalence between the Strehl ratio and the phase efficiency gives the designer/user of the telescope the opportunity to use the faster commercial ray-tracing software to optimize the design. We also discuss the results of several tests performed to check the validity of this relationship that we carried out using a ray-tracing software, ZEMAX, and a full Physical Optics software, GRASP9.3, applied to three different telescope designs that span a factor of approximately 10 in terms of D/lambda. The maximum measured discrepancy between phase efficiency and Strehl ratio varies between approximately 0.4% and 1.9% up to an offset angle of >40 beams, depending on the optical configuration, but it is always less than 0.5% where the Strehl ratio is >0.95. PMID:17571151

Olmi, Luca; Bolli, Pietro

2007-07-01

72

Overview and Status Report on the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The ATST is a 4-m aperture, off-axis solar telescope with integrated adaptive optics, low-scattered light, infrared, coronagraphic, and polarimetric capabilities. It will resolve the essential, fine-scale magnetic features and their dynamics that dictate the varying release of energy from the Sun's atmosphere. The ATST design is optimized in terms of throughput, scattered light, and instrumental polarization properties to perform precision vector magnetic field measurements down to its diffraction limit (0.03 arcsec at 500 nm) and throughout the solar atmosphere. Its collecting area, which is a factor of 16 greater than today's solar telescopes, will provide the sensitivity to measure both weak fields and rapidly evolving stronger fields. It has a factor of 64 greater collecting area than the largest existing coronagraph, and will provide the sensitivity and coronagraphic capability needed to measure the weak, fine-scale coronal magnetic fields. With adaptive optics and a set of facility class instrumentation the ATST will be the worlds leading resource for studying solar magnetism. ATST will be the successor to the solar telescopes built in the 1960s and 1970s, and is a natural complement to planned space missions. Starting in late 2001, ATST began a design and development phase. To date the D&D phase has produced and refined a science requirements document and a conceptual design that would meet those requirements. A conceptual design review was held in August of 2003. Following the review, a construction proposal, including a complete work breakdown structure and cost, was submitted in early 2004 and was successfully peer reviewed. NSF astronomy is now in the process of submitting ATST to the NSF Major Research Equipment and Facilities Construction program review process. During the D&D phase, a thorough site survey was also conducted resulting in Haleakala as the site best able to fulfill the ATST science requirements. We present a brief overview of the ATST program, how it fits into the broader picture of solar facilities and capabilities, and discuss the current status of the ATST project and plans for constructing and commissioning the ATST.

Keil, S. L.; Rimmele, T.; Wagner, J.; ATST Team

2005-05-01

73

The pre-research of the deploy technology for the large aperture space astronomical telescope  

NASA Astrophysics Data System (ADS)

The spherical primary mirror (Mb) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is segmented and composed of 37 hexagonal sub-mirrors, and segmented active optics method is successfully developed in it. LAMOST project has passed through the project acceptance in 2009. The success of LAMOST makes deployable primary mirror possible. The deployable large aperture space astronomical telescope is one of the most development potential space observation spacecrafts in the future. This paper is targeted at the reflecting Schmidt telescope LAMOST, which has a 6.67X6.05m primary mirror. The feasibility of the deployable structure of the large reflecting space telescope's primary mirror has been mainly researched. The analysis of the design scheme for the deployable primary mirror has been carried out, and according to the feature and the design of LAMOST, a subdivision type deployment scheme has been given; The locating principle of the both side wings and the locking device after deployment has been analyzed; In addition the problems in the process of deployment is also preliminary discussed. This paper is targeted at the reflecting Schmidt telescope LAMOST, which has a 6.67X6.05 primary mirror. The feasibility of the deployable structure of the large reflecting telescope's primary mirror has been mainly researched. The analysis of the design scheme for the deployable primary mirror has been carried out, and according to the feature and the design of LAMOST, a subdivision type deployment scheme has been given; The locating principle of the both side wings and the locking device after deployment has been analyzed; In addition the problems in the process of deployment have been preliminary discussed.

Jiang, Fanghua; Zuo, Heng; Li, Guoping

2012-09-01

74

The science challenges for large solar telescopes  

NASA Astrophysics Data System (ADS)

Looking at numerical simulations of highest spatial resolution and highest resolution observations, we endeavor extrapolating what science questions can be tackled with future large solar telescopes. By means of selected examples we shall try to determine the instrumental requirements for answering these questions. For example, what polarimetric accuracy do we need to make progress regarding the topography of the internetwork magnetic field? What spatial and temporal resolution is needed to track the driving forces of dynamic fibrils, spicules and other jet-like features of the solar chromosphere, what to asses the role of vortical flows in the photosphere and its impact on the chromosphere and corona, or what to shed light on the turbulent dynamo supposedly working in the surface layers of the convection zone. Will large solar telescopes help us resolving the remaining puzzles of the sunspot penumbra and the still largely enigmatic formation process of sunspots? Besides such foreseeable science questions however, we should be aware that the best discoveries come unexpectedly and therefore, it may be worthwhile to wonder about what instrumental capabilities may be best conducive to the unexpected.

Steiner, O.

2012-12-01

75

The Advanced Technology Solar Telescope enclosure  

NASA Astrophysics Data System (ADS)

Telescope enclosure design is based on an increasingly standard set of criteria. Enclosures must provide failsafe protection in a harsh environment for an irreplaceable piece of equipment; must allow effective air flushing to minimize local seeing while still attenuating wind-induced vibration of the telescope; must reliably operate so that the dome is never the reason for observatory down time; must provide access to utilities, lifting devices and support facilities; and they must be affordable within the overall project budget. The enclosure for the Advanced Technology Solar Telescope (ATST) has to satisfy all these challenging requirements plus one more. To eliminate so-called external dome seeing, the exterior surfaces of the enclosure must be maintained at or just below ambient air temperature while being subjected to the full solar loading of an observing day. Further complicating the design of the ATST enclosure and support facilities are the environmental sensitivities and high construction costs at the selected site - the summit of Haleakala on the island of Maui, Hawaii. Previous development work has determined an appropriate enclosure shape to minimize solar exposure while allowing effective interior flushing, and has demonstrated the feasibility of controlling the exterior skin temperature with an active cooling system. This paper presents the evolution of the design since site selection and how the enclosure and associated thermal systems have been tailored to the particular climatic and terrain conditions of the site. Also discussed are load-reduction strategies that have been identified through thermal modeling, CFD modeling, and other analyses to refine and economize the thermal control systems.

Phelps, L.; Barr, J.; Dalrymple, N.; Fraser, M.; Hubbard, R.; Wagner, J.; Warner, M.

2006-07-01

76

Solar site testing for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The location of the Advanced Technology Solar Telescope (ATST) is a critical factor in the overall performance of the telescope. We have developed a set of instrumentation to measure daytime seeing, sky brightness, cloud cover, water vapor, dust levels, and weather. The instruments have been located at six sites for periods of one to two years. Here we describe the sites and instrumentation, discuss the data reduction, and present some preliminary results. We demonstrate that it is possible to estimate seeing as a function of height near the ground with an array of scintillometers, and that there is a distinct qualitative difference in daytime seeing between sites with or without a nearby lake.

Hill, Frank; Beckers, Jacques; Brandt, Peter; Briggs, John; Brown, Timothy; Brown, W.; Collados, Manuel; Denker, Carsten; Fletcher, Steven; Hegwer, Steven; Horst, T.; Komsa, Mark; Kuhn, Jeff; Lecinski, Alice; Lin, Haosheng; Oncley, Steve; Penn, Matthew; Rimmele, Thomas R.; Socas-Navarro, Hector; Streander, Kim

2004-10-01

77

Coded-aperture gamma-ray telescope - Principles and application to the SIGMA gamma-ray-astronomy project  

Microsoft Academic Search

The design of a coded aperture and deconvolution\\/image-reconstruction software for the NaI-crystal\\/photomultiplier 100-300-keV gamma-ray imaging telescope SIGMA (Satellite d'Imagerie Gamma Montesur Ariane), a satellite observatory being developed by CNES, is presented, and the results of simulations and laboratory tests are summarized. The mathematical principles of coded apertures are reviewed; a technique for designing optimal imaging optics is proposed; the image-reconstruction

J.-P. Roques

1983-01-01

78

The Electron Proton Telescope for Solar Orbiter  

NASA Astrophysics Data System (ADS)

Solar Orbiter is a mission proposed to ESA for the cosmic vision program. It will provide the next major step forward in the exploration of the Sun and the heliosphere to investigate many of the fundamental problems remaining in solar and heliospheric science. Onboard, the Energetic Particle Detector (EPD) will measure the composition, time history and distribution functions of suprathermal and energetic particles. The EPD consists of five separate sensors. One of them is the Electron Proton Telescope (EPT), which is designed to measure electrons, protons with energies in the range from 20 keV to 600 keV for electrons and from 20 keV to 6 MeV for protons. Low energy electrons and nucleons stopping in the first detector are distinguished by using the foil/magnet-technique. In this contribution we will present the instrument design and its modeled performance.

Heber, Bernd; E., B.; Boettcher, Stephan; Burmeister, Soenke; Droege, Wolfgang; Mann, Gottfried; Martin, Cesar; Mueller-Mellin, Reinhold; Paspirgilis, R.; Schuster, B.; Seimetz, L.; Wimmer-Schweingruber, Robert F.

79

Subaru Telescope, Hawaii  

NASA Astrophysics Data System (ADS)

The Subaru Telescope, Hawaii is an 8.2 m aperture optical infrared telescope being operated by the NATIONAL ASTRONOMICAL OBSERVATORY, JAPAN (NAOJ) atop Mauna Kea, Hawaii. It is one of the new-generation telescopes with an actively controlled large monolithic mirror, and has been producing testing-phase observational results on solar system, star formation, active galactic nuclei and quasars, grou...

Murdin, P.

2000-11-01

80

Moon Dust Telescopes, Solar Concentrators, and Structures  

NASA Astrophysics Data System (ADS)

We report development of an ISRU (in situ resource utilization) process to fabricate large telescope mirrors, solar concentrators, and structures on the Moon. The Moon is an excellent site for a future space base and space astrophysics research. However transporting extremely large (10-50m) telescopes to the Moon, building up an observatory structure, and providing power for operation face the obstacles of high cost and logistical difficulties. We suggest a simple and novel approach to the problem. Large mirrors can be made by spincasting a liquid over or mixed with lunar surface soil (regolith). The liquid, which is a special vacuum stable cryogenic polymer, gradually solidifies while spun into a hard parabolic surface. Additives including carbon nanotubes and fibers can be used to increase tensile strength, reduce cure shrinkage, and enhance thermal conductivity. The process uses a single apparatus to make multiple mirrors. Large arrays of solar concentrators can be fabricated to provide power to a lunar base. For astronomy, the mirror surface can be polished or modified in situ with an ion beam like process taking advantage of the high vacuum of the lunar environment. Moreover, we have found that the simple process of mixing a small amount of polymer with lunar regolith yields after curing a material similar to cement in terms of strength, density, and consistency. This `lunar cement’ may be useful as building blocks for human habitats and telescope structures. We report on experiments carried out at GSFC to demonstrate feasibility of the concept. Mirrors and bricks have been made by curing a cryogenic polymer with added JSC-1A Fine lunar soil simulant and carbon nanotubes. Preliminary observations have been carried out using such `Moon dust’ mirrors.

Chen, Peter C.; Van Steenberg, M. E.; Oliversen, R. J.

2008-05-01

81

A balloon-borne coded aperture telescope for ARC-minute angular resolution at hard X-ray energies  

Microsoft Academic Search

We describe the development of a new balloon-borne telescope known as MARGIE (Minute-of-Arc Resolution Gamma ray Imaging Experiment). It is a coded aperture telescope designed to image photons (in various configurations) over the 20–600 keV range with an angular resolution approaching 1?. MARGIE will use one (or both) of two different detection plane technologies. One such technology involves the use

J. Ryan; V. Boykin; R. M. Kippen; K. Larson; J. Macri; M. Mayer; M. McConnell; P. Altice; M. L. Cherry; S. B. Ellison; B. Price; T. G. Guzik; R. Lockwood; M. B. Barakat; K. Johnston; N. Zotov; M. Elaasar

1998-01-01

82

Balloon-borne coded aperture telescope for arc-minute angular resolution at hard x-ray energies  

Microsoft Academic Search

We are working on the development of a new balloon-borne telescope, MARGIE (minute-of-arc resolution gamma ray imaging experiment). It will be a coded aperture telescope designed to image hard x-rays (in various configurations) over the 20 - 600 keV range with an angular resolution approaching one arc minute. MARGIE will use one (or both) of two different detection plane technologies,

Mark L. McConnell; Valerie Boykin; R. N. Kippen; K. Larson; John R. Macri; Michelle Mayer; James M. Ryan; Peter P. Altice; Michael L. Cherry; Steven B. Ellison; B. Price; T. Gregory Guzik; R. Lockwood; M. B. Barakat; K. Johnston; N. Zotov; M. Elaasar

1996-01-01

83

Developments of the wideband spectropolarimeter of the Domeless Solar Telescope at Hida Observatory  

NASA Astrophysics Data System (ADS)

We developed a new universal spectropolarimeter on the Domeless Solar Telescope at Hida Observatory to realize precise spectropolarimetric observations in a wide range of wavelength in visible and near infrared. The system aims to open a new window of plasma diagnostics by using Zeeman effect, Hanle effect, Stark effect, and impact polarization to measure the external magnetic field, electric field, and anisotropies in atomic excitation in solar atmosphere. The polarimeter consists of a 60 cm aperture vacuum telescope, a high dispersion vacuum spectrograph, polarization modulator and analyser composed of a continuously rotating waveplate whose retardation is constant in 400 - 1100 nm and Wallaston prisms located closely behind the focus of the telescope, and a fast and high sensitive CCD camera or a infrared camera. The duration for this polarimeter's achieving photometric accuracy of 10-3 is 30 - 60 s. Instrumental polarization of the telescope is calibrated by using a remotely controllable turret accommodating linear polarizer attached at the entrance window of the telescope to induce well known polarized light into the telescope. Thus a Mueller matrix model of the telescope is established to compensate the instrumental polarization included in observed data within the required accuracy.

Anan, Tetsu; Ichimoto, Kiyoshi; Oi, Akihito; Kimura, Goichi; Nakatani, Yoshikazu; Ueno, Satoru

2012-09-01

84

Diffractive imaging analysis of large-aperture segmented telescope based on partial Fourier transform  

NASA Astrophysics Data System (ADS)

Large-aperture segmented primary mirror will be widely used in next-generation space-based and ground-based telescopes. The effects of intersegment gaps, obstructions, position and figure errors of segments, which are all involved in the pupil plane, on the image quality metric should be analyzed using diffractive imaging theory. Traditional Fast Fourier Transform (FFT) method is very time-consuming and costs a lot of memory especially in dealing with large pupil-sampling matrix. A Partial Fourier Transform (PFT) method is first proposed to substantially speed up the computation and reduce memory usage for diffractive imaging analysis. Diffraction effects of a 6-meter segmented mirror including 18 hexagonal segments are simulated and analyzed using PFT method. The influence of intersegment gaps and position errors of segments on Strehl ratio is quantitatively analyzed by computing the Point Spread Function (PSF). By comparing simulation results with theoretical results, the correctness and feasibility of PFT method is confirmed.

Dong, Bing; Qin, Shun; Hu, Xinqi

2013-09-01

85

Solar synoptic telescope. Characteristics, possibilities, and limits of design  

NASA Astrophysics Data System (ADS)

A rapid evolution of electronics and information technologies makes it possible to use new original designs of synoptic telescopes for solar observations, to increase the demands on their functions, and to fully automate the observation. However, there are hardware and software limits that strongly influence the working capabilities of synoptic telescopes. In this contribution, we analyze relationships between the synoptic telescope's characteristics, the parameters of image digitization, the control, the achievable degree of automation of observations, and the possibilities to implement functions connected with the solar activity monitoring and image archiving. The principles listed above serve as a basis for the design study of the Auxiliary Full-Disc Telescope for the European Solar Telescope (EST), a pan-European project of a large 4-meter solar telescope.

Klva?a, M.; Sobotka, M.; Švanda, M.

2011-10-01

86

Measurements of solar magnetic fields and solar space project in China: Solar Space Telescope (SST)  

NASA Astrophysics Data System (ADS)

In this talk, we would like to briefly introduce some achievement on the study of solar magnetic fields at Huairou Solar Observing Station of National Astronomical Observatories of China in recent years based on the vector magnetogram observations in the last more than 20 years and also the space data from SOHO and Hinode etc. We also would like to introduce the progress of Chinese solar space project -Solar Space Telescope (SST). The major payloads of SST: 1 meter Main Optical Telescope (MOT), EUV Imager for the Solar Telescope (EUT), Wide Band Spectrometer (WBS), H and White-light Telescope (HWT), Solar and Interplanetary Radio-spectrometry (SIR). Some of new payloads of SST have been proposed recently.

Zhang, Hongqi

87

Limiting sensitivities of coded-aperture telescopes for gamma-ray astronomy: Balloon-Borne fixed-mask systems  

Microsoft Academic Search

The limiting sensitivities of coded-aperture imaging telescopes employing fixed masks are derived for continuum and line emission from cosmic point sources. The sensitivities are calculated for a single-source observation and do not take into consideration the many advantages offered by a multiplex system; for instance, low susceptibility to secular background changes and the ability to observe more than one source

Alan Owens

1990-01-01

88

Narrow-band Imager for Multi-Application Solar Telescope (MAST) at Udaipur Solar Observatory  

NASA Astrophysics Data System (ADS)

Multi-Application Solar Telescope (MAST) is an off-axis Gregorian solar telescope of 50 cm clear aperture installed at the lake site of Udaipur solar observatory (USO). A narrow band imager is being developed for near simultaneous observations of the solar atmosphere at different heights. The heart of the system is two Fabry-Perot (FP) etalons working in tandem. The substrate of the etalons is made of Lithium Niobate electro-optic crystal. The filter is tuned by changing the refractive index of the crystal with the application of the voltage. It is important to know the voltage required per unit wavelength shift to tune the system for different wavelength regions for near simultaneous observations. A littrow spectrograph was set up to calibrate the FP etalons. The achieved spectral resolution with the spectrograph at 6173 Å is 35 mÅ. Calibration is carried-out for the Fe I 6173 Å, H-alpha 6563 Å and Ca K 8542 Å. Free spectral range (FSR) obtained for FP1 and FP2 in tandem for 6173 Å is 6.7Å and 150 mÅ respectively. Voltage range of the system allows us to scan the entire line profile of 6173 in the range of ±220 mÅ with a sampling of 20 mÅ. We also performed temperature tuning and voltage tuning of the system. Similar exercise is performed for other two wavelengths. Here we present the details of the calibration set-up and obtained parameters and first-light results of the system.

Raja Bayanna, A.; Mathew, Shibu K.; Venkatakrishnan, Parameswaran; Srivastava, Nandita

2013-04-01

89

Ground demonstration of an optical control system for a space-based sparse aperture telescope  

NASA Astrophysics Data System (ADS)

SVS has recently completed a phase II small business innovative research (SBIR) project called Low Cost Space Imager. As part of the SBIR project, a sparse aperture telescope design concept was developed. This design includes an optical control system capable of correcting the primary segments to within 38 nm piston and 17 nrad tilt as required by the optical tolerance analysis. The optical system utilizes a common secondary and primaries arranged in a Golay-6 configuration. The primaries are spherical, which eliminates the need for translation and rotation control. A laboratory experiment to validate the controls concept has ben completed. This experiment culminated in the demonstration of autonomous capture, alignment, and phasing of an optical system with a three segment primary to tolerances consistent with the space optical system. The implementation of the controls scheme in the laboratory experiment is done using Matlab/Simulink for controller design and code generation. The code is implemented real- time on a VME based computer system. Closed loop piston control, which utilizes a four-bin sensing scheme, of an actuated mirror to 25 nm RMS mirror motion has been demonstrated. Additionally, autonomous capture and phasing of three segmented primaries has been demonstrated. The technique for the phasing capture involves real-time implementation of image processing techniques to measure the white light fringe visibility in the far field.

De Young, David B.; Dillow, James; Corcoran, Stephen; Andrews, Edwina V.; Yellowhair, Julius; Devries, Kevin

1998-09-01

90

Ground demonstration of an optical control system for a space-based sparse-aperture telescope  

NASA Astrophysics Data System (ADS)

SVS has recently completed a phase II small business innovative research (SBIR) project called low cost space imager (LCSI). As part of the SBIR project, a sparse aperture telescope design concept was developed. This design includes an optical control system capable of correcting the primary segments to within 38 nm piston and 17 nrad tilt as required by the optical tolerance analysis. The optical system utilizes a common secondary and primaries arranged in a Golay-6 configuration. The primaries are spherical, which eliminates the need for translation and rotation control. A laboratory experiment to validate the controls concept has been completed. This experiment culminated in the demonstration of autonomous capture, alignment, and phasing of an optical system with a three segment primary to tolerances consistent with the space optical system. The implementation of the controls scheme in the laboratory experiment is done using Matlab/Simulink for controller design and code generation the code is implemented real-time on a VME based computer system. Closed loop piston control, which utilizes a four-bin sensing scheme, of an actuated mirror to 25 nm RMS mirror motion has been demonstrated. Additionally, autonomous capture and phasing of three segmented primaries has been demonstrated. The technique for the phasing capture involves real-time implementation of image processing techniques to measure the white light fringe visibility in the far field.

De Young, David B.; Dillow, James; Corcoran, Stephen P.; Andrews, Edwina V.; Yellowhair, Julius; Devries, Kevin

1998-08-01

91

Solar System Observations with Spitzer Space Telescope: Preliminary Results.  

National Technical Information Service (NTIS)

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the albedos of...

D. P. Cruikshank

2005-01-01

92

Solar radio telescopes at ETH Zurich  

NASA Astrophysics Data System (ADS)

For more than 16 years the Radio Astronomy Group of the ETH Zurich has used solar radio telescopes, which were designed to run automatically in an unmanned observing station. The antennas are azimuthally mounted and the position of each axis is measured with absolute shaft encoders. One antenna is driven by stepping motors while the two others use analog motors. The latest version of the antenna steering uses a velocity control of both axes. The antenna follows the Sun continuously and the velocity is adjusted due to the difference of nominal and actual position of the antenna. The Sun's position is calculated in real time using date and time as input parameters. Pointing to galactic objects is also possible and is used for system calibration (Cassiopeia A). The clock of the antenna control is synchronized each minute with a radio controlled time receiver. In addition, the antennas can be operated manually or remotely. A status signal inhibits data recording, if the antenna is not positioned.

Stehling, Werner R.

1995-06-01

93

Solar System Observations with Spitzer Space Telescope  

NASA Astrophysics Data System (ADS)

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 ?m, and the detection of emission bands in the spectra of several distant asteroids (Trojans) around 10 and 25 ?m. The 10 Kuiper Belt objects observed to date have albedos in the range 0.08 -- 0.15, significantly higher than the earlier estimated 0.04. An additional KBO [(55565) 2002 AW197] has an albedo of 0.17 ± 0.03. The emission bands in the asteroid spectra are indicative of silicates, but specific minerals have not yet been identified. The Centaur/comet 29P/Schwassmann-Wachmann 1 has a nucleus surface albedo of 0.025 ± 0.01, and its dust production rate was calculated from the properties of the coma. Several other investigations are in progress as the incoming data are processed and analyzed.

Cruikshank, D. P.; Stansberry, J. A.; Emery, J. P.; van Cleve, J.; Fernández, Y. R.; Werner, M. W.; Reike, G. H.; Trilling, D. E.

2006-12-01

94

Beyond the Solar Corona: Mercury's Magnetic Fields seen with Large Solar Telescopes  

NASA Astrophysics Data System (ADS)

Solar telescopes have a potential in non-solar observations thanks to their instrumentation and their ability to observe in daylight, and despite their smaller mirror size compared to night-time telescopes. We review, as an illustration, THEMIS observations of Mercury's exosphere including the polarization of exospheric emission lines, and speculate that through analysis of this polarization made possible by the large photon-collecting capabilities of the upcoming large solar telescope we may expect to map Mercury's magnetosphere.

López Ariste, A.; Leblanc, F.

2012-12-01

95

The soft X ray telescope for Solar-A  

Microsoft Academic Search

The Solar-A satellite being prepared by the Institute for Sapce and Astronautical Sciences (ISAS) in Japan is dedicated to high energy observations of solar flares. The Soft X Ray Telescope (SXT) is being prepared to provide filtered images in the 2 to 60 A interval. The flight model is now undergoing tests in the 1000 foot tunnel at MSFC. Launch

W. A. Brown; L. W. Acton; M. E. Bruner; J. R. Lemen; K. T. Strong

1989-01-01

96

Ground-based giant solar telescope of China  

NASA Astrophysics Data System (ADS)

Ground-based giant facilities with capabilities of both visible and infrared observations has played essential role in solar observation, to meet the requirement of the present-day solar physics and Space weather research. It significantly throws light on our understanding of the Earth-Sun relation and predicting its effects on the terrestrial environment. We firstly review the present status of the existing ground-based solar telescopes over the world and programs of new generation telescopes in USA and European countries. This paper aims to overview the project of next generation ground-based solar telescope of China, including its scientific goal, key techniques, experiments, site-survey and the current situation.

Liu, Zhong; Deng, YuanYong; Ji, HaiSheng; Li, Hui

2012-12-01

97

The GREGOR Solar Telescope on Tenerife  

NASA Astrophysics Data System (ADS)

2011 was a successful year for the GREGOR project. The telescope was finally completed in May with the installation of the 1.5-meter primary mirror. The installation of the first-light focal plane instruments was completed by the end of the year. At the same time, the preparations for the installation of the high-order adaptive optics were finished, its integration to the telescope is scheduled for early 2012. This paper describes the telescope and its instrumentation in their present first-light configuration, and provides a brief overview of the science goals of GREGOR.

Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.; Solanki, S. K.; Balthasar, H.; Bello González, N.; Berkefeld, T.; Collados Vera, M.; Hofmann, A.; Kneer, F.; Lagg, A.; Puschmann, K. G.; Schmidt, D.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.

2012-12-01

98

THEMIS : a powerful solar telescope for spectro-polarimetry  

NASA Astrophysics Data System (ADS)

The scientific results obtained with THEMIS are shortly presented. In addition some indications about the improvements which are essential to maintain THEMIS in the group of the most relevant solar telescopes in the world are given. Based on observations made with THEMIS telescope operated on the island of Tenerife by THEMIS SL in the Spanish Observatorio del Teide of the Instituto de Astrofisica de Canarias

Ceppatelli, G.

99

The Advanced Technology Solar Telescope (ATST) project: a construction update  

NASA Astrophysics Data System (ADS)

The 4m Advance Technology Solar Telescope (ATST) will be the world's leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. The project has entered its construction phase. Major subsystems have been contracted, designs are complete, and fabrication has started. As its highest priority science driver ATST shall provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona at infrared wavelengths. A high order adaptive optics system delivers a corrected beam to the initial set of state-of-the-art, facility class instrumentation located in the Coudé laboratory facility. The initial set of five first generation instruments consists of imagers and spectro-polarimeters. Development and construction of a four-meter solar telescope presents many technical challenges, including thermal control of the enclosure, telescope structure and optics and wavefront control. A brief overview of the science goals and observational requirements of the ATST will be given, followed by a summary of the status of the telescope, its instrumentation, and the construction of the facility.

Warner, Mark; McMullin, Joseph; Rimmele, Thomas; Berger, Tom

2013-09-01

100

The Impact of Receiver Aperture Design and Telescope Properties on LIDAR Signal-to-Noise Ratio Improvements  

NASA Astrophysics Data System (ADS)

Range and sensitivities of lidar measurements in daylight are limited by sky background noise power (BGP). This is particularly important for Raman lidar techniques where the Raman backscattered signal is relatively weak. This often restricts Raman lidar measurements to nighttime where BGP is absent. The background noise elimination is particularly important in daytime measurements in case where full overlap between laser beam and receiver telescope field-of-view (FOV) is necessary. Results of numerical simulations for a vertically pointing Lidar show that significant improvements in Lidar signal to noise ratio (SNR) can be obtained, by minimizing the detected sky BGP. This can be, optimally achieved if the receiver telescope aperture is properly designed to track lidar target images, which are range dependant. In this context, the connection between receiver telescope field of view and optimum aperture size are examined. The SNR improvements, which can be obtained in this manner, translate to corresponding improvements in Lidar range for backscatter schemes including Raman and DIAL.

Hassebo, Yasser; El Sayed, Khaled

2007-02-01

101

The James Webb Space Telescope: Solar System Science  

NASA Astrophysics Data System (ADS)

The James Webb Space Telescope (JWST) is poised to revolutionize many areas of astrophysical research including Solar System Science. Scheduled for launch in 2018, JWST is ~100 times more powerful than the Hubble and Spitzer observatories. It has greater sensitivity, higher spatial resolution in the infrared, and significantly higher spectral resolution in the mid infrared. Imaging and spectroscopy (both long-slit and integral-field) will be available across the entire 0.6 - 28.5 micron wavelength range. Herein, we discuss the capabilities of the four science instruments with a focus on Solar System Science, including instrument modes that enable observations over the huge range of brightness presented by objects within the Solar System. The telescope is being built by Northrop Grumman Aerospace Systems for NASA, ESA, and CSA. JWST development is led by NASA's Goddard Space Flight Center. The Space Telescope Science Institute (STScI) is the Science and Operations Center (S&OC) for JWST.

Hines, Dean C.; Hammel, H. B.; Lunine, J. I.; Milam, S. N.; Kalirai, J. S.; Sonneborn, G.

2013-01-01

102

The study on servo-control system in the large aperture telescope  

NASA Astrophysics Data System (ADS)

Large astronomical telescope or extremely enormous astronomical telescope servo tracking technique will be one of crucial technology that must be solved in researching and manufacturing. To control technique feature of large astronomical telescope or extremely enormous astronomical telescope, this paper design a sort of large astronomical telescope servo tracking control system. This system composes a principal and subordinate distributed control system, host computer sends steering instruction and receive slave computer functional mode, slave computer accomplish control algorithm and execute real-time control. Large astronomical telescope servo control use direct drive machine, and adopt DSP technology to complete direct torque control algorithm, Such design can not only increase control system performance, but also greatly reduced volume and costs of control system, which has a significant occurrence. The system design scheme can be proved reasonably by calculating and simulating. This system can be applied to large astronomical telescope.

Hu, Wei; Zhang, Zhenchao; Wang, Daxing

2008-08-01

103

Solar System Science with the James Webb Space Telescope  

NASA Astrophysics Data System (ADS)

The James Webb Space Telescope (JWST) will succeed the Hubble Space Telescope as NASA’s premier space-based platform for observational astronomy. This 6.5-meter telescope, which is optimized for observations in the near and mid infrared, will be equipped with four state-of-the-art imaging, spectroscopic, and coronagraphic instruments. These instruments, along with the telescope’s moving target capabilities, will enable the infrared study of solar system objects with unprecedented detail (see companion presentation by Sonneborn et al.). This poster features highlights for planetary science applications, extracted from a white paper in preparation. We present a number of hypothetical solar system observations as a means of demonstrating potential planetary science observing scenarios; the list of applications discussed here is far from comprehensive. The goal of this poster and the subsequent white paper is to stimulate discussion and encourage participation in JWST planning among members of the planetary science community, and to encourage feedback to the JWST Project on any desired observing capabilities, data products, and analysis procedures that would enhance the use of JWST for solar system studies. The upcoming white paper updates and supersedes the solar system white paper published by the JWST Project in 2010 (Lunine et al., 2010), and is based in part on JWST events held at the 2012 DPS, the 2013 LPSC meeting, and this DPS (JWST Town Hall, Thursday, 10 October 2013, 12-1 pm).

Hammel, Heidi B.; Norwood, J.; Chanover, N.; Hines, D. C.; Stansberry, J.; Lunine, J. I.; Tiscareno, M. S.; Milam, S. N.; Sonneborn, G.; Brown, M.

2013-10-01

104

Receiver for solar energy collector having improved aperture aspect  

DOEpatents

A secondary concentrator for use in receiver systems for linear focusing primary concentrators is provided with reflector wings at each end. The wings increase the capture of light rays reflected from areas adjacent the rim of a primary concentrator, increasing the apparent aperture size of the absorber as viewed from the rim of the primary concentrator. The length, tilt, and curvature of the wing reflectors can be adjusted to provide an absorber having a desired aperture aspect.

McIntire, William R. (Downers Grove, IL)

1984-01-01

105

Receiver for solar-energy collector having improved aperture aspect  

DOEpatents

A secondary concentrator for use in receiver systems for linear focusing primary concentrators is provided with reflector wings at each end. The wings increase the capture of light rays reflected from areas adjacent the rim of a primary concentrator, increasing the apparent aperture size of the receiver as viewed from the rim of the primary concentrator. The length, tilt, and curvature of the wing reflectors can be adjusted to provide a receiver having a desired aperture aspect.

McIntire, W.R.

1981-03-13

106

A Simulation Research on the Solar Hard X-Ray Imaging Telescope  

NASA Astrophysics Data System (ADS)

High-energy phenomena always play an important role in solar research field. Observations of hard X-ray/gamma-ray can be divided into images and spectra, both of which give clues to reveal the secret of the energy release of solar flares. Instead of conventional imaging technique using mirrors or lens, which cannot work in energy above a few keV, direct imaging, coded aperture and Fourier transform are used for high-energy imaging. Fourier transform technique stands out because of its high sensitivity and high reliability. It can be implemented in various hardware configurations, among which spatial modulation collimator and rotating modulation collimator are widely used. Modulation collimator type hard X-ray imaging telescope is currently widely used in solar observation. For the possible Chinese solar mission in the near future, we make a design of hard X-ray imaging telescope using the common simulation software, GEANT4. The results are closer to the fact compared with the traditional geometric algorithm. An executable design is also proposed at last.

Teng, T.; Wu, J.; Chang, J.

2011-07-01

107

A High Resolution Integral Field Spectrograph for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

This paper presents the proposal of a high resolution, integral field spectrograph that is currently being designed for the 4-meter aperture European Solar Telescope that will be located in the Canary Islands. This instrument is optimized to study the solar chromosphere and photosphere to allow the investigation of several phenomena concentrated within these two layers. It will be able to observe simultaneously a bidimensional field of view of 80 arcsec2 that is reorganized, using an integral field unit, into 8 long slits of 200 arcsec length by 0.05 arcsec width. It will have the capability to observe different layers of the Sun at the same time due to its multi-wavelength capability that allows the observation of 5 visible and 3 near-infrared wavelength intervals from 3900 to 23,000 Å, with a spectral resolution of about 300,000. The designed instrument is telecentric and presents an optical quality limited by diffraction.

Calcines, A.; López, R. L.; Collados, M.

108

The Focal Plane Package for the Solar Optical Telescope on Solar-B  

NASA Astrophysics Data System (ADS)

Solar-B is a space science mission of the Japanese Aerospace Exploration Agency (JAXA) and a NASA Solar Terrestrial Probes mission. It includes the 50-cm aperture Solar Optical Telescope (SOT), with its Focal Plane Package (FPP) designed for high resolution photospheric and chromospheric imaging and spectro-polarimetry. There are also two coronal instruments, the X-Ray Telescope and Extreme-ultraviolet Imaging Spectrometer. Solar-B will be launched into a Sun-synchronous polar orbit in August, 2006. The SOT is provided by JAXA and is being built by the National Astronomical Observatory of Japan (NAOJ) and Mitsubishi Electric Co. A team of Lockheed Martin, High Altitude Observatory (HAO), and NAOJ scientists and engineers have built the FPP instrument. This paper gives an overview of the science goals of the FPP as well as the instrument performance characteristics. The primary goal is to understand the coupling between the fine magnetic structures in the photosphere and dynamic processes and heating in the chromosphere and corona. The FPP consists of a narrow-band tunable birefringent filter imager, broad-band interference filter imager, and spectro-polarimeter (SP), essentially a space version of the HAO Advanced Stokes Polarimeter. The image is stabilized by a correlation tracker and active tilt mirror. The SP makes vector magnetic measurements from Stokes spectra of the Fe I lines 630.1 and 630.2 nm, with 0.16 arcsec pixels and field of view up to 164 x 328 arcsec. The broad-band system takes diffraction-limited images (0.05 arcsec pixels) in the Ca II H line, CN and G bandheads, and continuum bands. The narrow-band system makes filtergrams, magnetograms, Dopplergrams, and Stokes images in several photospheric lines, Mg b, Na D, and H-alpha, similar to the SOUP filter at La Palma. It has 0.08 arcsec pixels and field-of-view same as that of the SP. SOT and FPP have been calibrated in great detail and have observed the sun in two end-to-end tests at NAOJ. Sample results of these observations will be shown. Observing programs and coordination with the other instruments and observatories during the mission will be managed by SOT/FPP science planners, similar to those of SOHO and TRACE. The FPP project is supported by NASA (NAS8-01002).

Tarbell, T. D.

2005-05-01

109

Optimum aperture size and operating temperature of a solar cavity-receiver  

Microsoft Academic Search

For solar cavity-receivers operating at high temperatures, the optimum aperture size results from a compromise between maximizing radiation capture and minimizing radiation losses. When the absorbed solar energy is utilized as high temperature process heat, the energy conversion efficiency can be represented as the product of the energy absorption efficiency and the Carnot efficiency. The authors describe a simple, semiempirical

A. Steinfeld; M. Schubnell

1993-01-01

110

The tandem Fabry-Perot filter imaging spectro-polarimeter for the Solar Magnetic Activity Research Telescope (SMART)  

NASA Astrophysics Data System (ADS)

In order to perform precise and high time cadence magnetic field measurement across the solar surface, the Tandem Fabry-Perot filter imaging spectro-polarimeter for the Solar Magnetic Activity Research Telescope (SMART) is revised. By using the CCD with moderate frame rate of 30fps, full Stokes vectors on the field-of-view 320"x240" can be obtained at 4 wavelengths around FeI6302 line within about 15s. The optical performance of the Tandem Fabry-Perof filters is investigated by using the spectrograph at the Domeless Solar Telescope at Hida Observatory. The test results show the full-width-half-maximum (FWHM) of the tandem filters is about 0.017nm over the 60mm clear aperture is achieved. The system is developed to start the regular observations from 2010.

Nagata, Shin'ichi; Otsuji, Kenichi; Ishii, Takako T.; Ichimoto, Kiyoshi; Ueno, Satoru; Kitai, Reizaburo; Kimura, Goichi; Shibata, Kazunari; Nakatani, Yoshikazu; Morita, Satoshi

2009-08-01

111

The Solar-A soft X-ray telescope experiment  

Microsoft Academic Search

The Japanese Solar-A mission for the study of high energy solar physics is timed to observe the sun during the next activity maximum. This small spacecraft includes a carefully coordinated complement of instruments for flare studies. In particular, the soft X-ray telescope (SXT) will provide X-ray images of flares with higher sensitivity and time resolution than have been available before.

L. Acton; M. Bruner; W. Brown; J. Lemen; T. Hirayama

1988-01-01

112

Vector Magnetograph Observations by the Solar Flare Telescope at Boao  

Microsoft Academic Search

We report that the vector magnetograph(VMG) observations of the solar photosphere are being carried out by the Solar Flare Telescope(SOFT) in BOAO(Bohyunsan Optical Astronomical Observatory) of Korea Astronomy Observatory. The VMG uses a narrow band Lyot filter (FWHM = 0.125A) for observations of Stokes parameters(I,Q,U,V) to obtain longitudinal and transversal fields. The Stokes images are acquired by Sony XC -77

Y. D. Park; Y.-J. Moon

1999-01-01

113

Solar feature correlation tracker for ground-based telescopes  

NASA Astrophysics Data System (ADS)

A tracking system that stabilizes atmospheric and instrumental image motion has been tested at the vacuum tower telescope of the National Solar Observatory at Sacramento Peak. The system locks anywhere on the sun, using solar granulation or other small scale structures as tracers. A matrix diode array rapidly scans the scene of interest; pictures are cross-correlated in real time with a previously recorded reference image of the same area on the sun.

von der Luehe, O.; Widener, A. L.; Rimmele, Th.; Spence, G.; Dunn, R. B.

1989-10-01

114

The 1.5 meter solar telescope GREGOR  

NASA Astrophysics Data System (ADS)

The 1.5 m telescope GREGOR opens a new window to the understanding of solar small-scale magnetism. The first light instrumentation includes the Gregor Fabry Pérot Interferometer (GFPI), a filter spectro-polarimeter for the visible wavelength range, the GRating Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The excellent performance of the first two instruments has already been demonstrated at the Vacuum Tower Telescope. GREGOR is Europe's largest solar telescope and number 3 in the world. Its all-reflective Gregory design provides a large wavelength coverage from the near UV up to at least 5 microns. The field of view has a diameter of 150 arcsec. GREGOR is equipped with a high-order adaptive optics system, with a subaperture size of 10 cm, and a deformable mirror with 256 actuators. The science goals are focused on, but not limited to, solar magnetism. GREGOR allows us to measure the emergence and disappearance of magnetic flux at the solar surface at spatial scales well below 100 km. Thanks to its spectro-polarimetric capabilities, GREGOR will measure the interaction between the plasma flows, different kinds of waves, and the magnetic field. This will foster our understanding of the processes that heat the chromosphere and the outer layers of the solar atmosphere. Observations of the surface magnetic field at very small spatial scales will shed light on the variability of the solar brightness.

Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.; Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, Th.; Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.; Schmidt, D.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Waldmann , T. A.

2012-11-01

115

Solar system observations with Spitzer Space Telescope: Preliminary results  

Microsoft Academic Search

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the geometric albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 ?m,

Dale P. Cruikshank

2005-01-01

116

Solar system observations with Spitzer Space Telescope: Preliminary results  

Microsoft Academic Search

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the geometric albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 mum,

Dale P. Cruikshank

2005-01-01

117

Utilization of vibrator and ring feeds in solar radio telescopes  

Microsoft Academic Search

The paper briefly considers several feed designs for solar radio telescopes. These include a vibrator feed based on a corner antenna, a waveguide-vibrator feed for two-reflector antennas, and two types of ring-antenna feeds for the centimeter and decimeter ranges. Attention is given to the electrical properties and radiation patterns of the feeds.

V. M. Viatkina; V. G. Ioganson

1977-01-01

118

Telescope in a bottle: a novel approach to upgrading a 32-in.-aperture classical Cassegrainian telescope for range instrumentation with IR sensors  

NASA Astrophysics Data System (ADS)

The title for this paper derives from the method selected for upgrading an older telescope which needed to meet current range instrumentation requirements in the infrared portion of the optical spectrum. A major constraint imposed on the project at its outset was the need to keep the older telescope tube, tracking mount and mobile platform at its home base in Florida. In contrast to the traditional way of building telescopes by first designing the optical system and then designing the housing and mount, this upgrade began with fitting a new structure within the confines of the existing housing while increasing the usable aperture from a 29.5 inch diameter Classical Cassegrainian design to a 32 inch aperture system. This new structure evolved from an improved design approach including the use of low thermal coefficient of expansion materials, special baffles and modern alignment techniques. The tube which was to serve as the bottle, was stripped of its optical components while a completely new internal structure was fabricated independently at a facility in California. The redesign and fabrication process began with a search for the original optical design data and a shopping list of parts to be either modified or redesigned to fit the existing light path through a donut ring which incorporates the telescope's trunnion axis, to a second folding mirror thus enabling an infrared camera to be focused along an overhead track parallel to the telescope's optical axis. All of the original optics were reassembled and potted into new mounts. The secondary mirror was placed into a large ball-knuckle assembly which insured rapid and precise alignment. During the process of building the independent structure, an installation kit or erector set was created. This erector set included special tooling for attaching a large headring, all four metering rods, baffles and adapters as well as the primary mirror retaining ring, inside the original tube. All hardware was shipped to the field site in Florida where final assembly took place using only heavy lifting equipment and a minimum of inexpensive alignment devices.

Houston, Joseph B.

2002-09-01

119

Coded-aperture gamma-ray telescope - Principles and application to the SIGMA gamma-ray-astronomy project  

NASA Astrophysics Data System (ADS)

The design of a coded aperture and deconvolution/image-reconstruction software for the NaI-crystal/photomultiplier 100-300-keV gamma-ray imaging telescope SIGMA (Satellite d'Imagerie Gamma Montesur Ariane), a satellite observatory being developed by CNES, is presented, and the results of simulations and laboratory tests are summarized. The mathematical principles of coded apertures are reviewed; a technique for designing optimal imaging optics is proposed; the image-reconstruction problem is examined with a focus on the effect of partially coded sources; the SIGMA project is briefly characterized; and the test results are presented in graphs, tables, and an image of a simulated source. Spatial resolution of 1-3 mm and energy resolution compatible with spectroscopic studies are predicted for a 15-mm-thick tungsten coded aperture comprising 29 x 31 elements and situated 2.5 m from the position detector. The software developed permits correction for pointing errors of + or - 30 arcmin on all three axes and real-time deconvolution.

Roques, J.-P.

120

The Focal Plane Package for the Solar Optical Telescope on Solar-B  

NASA Astrophysics Data System (ADS)

Solar-B is a Japanese space science mission of the Institute of Space and Astronautical Sciences (ISAS), with major participation of US and UK research groups. The mission includes the 50-cm aperture Solar Optical Telescope (SOT), with its Focal Plane Package (FPP) designed for high resolution photospheric and chromospheric imaging and spectro-polarimetry. There are also two coronal instruments, the X-Ray Telescope and Extreme-ultraviolet Imaging Spectrometer. Solar-B will be launched into a Sun-synchronous polar orbit in August, 2005. The SOT is provided by ISAS and is being built by the National Astronomical Observatory of Japan (NAOJ) and Mitsubishi Electric Co. A team of Lockheed Martin, High Altitude Observatory (HAO), and NAOJ scientists and engineers are designing the FPP instrument. This talk gives an overview of the science goals of the FPP as well as the current instrument design and performance characteristics. The primary goal is to understand the coupling between the fine magnetic structures in the photosphere and dynamic processes and heating in the chromosphere and corona. The FPP consists of a narrow-band tunable birefringent filter imager, broad-band interference filter imager, and spectro-polarimeter (SP), essentially a space version of the HAO Advanced Stokes Polarimeter. The image is stabilized by a correlation tracker and active tilt mirror. The SP makes vector magnetic measurements from Stokes spectra of the Fe I lines 630.1 and 630.2 nm, with 0.16 arcsec pixels and field of view up to 164 x 328 arcsec. The broad-band system takes diffraction-limited images (0.05 arcsec pixels) in the Ca II H line, CN and G bandheads, and continuum bands. The narrow-band system makes filtergrams, magnetograms, Dopplergrams, and Stokes images in several photospheric lines, Mg b, and H-alpha. It has 0.08 arcsec pixels and field-of-view same as that of the SP. The SP and filter imagers will usually observe simultaneously on the same target region. High-level observing sequences and coordination with the other instruments will be managed by FPP science planners, similar to those of SXT and TRACE. The FPP project is supported by NASA (NAS8-01002).

Tarbell, T.

2001-05-01

121

Effect of surface scatter upon the MTF of the solar ultra violet imager (SUVI) telescope  

NASA Astrophysics Data System (ADS)

The solar UV imager (SUVI) is an extreme ultraviolet instrument that will fly on the Geostationary Operational Environmental Satellite (GOES)-R and-S platforms, as part of NOAA's space weather monitoring fleet. It will provide important information on solar activity and the effects of the Sun on the earth and the near-earth environment. This instrument will image the full solar disc in 6 EUV wavebands between 303.8 Å and 93.9 Å. A generalized Cassegrain telescope configuration is employed where six mirror sectors utilize multilayer coatings optimized for the six wavelengths of interest. An aperture shutter is used to select the appropriate sector for observations at a particular wavelength. A thinned, back-illuminated CCD sensor with 21?m (2.5 arcsec) pixels resides in the telescope focal plane. The modulation transfer function (MTF) is usually considered to be the image quality criterion of choice for applications where fine detail in extended images needs to be specified or evaluated. However, the contractual image quality requirement was specified in terms of fractional ensquared energy for a variety of different wavelengths and square sizes. In this paper we will calculate and present MTF plots (as degraded by diffraction, geometrical aberrations, surface scatter effects and detector effects) for each of the SUVI wavelengths of interest. Surface scatter due to residual optical fabrication errors is a major factor limiting the performance at the shorter wavelengths, and the large detector size severely limits the performance at all SUVI wavelengths.

Harvey, James E.; Choi, Narak

2013-09-01

122

The research on direct drives control system in the large aperture telescope  

NASA Astrophysics Data System (ADS)

A 30m giant telescope project, Chinese Future Giant Telescope (CFGT), has been proposed by Chinese astronomers. At present, a series of key techniques are being developed. This paper explores a method to control direct drive servo motor in giant telescope application, which is based on a segmented Surface-mounted Permanent Magnet Synchronous Motor (SMPMSM). The losses of SMPMSM and the method of reducing the losses are discussed in this paper. Phase-controlled rectification circuit is chosen to regulate rectified voltage according to the telescope status. Such design can decrease the losses of the motor to some extent. In the control system Space-vector PWM (SVPWM) algorithm acts as a control algorithm and three-phase voltage source inverter circuit acts as drive circuit. This project is subsidized by Chinese National Natural Science Funds (10833004).

Li, Xiaoyan; Zhang, Zhenchao; Wang, Daxing

2010-07-01

123

Research of active panel technology for large aperture millimeter-wave/sub-millimeter-wave telescope  

NASA Astrophysics Data System (ADS)

As Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) project was completed successfully, indicating the key technology of active optics has been mastered by the Chinese astronomical community, experts of Nanjing Institute of Astronomical Optics and Technology (NIAOT), builders of this project, started to consider how to use the technology developed in large optical telescope such as LAMOST to improve the performance of millimeterwave / sub-millimeter-wave telescope. In order to do more research work about active optics of millimeter submillimeter band and improve the performance of Delingha 13.7m millimeter-wave telescope, researchers of NIAOT intend to upgrade the reflect panel accuracy of this telescope. This paper will introduce the preliminary work of the accuracy-upgrading task, numerical simulation of the 13.7m telescope. In this presentation, the primary reflector finite element model (FEM) construction, gravity and thermal deformation, and modal analyze are described. The result shows that the gravity and thermal distortion of the reflector are contributed mostly by the back-structure and the active support for the panels is very necessary to restrain this kind of distortion.

Wu, Xuhao; Cui, Xiangqun

2010-05-01

124

Multi-Spectral Solar Telescope Array (MSSTA).  

National Technical Information Service (NTIS)

In 1987, our consortium pioneered the application of normal incidence multilayer X-ray optics to solar physics by obtaining the first high resolution narrow band, 'thermally differentiated' images of the corona', using the emissions of the Fe IX/Fe X comp...

A. B. C. Walker R. B. Hoover T. W. Barbee

1997-01-01

125

IMAGING FAINT BROWN DWARF COMPANIONS CLOSE TO BRIGHT STARS WITH A SMALL, WELL-CORRECTED TELESCOPE APERTURE  

SciTech Connect

We have used our 1.6 m diameter off-axis well-corrected subaperture (WCS) on the Palomar Hale telescope in concert with a small inner-working-angle phase-mask coronagraph to image the immediate environs of a small number of nearby stars. Test cases included three stars (HD 130948, HD 49197, and HR7672) with known brown dwarf companions at small separations, all of which were detected. We also present the initial detection of a new object close to the nearby young G0V star HD171488. Follow-up observations are needed to determine if this object is a bona fide companion, but its flux is consistent with the flux of a young brown dwarf or low-mass M star at the same distance as the primary. Interestingly, at small angles our WCS coronagraph demonstrates a limiting detectable contrast comparable to that of extant Lyot coronagraphs on much larger telescopes corrected with current-generation adaptive optics (AO) systems. This suggests that small apertures corrected to extreme AO (ExAO) levels can be used to carry out initial surveys for close brown dwarf and stellar companions, leaving follow-up observations for larger telescopes.

Serabyn, E.; Mawet, D.; Bloemhof, E.; Haguenauer, P.; Mennesson, B.; Wallace, K. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Hickey, J. [Palomar Observatory, California Institute of Technology, P.O. Box 200, Palomar Mountain, CA 92060 (United States)

2009-05-01

126

The Advanced Technology Solar Telescope: Science Goals, Design and Project Status. (Invited)  

NASA Astrophysics Data System (ADS)

The 4m Advance Technology Solar Telescope (ATST) on Haleakala will be the most powerful solar telescope and the world’s leading resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun’s output. The project is about to enter the construction phase and is expected to be fully commissioned in 2017. A brief overview of the science goals and observational requirements of the ATST will be given followed by a summary of the design status of the telescope and its instrumentation will during which the technical and engineering challenges the ATST project faces will be discussed. ATST will provide high resolution and high sensitivity observations of the dynamic solar magnetic fields throughout the solar atmosphere, including the corona. With its 4 m aperture, ATST will resolve features at 0.”03 (20km on the sun) at visible wavelengths. The science requirement for polarimetric sensitivity (10-5 relative to intensity) and accuracy (5x10-4 relative to intensity) place strong constraints on the polarization analysis and calibration units. A high order adaptive optics system delivers a corrected beam to the initial set of state-of-the-art, facility class instrumentation located in the Coude lab facility. A few examples of the many unique science capabilities of the 4m ATST will be discussed. The initial set of first generation instruments includes: 1: the Visible Broadband Imager will provide images at the highest possible spatial and temporal resolution at a number of specified wavelengths in the range from 390 nm to 860 nm. 2: the Visible Spectro-Polarimeter will provide precision vector field measurements simultaneously at diverse wavelengths in the visible spectrum and thus deliver quantitative diagnostics of the magnetic field vector as a function of height in the solar atmosphere, along with the associated variation of the thermodynamic properties. 3: the Diffraction-Limited Near-Infrared Spectro-Polarimeter will record with high temporal cadence the full polarization state of spectral lines in the near infrared wavelength regime from 900 nm to 2300 nm. 4: the Cryogenic Near Infrared-Spectro-Polarimeter will measure solar magnetic fields over a large field-of-view at infrared wavelengths from 1000 nm to 5000 nm in the solar corona. 5: the Visible Tunable Filter will provide two-dimensional spectroscopy and polarimetry by recording diffraction-limited narrow-bandpass images with high temporal resolution.

Rimmele, T.; Keil, S. L.; Wagner, J.

2009-12-01

127

SolarB X-Ray Telescope (XRT)  

NASA Astrophysics Data System (ADS)

The Soft X-ray Telescope (XRT) aboard SolarB is a grazing incidence X-ray telescope equipped with 2k × 2k CCD. XRT has 1 arcsec resolution with wide field-of-view of 34 × 34 arcmin. It is sensitive to <1 MK to 30 MK, allowing us to obtain TRACE-like low temperature images as well. Co-alignment with SOT and EIS is realized through the XRT visible light telescope and with temperature overlap with EIS. Spacecraft mission data processor (MDP) controls XRT through the sequence tables with versatile autonomous functions such as exposure control, region-of-interest tracking, flare detection and flare location identification. Data are compressed either with DPCM or JPEG, depending on the purpose. This results in higher cadence and/or wider field-of-view for given telemetry bandwidth. With focus adjust mechanism, higher resolution of Gaussian focus may be available on-axis.

Kano, R.; Hara, H.; Shimojo, M.; Tsuneta, S.; Sakao, T.; Matsuzaki, K.; Kosugi, T.; Golub, L.; Deluca, E. E.; Bookbinder, J. A.; Cheimets, P.; Owens, J. K.; Hill, L. D.

2004-12-01

128

Simultaneous design of an optical system and null tests of the components: examples and results from the Large-aperture Synoptic Survey Telescope  

NASA Astrophysics Data System (ADS)

Optical null tests for three lenses and two subsystems were incorporated into the optical design procedure for the Large-aperture Synoptic Survey Telescope [1]. The "skip surfaces" feature in the OSLO optical design program was crucial. The resulting optical tests were extremely simple, requiring only a retro reflecting spherical or flat mirror. This is only possible because the optical tests were simultaneously designed and optimized as the telescope was designed.

Seppala, Lynn G.

2010-07-01

129

The Design, Construction and Testing of the Optics for a 147-cm-Aperture Telescope.  

National Technical Information Service (NTIS)

Geodetic optics research for the Air Force Cambridge Research Laboratories (AFCRL) is described. The work consisted mainly of the fabrication of the optical components for a telescope with a 152-cm-diam (60-in.) primary mirror masked down to 147-cm-diam f...

R. A. Buchroeder L. H. Elmore R. V. Shack P. N. Slater

1972-01-01

130

Modal phase correction for large-aperture ground-based telescope with multiguide stars  

Microsoft Academic Search

Simple analytical expressions for parameter Strehl of ground-based astronomical telescope: (i) without adaptive correction, (ii) phase correction with use single laser guide star, (iii) phase correction with use multi-guide stars (square matrix system of guide stars with variable number of elements) are obtained. Models of the vertical dependence of the structure parameter of refractive index of the turbulent atmosphere for

Lidia A. Bolbasova; Vladimir P. Lukin

2009-01-01

131

Advanced electrostatically clean solar array panel design using reflective aperture grids  

Microsoft Academic Search

An improved design for an electrostatically clean solar array (ECSA) is described. The baseline ECSA uses a frontside shield with apertures (FSA) to establish a continuously grounded frontside plane, and cover exposed conductors. The improved design adds a tent-shaped reflective cover onto the FSA which collects the energy that would normally be lost in the area covered by the FSA,

T. G. Stern

2002-01-01

132

A balloon-borne coded aperture telescope for low-energy gamma-ray astronomy  

Microsoft Academic Search

A telescope for imaging cosmic gamma-ray emission over the energy range 160 keV to 9.3 MeV has been developed and successfully flown on a high altitude balloon over Palestine, Texas on 1 October, 1984. This instrument consists of a coded mask based on a 5 × 7 uniformly redundant array (URA) and a scintillator array consisting of 35 bismuth germanate

Philip P. Dunphy; Mark L. McConnell; Alan Owens; Edward L. Chupp; David J. Forrest; Jonathan Googins

1989-01-01

133

Considerations for the next generation of solar telescopes: A systems approach to solar physics  

NASA Astrophysics Data System (ADS)

The exciting new high resolution images from the one meter Sunrise balloon telescope and the first images from the 1.6 meter Big Bear telescope together with the continuing data from the 1 meter Swedish Solar Observatory demonstrate the promise of the new generation of multimeter solar telescopes. While the promise of the new generation of telescopes is great the technical challenges to build them will require the efforts of a significant fraction of the solar community. In this talk I will emphasize the need for an integrated systems approach to the development of the telescope, its instruments, its software, and its operations and management structures. The experience of several decades of space mission has taught us a great deal about the value of planning mission development from the definition of the primary scientific objectives to the delivery of the data to the science community. Much of these lessons learned, often painfully, should provide guidance to those in developing the new telescope systems.

Title, A.

2010-06-01

134

FalconSAT-7: A Photon Sieve Solar Telescope  

NASA Astrophysics Data System (ADS)

In the event of a sudden loss of space-based surveillance assets, a limited, rapidly deployed replacement system is desirable until more capable satellites can be built and launched. Cadets and staff at the USAF Academy are currently building FalconSat-7, a 0.2m diameter solar observatory to be deployed from a 3U Colony II CubeSat (10x10x30cm). While not optimized for ground observation, such a telescope would have a 1.8m resolution at an orbital altitude of 450km.

Andersen, G.; Dearborn, M.; McHarg, G.

2011-09-01

135

POlarization Emission of Millimeter Activity at the Sun (POEMAS): New Circular Polarization Solar Telescopes at Two Millimeter Wavelength Ranges  

NASA Astrophysics Data System (ADS)

We present a new system of two circular polarization solar radio telescopes, POEMAS, for observations of the Sun at 45 and 90 GHz. The novel characteristic of these instruments is the capability to measure circular right- and left-hand polarizations at these high frequencies. The two frequencies were chosen so as to bridge the gap at radio frequencies between 20 and 200 GHz of solar flare spectra. The telescopes, installed at CASLEO Observatory (Argentina), observe the full disk of the Sun with a half power beam width of 1.4?, a time resolution of 10 ms at both frequencies, a sensitivity of 2 - 4 K that corresponds to 4 and 20 solar flux unit (=104 Jy), considering aperture efficiencies of 50±5 % and 75±8 % at 45 and 90 GHz, respectively. The telescope system saw first light in November 2011 and is satisfactorily operating daily since then. A few flares were observed and are presented here. The millimeter spectra of some flares are seen to rise toward higher frequencies, indicating the presence of a new spectral component distinct from the microwave one.

Valio, Adriana; Kaufmann, P.; Giménez de Castro, C. G.; Raulin, J.-P.; Fernandes, L. O. T.; Marun, A.

2013-04-01

136

Advanced Technology Solar Telescope lower enclosure thermal system  

NASA Astrophysics Data System (ADS)

The exterior of the Advanced Technology Solar Telescope enclosure requires cooling to eliminate so-called external dome seeing caused by solar loading during the observing day. This is achieved by way of coolant circulation through external plate coil panels, thereby maintaining the exterior surfaces of the enclosure at or just below ambient air temperature. As the distance from the optical path increases (e.g., on the surface of the lower enclosure), the stringency of the temperature requirement is diminished, thereby allowing a greater difference between the surface temperature and the ambient air temperature. This paper presents a comparison of the modeled performance of an active thermal control strategy on the lower enclosure to a passive strategy that employs concrete panels. A life-cycle cost analysis of each option is also presented.

Phelps, L.; Warner, M.

2008-07-01

137

Goldhelox: a soft x-ray solar telescope.  

PubMed

The Goldhelox Project is the construction and use of a near-normal incidence soft x-ray robotic solar telescope by undergraduate students at Brigham Young University. Once it is completed and tested, it will be deployed from a Get-Away-Special (GAS) canister in the bay of a space shuttle. It will image the sun at a wavelength of 171-181Å with a time resolution of 1 sec and a spatial resolution of 2.5 arcsec. The observational bandpass was chosen to image x-rays from highly ionized coronal Fe lines. The data will be an aid in better understanding the beginning phases of solar flares and how flaring relates to the physics of the corona-chromosphere transition region. Goldhelox is tentatively scheduled to fly on a space shuttle sometime in 1995 or 1996. This paper outlines the project goals, basic instrument design, and the unique aspects of making this an undergraduate endeavor. PMID:21307474

Durfee, D S; Moody, J W; Brady, K D; Brown, C; Campbell, B; Durfee, M K; Early, D; Hansen, E; Madsen, D W; Morey, D B; Roming, P W; Savage, M B; Eastman, P F; Jensen, V

1995-01-01

138

Development of multilayer coatings for solar orbiter EUV imaging telescopes  

NASA Astrophysics Data System (ADS)

Since more than 20 years, Laboratoire Charles Fabry and Institut d'Astrophysique Spatiale are involved in development of the EUV multilayer coating for solar imaging. Previous instruments, such as the SOHO EIT and STEREO EUVI telescopes, employed the Mo/Si multilayer coatings, which offered at that time the best efficiency and stability. We present here recent results of the development of highly efficient EUV multilayers coatings at 17.4 nm and 30.4 nm for the Solar Orbiter mission. New multilayer structures, based on a combination of three materials including aluminum, have been optimized both theoretically and experimentally. We have succeeded to reduce interfacial roughness of Albased multilayers down to 0.5 nm via optimization of the multilayer design and the deposition process. The EUV peak reflectance of Al/Mo/SiC and Al/Mo/B4C multilayer coatings reaches 56% at 17.4 nm, the highest value reported up to now for this wavelength. We have also optimized specific bi-periodic structures that possess two reflection bands in the EUV range with high spectral selectivity. The EUV reflectivity of these Al-based dual-band coatings are compared with the Si/Mo/B4C baseline coating for Solar Orbiter. Since the stability of reflecting multilayer coating is an important issue for space missions, we have also studied the temporal stability as well as the resistivity of the coatings to thermal cycling and to proton irradiation. Experimental results confirm that Al/Mo/SiC and Al/Mo/B4C multilayer coatings are good candidates for the Solar Orbiter EUV imaging telescopes.

Delmotte, Franck; Meltchakov, Evgueni; de Rossi, Sébastien; Bridou, Françoise; Jérome, Arnaud; Varnière, François; Mercier, Raymond; Auchère, Frédéric; Zhang, Xueyan; Borgo, Bruno; Dumesnil, Cydalise; François, Serge; Roulliay, Marc; Strauch, Udo

2013-09-01

139

Solar Adaptive Optics  

Microsoft Academic Search

Adaptive optics (AO) has become an indispensable tool at ground-based solar telescopes. AO enables the ground-based observer to overcome the adverse effects of atmospheric seeing and obtain diffraction limited observations. Over the last decade adaptive optics systems have been deployed at major ground-based solar telescopes and revitalized ground-based solar astronomy. The relatively small aperture of solar telescopes and the bright

Thomas R. Rimmele; Jose Marino

2011-01-01

140

BAND-LIMITED CORONAGRAPHS USING A HALFTONE-DOT PROCESS. II. ADVANCES AND LABORATORY RESULTS FOR ARBITRARY TELESCOPE APERTURES  

SciTech Connect

The band-limited coronagraph is a nearly ideal concept that theoretically enables perfect cancellation of all the light of an on-axis source. Over the past several years, several prototypes have been developed and tested in the laboratory, and more emphasis is now on developing optimal technologies that can efficiently deliver the expected high-contrast levels of such a concept. Following the development of an early near-IR demonstrator, we present and discuss the results of a second-generation prototype using halftone-dot technology. We report improvement in the accuracy of the control of the local transmission of the manufactured prototype, which was measured to be less than 1%. This advanced H-band band-limited device demonstrated excellent contrast levels in the laboratory, down to {approx}10{sup -6} at farther angular separations than 3{lambda}/D over 24% spectral bandwidth. These performances outperform the ones of our former prototype by more than an order of magnitude and confirm the maturity of the manufacturing process. Current and next-generation high-contrast instruments can directly benefit from such capabilities. In this context, we experimentally examine the ability of the band-limited coronagraph to withstand various complex telescope apertures.

Martinez, P. [UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041 (France); Dorrer, C. [Aktiwave, 241 Ashley Drive, Rochester, NY 14620 (United States); Kasper, M. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany)

2012-01-01

141

Structural analysis and thermal influence of Space Solar Telescope  

NASA Astrophysics Data System (ADS)

The Space Solar Telescope (SST), the first astronomical satellite proposal in China, is under researched, developed and manufactured. It is designed to make observations of transient and steady state solar hydrodynamic and magnetohydrodynamic processes. The space-frame of SST provides the mechanical interface between the telescope and instruments, and it is a crucial linker for all the optical, mechanical, and electronic subsystems. Therefore, the structural parts of SST must satisfy sufficient strength, stiffness, and thermal stability requirements of optical and other subsystems under the space environment and in the launching process. This paper first describes the static and dynamic analyses of the original structure by the Finite Element Analysis (FEA) tool. Then, it presents the structure optimization with the objective to enhance the natural frequency under the total weight unchanged. Finally, it verifies the optimized structure and analyzes the thermal influence of SST. The analysis results and structural responses with all the payloads being considered are discussed and illustrated in this paper. Now, SST is in the phase of test and key technology tackle, and some main parts have been finished. All analysis results shown in this paper will be applied to further research and fabrication.

Zhiping, Chen; Yang, Shimo; Hu, Qi-qian

2003-02-01

142

Image Stabilization System for Hinode (Solar-B) Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

The Hinode Solar Optical Telescope (SOT) is the first space-borne visible-light telescope that enables us to observe magnetic-field dynamics in the solar lower atmosphere with 0.2 0.3 arcsec spatial resolution under extremely stable (seeing-free) conditions. To achieve precise measurements of the polarization with diffraction-limited images, stable pointing of the telescope (<0.09 arcsec, 3 ?) is required for solar images exposed on the focal plane CCD detectors. SOT has an image stabilization system that uses image displacements calculated from correlation tracking of solar granules to control a piezo-driven tip-tilt mirror. The system minimizes the motions of images for frequencies lower than 14 Hz while the satellite and telescope structural design damps microvibration in higher frequency ranges. It has been confirmed from the data taken on orbit that the remaining jitter is less than 0.03 arcsec (3 ?) on the Sun. This excellent performance makes a major contribution to successful precise polarimetric measurements with 0.2 0.3 arcsec resolution.

Shimizu, T.; Nagata, S.; Tsuneta, S.; Tarbell, T.; Edwards, C.; Shine, R.; Hoffmann, C.; Thomas, E.; Sour, S.; Rehse, R.; Ito, O.; Kashiwagi, Y.; Tabata, M.; Kodeki, K.; Nagase, M.; Matsuzaki, K.; Kobayashi, K.; Ichimoto, K.; Suematsu, Y.

2008-06-01

143

An integral field spectrograph for the 4-m European Solar Telescope  

NASA Astrophysics Data System (ADS)

This paper presents the proposal of a high resolution, integral field spectrograph that is currently being designed for the 4-meter aperture European Solar Telescope. This instrument is optimized for the study of the solar chromosphere and photosphere to allow the investigation of magnetic phenomena concentrated within these two layers. It will observe a bidimensional field of view of 80 arcsec2 that is reorganized, using an integral field unit, into eight long slits of 200 arcsec length by 0.05 arcsec width. A new concept of image slicer has been specifically designed for this instrument. It is a telecentric system and, because of the symmetry of its layout, it presents several advantages, which are presented in this paper. The spectrograph will have capabilities to observe different layers of the Sun at the same time due to its multi-wavelength capability that allows the observation of 5 visible and 3 near-infrared wavelength intervals from 3900 to 23000 Å{}, with a spectral resolution of about 300,000. In addition, it is designed to offer two modes of operation: spectroscopic and spectro-polarimetric. The optical quality of the instrument is diffraction limited.

Calcines, A.; Collados, M.; López, R. L.

144

Performance simulations for the conceptual design of the European Solar Telescope (EST)  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) is a European collaborative project promoted by the European Association for Solar Telescopes (EAST) to build a high resolution 4m class solar telescope in the Canary Islands. Since 2008 to 2011 a Design Study has been developed to define the Conceptual Design of EST. During the Design Study, several preliminary performance simulations have been developed in order to demonstrate the feasibility of the proposed conceptual design and provide preliminary feedback for the defined top-down error budgets. Performance simulations developed during the Design study include structural FE, servo-control of telescope main axes, CFD analyses of wind load on the telescope, CFD analyses of local seeing, transient thermal analysis of the telescope structure and environment and AO performance. This paper presents a description of the conceptual design of EST and the results of the preliminary performance simulations, mainly focused to obtain the best telescope image quality.

Cavaller, L.; Collados, M.; Castro, J.

2011-09-01

145

Solar System Capabilities of the Thirty Meter Telescope  

NASA Astrophysics Data System (ADS)

The TMT Project is completing the design of a telescope with a primary mirror diameter of 30 m, yielding ten times more light gathering power than the largest current telescopes. It is being designed from the outset as a system that will deliver diffraction-limited resolution (8, 15 and 70 milliarcsec at 1.2, 2.2 and 10 microns, respectively) and high Strehl ratios over a 30 arcsecond science field with good performance over a 2 arcmin field. Studies of a representative suite of instruments that span a very large discovery space in wavelength (0.3-30 microns), spatial resolution, spectral resolution and field-of-view demonstrate their feasibility and their tremendous scientific potential. Of particular interest for solar system research, one of these will be IRIS (Infrared Imaging Spectrometer), a NIR instrument consisting of a diffraction-limited imager and an integral-field spectrometer. IRIS will be able to investigate structures with dimensions of only a few tens of kilometers at the distance of Jupiter. Two other instruments, NIRES and MIRES (Near- and Mid IR Echelle Spectrographs) will enable high angular, high spectral resolution observations of solar system objects from the ground with sensitivities comparable to space-based missions. The TMT system is being designed for extremely efficient operation including the ability to rapidly switch to observations with different instruments to take advantage of “targets-of-opportunity” or changing conditions. Thus TMT will provide capabilities that will enable very significant solar system science and be highly synergistic with JWST, ALMA and other planned astronomy missions.

Crampton, David; Simard, Luc

2009-09-01

146

The tandem Fabry Perot Full-Disk Solar Vector Magnetogram system for the Solar Magnetic Activity Research Telescope (SMART)  

Microsoft Academic Search

For solar and heliospheric physics, energy release mechanism of solar flares and onset of CMEs are one of the most the most important issues. Solar Magnetic Activity Research Telescope (SMART) in Hida observatory Kyoto University aims to investigate the relation between the solar flares and photospheric vector magnetic field. Full disk high resolution H-alpha images as well as and photospheric

K. Otsuji; S. Nagata; S. Ueno; R. Kitai; G. Kimura; Y. Nakatani; T. Ishii; S. Morita; K. Shibata

2009-01-01

147

The Solar Optical Telescope for the Hinode Mission: An Overview  

Microsoft Academic Search

The Solar Optical Telescope (SOT) aboard the Hinode satellite (formerly called Solar-B) consists of the Optical Telescope Assembly (OTA) and the Focal Plane Package (FPP). The OTA is a 50-cm diffraction-limited\\u000a Gregorian telescope, and the FPP includes the narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus the Stokes\\u000a Spectro-Polarimeter (SP). The SOT provides unprecedented high-resolution photometric and vector magnetic

S. Tsuneta; K. Ichimoto; Y. Katsukawa; S. Nagata; M. Otsubo; T. Shimizu; Y. Suematsu; M. Nakagiri; M. Noguchi; T. Tarbell; R. Shine; W. Rosenberg; C. Hoffmann; B. Jurcevich; G. Kushner; M. Levay; B. Lites; D. Elmore; T. Matsushita; N. Kawaguchi; H. Saito; I. Mikami; L. D. Hill; J. K. Owens

2008-01-01

148

Electron-Proton and High Energy Telescopes for Solar Orbiter  

NASA Astrophysics Data System (ADS)

The Energetic Particle Detector (EPD) suite for ESA's Solar Orbiter will provide key measurements to address particle acceleration at and near the Sun. The EPD suite consists of five sensors (STEIN, SIS, EPT, LET and HET). The University of Kiel in Germany is responsible for the design, development, and build of EPT and HET which are presented here. The Electron Proton Telescope (EPT) is designed to cleanly separate and measure electrons in the energy range from 20 - 400 keV and protons from 20 - 7000 keV. The Solar Orbiter EPT electron measurements from 20 - 400 keV will cover the gap with some overlap between suprathermal electrons measured by STEIN and high energy electrons measured by HET. The proton measurements from 20 -7000 keV will cover the gap between STEIN and LET. The Electron and Proton Telescope relies on the magnet/foil-technique. The High-Energy Telescope (HET) on ESA's Solar Orbiter mission, will measure electrons from 300 keV up to about 30 MeV, protons from 10 -100 MeV, and heavy ions from ~20 to 200 MeV/nuc. Thus, HET covers the energy range which is of specific interest for studies of the space environment and will perform the measurements needed to understand the origin of high-energy events at the Sun which occasionally accelerate particles to such high energies that they can penetrate the Earth's atmosphere and be measured at ground level (ground-level events). These measurement capabilities are reached by a combination of solid-state detectors and a scintillator calorimeter which allows use of the dE/dx vs. total E technique for particle identification and energy measurement. The upper limits on energy listed above refer to particles (ions) stopping in the scintillator and careful modeling of HET properties will allow discrimination of forward/backward penetrating particles in a wider energy range. Here we present the current development status of EPT-HET units focusing on the test and calibration results obtained with the demonstration models and present plans for future activities.

Kulkarni, Shrinivasrao R.; Grunau, Jan; Boden, Sebastian; Steinhagen, Jan; Martin, Cesar; Wimmer-Schweingruber, Robert F.; Boettcher, Stephan; Rodríguez-Pacheco, Javier; Seimetz, Lars; Schuster, Bjoern; Kulemzin, Alexander; Wetzel, Moritz; Ravanbakhsh, Ali

2013-04-01

149

Hubble Space Telescope solar array change-out, mission anomalies and returned flight hardware  

Microsoft Academic Search

During the successful First Servicing Mission on the Hubble Space Telescope the two solar arrays were replaced with new and improved solar arrays. An electrical short and four solar array mechanical system anomalies occurred: (1) the upper outer bistem on the +V2 wing had developed kinks and then failed to retract; (2) additional friction between the solar array latch fitting

Cindy Winslow

1995-01-01

150

Layer-oriented adaptive optics for solar telescopes.  

PubMed

First multiconjugate adaptive-optical (MCAO) systems are currently being installed on solar telescopes. The aim of these systems is to increase the corrected field of view with respect to conventional adaptive optics. However, this first generation is based on a star-oriented approach, and it is then difficult to increase the size of the field of view beyond 60-80 arc sec in diameter. We propose to implement the layer-oriented approach in solar MCAO systems by use of wide-field Shack-Hartmann wavefront sensors conjugated to the strongest turbulent layers. The wavefront distortions are averaged over a wide field: the signal from distant turbulence is attenuated and the tomographic reconstruction is thus done optically. The system consists of independent correction loops, which only need to account for local turbulence: the subapertures can be enlarged and the correction frequency reduced. Most importantly, a star-oriented MCAO system becomes more complex with increasing field size, while the layer-oriented approach benefits from larger fields and will therefore be an attractive solution for the future generation of solar MCAO systems. PMID:22885589

Kellerer, Aglaé

2012-08-10

151

A conceptual design for a Cassegrain-mounted high-resolution optical spectrograph for large-aperture telescopes  

NASA Astrophysics Data System (ADS)

We present a conceptual design for a high-resolution optical spectrograph appropriate for mounting at Cassegrain on a large aperture telescope. The design is based on our work for the Gemini High Resolution Optical Spectrograph (CUGHOS) project. Our design places the spectrograph at Cassegrain focus to maximize throughput and blue wavelength coverage, delivering R=40,000 resolving power over a continuous 320-1050 nm waveband with throughputs twice those of current instruments. The optical design uses a two-arm, cross-dispersed echelle format with each arm optimized to maximize efficiency. A fixed image slicer is used to minimize optics sizes. The principal challenge for the instrument design is to minimize flexure and degradation of the optical image. To ensure image stability, our opto-mechanical design combines a cost-effective, passively stable bench employing a honeycomb aluminum structure with active flexure control. The active flexure compensation consists of hexapod mounts for each focal plane with full 6-axis range of motion capability to correct for focus and beam displacement. We verified instrument performance using an integrated model that couples the optical and mechanical design to image performance. The full end-to-end modeling of the system under gravitational, thermal, and vibrational perturbations shows that deflections of the optical beam at the focal plane are <29 ?m per exposure under the worst case scenario (<10 ?m for most orientations), with final correction to 5 ?m or better using open-loop active control to meet the stability requirement. The design elements and high fidelity modeling process are generally applicable to instruments requiring high stability under a varying gravity vector.

Froning, Cynthia S.; Osterman, Steven; Burgh, Eric; Beasley, Matthew; Scowen, Paul; Veach, Todd; Jordan, Steven; Ebbets, Dennis; Lieber, Michael; deCino, James; Castilho, Bruno Vaz; Gneiding, Clemens; César de Oliveira, Antonio

2013-09-01

152

Telescopes and recording systems used by amateurs for studying planets in our solar system - an overview  

NASA Astrophysics Data System (ADS)

During the last couple of years, engaged amateur astronomers have benefited by the rapid development in the field of commercial CCD cameras, video techniques, and the availability of mirror telescopes with high quality. Until recently, such technical equipment and the related handling experience had been reserved to research institutes. This contribution presents the potential capabilities of amateur astronomers and describes the approach to the production of data. The quality of the used telescopes is described with respect to aperture and resolving power; as well as the quantum efficiency of the used sensitive b/w CCD cameras with respect to the detectable wavelength. Beyond these facts the necessary exposure times for CCD images using special filters are discussed. Today's amateur astronomers are able to image the bodies of the solar system in the wavelength range between 340 and 1050 nm [1], [2], [3], [4]. This covers a wide range of the spectrum which is investigated with cameras on board of space telescopes or planetary probes. While space probes usually obtain high-resolution images of individual Surface or atmospheric features of the planets, the images of amateur astronomers show the entire surface of the observed planet. Both datasets together permit a more comprehensive analysis of the data aquired in each case. The "Venus Amateur Observing Project" of the European Space Agency [5] is a first step into a successful co-operation between amateur astronomers and planetary scientists. Individual CCD images captured through the turbulent atmosphere of the Earth usually show characteristic distortions of the arriving wave fronts. If one captures hundreds or thousands of images on a video stream in very short time, there will be always also undistorted images within the data. Computer programmes are available to identify and retrieve these undistorted images and store them for further processing [7]. This method is called "Lucky Imaging" and it allows to achieve nearly the theoretical limit of telescopic resolution. By stacking the undistorted images, the signal-to-noise ratio of the data can be increased significantly. "Lucky Imaging" has become a standard in the amateur community since several years. Contrary to space based observations the data rate is not limited by the capacity of any radio transmission, but only limited by the scanning rate and capacity of a modern computer hard disk. An individual video with the uncompreesed raw data can be as large as 4 to 5 GB. EPSC Abstracts, Vol. 3, EPSC2008-A-00191, 2008 European Planetary Science Congress, Author(s) 2008 In addition to the video data, so-called meta data such as the observing location, the recording time, the used filter, environmental conditions (air temperature, wind velocity, air humidity and Seeing) are also documented. From these meta data, the central meridian (CM) of the observed planet during the time of image acqusition can be determined. After data reduction the resulting images can be used to produce map projections or position measurements of albedo structures on the planetary surface or of details within atmospheric features. Amateur astronomers can observe objects in the solar system for large continuous time periods due to the large number of the existing observers e. g. the members of the Association of Lunar & Planetary Observers [6] and their telescopes. They can and react very fast to special events, since they do not have to submit requests for telescope time to a national or international organization. References: [1] Venusimages in uv-light: B. Gährken: http://www.astrode.de/venus07.htm R. Gerstheimer: http://www.astromanie.de/astromania/galerie/venus/venus.html S. Kowollik: http://www.sternwarte-zollern-alb.de/mitarbeiterseiten/kowollik/venus M. Weigand: http://www.skytrip.de/venus2007.htm [2] Images of planets in visible light: M. Fiedler: http://bilder.astroclub-radebeul.de/kategorien.php?action=showukats&kat=0 R. Gerstheimer: http://www.astromanie.de/ S. Kowollik: http://www.sternwarte-zoll

Kowollik, S.; Gaehrken, B.; Fiedler, M.; Gerstheimer, R.; Sohl, F.; Koschny, D.

2008-09-01

153

Multi-conjugate solar adaptive optics at the Vacuum Tower Telescope on Tenerife  

Microsoft Academic Search

We present a breadboard multi-conjugate adaptive optics (MCAO) system for high angular resolution solar observations which we operate at the Vacuum Tower Telescope. We have developed methods to estimate quantitatively the performance of solar adaptive optics from science data. Several sets of short exposure images of the solar photosphere were analyzed to assess the performance of the MCAO. We demonstrate

Oskar von der Lühe; Thomas Berkefeld; Dirk Soltau

2005-01-01

154

Multispectral solar telescope array II; Soft x-ray\\/euv reflectivity of the multilayer mirrors  

Microsoft Academic Search

In this paper, the authors have developed seven compact soft x-ray\\/EUV (XUV) multilayer-coated and two compact FUV interference-film-coated Cassegrain and Ritchey-Chretien telescopes for a rocket-borne observatory, the Multi-Spectral Solar Telescope Array. The authors report on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

J. W. Weed; R. M. Hoover; M. J. Allen; J. F. Lindblom; R. H. ONeal; C. C. Kankelborg; C. E. DeForest; E. S. Paris; A. B. C. Jr. Walker; T. D. Willis; E. Gluskin; P. Pianetta; P. C. Baker

1991-01-01

155

Multi-conjugate AO for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) will be a 4-meter diameter world-class facility, optimized for studies of the magnetic coupling between the deep photosphere and upper chromosphere. It will specialize in high spatial resolution observations and therefore it has been designed to incorporate an innovative built-in Multi-Conjugate Adaptive Optics system (MCAO). It combines a narrow field high order sensor that will provide the information to correct the ground layer and a wide field low order sensor for the high altitude mirrors used in the MCAO mode. One of the challenging particularities of solar AO is that it has to be able to correct the turbulence for a wide range of observing elevations, from zenith to almost horizon. Also, seeing is usually worse at day-time, and most science is done at visible wavelengths. Therefore, the system has to include a large number of high altitude deformable mirrors. In the case of the EST, an arrangement of 4 high altitude DMs is used. Controlling such a number of mirrors makes it necessary to use fast reconstruction algorithms to deal with such large amount of degrees of freedom. For this reason, we have studied the performance of the Fractal Iterative Method (FriM) and the Fourier Transform Reconstructor (FTR), to the EST MCAO case. Using OCTOPUS, the end-to-end simulator of the European Southern Observatory, we have performed several simulations with both algorithms, being able to reach the science requirement of a homogeneous Strehl higher that 50% all over the 1 arcmin field of view.

Montilla, I.; Béchet, C.; Le Louarn, M.; Tallon, M.; Sánchez-Capuchino, J.; Collados Vera, M.

2012-07-01

156

Conceptual design of the data handling system for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

We present an overview of the conceptual design of the data handling unit of the ECS, the Control System for the European Solar Telescope (EST). We will focus on describing the critical requirements for this unit resulting from the overall design of the telescope, together with its architecture and the results of the feasibility analysis carried out to date.

Ermolli, Ilaria; Cauzzi, Gianna; Collados, Manuel; Paletou, Frederic; Reardon, Kevin; Aboudarham, Jean; Cirami, Roberto; Cosentino, Rosario; Del Moro, Dario; Di Marcantonio, Paolo; Giorgi, Fabrizio; Lafon, Martine; Pietropaolo, Ermanno; Romano, Paolo

2012-09-01

157

Space Solar Telescope Data format Analysis and Configuration  

NASA Astrophysics Data System (ADS)

The Space Solar Telescope (SST) with five payloads onboard is now under researching, developing and manufacturing. These payloads with different observation modes and different original data formats will produce up to 50GB scientific data per day. On board data processing units, such as integration, compression and computation unit, are needed to reduce the data amount to about 10GB to fit the ability of X-band scientific data translating system. And data encoding unit is also necessary to transfer the data into transmittable data format. So the scientific data will have different data formats. In Researching and Developing the SDPU of the SST, how to manage the science data storied in Data Storage Unit (DUS) has become one of the important issues, for the data format should be very convenient for post processing and data recovering on ground. In this paper, the detailed science data flow, corresponding to different observation modes, different data processing sequences and different data formats, will be discussed. Tables and figures are also used to show preliminarily the complex configurations of SST data format.

Geng, Lihong; Sun, Caihong; Wang, Jingyu; Jin, Shengzheng; Xu, Zhiheng

2003-02-01

158

Solar system observations with Spitzer Space Telescope: Preliminary results  

NASA Astrophysics Data System (ADS)

The programs of observations of Solar System bodies conducted in the first year of the operation of the Spitzer Space Telescope as part of the Guaranteed Observing Time allocations are described. Initial results include the determination of the geometric albedos of a number of Kuiper Belt objects and Centaurs from observations of their flux densities at 24 and 70 ?m, and the detection of emission bands in the spectra of several distant asteroids (Trojans) around 10 and 25 ?m. The 10 Kuiper Belt objects observed to date have geometric albedos in the range 0.08-0.15, significantly higher than the earlier estimated 0.04. An additional KBO [(55565) 2002 AW 197] has a geometric albedo of 0.17 ± 0.03. The emission bands in the asteroid spectra are indicative of silicates, but specific minerals have not yet been identified. The Centaur/comet 29P/Schwassmann-Wachmann 1 has a nucleus surface geometric albedo of 0.025 ± 0.01 and its dust production rate was calculated from the properties of the coma. Several other investigations are in progress as the incoming data are processed and analyzed.

Cruikshank, Dale P.

159

Optical focusing and alignment of the Multi-Spectral Solar Telescope Array II payload  

NASA Astrophysics Data System (ADS)

The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket borne observatory designed to image the sun at many spectral lines in soft x-ray, EUV, and FUV wavelengths. Of the nineteen telescopes flown on November 3, 1994 the two Cassegrain telescopes and three of the six Ritchey-Cretien telescopes were focussed at NASA/Marshall Space Flight Center (MSFC) with a Zygo double-pass interferometer to determine the best positions of back focus. The remaining three Ritchey-Cretien and eleven Herschellian telescopes were focussed in situ at White Sands Missile Range by magnifying the telescopic image through a Gaertner traveling microscope and recording the position of best focus. From the data obtained at visible wavelengths, it is not unreasonable to expect that many of our telescopes did attain the sub-arc second resolution for which they were designed.

Gore, David B.; Hadaway, James B.; Hoover, Richard B.; Walker, Arthur B.; Kankelborg, Charles C.

1995-06-01

160

First-order adaptive system for correction of images in solar ground-based telescopes  

Microsoft Academic Search

The possibility of applying adaptive-optics devices to ground- based solar astronomy and high-resolution spectroscopy is considered. Due to atmospheric turbulence the resolution of ground-based solar telescopes are limited to 1 arcsec on the average with short period of subarcsecond resolution at good sites. Application of adaptive correction is a ground-based telescope to improve image quality is possible to improve whole

Leonid V. Antoshkin; A. B. Borovik; Nina N. Botygina; Alexei V. Bulatov; Oleg N. Emaleev; N. M. Firstova; Boris V. Fortes; Victor M. Grigoryev; P. G. Kovadlo; L. N. Lavrinova; Vladimir P. Lukin; A. I. Petrov; Valery I. Skomorovsky; A. P. Yankov

2000-01-01

161

Telescopes  

NSDL National Science Digital Library

Astronomy notes is an educational resource for introductory astronomy classes for undergraduates. This section discusses refracting, reflecting, and radio telescopes. Definitions and properties of light-gathering power, resolving power, and magnifying power are also included.

Strobel, Nick

2004-07-16

162

Current concept for the 4m European Solar Telescope (EST) optical design  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) is a pan-european project (with 29 partners, plus 7 collaborating institutions, from 14 countries) for the conceptual design study of a 4-meter class solar telescope promoted by the European Association for Solar Telescopes (EAST) to be located in the Canary Islands. The telescope, in the conceptual study, provides a Coudé focus with an F/50 telecentric beam. It is diffraction-limited in a FOV of 1 arcmin and it will be optimized in throughput for several instruments observing simultaneously in a spectral range from 0.39 ?m to 2.3 ?m. Its innovative concept integrates an optical transfer stage assembling multiconjugated adaptive optics with optical field de-rotation and with a perfect balance of the whole system in terms of polarization being time and wavelength invariant.

Sánchez-Capuchino, J.; Collados, M.; Soltau, D.; López, R.; Rasilla, J. L.; Gelly, B.

2010-07-01

163

Paraboloidal X-ray telescope mirror for solar coronal spectroscopy  

Microsoft Academic Search

The telescope mirror for the X-ray Spectrograph Spectrometer Telescope System is a sixty degree sector of an extreme off-axis paraboloid of revolution. It was designed to focus a coronal region 1 by 10 arc seconds in size on the entrance slit of the spectrometer after reflection from the gold surface. This paper discusses the design, manufacture, and metrology of the

W. A. Brown; E. C. Bruner Jr.; L. W. Acton; A. Franks; M. Stedman; R. J. Speer

1979-01-01

164

Telescopes  

NSDL National Science Digital Library

These lecture notes describe the main features of optical-band telescopes---i.e. those which operate in or near the part of the EM spectrum to which our eyes are sensitive. It also provides a link to an applet illustrating the differences between refraction, reflection, and diffraction and a video on "seeing" produced by the Earth's atmosphere.

O'Connell, Robert

2005-06-28

165

Solar System Capabilities of the Thirty Meter Telescope  

Microsoft Academic Search

The TMT Project is completing the design of a telescope with a primary mirror diameter of 30 m, yielding ten times more light\\u000a gathering power than the largest current telescopes. It is being designed from the outset as a system that will deliver diffraction-limited\\u000a resolution (8, 15 and 70 milliarcsec at 1.2, 2.2 and 10 microns, respectively) and high Strehl ratios over a

David Crampton; Luc Simard

2009-01-01

166

New telescopes in China  

NASA Astrophysics Data System (ADS)

This paper covers the main aspects of three new optical telescopes: a 1.26 m aperture one for use in the infrared, a 1.56 m aperture one for astrometry, and a 2.16 m reflector for general astrophysical work. It also briefly mentions the 13.7 m telescope designed for the mm wavelength band, the first VLBI in China and the meter wavelength aperture synthesis telescope. All these telescopes, optical and radio, are now being built in China.

Gong, S.-M.

1986-01-01

167

Simulation Research on the Solar Hard X-Ray Imaging Telescope  

NASA Astrophysics Data System (ADS)

The hard X-ray imaging telescope of the modulation collimator type is widely used in current solar observations. The spatial modulation telescope is the telescope which keeps its central axis not rotate, suitable for the satellite of 3-axis attitude stabilization. For the possible Chinese solar mission in the near future, we make a design of hard X-ray imaging telescope, and simulate the photon counting using the common simulation software GEANT4. Then we implement the image reconstruction with MATLAB, and compare the reconstructed image of the photons simulated by GEANT4 with that of the photons calculated by the geometric algorithm. The results show that the simulated one by GEANT4 is more closer to the reality than that obtained by the geometric algorithm. An executable design is also proposed at last.

Teng, Teng; Wu, Jian; Chang, Jin

2012-04-01

168

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Astrophysics Data System (ADS)

In parabolic dish solar collectors, walk-off of the spot of concentrated sunlight is a hazard if a malfunction causes the concentrator to stop following the Sun. Therefore, a test program was carried out to evaluate the behavior of various ceramics, metals, and polymers under solar irradiation of about 7000 kW/sq m. (peak) for 15 minutes. The only materials that did not slump or shatter were two grades of medium-grain extruded graphite. High purity, slip-cast silica might be satisfactory at somewhat lower flux. Oxidation of the graphite appeared acceptable during tests simulating walk-off, acquisition (2000 cycles on/off Sun), and spillage (continuous on-Sun operation).

Jaffe, L. D.

1983-08-01

169

The MultiSpectral Solar Telescope Array. II - Soft X-ray\\/EUV reflectivity of the multilayer mirrors  

Microsoft Academic Search

We have developed seven compact soft X-ray\\/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chretien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

Troy W. Barbee Jr.; J. W. Weed; Richard B. C. Hoover Jr.; Max J. Allen; Joakim F. Lindblom; Ray H. O'Neal; Charles C. Kankelborg; Craig E. Deforest; Elizabeth S. Paris; Arthur B. C. Walker

1992-01-01

170

The MultiSpectral Solar Telescope Array II: Soft X-ray\\/EUV reflectivity of the multilayer mirrors  

Microsoft Academic Search

The authors have developed seven compact soft X-ray\\/EUV (XUV) multilayer coated and two compact FUV interference film coated Cassegrain and Ritchey-Chrétien telescopes for a rocket borne observatory, the Multi-Spectral Solar Telescope Array. They report on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes.

T. W. Barbee; J. W. Weed; R. B. Hoover; M. J. Allen; J. F. Lindblom; R. H. O'Neal; C. C. Kankelborg; C. E. Deforest; E. S. Paris; A. B. C. Walker Jr.; T. D. Willis; E. Gluskin; P. Pianetta; P. C. Baker

1992-01-01

171

Adaptive optics real time processing design for the advanced technology solar telescope  

NASA Astrophysics Data System (ADS)

The four meter Advanced Technology Solar Telescope (ATST) adaptive optics (AO) system will require at least twenty-four times the real time processing power as the Dunn Solar Telescope AO system. An FPGA solution for ATST AO real time processing is being pursued instead of the parallel DSP approach used for the Dunn AO76 system. An analysis shows FPGAs will have lower latency and lower hardware cost than an equivalent DSP solution. Interfacing to the proposed high speed camera and the deformable mirror will be simpler and have lower latency than with DSPs. This paper will discuss the current design and progress toward implementing the FPGA solution.

Richards, Kit

2012-07-01

172

Effect of High Receiver Thermal Loss Per Unit Area on the Performance of Solar Central Receiver Systems Having Optimum Heliostat Fields and Optimum Receiver Aperture Areas  

Microsoft Academic Search

Recent efforts in solar central receiver research have been directed toward high temperature applications. Associated with high temperature processes are greater receiver thermal losses due to reradiation and convection. This dissertation examines the performance of central receiver systems having optimum heliostate fields and receiver aperture areas as a function of receiver thermal loss per unit area of receiver aperture. The

Charles L. Pitman

1983-01-01

173

Study of a Solar X-Ray Telescope  

Microsoft Academic Search

The highly structured nature of the outer solar atmosphere seems to be intimately linked to the presence, at the solar surface, of magnetic fields that have been generated inside the Sun and have emerged to the surface. The corona is brightest (and also hottest) at just those locations where the magnetic field has emerged from inside the Sun. Dynamo theory

Leon Golub

1997-01-01

174

Study of a Solar X-Ray Telescope.  

National Technical Information Service (NTIS)

The highly structured nature of the outer solar atmosphere seems to be intimately linked to the presence, at the solar surface, of magnetic fields that have been generated inside the Sun and have emerged to the surface. The corona is brightest (and also h...

L. Golub

1997-01-01

175

Impacts on Hubble Space Telescope solar arrays: Discrimination between natural and man-made particles  

Microsoft Academic Search

A Post-Flight Investigation was initiated by the European Space Agency to analyze impacts on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600km altitude. The solar cells deployed during the first Service Mission (SM-1 in December 1993) were retrieved in March 2002 as part of Service Mission 3B (SM-3B). A sub-panel of

A. T. Kearsley; G. Drolshagen; J. A. M. McDonnell; J.-C. Mandeville; A. Moussi

2005-01-01

176

Impacts on Hubble Space Telescope solar arrays: Discrimination between natural and man-made particles  

Microsoft Academic Search

A Post-Flight Investigation was initiated by the European Space Agency to analyze impacts on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600 km altitude. The solar cells deployed during the first Service Mission (SM-1 in December 1993) were retrieved in March 2002 as part of Service Mission 3B (SM-3B). A sub-panel

A. T. Kearsley; G. Drolshagen; J. A. M. McDonnell; J.-C. Mandeville; A. Moussi

2005-01-01

177

Plasma diagnostic capabilities of the Soft X-ray Telescope on Solar-A  

Microsoft Academic Search

The predicted response of the Solar-A Soft X-ray Telescope (SXT) to various solar targets is presented. It is found that the SXT is very sensitive and should be able to observe active regions and flares at its nominal cadence with exposure times ranging from 0.0001 to 1 s. The SXT temperature diagnostic capabilities are presented for various combinations of the

K. T. Strong; L. W. Acton; W. A. Brown; E. S. Claflin; J. R. Lemen

1991-01-01

178

PET: a proton\\/electron telescope for studies of magnetospheric, solar, and galactic particles  

Microsoft Academic Search

The proton\\/electron telescope (PET) on SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) is designed to provide measurements of energetic electrons and light nuclei from solar, Galactic, and magnetospheric sources. PET is an all solid-state system that will measure the differential energy spectra of electrons from ~1 to ~30 MeV and H and He nuclei from ~20 to ~300 MeV\\/nucleon, with

W. R. Cook; A. C. Cummings; J. R. Cummings; T. L. Garrard; B. Kecman; R. A. Mewaldt; R. S. Selesnick; E. C. Stone; D. N. Baker; T. T. von Rosenvinge; J. B. Blake; L. B. Callis

1993-01-01

179

The Soft X-ray Telescope for the SOLAR-A mission  

Microsoft Academic Search

The Soft X-ray Telescope (SXT) of the SOLAR-A mission is designed to produce X-ray movies of flares with excellent angular and time resolution as well as full-disk X-ray images for general studies. A selection of thin metal filters provide a measure of temperature discrimination and aid in obtaining the wide dynamic range required for solar observing. The co-aligned SXT aspect

S. Tsuneta; L. Acton; M. Bruner; J. Lemen; W. Brown; R. Caravalho; R. Catura; S. Freeland; B. Jurcevich; M. Morrison; Y. Ogawara; T. Hirayama; J. Owens

1991-01-01

180

The daytime use of Adaptive Optics for solar and stellar Extremely Large Telescopes  

Microsoft Academic Search

Now Single Conjugate Adaptive Optics (SCAO) has been successfully implemented on both nighttime and solar telescopes, there is a rapidly growing interest in developing, what will be the next step in astronomical adaptive optics, Multi-Conjugate Adaptive Optics (MCAO). MCAO aims at breaking the small field-of-view barrier inherent in SCAO. MCAO is considered an essential component for both future solar and

Jacques Beckers

2002-01-01

181

A long duration balloon-borne telescope for solar gamma-ray astronomy  

Microsoft Academic Search

A new solar ?-ray telescope is described which is intended to take advantage of current long-duration balloon facilities such as the RACOON system. The primary scientific objective is to detect and measure ?-ray lines from solar flares along with the associated low-energy continuum. The proposed instrument is centered on a multi-headed germanium system and is designed to operate over the

Alan Owens; Edward L. Chupp; Philip P. Dunphy

1989-01-01

182

The Large Millimeter Telescope and Solar Like Stars  

NASA Astrophysics Data System (ADS)

This paper describes the current status of the Large Millimeter Telescope (LMT), the near-term plans for the telescope and the initial suite of instrumentation. It also briefly describes two astronomical branches in which the LMT will certainly have a major impact: the study of thermal emission of circumstellar material around main sequence stars and the analysis of the molecular contents of this material in relatively young stars. The LMT is a bi-national collaboration between Mexico and the USA, led by the Instituto Nacional de Astrofísica, Optica y Electrónica (INAOE) and the University of Massachusetts at Amherst, to construct, commission and operate a 50m-diameter millimeter-wave radio telescope. Construction of the telescope structure is complete at the 4600 m LMT site on the summit of Volcán Sierra Negra, an extinct volcano in the Mexican state of Puebla. First-light with the LMT was successfully conducted in June and July 2011 with observations at both 3 and 1.1 mm. The commissioning and future scientific operation of the LMT is divided into two major phases. As part of phase I, following the improvement in the alignment of the surface segments within the inner 32 meter diameter of the antenna, the project will begin the first shared risk scientific observations in the spring of 2013. In phase II, we will continue the installation and alignment of the remainder of the reflector surface, after which the final commissioning of the full 50m LMT will take place. The LMT antenna, outfitted with its initial complement of scientific instruments, will be a world-leading scientific research facility for millimeter-wave astronomy.

Chavez, M.; Hughes, D.; LMT Project Team

2013-04-01

183

Progress Report of the New Solar Submm-Wave Telescope (SST) Installation  

Microsoft Academic Search

The Solar Sub-Millimeter wave Telescope (SST) is now in its final stage of construction and a definite schedule has been established. The 1.5 m diameter reflector has been completed and presents an excellent surface with a deviation of 18 microns (r.m.s.). The reflector construction employed the new \\

P. Kaufman; Andreas Magun; Hugo Levato; Marta Rovira; Kaspar Arzner; Emilia Correia; J. E. R. Costa; C. G. Giménez de Castro; N. Kämpfer; J.-P. Raulin; Eric Rolli; A. V. R. Silva

1999-01-01

184

Power emitted by a nearby solar system and intercepted by a system of apertures near Earth  

Microsoft Academic Search

We analyze the power collection ability of a multiple aperture configuration for geometry where the source and the collector lateral distances are enormously smaller than their separation, as in the case of detection of a nearby planetary system from the Earth or its vicinity. We show that the size, shape, orientation of, or spacing between the individual apertures in a

Marija Strojnik

2009-01-01

185

Progress toward large-aperture membrane mirrors  

NASA Astrophysics Data System (ADS)

The Air Force Research Laboratory (AFRL) is exploring the feasibility of large-aperture, deployable, space-based membrane telescopes operating in the visible and/or near- infrared spectral regions. One of the near-term goals of this work is to develop an understanding of available and achievable membrane materials, specifically concentrating on practical techniques to form large aperture membranes with the necessary surface quality and economy. When this research began a little more than three years ago, the conceptual design was based upon a totally inflatable structure. An inflatable structure has been used for space solar power collection and radio frequency antennas. This totally inflatable lenticular design is simple and relatively easy to demonstrate, but maintaining inflation during an extended lifetime in near-earth orbit may not be feasible. Recently, a new concept for a membrane telescope has emerged which does not depend on sustained inflation during operation. Thin membranes on the order of 10 to 100 micrometer thick will be packaged and deployed, maintaining their surface figure by means other than inflation. Given the fact that the sub- wavelength level surface tolerances required of imaging telescopes will probably not be practical with a membrane- based telescope, such systems will probably rely on real-time holography or some other wavefront correction or compensation technique. We will discuss the primary experimental work ongoing in the AFRL Membrane Mirror Laboratory, and in doing so, some of the issues relevant to demonstrating a practical, large-aperture membrane mirror system.

Rotge, James R.; Dass, Shiv C.; Marker, Dan K.; Carreras, Richard A.; Lutz, B.; Duneman, Dennis C.

2000-10-01

186

The SOLAR-C Mission: Plan B Payload Concept  

NASA Astrophysics Data System (ADS)

The telescope concepts for the SOLAR-C Plan B mission as of the time of the Hinode-3 meeting were briefly presented for having comments from the international solar physics community. The telescope candidates are 1) near IR-visible-UV telescope with 1.5m aperture and enhanced spectro-polarimetric capability, 2) UV/EUV high throughput spectrometer, and 3) next generation X-ray telescope.

Shimizu, T.; Sakao, T.; Katsukawa, Y.; Group, J. S. W.

2012-08-01

187

Solar observations with a low frequency radio telescope  

NASA Astrophysics Data System (ADS)

We have set up a low frequency radio monitoring station for solar bursts at the Observatory of the Aristotle University in Thessaloniki. The station consists of a dual dipole phased array, a radio receiver and a dedicated computer with the necessary software installed. The constructed radio receiver is based on NASA's Radio Jove project. It operates continuously, since July 2010, at 20.1 MHz (close to the long-wavelength ionospheric cut-off of the radio window) with a narrow bandwidth (~5 kHz). The system is properly calibrated, so that the recorded data are expressed in antenna temperature. Despite the high interference level of an urban region like Thessaloniki (strong broadcasting shortwave radio stations, periodic experimental signals, CBs, etc), we have detected several low frequency solar radio bursts and correlated them with solar flares, X-ray events and other low frequency solar observations. The received signal is monitored in ordinary ASCII format and as audio signal, in order to investigate and exclude man-made radio interference. In order to exclude narrow band interference and calculate the spectral indices of the observed events, a second monitoring station, working at 36 MHz, is under construction at the village of Nikiforos near the town of Drama, about 130 km away of Thessaloniki. Finally, we plan to construct a third monitoring station at 58 MHz, in Thessaloniki. This frequency was revealed to be relatively free of interference, after a thorough investigation of the region.

Myserlis, I.; Seiradakis, J.; Dogramatzidis, M.

2012-01-01

188

Current concept for the 4m European Solar Telescope (EST) optical design  

NASA Astrophysics Data System (ADS)

The European Solar Telescope (EST) is a 4-m class solar telescope to be located in the Canary Islands which is currently in its conceptual design study. EST is a pan-european project (with 29 partners, plus 7 collaborating institutions, from 14 countries) promoted by the European Association for Solar Telescopes (EAST). In the current concept, the main telescope and its transfer optics assemblies 14 mirrors to provide a Science Coudé Focus with an F/50 telecentric beam. It is diffraction-limited in a FOV of 1 arcmin with an unvignetted FOV of 2'x2'. The whole system is being optimized in throughput for several instruments observing simultaneously in a spectral range from 0.39 ?m to 2.3 ?m. Its innovative concept integrates an optical transfer stage assembling multiconjugated adaptive optics with optical field de-rotation and with a perfect balance of the whole system in terms of polarization being also time and wavelength invariant.

Sánchez Capuchino, J.; Collados, M.; Soltau, D.; López, R.; Rasilla, J. L.; Gelly, B.

2010-07-01

189

Concept study of an Extremely Large Hyper Telescope (ELHyT) with 1200m sparse aperture for direct imaging at 100 micro-arcsecond resolution  

NASA Astrophysics Data System (ADS)

The hypertelescope construction initiated in the Southern Alps (Labeyrie et al., this conference) has provided some preliminary operating experience indicating that larger versions, up to perhaps 1200m, are probably feasible at suitable sites. The Arecibo-like architecture of such instruments does not require the large mount and dome which dominate the cost of a 40m ELT. For the same cost, an "Extremely Large Hyper Telescope” ( ELHyT) may therefore have a larger collecting area. It may thus in principle reach higher limiting magnitudes, both for seeing-limited and, if equipped with a Laser Guide Star and adaptive phasing, for high-resolution imaging with gain as the size ratio, i.e. about 30 with respect to a 40m ELT. Like the radio arrays of antennas, such instruments can be grown progressively. Also, they can be up-graded with several focal gondolas, independently tracking different sources. Candidate sites have been identified in the Himalaya and the Andes. We describe several design options and compare the science achievable for both instruments, ELTs and ELHyTs. The broad science addressed by an ELHyT covers stellar chromospheres, transiting exoplanets and those requiring a high dynamic range, achieved by array apodization or coronagraphy. With a Laser Guide Star, it extends to faint compact sources beyond the limits of telescopes having a smaller collecting area, supernovae, active galactic nuclei, gamma ray bursts. The sparse content of remote galaxies seen in the Hubble Deep Field appears compatible with the crowding limitations of an ELHyT having 1000 apertures.

Labeyrie, Antoine; Mourard, Denis; Allouche, Fatmé; Chakraborthy, Rijuparna; Dejonghe, Julien; Surya, Arun; Bresson, Yves; Aime, Claude; Mary, David; Carlotti, Alexis

2012-07-01

190

Implementation of 1-bit Image Correlator on the Space Solar Telescope  

NASA Astrophysics Data System (ADS)

2-D image correlation tracking is a key factor for the Main Optical Telescope on the Space Solar Telescope to reach its 0.1" spatial resolution. In order to realize fast image correlation, 1-bit correlation arithmetic is proposed, and the hardware design of 1-bit correlator based on DSP and FPGA is given. Only 0.33 ms is needed to realize a 32 × 32 image correlation algorithm on XCV800 FPGA chip with 20 MHz clock. The FPGA resource consumption is only 1/9 that of FFT - based (12-bit data) correlator.

Jiang, Zhao; Jin, Sheng-Zhen; Jiang, Ai-Min

2007-06-01

191

STELLAR TIDAL STREAMS IN SPIRAL GALAXIES OF THE LOCAL VOLUME: A PILOT SURVEY WITH MODEST APERTURE TELESCOPES  

SciTech Connect

Within the hierarchical framework for galaxy formation, minor merging and tidal interactions are expected to shape all large galaxies to the present day. As a consequence, most seemingly normal disk galaxies should be surrounded by spatially extended stellar 'tidal features' of low surface brightness. As part of a pilot survey for such interaction signatures, we have carried out ultra deep, wide field imaging of eight isolated spiral galaxies in the Local Volume, with data taken at small (D = 0.1-0.5 m) robotic telescopes that provide exquisite surface brightness sensitivity ({mu}{sub lim}(V) {approx} 28.5 mag arcsec{sup -2}). This initial observational effort has led to the discovery of six previously undetected extensive (to {approx}30 kpc) stellar structures in the halos surrounding these galaxies, likely debris from tidally disrupted satellites. In addition, we confirm and clarify several enormous stellar over-densities previously reported in the literature, but never before interpreted as tidal streams. Even this pilot sample of galaxies exhibits strikingly diverse morphological characteristics of these extended stellar features: great circle-like features that resemble the Sagittarius stream surrounding the Milky Way, remote shells and giant clouds of presumed tidal debris far beyond the main stellar body, as well as jet-like features emerging from galactic disks. Together with presumed remains of already disrupted companions, our observations also capture surviving satellites caught in the act of tidal disruption. A qualitative comparison with available simulations set in a {Lambda}Cold Dark Matter cosmology (that model the stellar halo as the result of satellite disruption evolution) shows that the extraordinary variety of stellar morphologies detected in this pilot survey matches that seen in those simulations. The common existence of these tidal features around 'normal' disk galaxies and the morphological match to the simulations constitutes new evidence that these theoretical models also apply to a large number of other Milky Way-mass disk galaxies in the Local Volume.

MartInez-Delgado, David; Zibetti, Stefano; Rix, Hans-Walter [Max Planck Institut fuer Astronomie, Heidelberg (Germany); Gabany, R. Jay [Black Bird Observatory, Mayhill, NM (United States); Crawford, Ken [Rancho del Sol Observatory, Modesto, CA (United States); Majewski, Steven R.; McDavid, David A. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Fliri, Juergen; Carballo-Bello, Julio A.; Bardalez-Gagliuffi, Daniella C.; Trujillo, Ignacio [Instituto de Astrofisica de Canarias, La Laguna (Spain); Penarrubia, Jorge [Institute of Astronomy, University of Cambridge (United Kingdom); Chonis, Taylor S. [Department of Astronomy, University of Texas, Austin, TX 78712-0259 (United States); Madore, Barry [The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Schirmer, Mischa [Argelander Institut fuer Astronomie, Universitaet Bonn (Germany)

2010-10-15

192

Measurement of solar vector magnetic fields using Kodaikanal tower telescope  

NASA Astrophysics Data System (ADS)

A Stokes polarimeter was built at the Kodaikanal Tower Telescope to study the vector field map of active regions like sunspot using the well known Fe I lines 6301.5 Å and 6302.5 Å lines. The Mueller matrix of the polarimeter was obtained using simple laboratory and field tests. The instrumental polarisation due to the oblique reflections are removed before the observed Stokes profiles were analysed. The advanced Stokes Polarimeter data analysis program (ASP code) was used to invert the corrected Stokes profiles to calculate the vector magnetic field parameters of NOAA 8951. The maximum field strength obtained at the umbra of the sunspot was 2500 Gauss. The variation of the field strength, the line-of-sight angle and the azimuthal angle along a cut which passes through the umbra resembles that of a simple round sunspot. The accuracy in the calculation of the vector field is high in the umbra and low in the outer edge of the penumbra of the observed sunspot. The range of errors in the calculation of the field strength, line-of-sight inclination angle, and the azimuthal angle of the magnetic vector are 20-100 Gauss, 1-5O, and 12-20O respectively. We also find a good fit for the observed Stokes profiles of the Ti I line at 6303.78 Å with a synthetic profile produced using the vector field parameters derived from the Fe I 6301.5 Å and 6302.5 Å lines.

Sankarasubramanian, R.; Rangarajan, K. E.; Ramesh, K. B.

2002-06-01

193

Modeling and analysis of ring telescope  

NASA Astrophysics Data System (ADS)

Ring aperture telescope is a new kind of telescope, it has complete U-V coverage and the limiting resolution equivalent to that of a full aperture telescope with the same diameter. There are two ring telescope proposals in China. One is 30m Ring Interferometric Telescope (RIT), its primary mirror is expected to be composed by 90 segments; another is 8m Chinese Giant Solar Telescope (CGST), its primary mirror is expected to be composed by 24 segments if segmented mirror scheme is adopted . In this paper, an overview of ring telescope and modeling for it are introduced. The main difference and characteristic in active control strategy and adaptive optics implementation between ring segmented telescope and full segmented telescope are pointed out. Detailed analysis about these two aspects are presented. The results of simulation and analysis show that the current strategies on active control and adaptive optics could meet the demand of most science cases not only in infrared waveband but also in near infrared even in visible waveband.

Dai, Yichun; Lin, Jing

2011-09-01

194

Multi-spectral solar telescope array II; Soft x-ray/euv reflectivity of the multilayer mirrors  

SciTech Connect

In this paper, the authors have developed seven compact soft x-ray/EUV (XUV) multilayer-coated and two compact FUV interference-film-coated Cassegrain and Ritchey-Chretien telescopes for a rocket-borne observatory, the Multi-Spectral Solar Telescope Array. The authors report on extensive measurements of the efficiency and spectral bandpass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

Barbee, T.W. Jr.; Weed, J.W. (Lawrence Livermore National Lab., Livermore, CA (US)); Hoover, R.M. (NASA Marshall Space Flight Center, Space Science Lab., Huntsville, AL (US)); Allen, M.J.; Lindblom, J.F.; O'Neal, R.H.; Kankelborg, C.C.; DeForest, C.E.; Paris, E.S.; Walker, A.B.C. Jr.; Willis, T.D. (Stanford Univ., Center for Space Science and Astrophysics, Stanford, CA (US)); Gluskin, E. (Argonne National Lab., Argonne, IL (US)); Pianetta, P. (Stanford Univ., Stanford Synchrotron Radiation Lab., Stanford, CA (US)); Baker, P.C. (Baker Consulting, Walnut Creek, CA (US))

1991-08-01

195

An updated 37-element low-order solar adaptive optics system for 1-m new vacuum solar telescope at Full-Shine Lake Solar Observatory  

NASA Astrophysics Data System (ADS)

A low-order solar adaptive optics (AO) system, which consists of a fine tracking loop with a tip/tilt mirror and a correlation tracker, and a high-order correction loop with a 37-element deformable mirror, a correlating Shack-Hartmann wavefront sensor and a high-order wavefront correction controller, had been successfully developed and installed at 1-m New Vacuum Solar Telescope of Full-shine Lake (also called Fuxian Lake) Solar Observatory. This system is an update of the 37-element solar AO system designed for the 26-cm Solar Fine Structure Telescope at Yunnan Astronomical Observatory in 2009. The arrangement of subapertures of the Shack-Hartmann wavefront sensor was changed from square to hexagon to achieve better compensation performance. Moreover, the imaging channel of the updated system was designed to observe the Sun at 710nm and 1555nm simultaneously. The AO system was integrated into the solar telescope in 2011, and AO-corrected high resolution sunspots and granulation images were obtained. The observational results show that the contrast and resolution of the solar images are improved evidently after the correction by the AO system.

Rao, Changhui; Zhu, Lei; Gu, Naiting; Rao, Xuejun; Zhang, Lanqiang; Guan, Chunlin; Chen, Donghong; Chen, Shanqiu; Wang, Cheng; Lin, Jun; Liu, Zhong

2012-07-01

196

Solar-array-induced disturbance of the Hubble space telescope pointing system  

NASA Astrophysics Data System (ADS)

The investigation of the vibrational disturbances of the Hubble Space Telescope that were discovered soon after deployment in orbit is described in detail. It was found that the disturbances were particularly evident during orbital day-night crossings, and that the magnitude of the disturbances was considerably larger than the design jitter requirement. This paper describes the process by which the vibrations were characterized and isolated to a particular mechanism. The analysis of the flight data and comparisons with computer simulation results showed that the source of the disturbances was the thermally driven deformation of the solar arrays in conjunction with frictional effects in the array mechanisms. The control system was successfully modified to attenuate the disturbances to tolerable levels pending mechanical and thermal redesign of the solar arrays. The new arrays were installed during the first Space Telescope servicing mission, and in combination with the enhanced control system algorithm reduced the disturbances to satisfactory levels.

Foster, Carlton L.; Tinker, Michael L.; Nurre, Gerald S.; Till, William A.

1995-07-01

197

Study of a Solar X-Ray Telescope  

NASA Astrophysics Data System (ADS)

The highly structured nature of the outer solar atmosphere seems to be intimately linked to the presence, at the solar surface, of magnetic fields that have been generated inside the Sun and have emerged to the surface. The corona is brightest (and also hottest) at just those locations where the magnetic field has emerged from inside the Sun. Dynamo theory predicts that strong magnetic fields will be generated deep in the solar interior and that bundles or 'ropes' of magnetic flux will float to the surface. When this happens, a magnetically bipolar region will become visible, extending above the surface in a three-dimensional structure. The field lines penetrate through the surface, showing two magnetic poles, and also exhibit a three-dimensional structure above the surface. The structure created by the field emergence is rooted in the (relatively) cool photosphere and extends through the chromosphere and transition region to the corona. Thus, the magnetic field creates a region, called an active region, which contains portions at temperatures from less than 104 K to greater than 106 K, and is therefore visible at wavelengths from the infrared through x-rays. The locations where the magnetic field leaves and reenters the visible surface are called the 'footpoints' of the coronal structures associated with the magnetic field. The magnetic fields themselves are not directly visible. However, the hot coronal plasma is, for the most part, constrained to follow the direction of the magnetic field lines in the atmosphere. Now, 100 years after the discovery of x-rays by Wilhelm Roentgen in 1896, we can routinely make observations of the solar corona from outside the Earth's atmosphere in this region of the electromagnetic spectrum. As shown by comparing x-ray images with magnetograms, the bright corona over these bipolar magnetic regions consists of closed structures that seem to follow the orientation of the magnetic field. Although we can see down to the photosphere at x-ray wavelengths when observing the disk of the Sun, this part of the solar atmosphere emits so little that far from the peak of its Planck curve it appears dark in x-ray images. This impression of hot plasma following the magnetic field direction is further strengthened by quantitative studies that calculate coronal magnetic field strength and direction based on photospheric measurements and compare them with the observed brightness and location of the x-ray emitting structures. Such comparisons make it clear that, for the most part, the hot plasma conforms to the geometry of the magnetic field and that the coronal brightness is strongly linked to the strength of the magnetic fields which have erupted to the solar surface from the interior. It is also the case that the larger-scale, fainter corona, as well as coronal holes, are strongly influenced by the large-scale solar magnetic field. We may get a small hint of the reason that the coronal plasma outlines the direction of B by examining the thermal conductivity of a hot plasma in the presence of a magnetic field. This quantity has enormously different values in the directions parallel and perpendicular to the field for a coronal temperature of 106 K, a particle density of 109/cu cm and a magnetic field strength of 100 G, the conductivity along the field is approximately 13 orders of magnitude greater than that perpendicular to the field. It is therefore not surprising that a parcel of plasma which is locally heated would conduct that heat preferentially in the direction of the field. We also note that the thermal conductivity parallel to the magnetic field increases with temperature T, while the perpendicular conductivity decreases. To the extent that the loop aspect ratio, i.e., the ratio of loop length to loop width, is determined by the thermal conductivity, we would expect that higher temperature loops are longer and thinner than cooler ones. However, if the loop width becomes smaller than the spatial resolution of the observing instrument, this effect will not be directly observable. For organizational

Golub, Leon

1997-05-01

198

Prototype tests for the CELESTE solar array gamma-ray telescope.  

NASA Astrophysics Data System (ADS)

The CELESTE experiment will be an atmospheric Cherenkov detector designed to bridge the gap in energy sensitivity between current satellite and ground-based gamma-ray telescopes, 20 - 300 GeV. The authors present test results made at the former solar power plant, Themis, in the French Pyrenees. The tests confirm the viability of using a central tower heliostat array for Cherenkov wavefront sampling.

Giebels, B.; Bazer-Bachi, R.; Bergeret, H.; Cordier, A.; Debiais, G.; Denaurois, M.; Dezalay, J. P.; Dumora, D.; Eschstruth, P.; Espigat, P.; Fabre, B.; Fleury, P.; Ghesquiere, C.; Herault, N.; Malet, I.; Merkel, B.; Meynadier, C.; Palatka, M.; Pare, E.; Procureur, J.; Punch, M.; Quebert, J.; Ragan, K.; Rob, L.; Schovanek, P.; Smith, D. A.; Vrana, J.

1998-08-01

199

Prototype tests for the CELESTE solar array gamma-ray telescope  

Microsoft Academic Search

The CELESTE experiment will be an atmospheric Cherenkov detector designed to bridge the gap in energy sensitivity between current satellite and ground-based gamma-ray telescopes, 20–300GeV. We present test results made at the former solar power plant, Themis, in the French Pyrenees. The tests confirm the viability of using a central tower heliostat array for Cherenkov wavefront sampling.

B. Giebels; R. Bazer-Bachi; H. Bergeret; A. Cordier; G. Debiais; M. Denaurois; J. P. Dezalay; D. Dumora; P. Eschstruth; P. Espigat; B. Fabre; P. Fleury; C. Ghesquiere; N. Herault; I. Malet; B. Merkel; C. Meynadier; M. Palatka; E. Pare; J. Procureur; M. Punch; J. Quebert; K. Ragan; L. Rob; P. Schovanek; D. A. Smith; J. Vrana

1998-01-01

200

X-ray photographs of a solar active region with a multilayer telescope at normal incidence  

Microsoft Academic Search

A photograph was obtained with a multilayer X-ray telescope. A 4-centimeter tungsten-carbon multilayer mirror was flown as part of an experimental solar rocket payload, and successful images were taken of the sun at normal incidence at a wavelength of 44 angstroms. Coronal Si-XII emission from an active region was recorded on film; as expected, the structure is very similar to

J. H. Underwood; M. E. Bruner; B. M. Haisch; W. A. Brown; L. W. Acton

1987-01-01

201

The Hard X-ray Telescope (HXT) for the SOLAR-A mission  

Microsoft Academic Search

The Hard X-ray Telescope (HXT) is a Fourier-synthesis imager; a set of spatially-modulated photon count data are taken from 64 independent subcollimators and are Fourier-transformed into an image by using procedures such as the maximum entropy method (MEM) or CLEAN. The HXT takes images of solar flares simultaneously in four energy bands, nominally 15 (or 19)–24, 24–35, 35–57, and 57–100

T. Kosugi; K. Makishima; T. Murakami; T. Sakao; T. Dotani; M. Inda; K. Kai; S. Masuda; H. Nakajima; Y. Ogawara; M. Sawa; K. Shibasaki

1991-01-01

202

Solar far-infrared observations with a balloon-borne telescope  

Microsoft Academic Search

In September 1982 the scientific high-altitude balloon developed by the balloon cooperative units of the Academia Sinica was used to perform astronomical observational tests above Xianghe County. During the flight, solar far-infrared radiation was investigated (lambda = 4.6 mum and 18 mum). This flight test was supplied with a 15 cm diameter Newton telescope. The infrared detection system consisted of

H.-C. Zou

1984-01-01

203

The CERN Axion Solar Telescope (CAST): Status and Prospects  

SciTech Connect

The CAST experiment is being mounted at CERN. It will make use of a decommissioned LHC test magnet to look for solar axions through its conversion into Photons inside the magnetic field. The magnet has a field of 9.6 Tesla and length of 10 m and is installed in a platform which allows to move it+ or - 8 degrees vertically and+ or - 10 to the 11th power horizontally. According to these numbers we expect a sensitivity in axion-photon coupling gaT"~ ,~< 5 10 -11 GeV -1 for ma~< 0.02 eV, and with a gas filled tube ga~~< 10 -l GeV -a for ma~< 1 eV.

Irastorza, I. G. (Universidad de Zaragoza); Andriamonje, S (DAPNIA, Centre d'Etudes de Saclay); Arik, E (Bogazici Universitesi); Autiero, D (European Organization for Nuclear Research); Avignone, F T. (South Carolina, Univ Of); Barth, K (European Organization for Nuclear Research); Brauninger, H (Max-Planck-Institut fur Extraterrestrische Physik); Brodzinski, Ronald L. (BATTELLE (PACIFIC NW LAB)); Carmona, J. M. (Universidad de Zaragoza); Cebrian, S (Unknown); Cetin, S (Bogazici Universitesi); Collar, J I. (Chicago, University Of); Creswick, R (South Carolina, Univ Of); De Oliveira, R (European Organization for Nuclear Research); Delbart, A (Centre d'Etudes de Saclay); Di Lella, L (European Organization for Nuclear Research); Eleftheriadis, Ch (Aristotle University of Thessaloniki); Fanourakis, G (National Research Center for Physical Sciences, Demokritos, Greece); Farach, H A. (South Carolina, Univ Of); Fischer, H (Albert-Ludwigs-Universitat Freiburg); Formenti, F (European Org for Nuclear Research); Geralis, Th. (National Research Center for Physical Sciences, Demokritos, Greece); Giomataris, I (Centre d'Etudes de Saclay, Gif-Sur-Yvette, France); Gninenko, S. N. (Institue for Nuclear Research, Moscow, Russia); Goloubev, N (Institute for Nuclear Research); Hartman, R (Max-Planck-Institut fur Extraterrestrische Physik); Hasinoff, M (British Columbia,University of); Hoffmann, D (Technische Universitat Darmstadt); Jacoby, J (Technische Universitat Darmstadt); Kang, D (Albert-Ludwigs-Universitat Freiburg); Konigsmann, K (Albert-Ludwigs-Universitat Freiburg); Kotthaus, R (Max-Planck-Institut fur Physik, Muenchen, Germany); Krcmar, M (Ruder Boskovic Institute); Kuster, M (Max-Planck-Institute fur Extraterrestrische Physik); Lakic, B (Ruder Boskovic Institute, Zagreb, Croatia); Liolios, A (Universidade de Lisboa); Ljubicic, A (Ruder Boskovic Institute, Zagreb, Croatia); Lutz, G (Max-Planck-Institut fur Physik, Muenchen, Germany); Luzon, G (Universidad de Zaragoza); Miley, Harr

2003-02-10

204

A dual Fabry-Perot based narrow band imager for the National Large Solar Telescope  

NASA Astrophysics Data System (ADS)

A large solar telescope is usually equipped with several post-focus instruments deployed to study the dynamics of the solar features at different wavelengths. Indian Institute of Astrophysics (IIA) has proposed to build a 2-m class National Large Solar Telescope (NLST) to be located at a site which is suitable for high resolution observations of the sun. The narrow band imager (NBI) is proposed to be one of the back-end instrument for NLST to provide a spectral resolution of 40 m Å or better. The NBI comprised of two Fabry-Perot interferometers kept in tandem. The instrument will be capable of observing the solar atmosphere at various wavelength positions of the spectral line with the expected temporal cadence of about one spectral image per second. The instrument will also have the additional capability of making Dopplergrams at very high cadence.The instrument can be combined with a high precision polarimeter to obtain the vector magnetic fields of the solar atmosphere (one or more levels) with good temporal cadence. Several simulations and numerical studies have been carried out to arrive at the optimal design of the instrument. In this paper, we present the important design parameters of the instrument such as wavelength coverage, optimum spacing ratio, parasitic light contribution, field-of-view, spectral and spatial resolution, signal-to-noise ratio etc. The theoretically estimated performance of the proposed NBI is also compared with similar instruments used around the world.

Ravindra, B.; Banyal, Ravinder Kumar

205

Observations of small bodies in the Solar system with the 50/70-cm Schmidt telescope of the Rozhen NAO  

NASA Astrophysics Data System (ADS)

Observations of small bodies in the Solar system is the main field of research of sector "Solar system" in the Institute of Astronomy at the Bulgarian Academy of Sciences. In this work we present our methods for observing comets and asteroids with the 50/70 cm Schmidt telescope, and the following data reduction. The astrometric parameters of the Schmidt telescope are presented and discussed. As an example we present astrometrically and photometrically reduced observations of comet 9P/Tempel 1.

Kostov, A.; Bonev, T.; Bilkina, B.; Krumov, V.; Borisov, G.; Ivanova, V.

206

Computational geometry and the design of aperture-synthesis telescopes. I. A measure of the quality of the uv-plane coverage  

NASA Astrophysics Data System (ADS)

When designing an aperture-synthesis telescope for use in astronomy it is essential to find a layout of the antennas on the site that provides good coverage of the uv-plane. Large holes in the distribution of baseline points in that plane are particularly undesirable, and so an algorithm was devised for locating all the holes in any given design and assessing whether they are unacceptably large. It finds, in each region of the uv-plane, the largest circle that does not contain any of the baseline points and then takes the properties of that empty circle, such as the radius and the position of the centre, as measures of the properties of the local hole. The algorithm is based on the Delaunay triangulation of the set of baseline points and makes use of the result that the circumscribed circle of any Delaunay triangle is always empty. The largest empty circles in the uv-plane are readily found in this way, and the algorithm selects from these circles a non-overlapping set that is a good match to the intuitive concept of the largest holes in the distribution of baseline points. Modified algorithms are also presented that rank each circle not by its absolute radius but by the radius normalized to the mean radius of the circles in the same neighbourhood of the uv-plane; these versions make proper allowance for the large-scale variation of the density of baselines caused by the taper and are therefore of greater use to the designers of a telescope. The algorithms are efficient, requiring O(N_B log N_B) operations where N_B is the number of baselines, and may be used in several ways. One is to take the radius of the largest empty circle as a figure of demerit so that, of a set of trial configurations, the one with the smallest value may be regarded as having the best uv-plane coverage. Another is to take the baselines on the circumference of the largest circle to indicate which antennas are the most suitable for repositioning in order to improve the quality of the uv-plane coverage of a trial configuration.

Webster, A. S.

2004-11-01

207

The Kilodegree Extremely Little Telescope (KELT): A Small Robotic Telescope for Large-Area Synoptic Surveys  

NASA Astrophysics Data System (ADS)

The Kilodegree Extremely Little Telescope (KELT) project is a survey for planetary transits of bright stars. It consists of a small-aperture, wide-field automated telescope located at Winer Observatory near Sonoita, Arizona. The telescope surveys a set of 26° × 26° fields that together cover about 25% of the northern sky, and targets stars in the range of 8solar-type main-sequence stars.

Pepper, Joshua; Pogge, Richard W.; DePoy, D. L.; Marshall, J. L.; Stanek, K. Z.; Stutz, Amelia M.; Poindexter, Shawn; Siverd, Robert; O'Brien, Thomas P.; Trueblood, Mark; Trueblood, Patricia

2007-08-01

208

Preliminary design of the visible spectro-polarimeter for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Visible Spectro-Polarimeter (ViSP) is one of the first light instruments for the Advanced Technology Solar Telescope (ATST). It is an echelle spectrograph designed to measure three different regions of the solar spectrum in three separate focal planes simultaneously between 380 and 900 nm. It will use the polarimetric capabilities of the ATST to measure the full Stokes parameters across the line profiles. By measuring the polarization in magnetically sensitive spectral lines the magnetic field vector as a function of height in the solar atmosphere can be obtained, along with the associated variation of the thermodynamic properties. The ViSP will have a spatial resolution of 0.04 arcsec over a 2 arcmin field of view (at 600 nm). The minimum spectral resolving power for all the focal planes is 180,000. The spectrograph supports up to 4 diffraction gratings and is fully automated to allow for rapid reconfiguration.

de Wijn, Alfred G.; Casini, Roberto; Nelson, Peter G.; Huang, Pei

2012-09-01

209

The Use of Small Telescopes for Spectral Imaging of Low-light-level Extended Atmospheres in the Solar System  

Microsoft Academic Search

A 10-cm aperture telescope equipped with coronagraphic capabilities, using occulting masks of various size and material, has\\u000a been developed to obtain low-light-level, wide-angle (~7o FOV), narrow-band filtered images of sodium exospheres at Io, the Moon and Mercury. Here we describe new instrument capabilities\\u000a and recent findings about the extraordinarily long tails of sodium gas discovered in the lunar and hermean

Jeffrey Baumgardner; Michael Mendillo

2009-01-01

210

The wavefront correction control system for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The ATST Wavefront Correction Control System (WCCS) is the high-level control software for the Wavefront Correction (WFC) system to be employed in the new Advanced Technology Solar Telescope. The WFC is comprised of a set of subsystems: the high-order adaptive optics system for correction of wavefront aberrations, an active optics system that calculates corrections for low-order distortions caused by optical misalignments, a context viewing camera to provide quick-look quality analysis data, and a limb guider for positioning an occulting mask on the solar disk. The operation and configuration of the WFC is determined by the operational modes set by the operator. The Telescope Control System (TCS) sends these operational modes to the WCCS, which is the interface between the telescope and the WFC. The WCCS adopts a modular approach to the organization of the software. At the top-level there is a high-level management controller which is the interface to the TCS. This management controller is responsible for the validation of commands received from the TCS and for the coordination and synchronization of the operation of the WFC subsystems. Separate subsystem controllers manage the functional behavior of each WFC subsystem. In this way the WCCS provides a consistent interface to the TCS for each subsystem while synchronizing and coordinating the components of the Wavefront Correction system.

Kinney, Ellyne K.; Richards, Kit; Johnson, Luke; Rimmele, Thomas R.; Barden, Samuel C.

2012-07-01

211

Use of ground-based telescopes in determining the composition of the surfaces of solar system objects  

Microsoft Academic Search

Recent evidence suggests that the way that the surfaces of the solar system objects reflect solar radiation is controlled by the composition and mineralogy of the surface materials. The way sunlight is reflected from the surface as a function of wavelength, i.e., the spectral reflectance, is the most important property. Laboratory efforts to use ground-based optical telescope measurements to determine

T. B. McCord; J. B. Adams

1977-01-01

212

The tandem Fabry-Perot filter imaging spectro-polarimeter for the Solar Magnetic Activity Research Telescope (SMART)  

Microsoft Academic Search

In order to perform precise and high time cadence magnetic field measurement across the solar surface, the Tandem Fabry-Perot filter imaging spectro-polarimeter for the Solar Magnetic Activity Research Telescope (SMART) is revised. By using the CCD with moderate frame rate of 30fps, full Stokes vectors on the field-of-view 320\\

Shin'ichi Nagata; Kenichi Otsuji; Takako T. Ishii; Kiyoshi Ichimoto; Satoru Ueno; Reizaburo Kitai; Goichi Kimura; Kazunari Shibata; Yoshikazu Nakatani; Satoshi Morita

2009-01-01

213

The Lyman-? Imaging Solar Telescope (LIST) on the Korea Science and Technology Satellite-2 (STSat-2)  

NASA Astrophysics Data System (ADS)

LIST is the Lyman-alpha Imaging Solar Telescope, a project funded by the Korean government to fly on the second Korean Science and Technology research Satellite (STSat-2) due to launch in December 2005. The Principal Investigator is Dr. Minhwan Jang of Kyung-Hee University and of the Space Payload Research Center (SPARC), a consortium of Korean universities and institutions formed to develop scientific research projects in space. The purpose of the LIST project is to design, build, and operate an instrument on STSat-2 which will make images of the Sun from Earth orbit at the wavelength of the Hydrogen Lyman-? emission line at 121.6 nm. LIST has a simple design concept comprised of a small telescope to image the full disk of the Sun onto a CCD detector and a set of filters to isolate the 121.6 nm wavelength.

Jang, M.

2003-06-01

214

System safety and hazard analysis for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) is a four-meter class instrument being built to perform diffractionlimited observations of the sun. This paper describes how ATST has dealt with system safety and in particular hazard analysis during the design and development (D&D) phase. For ATST the development of a system safety plan and the oversight of the hazard analysis fell, appropriately, to systems engineering. We have adopted the methodology described in MIL-STD-882E, "Standard Practice for System Safety." While these methods were developed for use by the U.S. Department of Defense, they are readily applicable to the safety needs of telescope projects. We describe the details of our process, how it was implemented by the ATST design team, and some useful lessons learned. We conclude with a discussion of our safety related plans during the construction phase of ATST and beyond.

Hubbard, Robert P.

2010-07-01

215

Studying instrumental linear polarization at the Large Solar Vacuum Telescope (LSVT)  

NASA Astrophysics Data System (ADS)

Impact linear polarization in solar flares is studied with the Large Solar Vacuum Telescope (LSVT) using the spectral polarimetric method. This method makes it possible to minimize the effect of instrumental polarization with an error of up to 10-2 owing to the normalization of the spectral line intensity to the continuum spectrum intensity with negligible linear polarization. As a result, the H? line intensity in two orthogonally polarized spectral stripes coincides in the absence of solar polarization. However, in the presence of linear polarization in a flare, the spectral polarimetric method does not rule out that the error can be present in determining the Stokes parameters Q and U because of their possible relative “leakage.” Linear instrumental polarization of LSVT has been performed using polaroid rotation before the major mirror. Twelve elements of a telescope matrix, characterizing linear polarization, have been determined. The usage of a matrix makes it possible to specify the observed Q and U values accurate to 10-3 of their magnitude.

Firstova, N. M.; Polyakov, V. I.; Skomorovsky, V. I.; Grigoriev, V. M.

2009-12-01

216

The New Solar Shape and Oscillations Telescope (NSSOT) Experiment for SOLARNET  

NASA Astrophysics Data System (ADS)

The diameter was observed to be constant over the solar cycle and as such will never be a proper solar-terrestrial climate indicator ground measures with small telescopes are spurius the Maunder Minimum ones of Picard during the XVII century not being an exception Large instruments like the 45 cm Gregorys of Axel Wittmann in Locarno and Tenerife which average seeing cells see no variations ll 40 mas as well as the space instrument MDI SOHO naturally not affected by turbulence either We present the 4 approaches Wittmann on ground with large telescopes Emilio et al 2000 and Kuhn et al 2004 whom used the 6 pixels limb data of MDI Antia 2003 with a completely different method since using the ultra-precise frequency variation of the f-modes and our approach Dam e and Cugnet 2006 using the complete 7 years of filtergrams data 150 000 photograms and magnetograms of the SOHO MDI experiment These 4 careful analysis converge towards the same insignificant below 15 mas variations or even less 0 6 km 0 8 mas in the helioseismology approach Following Antia we can conclude that If a careful analysis is performed then it turns out that there is no evidence for any variation in the solar radius There were no theoretical reasons for large solar radius variations and there is no observational evidence for them with consistent ground and space observations This being stated and admitted the radius measure keeps interest through the solar shape that might change along the cycle sub-surface convective flows

Damé, L.

217

Real time controller for 37-element low-order solar adaptive optics system at 1m new vacuum solar telescope  

NASA Astrophysics Data System (ADS)

A low-order solar adaptive optics (AO) system had been successfully built and installed at 1m New Vacuum Solar Telescope (NVST) of Full-shine Lake Solar Observatory. The real time controller (RTC) of the AO system, which consists of a correlation tracker and a high-order wavefront correction controller, was developed. In this system, the absolute difference algorithm is used to detect wavefront gradients. A new architecture with field-programmable gate array (FPGA) and digital signal processor (DSP) for the real-time controller based on systolic array and pipeline was designed. The controller was integrated into the AO system and saw the first light on February 24th, 2011, using solar granulation as the beacon. Later, the AO-corrected high resolution sunspots images were obtained using sunspots as the beacon. The observational results show that the contrast and resolution of the solar images are improved evidently after the correction by the AO system. The design of the RTC and the observational results will be presented.

Zhu, Lei; Gu, Naiting; Chen, Shanqiu; Zhang, Lanqiang; Wang, Xiaoyun; Rao, Xuejun; Li, Mei; Rao, Changhui

218

MAST: a mass spectrometer telescope for studies of the isotopic composition of solar, anomalous, and galactic cosmic ray nuclei  

Microsoft Academic Search

The mass spectrometer telescope (MAST) on SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) is designed to provide high-resolution measurements of the isotopic composition of energetic nuclei from He to Ni (Z=2 to 28) over the energy range from ~10 to several hundred MeV\\/nucleon. During large solar flares MAST will measure the isotopic abundances of solar energetic particles to determine directly

W. R. Cook; A. C. Cummings; J. R. Cummings; T. L. Garrard; B. Kecman; R. A. Mewaldt; R. S. Selesnick; E. C. Stone; T. T. von Rosenvinge

1993-01-01

219

Design and analysis of the aperture shield assembly for a space solar receiver  

Microsoft Academic Search

A joint US\\/Russia program has been conducted to design, develop, fabricate, launch and operate the world's first space solar dynamic power system on the Russian Space Station Mir. The goal of the program was to demonstrate and confirm that solar dynamic power systems are viable for future space applications such as the International Space Station (ISS). The major components of

Hal J. Strumpf; Tuan Trinh; William Westelaken; Christopher Krystkowiak; Vahe Avanessian; Thomas W. Kerslake

1997-01-01

220

Linear-array apertures for in-flight dynamic solar calibration of radiometric channels for Earth radiation-budget applications.  

PubMed

The zero-frequency gain of nonimaging radiometers used in Earth radiation-budget applications is usually verified by a procedure that allows the instrument to view the Sun through an appropriate attenuating aperture and then equates its response to the known attenuated solar constant. However, channel intercomparison often requires that data from a low-resolution, relatively slow instrument such as an active-cavity radiometer be compared with data from a high-resolution, fast instrument such as a scanning thermistor-bolometer radiometer. In such a case, consideration of the difference in the dynamic responses of the two channels may be important. A novel technique for in-flight measurement of the radiometric transfer function of such instruments is described and then demonstrated through the use of a high-order dynamic model of the total, wide-field-of-view, nonscanning channel of NASA's Earth Radiation Budget Experiment (ERBE). PMID:20935961

Tira, N E; Mahan, J R; Lee Iii, R B; Keynton, R J

1994-08-20

221

DYNAMICALLY EXCITED OUTER SOLAR SYSTEM OBJECTS IN THE HUBBLE SPACE TELESCOPE ARCHIVE  

SciTech Connect

We present the faintest mid-ecliptic latitude survey in the second part of Hubble Space Telescope archival search for outer solar system bodies. We report the discovery of 28 new trans-Neptunian objects and one small centaur (R {approx} 2 km) in the band 5 Degree-Sign -20 Degree-Sign off the ecliptic. The inclination distribution of these excited objects is consistent with the distribution derived from brighter ecliptic surveys. We suggest that the size and inclination distribution should be estimated consistently using suitable surveys with calibrated search algorithms and reliable orbital information.

Fuentes, Cesar I.; Trilling, David E. [Department of Physics and Astronomy, Northern Arizona University, P.O. Box 6010, Flagstaff, AZ 86011 (United States); Holman, Matthew J., E-mail: cesar.i.fuentes@nau.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2011-12-01

222

Conceptual design of the control software for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

Aim of this paper is to present an overview of the conceptual design of the Control Software for the European Solar Telescope (EST), as emerged after the successful Conceptual Design Review held in June 2011 which formally concluded the EST Preliminary Design Study. After a general description of ECS (EST Control Software) architecture end-to-end, from operation concepts and observation preparations to the control of the planned focal plane instruments, the paper focuses on the arrangement devised to date of ECS to cope with the foreseen scientific requirements. EST major subsystems together with the functions to be controlled are eventually detailed and discussed.

Di Marcantonio, P.; Cirami, R.; Romano, P.; Cosentino, R.; Ermolli, I.; Giorgi, F.

2012-09-01

223

FalconSAT-7: a membrane photon sieve CubeSat solar telescope  

NASA Astrophysics Data System (ADS)

We are currently constructing FalconSAT-7 for launch in mid-2014. The low-Earth, 3U CubeSat solar telescope incorporates a 0.2m deployable membrane photon sieve with over 2.5 billion holes. The aim of the experiment is to demonstrate diffraction limited imaging of a collapsible, diffractive primary over a narrow bandwidth. As well as being simpler to manufacture and deploy than curved, polished surfaces, the sheets do not have to be optically flat, greatly reducing many engineering issues. As such, the technology is particularly promising as a means to achieve extremely large optical primaries from compact, lightweight packages.

Andersen, Geoff; Asmolov, Olha; Dearborn, Michael E.; McHarg, Matthew G.

2012-09-01

224

The Spacewatch 1.8-meter Telescope  

Microsoft Academic Search

The largest telescope in the world dedicated to the search for Earth-approaching asteroids and other previously unknown members of the solar system will soon be operational. Its 1.8-m aperture, large and sensitive CCD, and dedication to surveying will make it possible to find as many as 80,000 new asteroids per year. The mechanical design by Barr is optimized by finite-element

M. L. Perry; R. S. McMillan; L. D. Barr; T. H. Bressi; T. Gehrels

1996-01-01

225

The spectrometer telescope for imaging x-rays on board the Solar Orbiter mission  

NASA Astrophysics Data System (ADS)

The Spectrometer Telescope for Imaging X-rays (STIX) is one of 10 instruments on board Solar Orbiter, a confirmed Mclass mission of the European Space Agency (ESA) within the Cosmic Vision program scheduled to be launched in 2017. STIX applies a Fourier-imaging technique using a set of tungsten grids (at pitches from 0.038 to 1 mm) in front of 32 pixelized CdTe detectors to provide imaging spectroscopy of solar thermal and non-thermal hard X-ray emissions from 4 to 150 keV. The status of the instrument reviewed in this paper is based on the design that passed the Preliminary Design Review (PDR) in early 2012. Particular emphasis is given to the first light of the detector system called Caliste-SO.

Benz, A. O.; Krucker, S.; Hurford, G. J.; Arnold, N. G.; Orleanski, P.; Gröbelbauer, H.-P.; Klober, S.; Iseli, L.; Wiehl, H. J.; Csillaghy, A.; Etesi, L.; Hochmuth, N.; Battaglia, M.; Bednarzik, M.; Resanovic, R.; Grimm, O.; Viertel, G.; Commichau, V.; Meuris, A.; Limousin, O.; Brun, S.; Vilmer, N.; Skup, K. R.; Graczyk, R.; Stolarski, M.; Michalska, M.; Nowosielski, W.; Cichocki, A.; Mosdorf, M.; Seweryn, K.; Przepiórka, A.; Sylwester, J.; Kowalinski, M.; Mrozek, T.; Podgorski, P.; Mann, G.; Aurass, H.; Popow, E.; Önel, H.; Dionies, F.; Bauer, S.; Rendtel, J.; Warmuth, A.; Woche, M.; Plüschke, D.; Bittner, W.; Paschke, J.; Wolker, D.; Van Beek, H. F.; Farnik, F.; Kasparova, J.; Veronig, A. M.; Kienreich, I. W.; Gallagher, P. T.; Bloomfield, D. S.; Piana, M.; Massone, A. M.; Dennis, B. R.; Schwarz, R. A.; Lin, R. P.

2012-09-01

226

Design for birefringent filter with 8-channel for Space Solar Telescope  

NASA Astrophysics Data System (ADS)

The principles of birefringent filter (BF) which consists of 8-channel and will be used in Space Solar Telescope (SST) is described in this article. The BF will be the main focus plane instrument of the payload of SST. It is a kind of birefringent filter with Polaroid replaced by polarizing beam splitter. It permits observations of solar vector magnetic field or line-of-sight velocity fields in any Fraunhofer line between the wavelength from 3900 to 6600 Å with half width from 0.03 to 0.12 Å. It can be turned across the spectral line to obtain line profiles of two-dimensional field of view with 8 channels. Because of this, we also call the BF with 8-channel as Two-Dimensional Spectrograph (TDS). This article also describes the analysis of mechanical and thermal control of the TDS. In the final, a new polarimeter of this system is introduced.

Jiang, Yuesong; Song, Guofeng; Ai, Guoxiang

2002-03-01

227

RSTN (Radio Solar Telescope Network) observations of the 16 February 1984 cosmic-ray flare  

SciTech Connect

The radio Solar Telescope Network (RSTN) are located at Sagamore Hill (Massachusetts), Palehua (Hawaii), and Learmonth (Australia). A fourth site at San Vito (Italy) will begin making observations in 1986. The RSTN stations monitor the quiet and disturbed Sun at eight fixed frequencies logarithmically spaced from 245-15400 MHz. The radiometer patrols are operated from sunrise to sunset. Data are stored on magnetic tape with 1 second time resolution and archived at the World Data Center A in Boulder for dissemination to the scientific community. The Palehua site became operational in July 1980, followed by Learmonth in August 1980, and Sagamore Hill in October 1981. Thus digitized radiometer observations of the Sun are available for a significant fraction of the maximum phase of solar cycle 21.

Cliver, E.W.; Gentile, L.C.; Wells, G.D.

1987-07-01

228

TRANSVERSE OSCILLATIONS OF LOOPS WITH CORONAL RAIN OBSERVED BY HINODE/SOLAR OPTICAL TELESCOPE  

SciTech Connect

The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as H{alpha} and Ca II H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high-resolution observations with instruments such as the Hinode/Solar Optical Telescope (SOT), CRISP of the Swedish 1-m Solar Telescope, and the Solar Dynamics Observatory. Furthermore, numerical simulations have shown that coronal rain is the loss of thermal equilibrium of loops linked to footpoint heating. This result has highlighted the importance that coronal rain can play in the field of coronal heating. In this work, we further stress the importance of coronal rain by showing the role it can play in the understanding of the coronal magnetic field topology. We analyze Hinode/SOT observations in the Ca II H line of a loop in which coronal rain puts in evidence in-phase transverse oscillations of multiple strand-like structures. The periods, amplitudes, transverse velocities, and phase velocities are calculated, allowing an estimation of the energy flux of the wave and the coronal magnetic field inside the loop through means of coronal seismology. We discuss the possible interpretations of the wave as either standing or propagating torsional Alfven or fast kink waves. An estimate of the plasma beta parameter of the condensations indicates a condition that may allow the often observed separation and elongation processes of the condensations. We also show that the wave pressure from the transverse wave can be responsible for the observed low downward acceleration of coronal rain.

Antolin, P. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Verwichte, E., E-mail: patrick.antolin@astro.uio.no, E-mail: erwin.verwichte@warwick.ac.uk [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

2011-08-01

229

Transverse Oscillations of Loops with Coronal Rain Observed by Hinode/Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

The condensations composing coronal rain, falling down along loop-like structures observed in cool chromospheric lines such as H? and Ca II H, have long been a spectacular phenomenon of the solar corona. However, considered a peculiar sporadic phenomenon, it has not received much attention. This picture is rapidly changing due to recent high-resolution observations with instruments such as the Hinode/Solar Optical Telescope (SOT), CRISP of the Swedish 1-m Solar Telescope, and the Solar Dynamics Observatory. Furthermore, numerical simulations have shown that coronal rain is the loss of thermal equilibrium of loops linked to footpoint heating. This result has highlighted the importance that coronal rain can play in the field of coronal heating. In this work, we further stress the importance of coronal rain by showing the role it can play in the understanding of the coronal magnetic field topology. We analyze Hinode/SOT observations in the Ca II H line of a loop in which coronal rain puts in evidence in-phase transverse oscillations of multiple strand-like structures. The periods, amplitudes, transverse velocities, and phase velocities are calculated, allowing an estimation of the energy flux of the wave and the coronal magnetic field inside the loop through means of coronal seismology. We discuss the possible interpretations of the wave as either standing or propagating torsional Alfvén or fast kink waves. An estimate of the plasma beta parameter of the condensations indicates a condition that may allow the often observed separation and elongation processes of the condensations. We also show that the wave pressure from the transverse wave can be responsible for the observed low downward acceleration of coronal rain.

Antolin, P.; Verwichte, E.

2011-08-01

230

Concepts for Multi-wavelength Observations with the 1.5 m Solar Telescope GREGOR  

NASA Astrophysics Data System (ADS)

The initial instrumentation of the 1.5 m solar telescope GREGOR on Tenerife will include a grating spectrograph with a spectro-polarimeter for the near infrared and a dual Fabry-Perot filter spectro-polarimeter for the "red" wavelength range from 530 to 860 nm. Both instruments are based on their predecessors that are presently operated at the Vacuum-Tower Telescope on Tenerife. In order to fully exploit the scientific capability of GREGOR, simultaneous multi-wavelength observations are necessary. Such observations will allow studying the coupling of different layers of the solar atmosphere. Simultaneous measurements of the magnetic field, using different spectral lines, increase the sensitivity and the accuracy of such measurements. We present concepts for multi-wavelength observations with GREGOR based on the first-light instruments. As a first step, fast large-format CCD cameras will be used in the slit-jaw imaging system of the spectrograph or in an additional medium-band imaging channel for post-facto image restoration combined with the spectro-polarimeter. These observations with high spatial resolution would provide the context for the spectrally resolved data. Beyond simple time-share concepts, the different characteristics of imaging and spectrograph-based instruments require more sophisticated approaches, which should neither sacrifice adaptive optics performance nor diminish polarimetric efficiency and accuracy. Here, we will discuss a beam splitter option and variants of scanning spectrograph systems. Finally, we introduce a concept for a second-generation instrument the "Blue Imaging Solar Spectrometer" (BLISS), a dual Fabry-Perot interferometer to explore the blue solar spectrum (from 380 to 530 nm) in tandem with the "red" instrument.

Schmidt, W.; Beck, C.; Denker, C.; Soltau, D.; Volkmer, R.

2008-09-01

231

Neutron Emission from the Solar Flare of September 07, 2005, Detected by the Solar Neutron Telescope at Sierra Negra, Mexico  

NASA Astrophysics Data System (ADS)

The X17.0 solar flare of September 07, 2005 released high-energy neutrons, that were detected by the Solar Neutron Telescope (SNT) at Sierra Negra, Mexico. In two separate and independent studies of this solar neutron event, the energy spectra as a power law was calculated ( Sako, T., et al., 2006, ApJ, 651, 69. Watanabe, K., et al., 2006. ApJ, 636, 1135) In this paper, we show an alternative analysis, based on an improved numerical simulations of the detector using GEANT 4, and a different technique to treat the SNT data. The results indicate that the spectral index which best fits the neutron flux is nearly 3, in agreement with previous works. Based in the numerically calculated energy deposition of SNT, we confirm that neutrons were detected with at least 1GeV, which implies that the solar flare might have produced 10GeV protons; these could not be observed at Earth, as the source flare was in the east limb of the Sun.

Valdes-Galicia, J. F.; Gonzalez, L.; Sanchez, F.; Watanabe, K.; Sako, T.; Matsubara, Y.; Muraki, Y.; Shibata, S.; Hurtado, A.; Musalem, O.

2011-12-01

232

Science with Large Solar Telescopes: Addressing Key Science Questions with New Observing Modes  

NASA Astrophysics Data System (ADS)

We review the capabilities of existing and future large solar telescopes with an emphasis on the key science questions that these instruments must address. Large solar telescopes coming online now, as well as the 4-meter ATST coming online in 2018 are tasked with extending high resolution and polarimetric investigations from the lower atmospheric regions into the higher regions and connecting the dynamics between the two. The overall goal is to understand the interaction of flows and magnetic fields in the convection zone down to O(10) km scales and the magnetohydrodynamic transport, storage, and release of energy in the upper atmosphere leading to coronal heating and eruptive events. The ATST in particular will have unique opportunities to address this goal with new observations of the infrared atmosphere at very high spatial resolution and with coronagraphic capabilities. We discuss some of the multi-instrument ATST observing programs that will investigate such topics as small-scale magnetoconvection and energetic events in the lower atmosphere and energy release in filament eruptions.

Berger, T.

2012-12-01

233

SOLAR-LIKE OSCILLATIONS IN A METAL-POOR GLOBULAR CLUSTER WITH THE HUBBLE SPACE TELESCOPE  

SciTech Connect

We present analyses of variability in the red giant stars in the metal-poor globular cluster NGC 6397, based on data obtained with the Hubble Space Telescope. We use a nonstandard data reduction approach to turn a 23 day observing run originally aimed at imaging the white dwarf population, into time-series photometry of the cluster's highly saturated red giant stars. With this technique we obtain noise levels in the final power spectra down to 50 parts per million, which allows us to search for low-amplitude solar-like oscillations. We compare the observed excess power seen in the power spectra with estimates of the typical frequency range, frequency spacing, and amplitude from scaling the solar oscillations. We see evidence that the detected variability is consistent with solar-like oscillations in at least one and perhaps up to four stars. With metallicities 2 orders of magnitude lower than those of the Sun, these stars present so far the best evidence of solar-like oscillations in such a low-metallicity environment.

Stello, Dennis [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Gilliland, Ronald L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: stello@physics.usyd.edu.au, E-mail: gillil@stsci.edu

2009-08-01

234

The Siberian Solar Radio Telescope: the current state of the instrument, observations, and data  

NASA Astrophysics Data System (ADS)

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, H? filtergrams and magnetograms, extreme-ultraviolet and X-ray observations, and dynamic radio spectra.

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.

2003-09-01

235

High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield.  

National Technical Information Service (NTIS)

As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russ...

T. W. Kerslake L. S. Mason H. J. Strumpf

1997-01-01

236

HINODE SOLAR OPTICAL TELESCOPE OBSERVATIONS OF THE SOURCE REGIONS AND EVOLUTION OF 'TYPE II' SPICULES AT THE SOLAR POLAR LIMB  

SciTech Connect

We examine solar spicules using high-cadence Ca II data of the north pole coronal hole region, using the Solar Optical Telescope (SOT) on the Hinode spacecraft. The features we observe are referred to as 'Type II' spicules by De Pontieu et al. in 2007. By convolving the images with the inverse-point-spread function for the SOT Ca II filter, we are able to investigate the roots of some spicules on the solar disk, and the evolution of some spicules after they are ejected from the solar surface. We find that the source regions of at least some of the spicules correspond to locations of apparent-fast-moving ({approx}few x 10 km s{sup -1}), transient (few 100 s), Ca II brightenings on the disk. Frequently the spicules occur when these brightenings appear to collide and disappear. After ejection, when seen above the limb, many of the spicules fade by expanding laterally (i.e., roughly transverse to their motion away from the solar surface), splitting into two or more spicule 'strands', and the spicules then fade without showing any downward motion. Photospheric/chromospheric acoustic shocks alone likely cannot explain the high velocities ({approx}100 km s{sup -1}) of the spicules. If the Ca II brightenings represent magnetic elements, then reconnection among those elements may be a candidate to explain the spicules. Alternatively, many of the spicules could be small-scale magnetic eruptions, analogous to coronal mass ejections, and the apparent fast motions of the Ca II brightenings could be analogs of flare loops heated by magnetic reconnection in these eruptions.

Sterling, Alphonse C.; Moore, Ronald L. [Space Science Office, VP62, NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); DeForest, Craig E. [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)], E-mail: alphonse.sterling@nasa.gov, E-mail: ron.moore@nasa.gov, E-mail: deforest@boulder.swri.edu

2010-05-01

237

[Telescope] Tutorials  

NSDL National Science Digital Library

This website provides brief tutorials on spectroscopy, cosmology, galaxies, light pollution, solar system scale, the sun, stellar properties, telescopes, the history of astronomy, and stars. This site also contains a magnification and astronomical distance conversion calculator.

2005-06-07

238

Simultaneous control of multiple instruments at the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) is a 4-meter solar observatory under construction at Haleakala, Hawaii. The simultaneous use of multiple instruments is one of the unique capabilities that makes the ATST a premier ground based solar observatory. Control of the instrument suite is accomplished by the Instrument Control System (ICS), a layer of software between the Observatory Control System (OCS) and the instruments. The ICS presents a single narrow interface to the OCS and provides a standard interface for the instruments to be controlled. It is built upon the ATST Common Services Framework (CSF), an infrastructure for the implementation of a distributed control system. The ICS responds to OCS commands and events, coordinating and distributing them to the various instruments while monitoring their progress and reporting the status back to the OCS. The ICS requires no specific knowledge about the instruments. All information about the instruments used in an experiment is passed by the OCS to the ICS, which extracts and forwards the parameters to the appropriate instrument controllers. The instruments participating in an experiment define the active instrument set. A subset of those instruments must complete their observing activities in order for the experiment to be considered complete and are referred to as the must-complete instrument set. In addition, instruments may participate in eavesdrop mode, outside of the control of the ICS. All instrument controllers use the same standard narrow interface, which allows new instruments to be added without having to modify the interface or any existing instrument controllers.

Johansson, Erik M.; Goodrich, Bret

2012-09-01

239

Diffraction-limited constant-resolution zoom lens across multi- wavelengths for the Advanced Technology Solar Telescope  

Microsoft Academic Search

Zoom lenses are usually designed for a specified waveband and change magnification, and thus resolution, for different object sizes or different object distances. However, the Advanced Technology Solar Telescope (ATST)\\/ Visible Light Broadband Imager (VLBI), under development by the National Solar Observatory, require constant resolution for different wavelengths over a wide spectral range (388.3 nm 3o 854.2 nm). An eight-element

Hyun Kyoung An; Stephen K. Pitalo

2006-01-01

240

Improvements in optical telescope performance through adaptive optics: results from the National Solar Observatory prototype adaptive optics system  

Microsoft Academic Search

Earth-based telescopes are limited in their performance primarily by aberrations introduced to the light by the atmosphere. This problem can be compensated for by the introduction of an adaptive optics (AO) system, and at the National Solar Observatory at Sunspot, New Mexico, work has been underway to develop a real time (100 - 300 Hz) AO system to work in

Steve P. Doinidis; Wiley E. Thompson

1995-01-01

241

Detection and localization of a hard X-ray solar burst with a balloon-borne coded mask telescope  

Microsoft Academic Search

A hard X-ray solar burst has been observed with a balloon-borne coded mask telescope with a very wide field of view. A clear image, with a 5°.5×4°.5 FWHM, has been obtained. The light curve is reported. The spectrum derived is consistent with a power law with spectral index alpha = -2.7±0.6.

A. Emanuele; M. Badiali; D. Cardini; M. Ranieri; M. G. Catanesi; G. Selvaggi; F. Waldner; G. Maggi

1984-01-01

242

Design of the Polarimeter for the Fibre Arrayed Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

The theoretical design of the polarimeter used for the Fibre Arrayed Solar Optical Telescope (FASOT) is described. It has the following characteris- tics: (1) It is provided with the function of optical polarization switching, which makes the high-effciency polarimetry possible; (2) In the waveband of 750 nm, the polarimetric effciency is higher than 50% for the every Stokes parameter, and higher than 86.6% for the total polarization, thus an observer can make the simultaneous polarization measurements on multiple magnetosensitive lines in such a broad range of wavelength; (3) According to the selected photospheric and chromospheric lines, the measurement can be focused on either linear polarization or circular polarization; (4) The polarimeter has a loose tolerance on the manufacturing technology of polarimetric elements and installation errors. All this makes this polarimeter become a high-performance polarimetric device.

Dun, Guang-tao; Qu, Zhong-quan

2013-01-01

243

Geant4 simulation of the solar neutron telescope at Sierra Negra, Mexico  

NASA Astrophysics Data System (ADS)

The solar neutron telescope (SNT) at Sierra Negra (19.0°N, 97.3°W and 4580 m.a.s.l) is part of a worldwide network of similar detectors (Valdés-Galicia et al., (2004) [1]). This SNT has an area of 4 m2; it is composed by four 1 m×1 m×30 cm plastic scintillators (Sci). The Telescope is completely surrounded by anti-coincidence proportional counters (PRCs) to separate charged particles from the neutron flux. In order to discard photon background it is shielded on its sides by 10 mm thick iron plates and on its top by 5 mm lead plates. It is capable of registering four different channels corresponding to four energy deposition thresholds: E>30, >60, >90 and >120 MeV. The arrival direction of neutrons is determined by gondolas of PRCs in electronic coincidence, four layers of these gondolas orthogonally located underneath the SNT, two in the NS direction and two in the EW direction. We present here simulations of the detector response to neutrons, protons, electrons and gammas in range of energies from 100 to 1000 MeV. We report on the detector efficiency and on its angular resolution for particles impinging the device with different zenith angles. The simulation code was written using the Geant4 package (Agostinelli et al., (2003) [2]), taking into account all relevant physical processes.

González, L. X.; Sánchez, F.; Valdés-Galicia, J. F.

2010-02-01

244

Software control of the Advanced Technology Solar Telescope enclosure PLC hardware using COTS software  

NASA Astrophysics Data System (ADS)

As PLCs evolve from simple logic controllers into more capable Programmable Automation Controllers (PACs), observatories are increasingly using such devices to control complex mechanisms1, 2. This paper describes use of COTS software to control such hardware using the Advanced Technology Solar Telescope (ATST) Common Services Framework (CSF). We present the Enclosure Control System (ECS) under development in Spain and the UK. The paper details selection of the commercial PLC communication library PLCIO. Implemented in C and delivered with source code, the library separates the programmer from communication details through a simple API. Capable of communicating with many types of PLCs (including Allen-Bradley and Siemens) the API remains the same irrespective of PLC in use. The ECS is implemented in Java using the observatory's framework that provides common services for software components. We present a design following a connection-based approach where all components access the PLC through a single connection class. The link between Java and PLCIO C library is provided by a thin Java Native Interface (JNI) layer. Also presented is a software simulator of the PLC based upon the PLCIO Virtual PLC. This creates a simulator operating below the library's API and thus requires no change to ECS software. It also provides enhanced software testing capabilities prior to hardware becoming available. Results are presented in the form of communication timing test data, showing that the use of CSF, JNI and PLCIO provide a control system capable of controlling enclosure tracking mechanisms, that would be equally valid for telescope mount control.

Borrowman, Alastair J.; de Bilbao, Lander; Ariño, Javier; Murga, Gaizka; Goodrich, Bret; Hubbard, John R.; Greer, Alan; Mayer, Chris; Taylor, Philip

2012-09-01

245

Design of a space telescope for vibration control  

NASA Astrophysics Data System (ADS)

The end of the Cold War has made large-aperture telescope technologies from the U.S. Strategic Defense Initiative program available for non-defense missions. Now, a four-meter aperture space telescope, a seventy percent larger aperture than that of the Hubble space telescope, has been proposed for a dual military and astronomical mission. An important part of the preliminary design work was to determine how to meet the telescope's pointing and jitter criteria. The telescope will be required to maintain an rms pointing accuracy of 24 nrad, preferably over periods of several hours. Vibration was a critical issue in the study because of the stringent pointing requirement, the relatively light structures desirable for spacecraft, thermal transients, the presence of disturbances from many spacecraft mechanisms (solar array drives, momentum wheels, thrusters, antenna steering mechanisms, etc.), and the many external appendages. The four-meter telescope design uses an inertial optical reference system combined with an actively controlled `fast steering mirror' in the target beam path to actively counteract vibration.

Dresner, Thomas L.; Freier, Larry J.; Chien, Tze T.; Gilmore, Jerold P.

1994-10-01

246

Ten-antenna prototype of a radio heliograph based on the Siberian Solar Radio Telescope  

NASA Astrophysics Data System (ADS)

An upgrade of the Siberian Solar Radio Telescope (SSRT) [Smolkov et al., 1986; Grechnev et al., 2003] to a multiwave radio heliograph has been started. The radio heliograph being created will be designed mainly to measure coronal magnetic fields, to determine the locations of solar-flare energy release, and to investigate coronal mass ejections. These tasks define the parameters of next-generation radio heliographs. A high spatial resolution, a high image acquisition rate, and a high sensitivity are required simultaneously. All these parameters should be realized in the widest possible frequency range—from fractions to tens of GHz). The expected parameters of the future SSRT-based radio heliograph are listed below: spatial resolution 12?-24?, temporal resolution 0.02-1.0 s, frequency range 4-8 GHz, sensitivity up to 100 K, left-hand and right-hand circular polarizations, data rate 0.5-20 Mb s-1 (normal and flare modes). In this paper, we describe the broadband antennas, analog optical data transmission lines, and correlator used in the 10-antenna radio heliograph prototype.

Lesovoy, S. V.; Altyntsev, A. T.; Zandanov, V. G.; Ivanov, E. F.; Gubin, A. V.; Maslov, A. I.

2009-12-01

247

New Digital H-alpha Observation by Solar Flare Telescope at BOAO  

NASA Astrophysics Data System (ADS)

Recently, we have set up a new digital CCD camera system, MicroMax YHS-1300 manufactured by Roper Scientific for H-alpha observation by Solar Flare Telescope at Bohyunsan Optical Astronomical Observatory. It has a 12 bit dynamic range, a pixel number of 1300x1030, a thermoelectric cooler, and an electric shutter. Its readout speed is about 3 frames per second and the dark current is about 0.05 e-/p/s at -10 C degree. We have made a system performance test by confirming the system linearity, system gain, and system noise that its specification requires. We have also developed a data acquisition software which connects a digital camera controller to a PC and acquires H-alpha images via Microsoft C++ 6.0 under Windows 98. Comparisons of high quality H-alpha images of AR 9169 and AR 9283 obtained from SOFT with the corresponding images from Learmonth Solar Observatory in Australia confirm that our H-alpha digital observational system is performed properly. Finally, we present a set of H-alpha images taken from a two ribbon flare occurred in AR 9283.

Lee, C.-W.; Moon, Y.-J.; Park, Y. D.; Jang, B.-H.; Kim, Kap-Sung

2001-06-01

248

The telescope and the double Fabry-Pérot interferometer for the ADAHELI solar space mission  

NASA Astrophysics Data System (ADS)

ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises a Gregorian telescope and its focal plane suite. The advanced design focal plane suite uses fast CMOS cameras for investigating photospheric and chromospheric fast dynamics and structure. ISODY is equipped with a pioneering focal plane suite composed of a spectral channel, based upon a tandem of Fabry-Perot interferometers operating in the visible-NIR spectral region, a broad band channel for high resolution imaging, and a correlation tracker used as an image stabilization system. ADAHELI's mission profile has been tailored to limit the spacecraft's radial velocity in the Sunward direction, to not exceed +/-4 km/s, during 95% of the yearly orbit, to allow a continuous use of the on-board interferometer.

Greco, V.; Cavallini, F.; Berrilli, F.

2010-07-01

249

Turbulent Characteristics in the Intensity Fluctuations of a Solar Quiescent Prominence Observed by the Hinode Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

We focus on Hinode Solar Optical Telescope (SOT) calcium II H-line observations of a solar quiescent prominence (QP) that exhibits highly variable dynamics suggestive of turbulence. These images capture a sufficient range of scales spatially (~0.1-100 arcsec) and temporally (~16.8 s-4.5 hr) to allow the application of statistical methods used to quantify finite range fluid turbulence. We present the first such application of these techniques to the spatial intensity field of a long-lived solar prominence. Fully evolved inertial range turbulence in an infinite medium exhibits multifractal scale invariance in the statistics of its fluctuations, seen as power-law power spectra and as scaling of the higher order moments (structure functions) of fluctuations which have non-Gaussian statistics; fluctuations ?I(r, L) = I(r + L) - I(r) on length scale L along a given direction in observed spatial field I have moments that scale as lang?I(r, L) p rang ~ L ?(p). For turbulence in a system that is of finite size, or that is not fully developed, one anticipates a generalized scale invariance or extended self-similarity (ESS) lang?I(r, L) p rang ~ G(L)?(p). For these QP intensity measurements we find scaling in the power spectra and ESS. We find that the fluctuation statistics are non-Gaussian and we use ESS to obtain ratios of the scaling exponents ?(p): these are consistent with a multifractal field and show distinct values for directions longitudinal and transverse to the bulk (driving) flow. Thus, the intensity fluctuations of the QP exhibit statistical properties consistent with an underlying turbulent flow.

Leonardis, E.; Chapman, S. C.; Foullon, C.

2012-02-01

250

The development of filter vector magnetographs for the Solar Magnetic Activity Research Telescope (SMART)  

NASA Astrophysics Data System (ADS)

In recent years, it is beginning to be shown observationally and theoretically that the existence of the magnetic field is indispensable for active phenomena on the solar surface. In particular, the rotation or helicity of the magnetic field and their temporal variation are considered to be important factors which influence solar activity. In order to confirm this, it is necessary to compute vector components of the magnetic field with a higher accuracy than before. Therefore, we developed two kinds of filter-type magnetographs for the Solar Magnetic Activity Research Telescope (SMART) at Hida observatory, which allow us to observe the polarization components in sunlight with high accuracy. We use a Lyot filter in one of two sets of magnetographs. On the other hand, a tandem-typed Fabry-Perot filter is used in one more set. For these two instruments, we made the following concrete advances. 1. The method of coating of the pre-filters. 2. Special fine-anneal on the main lenses. 3. Highly accurate rotating wave-plate. 4. Simultaneous observation of two kinds of filtergrams which have orthogonally polarized light mutually by using Fabry-Perot channel. 5. Observation in four wavelengths which can suppress various errors. 6. Low apparent Doppler shift in the FOV due to the oblique incidence of the rays to the filters. 7. Large format CCD (large-sized chip, large full-well). 8. High speed data transfer interface between the CCD and PC. In this paper, we report the details of these points, the expected effect of them, and the results of initial measurements.

UeNo, Satoru; Nagata, Shin-ichi; Kitai, Reizaburo; Kurokawa, Hiroki; Ichimoto, Kiyoshi

2004-09-01

251

The 2012 status of the MCAO testbed for the GREGOR solar telescope  

NASA Astrophysics Data System (ADS)

We look back on two years of experience with the laboratory MCAO testbed for the GREGOR solar telescope. GREGOR’s MCAO features four adaptive mirrors, i. e. one tip-tilt mirror, and three DMs to compensate for turbulence around 0 km, 5 km, and 15.5 km above ground. Two different Hartmann-Shack wavefront sensor units are used for wavefront tomography. A sensor with a narrow field of view and smaller subapertures is dedicated to high-order aberrations on the optical axis. This sensor directly follows the pupil plane DM and does not see the high-altitude DMs. The second sensor features larger subapertures and 19 guide regions spread over a wide field of view for off-axis wavefront sensing. We show that high-altitude DMs cause rapidly changing pupil distortions and thus misregistration, which renders the interaction of a pupil-plane DM and a subsequent wavefront sensor non-linear. We rewrote the control software for cleaner and more flexible code, and we switched to modal wavefront reconstruction from direct reconstruction. The original digital interfacing of the DMs high-voltage electronics didn’t prove to be reliable. Thus, we developed a new interface board that is based on CameraLink/ChannelLink technology to transmit the DM commands from the control computer. In this paper we present the innovations and some of the first experimental performance measurements with two DMs. One DM failed before scientific grade data was recorded with three DMs. This DM will be replaced soon. We conclude that GREGOR’s MCAO system is now ready for first on-sky tests at the telescope.

Schmidt, Dirk; Berkefeld, Thomas; Heidecke, Frank

2012-07-01

252

Analysis of telescope arrays for deep space optical communications  

Microsoft Academic Search

It has been very well established in the literature that the cost of a large aperture telescope grows exponentially as a function of its diameter. On Earth, large aperture telescopes in excess of 10m also have the disadvantage of undergoing gravitational and other environmental effects. Array configurations, instead, may be the potential alternatives when large aperture telescopes are considered for

Ali Asghar Eftekhar; S. Khjorasani; A. Adibi; F. Amoozegar; S. Piazzolla

2005-01-01

253

High resolution telescope  

NASA Astrophysics Data System (ADS)

A large effective-aperture, low-cost optical telescope with diffraction-limited resolution enables ground-based observation of near-earth space objects. The telescope has a non-redundant, thinned-aperture array in a center-mount, single-structure space frame. It employs speckle interferometric imaging to achieve diffraction-limited resolution. The signal-to-noise ratio problem is mitigated by moving the wavelength of operation to the near-IR, and the image is sensed by a Silicon CCD. The steerable, single-structure array presents a constant pupil. The center-mount, radar-like mount enables low-earth orbit space objects to be tracked as well as increases stiffness of the space frame. In the preferred embodiment, the array has elemental telescopes with subaperture of 2.1 m in a circle-of-nine configuration. The telescope array has an effective aperture of 12 m which provides a diffraction-limited resolution of 0.02 arc seconds. Pathlength matching of the telescope array is maintained by an electro-optical system employing laser metrology. Speckle imaging relaxes pathlength matching tolerance by one order of magnitude as compared to phased arrays. Many features of the telescope contribute to substantial reduction in costs. These include eliminating the conventional protective dome and reducing on-site construction activities. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.

Massie, N. A.; Oster, Y.

1990-05-01

254

The Green Bank Telescope  

Microsoft Academic Search

The Green Bank Telescope The 100-m NRAO Green Bank Telescope will be completed in early 2000. The GBT has a large number of unique design and performance features that will give it unprecedented scientific capability. This poster display will review those features, which include an offset feed (clear aperture) design, an active surface, a closed-loop laser metrology system for surface

P. R. Jewell

1999-01-01

255

Fine Structures and Kinematics of an Intriguing Chromospheric Jet Observed by Hinode Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

Transient, small-scale ejections of plasma from the lower atmosphere are common manifestations of solar activity. Hinode, with its superior resolutions, has spurred renewed interest in solar jets since its launch. Here we report a chromospheric jet lasting for more than 1 hr on 2007 February 9 observed by the Hinode Solar Optical Telescope (SOT) in unprecedented detail. SOT Ca II H passband observations at high resolution of 0.2 arcsecond and cadence of 8 s allowed us to investigate the fine structures and kinematics of the jet. The ejection occurred in three episodes, rather than continuously, with the amount and velocity of material decreasing with time. The upward velocities along the jet range from ~440 to ~30 km/s, while the downward velocities of the material falling back have much smaller values (mean: -60 km/s) and a narrower distribution. Some tracks in the space-time plot clearly show parabolic shapes and the inferred acceleration is a fraction of the solar gravitational acceleration. The jet consists of fine threads (0.5-2 arcsecond wide), which exhibit coherent, oscillatory transverse motions perpendicular to the jet axis and about a common equilibrium position. These motions propagate upward, with the maximum phase speed of ~740 km/s found at the leading front of the jet. The transverse oscillation velocities range from 150 to 30 km/s, amplitudes from 6 to 2 Mm, and periods from 250 to 550 s. The oscillations slow down with time and cease when the material starts to fall back. The falling material travels along almost straight lines in the original direction of ascent, showing no transverse motions. These observations are consistent with the models suggested by Shibata & Uchida (1985) and Canfield et al. (1996). In this scenario, the jet involves untwisting helical threads, which rotate about the axis of a single large cylinder and shed magnetic helicity into the upper atmosphere. Implications of this event in the context of multiwavelength data in H-alpha, EUV, and X-rays will be discussed. A chromospheric jet observed by Hinode SOT in the Ca II H passband (T=1-2×10 4 K). Note the helical-like fine threads.

Liu, W.; Berger, T. E.; Title, A. M.; Tarbell, T. D.

2009-12-01

256

UPDATED ANALYSIS OF THE UPWIND INTERPLANETARY HYDROGEN VELOCITY AS OBSERVED BY THE HUBBLE SPACE TELESCOPE DURING SOLAR CYCLE 23  

SciTech Connect

The interplanetary hydrogen (IPH), a population of neutrals that fill the space between planets inside the heliosphere, carries the signature of the interstellar medium (ISM) and the heliospheric interface. As the incoming ISM-ionized component deflects at the heliopause, charge exchange reactions decelerate the bulk motion of the neutrals that penetrate the heliosphere. Inside the heliosphere, the IPH bulk velocity is further affected by solar gravity, radiation pressure, and ionization processes, with the latter two processes dependent on solar activity. Solar cycle 23 provided the first partial temporal map of the IPH velocity, including measurements from the Hubble Space Telescope (HST) spectrometers (Goddard High Resolution Spectrograph (GHRS) and Space Telescope Imaging Spectrograph (STIS)) and the Solar and Heliospheric Observatory/Solar Wind ANisotropies (SWAN) instrument. We present an updated analysis of IPH velocity measurements from GHRS and STIS and compare these results with those of SWAN and two different time-dependent models. Our reanalysis of STIS data reveals a significant change in IPH velocity relative to earlier reports, because of the contamination by geocoronal oxygen that was not accounted for. While current models of the heliospheric interface predict the observed IPH velocity for solar maximum, they are not consistent with data covering solar minimum. With updates to the HST data points, we now find that all data can be fit by the existing models to within 1{sigma}, with the exception of SWAN observations taken at solar minimum (1997/1998). We conclude that the current data lack the temporal coverage and/or precision necessary to determine the detailed characteristics of the solar cycle dependence. Hence, new observations are merited.

Vincent, Frederic E.; Ben-Jaffel, Lotfi [Institut d'Astrophysique de Paris, CNRS-UPMC, 75014 Paris (France); Harris, Walter M. [Department of Mechanical and Aerospace Engineering, University of California, Davis, CA 95616 (United States)

2011-09-10

257

Updated analysis of the upwind interplanetary hydrogen velocity as observed by the Hubble Space Telescope during solar cycle 23  

NASA Astrophysics Data System (ADS)

The interplanetary hydrogen (IPH), a population of neutrals that fill the space between planets inside the heliosphere, carries the signature of the interstellar medium (ISM) and the heliospheric interface. As the ionized component of the incoming ISM deflects at the heliopause, charge exchange reactions decelerate the bulk motion of the neutrals that penetrate the heliosphere. Inside the heliosphere, the IPH bulk velocity is further affected by solar gravity, radiation pressure, and ionization processes, with the latter two processes dependent on solar activity. Solar cycle 23 provided the first partial temporal map of the IPH velocity, including measurements from the Hubble Space Telescope (HST) spectrometers (Goddard High Resolution Spectrograph (GHRS) and Space Telescope Imaging Spectrograph (STIS)) and the Solar and Heliospheric Observatory/Solar Wind ANisotropies (SWAN) instrument. We present an updated analysis of IPH velocity measurements from GHRS and STIS, and compare these results with those of SWAN and two different time-dependent models. Our reanalysis of STIS data reveals a significant change in IPH velocity relative to earlier reports, because of the contamination by geocoronal oxygen that was not accounted for. As a consequence, it corrects the discrepancy with SWAN data near solar maximum (2001) and we now find that all data can be fit by the existing models to within 1?, with the exception of SWAN observations taken at solar minimum (1997/1998). We suggest that this discrepancy at solar minimum could be due to an indirect effect of the local interstellar magnetic field, which should be included in future modeling efforts. There may be extra features as the geocoronal deuterium or a possible Fermi effect from the heliospheric interface but the diagnostic is difficult because the resolution of these observations is limited. We conclude that the current data lack the temporal coverage and/or precision necessary to determine the detailed characteristics of the solar cycle dependence. Hence, new observations are merited and regular Ly-? measurements will be extremely helpful to constrain the problem of the heliospheric interface.

Vincent, F.; Ben-Jaffel, L.; Harris, W.

2011-12-01

258

Magnetic Structure of Umbral Dots Observed with the Hinode Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

A high-resolution, seeing-free spectroscopic observation of a decaying sunspot was made with the Solar Optical Telescope aboard the Hinode satellite. The target was NOAA 10944, located in the west side of the solar surface from 2007 March 2 to March 4. The umbra included many umbral dots (UDs) with a size of ˜300 km in continuum light. We report on the magnetic structures and Doppler velocity fields around UDs, based on the Milne-Eddington inversions of the two iron absorption lines at 6302Å. Histograms of the magnetic field strength (B), inclination angle (i), and Doppler velocity (v) of UDs showed a center-to-limb variation; observed at the disk center, the UDs had (i) slightly smaller field strength (?B = -17Gauss) and (ii) relative blue shifts (?v = 28m s-1) compared to their surroundings. When the sunspot got close to the limb, UDs and their surroundings showed almost no difference in the magnetic and Doppler values. This center-to-limb variation can be understood by the formation height difference in a cusp-shaped magnetized atmosphere around UDs, due to the weakly magnetized hot gas intrusion. In addition, some UDs showed the oscillatory light curves with multiple peaks separated around 10min, which may indicate the presence of the oscillatory convection. We discuss our results within the frameworks of two theoretical models: the monolithic model (Schüssler & Vögler 2006, ApJ, 641, L73) and the field-free intrusion model (Spruit & Scharmer 2006, A&A, 447, 343).

Watanabe, Hiroko; Kitai, Reizaburo; Ichimoto, Kiyoshi; Katsukawa, Yukio

2009-02-01

259

PRECURSOR OF SUNSPOT PENUMBRAL FORMATION DISCOVERED WITH HINODE SOLAR OPTICAL TELESCOPE OBSERVATIONS  

SciTech Connect

We present observations of a precursory signature that would be helpful for understanding the formation process of sunspot penumbrae. The Hinode Solar Optical Telescope successfully captured the entire evolution of a sunspot from the pore to a large well-developed sunspot with penumbra in an emerging flux region appearing in NOAA Active Region 11039. We found an annular zone (width 3''-5'') surrounding the umbra (pore) in Ca II H images before the penumbra formed around the umbra. The penumbra developed as if to fill the annular zone. The annular zone shows weak magnetogram signals, meaning less magnetic flux or highly inclined fields there. Pre-existing ambient magnetic field islands were distributed at the outer edge of the annular zone and did not come into the zone. There are no strong systematic flow patterns in the zone, but we occasionally observed small magnetic flux patches streaming out. The observations indicate that the annular zone is different from the sunspot moat flow region and that it represents the structure in the chromosphere. We conclude that the annular zone reflects the formation of a magnetic canopy overlying the region surrounding the umbra at the chromospheric level, long before the formation of the penumbra at the photospheric level. The magnetic field structure in the chromosphere needs to be considered in the formation process of the penumbrae.

Shimizu, Toshifumi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Ichimoto, Kiyoshi [Kwasan and Hida Observatories, Kyoto University, Kamitakara-cho, Takayama, Gifu 506-1314 (Japan); Suematsu, Yoshinori, E-mail: shimizu.toshifumi@isas.jaxa.jp [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

2012-03-10

260

Formation Process of a Light Bridge Revealed with the Hinode Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

The Solar Optical Telescope (SOT) on-board Hinode successfully and continuously observed the formation process of a light bridge in a matured sunspot of the NOAA active region 10923 for several days with high spatial resolution. During its formation, many umbral dots were observed to be emerging from the leading edges of penumbral filaments, and rapidly intruding into the umbra. The precursor of the light bridge formation was also identified as a relatively slow inward motion of the umbral dots, which emerged not near the penumbra, but inside the umbra. The spectro-polarimeter on SOT provided physical conditions in the photosphere around the umbral dots and the light bridges. We found that the light bridges and the umbral dots had significantly weaker magnetic fields associated with upflows relative to the core of the umbra, which implies that there was hot gas with weak field strength penetrating from the subphotosphere to near the visible surface inside those structures. There needs to be a mechanism to drive the inward motion of the hot gas along the light bridges. We suggest that the emergence and the inward motion are triggered by a buoyant penumbral flux tube as well as subphotospheric flow crossing the sunspot.

Katsukawa, Yukio; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi; Kubo, Masahito; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.; Tsuneta, Saku

2007-11-01

261

Shuttle Infrared Telescope Facility  

Microsoft Academic Search

The Shuttle Infrared Telescope Facility (SIRTF) will combine high sensitivity with the flexibility offered by the Space Transportation System. A recently completed study has generated a preliminary design which demonstrates the feasibility of SIRTF. The 1.0 to 1.5 meter aperture, f\\/8 Gregorian telescope will be cooled to 20 K by a stored supercritical helium system. The telescope will be pointed

S. G. McCarthy

1976-01-01

262

FIB 601 focused ion beam fabrication of micron-sized apertures for the NASA AXAF x-ray telescope prelaunch calibration  

NASA Astrophysics Data System (ADS)

Focused ion-beams have proved to be a superior means of fabricating holes between 5 and 20 microns in diameter, through gold and tungsten sheets over 40 microns thick. These holes are milled with an FEI FIB800 Focused Ion Beam Workstation using a Ga liquid metal source, with and without an enhancement gaseous etchant. They will be used as apertures for detectors that probe the point response function of the X-ray optics (Wolter Type-I mirror pairs), which form part of the NASA Advanced X-ray Astrophysical Facility. It is found that both pure milling and gas-assisted etching produced micron-sized holes of a quality superior to those produced by laser beam sputtering.

Tsiang, Eugene Y.; Kellogg, Edwin M.; Porterfield, Don

1995-09-01

263

Reconstruction of Radio Images of the Sun Obtained by the Siberian Solar Radio Telescope  

NASA Astrophysics Data System (ADS)

Reconstruction of radio images of the Sun obtained by the Siberian Solar Radio Telescope (SSRT) encounters two main problems. First, since the solar radio images at a wavelength of 5.2 cm have a high contrast, the amplitude-phase distribution in the antenna-feeder section should be known with a very high accuracy. Second, since such images comprise not only bright compact components but also low-contrast diffuse areas, there is a problem of deconvolution of these diffuse sources, which is inherent to the CLEAN algorithm. To solve the first problem, we determine the amplitude-phase distortions by an iterative analysis of the image itself, in which the opposite sidelobes of the point-source response are compared. To suppress the influence of other sources on the response, we analyze several compact sources. The phase distortions are determined from the asymmetry of the sidelobes, and the amplitude distortions, from sidelobe values. The image is corrected in the spatial-spectrum domain after each iteration. On the one hand, the problems encountered when reconstructing extended sources are related to the fact that the CLEAN algorithm requires significant computer resources. On the other hand, reconstructing images of extended areas requires that the number of cycles of this algorithm should be increased. Another problem consists in the fact that the use of the same ``clean'' antenna pattern for reconstructing compact and extended sources results in appearance of high-frequency distortions of the latter sources. If the CLEAN algorithm is applied, then the computer resources are mainly spent to shift the pattern and to find the maximum of the initial image. We decrease the time necessary for shifting the pattern by excluding the points near the zero value from the antenna-pattern data set and by sorting the remaining data points. The time of finding the maximum was decreased by using a local search window. In addition, we use a number of cutoff levels and search the next maximum in the whole image only after reconstructing the windowed image down to the current cut level. To reconstruct bright compact sources, we use the ''clean'' antenna pattern close to the ideal pattern. To reconstruct low-contrast diffuse areas, we use the model patterns obtained by convolving the antenna pattern with the images of extended sources.

Lesovoy, S. V.

2002-11-01

264

Stray light control for asteroid detection at low solar elongation for the NEOSSat micro-satellite telescope  

NASA Astrophysics Data System (ADS)

The Near Earth Object Surveillance Satellite (NEOSSat) is a small satellite dedicated to finding near Earth asteroids. Its surveying strategy consists of imaging areas of the sky to low solar elongation, while in a sun synchronous polar orbit (dawn-dusk). A high performance baffle will control stray light mainly due to Earth shine. Observation scenarios require solar shielding down to 45 degree solar elongation over a wide range of ecliptic latitudes. In order to detect the faintest objects (approx 20th v mag) given a 15 cm telescope and CCD detection system, background from stray light is a critical operational concern. The required attenuation is in the order of 10-12. The requirement was verified by analyses; testing was not attempted because the level of attenuation is difficult to measure reliably. We report consistent results of stray light optical modelling from two independent analyses. Launch is expected for late 2012.

Isbrucker, Victor; Stauder, John; Laurin, Denis; Hollinger, Allan

2012-09-01

265

The first observation and data reduction of the Multi-wavelength Spectrometer on the New Vacuum Solar Telescope  

NASA Astrophysics Data System (ADS)

The Multi-wavelength Spectrometer is a medium-dispersion (R ~ 130000) grating spectrometer installed on the New Vacuum Solar Telescope at the Fuxian Solar Observatory, Yunnan Astronomical Observatory, Chinese Academy of Sciences. It is designed to accurately observe the velocity and magnetic fields of the Sun. The present configuration of this spectrometer allows us to simultaneously observe three different solar spectral lines. This work is dedicated to showing the first observations carried out in both the H? and Ca II 8542 Å lines. We give a detailed description of the data reduction process, focusing on the retrieval of a flat field from the high-resolution spectral data. Two different methods are also performed and compared to eliminate the residual fringe in the reduced data. The real spectral resolution and instrumental profile are analyzed based on the final results, which indicate that this spectrometer presently satisfies the expected performance and it is ready for further scientific observations.

Wang, Rui; Xu, Zhi; Jin, Zhen-Yu; Li, Zhi; Fu, Yu; Liu, Zhong

2013-10-01

266

Effect of High Receiver Thermal Loss Per Unit Area on the Performance of Solar Central Receiver Systems Having Optimum Heliostat Fields and Optimum Receiver Aperture Areas.  

NASA Astrophysics Data System (ADS)

Recent efforts in solar central receiver research have been directed toward high temperature applications. Associated with high temperature processes are greater receiver thermal losses due to reradiation and convection. This dissertation examines the performance of central receiver systems having optimum heliostate fields and receiver aperture areas as a function of receiver thermal loss per unit area of receiver aperture. The results address the problem of application optimization (loss varies) as opposed to the problem of optimization of a design for a specific application (loss fixed). A reasonable range of values for the primary independent variable L (the average reradiative and convective loss per unit area of receiver aperture) and a reasonable set of design assumptions were first established. The optimum receiver aperture area, number and spacings of heliostats, and field boundary were then determined for two tower focal heights and for each value of L. From this, the solar subsystem performance for each optimized system was calculated. Heliostat field analysis and optimization required a detailed computational analysis. A significant modification to the standard method of solving the optimization equations, effectively a decoupling of the solution process into collector and receiver subsystem parts, greatly aided the analysis. Results are presented for tower focal heights of 150 and 180 m. Values of L ranging from 0.04 to 0.50 MW m('-2) were considered, roughly corresponding to working fluid temperatures (at receiver exit) in the range of 650 to 1650 C. As L increases over this range, the receiver thermal efficiency and the receiver interception factor decrease. The optimal power level drops by almost half, and the cost per unit of energy produced increases by about 25% for the base case set of design assumptions. The resulting decrease in solar subsystem efficiency (relative to the defined annual input energy) from 0.57 to 0.35 is about 40% and is a significant effect. Unoptimized systems would experience an even greater degradation in performance. Further study of this problem would indicate the effects which other tower focal heights, receiver orientation, heliostat size, beam degrading, and better focusing heliostats have on the results.

Pitman, Charles L.

267

Effect of high receiver thermal loss per unit area on the performance of solar central receiver systems having optimum heliostat fields and optimum receiver aperture areas  

SciTech Connect

Recent efforts in solar central receiver research have been directed toward high temperature applications. Associated with high temperature processes are greater receiver thermal losses due to reradiation and convection. The performance of central receiver systems having optimum heliostat fields and receiver aperture areas as a function of receiver thermal loss per unit area of receiver aperture are examined. The results address the problem of application optimization (loss varies) as opposed to the problem of optimization of a design for a specific application (loss fixed). Results are presented for tower focal heights of 150 and 180 m. Values of L ranging from 0.04 to 0.50 MW m/sup -2/ were considered, roughly corresponding to working fluid temperatures (at receiver exit) in the range of 650 to 1650/sup 0/C. As L increases over this range, the receiver thermal efficiency and the receiver interception factor decrease. The optimal power level drops by almost half, and the cost per unit of energy produced increases by about 25% for the base case set of design assumptions. The resulting decrease in solar subsystem efficiency (relative to the defined annual input energy) from 0.57 to 0.35 is about 40% and is a significant effect. Unoptimized systems would experience an even greater degradation in performance.

Pitman, C.L.

1983-01-01

268

Advancement of Piezo-Stack DM technology at CILAS: Example of HODM for KIS Gregor Solar Telescope  

NASA Astrophysics Data System (ADS)

Cilas has designed, manufactured and tested the deformable mirror for use in the high order adaptive optics system in the 1.5 m Gregor solar telescope (Tenerife). In the scope of this project for Kiepenheuer-Institut für Sonnenphysik (KIS), we have reached the smallest spacing ever made with our piezo-stack technology (3.2 mm) while increasing the overall reliability of our DMs by significant design evolutions. We will present the main specifications of the DM (18x18 actuator array, > 2 ?m interactuator stroke, > 20 kHz main resonance frequency) and the study results on reliability. This study is focused on electrical and opto-mechanical stability of the DM vs. time. The improved piezo-stack technology will be used for next generation of DMs for large telescopes as TMT and ESO (VLT and E-ELT)

Sinquin, J. C.; Bastard, A.; Cousty, R.; Guillemard, C.; Pagès, H.

2011-09-01

269

Adaptive membrane for large lightweight space telescopes  

Microsoft Academic Search

Large, lightweight telescopes in space will enable future earth science, space science, and reconnaissance. The state of the art in space telescope is the Hubble Space Telescope launched in 1990 with its 2.4 m primary mirror. Missions within the decade such as the Next Generation Space Telescope will push this aperture diameter to over 6.5 m. But truly revolutionary observation

Dimitry Gorinevsky; T. Tupper Hyde

2002-01-01

270

Radon approach to shaped and apodized apertures for imaging exoplanets  

Microsoft Academic Search

In this paper, we present a new approach to the study of shaped and apodized apertures for the detection of exoplanets. It is based on a Radon transform of the telescope aperture and makes it possible to present the effects of shaped and apodized apertures in a unified manner for an objective comparison between them. An illustration of this approach

C. Aime

2005-01-01

271

Soft X-ray Images of the Solar Corona with a Normal-Incidence Cassegrain Multilayer Telescope.  

PubMed

High-resolution images of the sun in the soft x-ray to extreme ultraviolet(EUV) regime have been obtained with normal-incidence Cassegrain multilayer telescopes operated from a sounding rocket in space. The inherent energy-selective property of multilayer-coated optics allowed distinct groups of emission lines to be isolated in the solar corona and the transition region. The Cassegrain telescopes provided images in bands centered at 173 and 256 angstroms. The bandpass centered at 173 angstroms is dominated by emission from the ions Fe IX Fe X. This emission is from coronal plasma in the temperature range 0.8 x 10(6) to 1.4 x 10(6)K. The images have angular resolution of about 1.0 to 1.5 arc seconds, and show no degradation because of x-ray scattering. Many features of coronal structure, including magnetically confined loops of hot plasma, coronal plumes, polar coronal holes, faint structures on the size scale of supergranulation and smaller, and features due to overlying cool prominences are visible in the images. The density structure of polar plumes, which are thought to contribute to the solar wind, has been derived from the observations out to 1.7 solar radii. PMID:17783129

Walker, A B; Lindblom, J F; Barbee, T W; Hoover, R B

1988-09-30

272

Submillimeter Telescopes  

NASA Astrophysics Data System (ADS)

The submillimeter band is a critical one for astronomy. It contains spectral and spatial information on very distant newly formed galaxies and on the early stages of star formation within gas clouds. Yet it is one of the few regions of the electromagnetic spectrum still to be made fully available to astronomy. This is in part due to the general difficulties of construction of detectors, receivers, and telescopes for these wavelengths and in part to the attenuating nature of the Earth's atmosphere. In recent years, optical style telescopes have become available, either on high mountain sites, or in the case of the NASA Kuiper Airborne Observatory (KAO) or Stratospheric Observatory for Infrared Astronomy (SOFIA) on board a high-altitude airplane. The James Clerk Maxwell telescope at 15 m and the Caltech Submillimeter Observatory (CSO) telescope at 10.4 m are both large enough to have developed the field. However, the ESA satellite Herschel has now provided the required space platform for complete spectral coverage and the Atacama Large Millimeter/Submillimeter Array (ALMA) the high spatial resolution, aperture synthesis, high-sensitivity platform.

Phillips, Thomas G.; Padin, Stephen; Zmuidzinas, Jonas

273

GRIST: A Study of a Grazing Incidence Solar Telescope. Volume 2: Technical Report.  

National Technical Information Service (NTIS)

A study was done to design a large grazing incidence XUV telescope based upon WOLTER II sector optics and using mechanization of the main optical assembly to provide image stabilization and focal plane switching. An examination of two principal instrument...

H. M. Mooney M. Hammond D. C. Clayton B. T. Biddis A. Derrick

1978-01-01

274

Quiescent Prominence Dynamics Observed with the Hinode Solar Optical Telescope. I. Turbulent Upflow Plumes  

NASA Astrophysics Data System (ADS)

Hinode/Solar Optical Telescope (SOT) observations reveal two new dynamic modes in quiescent solar prominences: large-scale (20-50 Mm) "arches" or "bubbles" that "inflate" from below into prominences, and smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are related in that they are always dark in visible-light spectral bands, they rise through the bright prominence emission with approximately constant speeds, and the small-scale upflows are sometimes observed to emanate from the top of the larger bubbles. Here we present detailed kinematic measurements of the small-scale turbulent upflows seen in several prominences in the SOT database. The dark upflows typically initiate vertically from 5 to 10 Mm wide dark cavities between the bottom of the prominence and the top of the chromospheric spicule layer. Small perturbations on the order of 1 Mm or less in size grow on the upper boundaries of cavities to generate plumes up to 4-6 Mm across at their largest widths. All plumes develop highly turbulent profiles, including occasional Kelvin-Helmholtz vortex "roll-up" of the leading edge. The flows typically rise 10-15 Mm before decelerating to equilibrium. We measure the flowfield characteristics with a manual tracing method and with the Nonlinear Affine Velocity Estimator (NAVE) "optical flow" code to derive velocity, acceleration, lifetime, and height data for several representative plumes. Maximum initial speeds are in the range of 20-30 km s-1, which is supersonic for a ~10,000 K plasma. The plumes decelerate in the final few Mm of their trajectories resulting in mean ascent speeds of 13-17 km s-1. Typical lifetimes range from 300 to 1000 s (~5-15 minutes). The area growth rate of the plumes (observed as two-dimensional objects in the plane of the sky) is initially linear and ranges from 20,000 to 30,000 km2 s-1 reaching maximum projected areas from 2 to 15 Mm2. Maximum contrast of the dark flows relative to the bright prominence plasma in SOT images is negative and ranges from -10% for smaller flows to -50% for larger flows. Passive scalar "cork movies" derived from NAVE measurements show that prominence plasma is entrained by the upflows, helping to counter the ubiquitous downflow streams in the prominence. Plume formation shows no clear temporal periodicity. However, it is common to find "active cavities" beneath prominences that can spawn many upflows in succession before going dormant. The mean flow recurrence time in these active locations is roughly 300-500 s (5-8 minutes). Locations remain active on timescales of tens of minutes up to several hours. Using a column density ratio measurement and reasonable assumptions on plume and prominence geometries, we estimate that the mass density in the dark cavities is at most 20% of the visible prominence density, implying that a single large plume could supply up to 1% of the mass of a typical quiescent prominence. We hypothesize that the plumes are generated from a Rayleigh-Taylor instability taking place on the boundary between the buoyant cavities and the overlying prominence. Characteristics, such as plume size and frequency, may be modulated by the strength and direction of the cavity magnetic field relative to the prominence magnetic field. We conclude that buoyant plumes are a source of quiescent prominence mass as well as a mechanism by which prominence plasma is advected upward, countering constant gravitational drainage.

Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine, Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto, Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya; Suematsu, Yoshinori; Shimizu, Toshifumi

2010-06-01

275

New Solar System Researches expected by a New Telescope Project at Mt. Haleakala, Hawaii  

NASA Astrophysics Data System (ADS)

We Tohoku University starts the project for the new ground-based telescope dedicated to planets and exoplanets, in collaboration with the Institute for Astronomy of University of Hawaii(IfA/UH) and ETH Zurich. The summit of Mt. Haleakala in Maui, Hawaii is one of the best sites with clear skies, good seeing, and low humidity conditions as well as good accessibility despite its high altitude (elv. 3,000m). Haleakala High Altitude Observatory is operated by IfA/UH, and we have been making observation of planets there since 2000. Currently, our observation facility consists of a 40cm telescope. We have been making observations of faint atmospheric and plasma features around bright planets, Io plasma torus, Mercury and Lunar sodium tail, and so on. Atmospheric escapes from Mars and Venus, the exoplanets close to mother stars are also possible future important topics. When we try to observe those faint emissions surrounding the bright objects, intense scattered light causes a serious problem. The new telescope shall avoid the diffraction due to a spider structure that holds a secondary mirror and to minimize the scattered light from mirror surfaces as far as possible. Such telescope with a wide dynamic range dedicated to planetary and exoplanetary sciences does not exist yet. The project, called PLANETS (Poralized Light from Atmospheres of Nearby Extra Terrestrial Planets), develops a new telescope (tentatively named as JHET; Japan Hawaii Europe Telescope) which consists of an off-axis primary mirror with a diameter of 1.8m, and Gregorian optics on an equatorial mount. State-of-art adaptive optics and masking technologies will also be adopted to eliminate the scattering light. This telescope will enables us to do spectro-polarimetric observations and faint plasma and atmospheres around the bright bodies. We will introduce the progress of our ground-based observations and the future plan involving the wide area of the international communities.

Kagitani, Masato; Okano, S.; Kasaba, Y.; Kuhn, J.; Berdyugina, S.

2009-09-01

276

Development of Solar Scintillometer  

NASA Astrophysics Data System (ADS)

The index of scintillation measurement is a good parameter to compare different sites for image quality or `seeing'.We have developed a scintillometer, which is deployed on the high resolution SPAR telescope in the island site of Udaipur Solar Observatory, for the site characterization to specify the proposed MAST (Multi Application Solar Telescope). The scintillometer consists of a miniature telescope, termed as micro telescope (4mm aperture, 15mm focal length) mounted on a drive which tracks the Sun continuously, associated amplifiers and a data acquisition system. A photodiode is used as the detector. The telescope along with detector was obtained from National Solar Observatory (NSO), and is similar to the one used for Advanced Technology Solar Telescope (ATST) site survey. At USO we developed the amplifier and data acquisition system for the scintillometer. A 24-bit analog to digital converter based system was designed, assembled, tested and used as the data acquisition system (DAS). In this paper, we discuss the instrumentation and present the initial results.

Gupta, Sudhir Kumar; Mathew, Shibu K.; Venkatakrishnan, P.

2006-09-01

277

A UV/optical telescope for the New Worlds Observer mission  

NASA Astrophysics Data System (ADS)

The New Worlds Observer (NWO) mission uses a large external occulter, or "starshade," to block the light from nearby stars and cast a deep shadow over the entrance aperture of a space telescope, enabling it to detect and characterize Exo-Solar Planets. Since these planets are intrinsically faint (30th to 32nd magnitude), the telescope must have a large aperture (2.4 to 4 meters) and the starshade must be large enough (25 to 50 meters) to create a shadow that is deep enough (108 to 1010 starlight suppression) and large enough (5 to 10 meters in diameter) to envelop the telescope. The telescope must also be far enough from the starshade (30,000 to 80,000 kilometers) that planets close to the star (50 to 65 milli-arc-seconds) are not occulted. Since the starshade's performance is inversely proportional to the wavelength of the starlight, the telescope must operate in the visible and near infrared. The telescope should also have a significant capability for general astrophysics observations, since it will have more than half its time available for other observations while the starshade is moving from one target to the next. This paper describes our conceptual design for the NWO telescope, including its instrument suite and operations concept. We note that in addition to comparative planetology studies and the detection and characterization of terrestrial planets, the telescope could provide a UV/Optical observing capability for the general astronomical community in the post-HST era.

Lillie, Charles F.; Dailey, D.; Lo, Amy S.; Polidan, Ronald S.

2007-09-01

278

High resolution infrared solar observations by balloon  

Microsoft Academic Search

Results are presented for balloon-borne solar observations in near- and intermediate infrared regions not accessible from the ground, with as high a resolution as possible. The stratospheric equipment used consists mainly of a 38.5-cm aperture telescope coupled to a 2.5-m focal length Ebert-Fastie grating spectrometer used in double pass with a narrow slit. The solar spectrum between 1.8697 and 1.8753

R. Zander

1976-01-01

279

Diffraction limited imaging using large ground-based telescopes  

Microsoft Academic Search

It is generally thought that the resolution of large ground-based telescopes is limited by atmospheric turbulence rather than by diffraction from the telescope aperture. However, longer wavelengths are less affected by atmospheric turbulence than shorter wavelengths and, conversely, longer wavelengths are more affected by diffraction from the telescope aperture. An optimum wavelength exists where these two counteracting effects balance. At

Stewart McKechnie

1990-01-01

280

Surface and Bulk Degradation of Teflon® FEP Retrieved from the Hubble Space Telescope Solar Arrays  

Microsoft Academic Search

Teflon® fluorinated ethylene propylene (FEP) is used on the Hubble Space Telescope (HST) as the outer layer of multilayer insulation (MLI) blankets. During space shuttle servicing missions (SM) to HST through thickness cracks were observed in the FEP layers. Material brought to Earth for investigation showed signs of severe degradation. During servicing mission 3B, the 4th servicing mission to HST

M. Moser; C. O. A. Semprimoschnig; M. R. J. Van Eesbeek; R. Pippan

2008-01-01

281

A Phase Study of a Grazing Incidence Solar Telescope. Volume 1: Executive Summary.  

National Technical Information Service (NTIS)

A design for a large grazing incidence XUV telescope was done based on WOLTER II sector optics and using mechanization of the main optical assembly to provide image stabilization and focal plane switching is presented. An examination of two principal inst...

H. M. Mooney

1978-01-01

282

Large aperture scanning airborne lidar  

NASA Astrophysics Data System (ADS)

A large aperture scanning airborne lidar facility is being developed to provide important new capabilities for airborne lidar sensor systems. The proposed scanning mechanism allows for a large aperture telescope (25 in. diameter) in front of an elliptical flat (25 x 36 in.) turning mirror positioned at a 45 degree angle with respect to the telescope optical axis. The lidar scanning capability will provide opportunities for acquiring new data sets for atmospheric, earth resources, and oceans communities. This completed facility will also make available the opportunity to acquire simulated EOS lidar data on a near global basis. The design and construction of this unique scanning mechanism presents exciting technological challenges of maintaining the turning mirror optical flatness during scanning while exposed to extreme temperatures, ambient pressures, aircraft vibrations, etc.

Smith, J.; Bindschadler, R.; Boers, R.; Bufton, J. L.; Clem, D.; Garvin, J.; Melfi, S. H.

283

The development of filter vector magnetographs for the Solar Magnetic Activity Research Telescope (SMART)  

Microsoft Academic Search

In recent years, it is beginning to be shown observationally and theoretically that the existence of the magnetic field is indispensable for active phenomena on the solar surface. In particular, the rotation or helicity of the magnetic field and their temporal variation are considered to be important factors which influence solar activity. In order to confirm this, it is necessary

Satoru UeNo; Shin-ichi Nagata; Reizaburo Kitai; Hiroki Kurokawa; Kiyoshi Ichimoto

2004-01-01

284

Telescope costs and cost reduction  

NASA Astrophysics Data System (ADS)

The prices of more than 60 telescopes of the most diverse types and sizes are analyzed according to telescope aperture. Actualized prices in 1995 were calculated taking inflation into account, as well as fluctuations in the DM exchange rate. We discuss the dependence of prices on factors like size, mass, optical system, number of construction parts (similarity laws), as well as on special technical requirements. The relationship between telescope aperture and costs shows interesting differences between the classical astronomical telescopes and the new, large telescope projects. The number of repeated construction parts and the number of realized instruments with the same design is of great importance. Cost reductions are best achieved in the conception and design phase of telescope development.

Schmidt-Kaler, Theodor; Rucks, Peter

1997-03-01

285

Telescopes from the Ground Up  

NSDL National Science Digital Library

This tutorial traces the history of the telescope, beginning with Galileo's first small refractor, to the era of orbiting space telescopes. Topics include Galileo's trouble with the church over the observations he made with his new instrument, Sir Isaac Newton's invention of the reflecting telescope, and the development of technologies that made it possible to construct increasingly larger, more powerful optical telescopes. The tutorial concludes with the discovery of radio signals emanating from space and the construction of radio telescopes, multi-mirror optical telescopes, technologies to view other types of radiation, space telescopes, and solar telescopes. Links are provided to teaching tips and to online resources with additional information.

286

Mission design for the Space Infrared Telescope Facility (SIRTF)  

NASA Astrophysics Data System (ADS)

The Space Infrared Telescope Facility (SIRTF) is the fourth in NASA's series of Great Observatories. It will feature a one-meter class cryogenically cooled telescope. It is planned for a NASA fiscal start for the development phase in 1994 with a launch in about 2001. The launch vehicle will be the new upgraded Titan IV with a Centaur upper stage. The operational orbit will be circular at an altitude of about 100,000 km. The planned mission lifetime is 5 years. This paper addresses the rationale in the selection of the high altitude orbit, the performance of the launch vehicle in delivering the observatory to orbit, other orbit options, and the planned observational modes and capabilities of the observatory. The paper will also address the viewing geometry and viewing constraints affecting science observation, telescope aperture shade design, and spacecraft solar-panel and communication design.

Kwok, Johnny H.; Osmolovsky, Michael G.

1991-12-01

287

Atomic force microscopy characterization of Zerodur mirror substrates for the extreme ultraviolet telescopes aboard NASA's Solar Dynamics Observatory  

SciTech Connect

The high-spatial frequency roughness of a mirror operating at extreme ultraviolet (EUV)wavelengths is crucial for the reflective performance and is subject to very stringent specifications. To understand and predict mirror performance, precision metrology is required for measuring the surface roughness. Zerodur mirror substrates made by two different polishing vendors for a suite of EUV telescopes for solar physics were characterized by atomic force microscopy (AFM). The AFM measurements revealed features in the topography of each substrate that are associated with specific polishing techniques. Theoretical predictions of the mirror performance based on the AFM-measured high-spatial-frequency roughness are in good agreement with EUV reflectance measurements of the mirrors after multilayer coating.

Soufli, Regina; Baker, Sherry L.; Windt, David L.; Gullikson, Eric M.; Robinson, Jeff C.; Podgorski, William A.; Golub, Leon

2007-06-01

288

A CATALOG OF SOLAR X-RAY PLASMA EJECTIONS OBSERVED BY THE SOFT X-RAY TELESCOPE ON BOARD YOHKOH  

SciTech Connect

A catalog of X-ray plasma ejections (XPEs) observed by the Soft X-ray Telescope on board the Yohkoh satellite has been recently developed in the Astronomical Institute of University of Wroclaw. The catalog contains records of 368 events observed in years 1991-2001 including movies and cross-references to associated events like flares and coronal mass ejections (CMEs). One hundred sixty-three XPEs out of 368 in the catalog were not reported until now. A new classification scheme of XPEs is proposed in which morphology, kinematics, and recurrence are considered. The relation between individual subclasses of XPEs and the associated events was investigated. The results confirm that XPEs are strongly inhomogeneous, responding to different processes that occur in the solar corona. A subclass of erupting loop-like XPEs is a promising candidate to be a high-temperature precursor of CMEs.

Tomczak, M.; Chmielewska, E., E-mail: tomczak@astro.uni.wroc.pl, E-mail: chmielewska@astro.uni.wroc.pl [Astronomical Institute, University of Wroclaw, ul. Kopernika 11, PL-51-622 Wroclaw (Poland)

2012-03-01

289

Roof apertures in office buildings  

Microsoft Academic Search

An investigation has been made of potential lighting electricity reductions and associated thermal impacts of replacing electric light with sunlight admitted through rooftop glazing on a single-story, prototypical office building. Experimental scale models have been used to determine the fraction of the solar radiation entering the aperture which reaches the work plane as useful illumination. This information is used in

M. Fontoynont; C. Conner; R. C. Kammerud; B. Anderson; F. Bauman; W. Carroll; T. C. Howard; A. Mertol; T. Webster

1983-01-01

290

Cooling Technology for Large Space Telescopes  

Microsoft Academic Search

NASA's New Millennium Program funded an effort to develop a system cooling technology, which is applicable to all future infrared, sub-millimeter and millimeter cryogenic space telescopes. In particular, this technology is necessary for the proposed large space telescope Single Aperture Far-Infrared Telescope (SAFIR) mission. This technology will also enhance the performance and lower the risk and cost for other cryogenic

Michael DiPirro; Paul Cleveland; Dale Durand; Andy Klavins; Danniella Muheim; Christopher Paine; Mike Petach; Domenick Tenerelli; Jason Tolomeo; Keith Walyus

291

Search for Sub-eV Mass Solar Axions by the CERN Axion Solar Telescope with {sup 3}He Buffer Gas  

SciTech Connect

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using {sup 3}He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with {sup 4}He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV < or approx. m{sub a} < or approx. 0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g{sub a}{gamma} < or approx. 2.3x10{sup -10} GeV{sup -1} at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m{sub a} < or approx. 1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.

Arik, M.; Cetin, S. A.; Ezer, C.; Yildiz, S. C. [Dogus University, Istanbul (Turkey); Aune, S.; Ferrer-Ribas, E.; Giomataris, I.; Papaevangelou, T. [IRFU, Centre d'Etudes Nucleaires de Saclay (CEA-Saclay), Gif-sur-Yvette (France); Barth, K.; Borghi, S.; Davenport, M.; Elias, N.; Haug, F.; Laurent, J. M.; Niinikoski, T.; Silva, P. S.; Stewart, L. [European Organization for Nuclear Research (CERN), Geneve (Switzerland); Belov, A.; Gninenko, S. [Institute for Nuclear Research (INR), Russian Academy of Sciences, Moscow (Russian Federation); Braeuninger, H. [Max-Planck-Institut fuer Extraterrestrische Physik, Garching (Germany)

2011-12-23

292

Optica aperture synthesis  

NASA Astrophysics Data System (ADS)

Optical long baseline stellar interferometry is an observational technique in astronomy that already exists for over a century, but is truly blooming during the last decades. The undoubted value of stellar interferometry as a technique to measure stellar parameters beyond the classical resolution limit is more and more spreading to the regime of synthesis imaging. With optical aperture synthesis imaging, the measurement of parameters is extended to the reconstruction of high resolution stellar images. A number of optical telescope arrays for synthesis imaging are operational on Earth, while space-based telescope arrays are being designed. For all imaging arrays, the combination of the light collected by the telescopes in the array can be performed in a number of ways. In this thesis, methods are introduced to model these methods of beam combination and compare their effectiveness in the generation of data to be used to reconstruct the image of a stellar object. One of these methods of beam combination is to be applied in a future space telescope. The European Space Agency is developing a mission that can valuably be extended with an imaging beam combiner. This mission is labeled Darwin, as its main goal is to provide information on the origin of life. The primary objective is the detection of planets around nearby stars - called exoplanets- and more precisely, Earth-like exoplanets. This detection is based on a signal, rather than an image. With an imaging mode, designed as described in this thesis, Darwin can make images of, for example, the planetary system to which the detected exoplanet belongs or, as another example, of the dust disk around a star out of which planets form. Such images will greatly contribute to the understanding of the formation of our own planetary system and of how and when life became possible on Earth. The comparison of beam combination methods for interferometric imaging occupies most of the pages of this thesis. Additional chapters will treat related subjects, being experimental work on beam combination optics, a description of a novel formalism for aberration retrieval and experimental work on nulling interferometry. The Chapters on interferometric imaging are organized in such a way that not only the physical principles behind a stellar interferometer are clear, but these chapters also form a basis for the method of analysis applied to the interferometers - -or rather beam combination methods- under consideration. The imaging process in a stellar interferometer will be treated as the inversion of a linear system of equations. The definition of interferometric imaging in this thesis can be stated to be the reconstruction of a luminosity distribution function on the sky, that is, in angular measure, larger than the angular diffraction limited spot size -or Point-Spread Function (PSF)- of a single telescope in the array and that contains, again in angular measure, spatial structure that is much smaller than the PSF of a single telescope. This reconstruction has to be based on knowledge of the dimensions of the telescope array and the detector. The detector collects intensity data that is formed by observation of the polychromatic luminosity distribution on the sky and is deteriorated by the quantum-nature of light and an imperfect electronic detection process. Therefore, the imaging study presented in this thesis can be regarded to be a study on the signal characteristics of various interferometers while imaging a polychromatic wide-field stellar source. The collection of beam combination methods under consideration consists of four types. Among these are two well-known types, having either co-axially combined beams as in the Michelson-Morley experiment to demonstrate the existence of ether, or beams that follow optical paths as if an aperture mask were placed in front of a telescope, making the beams combine in the focus of that telescope, as suggested by Fizeau. For separated apertures rather than an aperture mask, these optical paths are stated to be homothetic. In short, these two types wi

van der Avoort, Casper

2006-05-01

293

AAVSO Solar Observers Worldwide  

NASA Astrophysics Data System (ADS)

(Abstract only) For visual solar observers there has been no biological change in the "detector" (human eye) - at century scales (eye + visual cortex) does not change much over time. Our capacity to "integrate" seeing distortions is not just simple averaging! The visual cortex plays an essential role, and until recently only the SDO-HMI (Solar Dynamics Observatory, Helioseismic and Magnetic Imager) has had the capacity to detect the smallest sunspots, called pores. Prior to this the eye was superior to photography and CCD. Imaged data are not directly comparable or substitutable to counts by eye, as the effects of sensor/optical resolution and seeing will have a different influence on the resulting sunspot counts for images when compared to the human eye. Also contributing to the complex task of counting sunspots is differentiating between a sunspot (which is usually defined as having a darker center (umbra) and lighter outer ring (penumbra)) and a pore, made even more complex by the conflicting definitions of the word "pore" in the solar context: "pore" can mean a small spot without penumbra or "pore" can mean a random intergranular blemish that is not a true sunspot. The overall agreement is that the smallest spot size is near 2,000 km or ~3 arc sec, (Loughhead, R. E. and Bray, R. J. 1961, Australian J. Phys., 14, 347). Sunspot size is dictated by granulation dynamics rather than spot size (cancellation of convective motion), and by the lifetime of the pore, which averages from 10 to 30 minutes. There is no specific aperture required for AAVSO observers contributing sunspot observations. However, the detection of the smallest spots is influenced by the resolution of the telescope. Two factors to consider are the theoretical optical resolution (unobstructed aperture), Rayleigh criterion: theta = 138 / D(mm), and Dawes criterion: theta = 116 / D(mm) (http://www.telescope-optics.net/telescope_resolution.htm). However, seeing is variable with time; daytime range will be similar for all low-altitude sites, within the range of 1.5 to 3 arc sec, (typically = 2 arc sec equivalent diameter D = 45-90 mm, the typical solar scope = 70 mm aperture). Where large apertures are more affected by size of turbulent eddies ~8-12 cm, small-aperture telescopes reduce these differences, i.e. large aperture is not always beneficial.

Howe, R.

2013-06-01

294

RATAN-600 radio telescope in the 24th solar-activity cycle. III. System of data acquisition and control of the solar spectral facility  

NASA Astrophysics Data System (ADS)

We report the development of a multichannel data acquisition and control system for the Spectral and Polarization High-Resolution Solar Research System, installed at the RATAN-600 radio telescope. This facility provides high-speed registration of signals from 240 channels and controls the preparation for observations and the process of automatic observations. The hardware is made in the form factor of 3U Evromekhanika modules. The measurement facility is controlled by the software based on the QT cross-platform library (the open source version), which can be run both on Linux and Windows operating systems. The data are written to a magnetic carrier and then transferred to the computer network of the Special Astrophysical Observatory for archiving, and can be accessed by external users.

Baldin, S. V.; Garaimov, V. I.

2011-07-01

295

Critical science for the largest telescopes: science drivers for a 100m ground-based optical-IR telescope  

NASA Astrophysics Data System (ADS)

Extremely large filled-aperture ground-based optical-IR telescopes, or ELTs, ranging from 20 to 100m in diameter, are now being proposed. The all-important choice of the aperture must clearly be driven by the potential science offered. We here highlight science goals from the Leiden Workshop in May 2001 suggesting that for certain critical observations the largest possible aperture - assumed to be 100m (the proposed European OverWhelmingly Large telescope (OWL) - is strongly to be desired. Examples from a long list include: COSMOLOGY: * Identifying the first sources of ionisation in the universe, out to z >=14 * Identifying and stufdying the first generation of dusty galaxies * More speculatively, observing the formation of the laws of physics, via the evolution of the fundamental physical contants in the very early Universe, by high-resolution spectroscopy of very distant quasars. NEARER GALAXIES: *Determining detailed star-formation histories of galaxies out to the Virtgo Cluster, and hence for all major galaxy types (not just those available close to the Local Group of galaxies). THE SOLAR SYSTEM: A 100-m telescope would do the work of a flotilla of fly-by space probes for investigations ranging from the evolution of planetary sutfaces and atmospheres to detailed surface spectroscopy of Kuiper Belt Objects. (Such studies could easily occupy it full-time.) EARTHLIKE PLANETS OF NEARBY STARS: A propsect so exciting as perhaps to justify the 100-m telescope on its own, is that of the direct detection of earthlike planets of solar-type stars by imaging, out to at least 25 parsecs (80 light years) from the sun, followed by spectroscopic and photometric searches for the signature of life on the surfaces of nearer examples.

Hawarden, Timothy G.; Dravins, Dainis; Gilmore, Gerard F.; Gilmozzi, Roberto; Hainaut, Olivier; Kuijken, K.; Leibindgut, Bruno; Merrifield, Michael; Queloz, Didier; Wyse, Rosie

2003-01-01

296

Terrestrial optical aperture synthesis technique (TOAST)  

NASA Astrophysics Data System (ADS)

An aperture-synthetic, high-resolution imaging technique, for obtaining near diffraction-limited images from a single telescope is described. The scheme yields model-independent reconstructions of the object under study and is suitable for operation simultaneously with other observing programmes such as spectroscopic studies or speckle imaging. A specific scheme suitable for use on the 2m5 Isaac Newton Telescope is presented, which would have a magnitude limit of about -11.

Greenaway, A. H.

1986-06-01

297

Search and study of electrostatic discharges in the Solar System with the radio telescope UTR-2  

NASA Astrophysics Data System (ADS)

Successful ground-based detection of Saturn's lightning despite terrestrial interferences is the necessary basis for further detailed study of their characteristics. Modern observational equipment provide high temporal and spectral resolution and allows to resolve the fine structure of lightning. Also it give us a hope to detect much weaker electrostatic discharges in the atmospheres of another planets of the Solar System.

Zakharenko, V.; Mylostna, K.; Konovalenko, A.; Kolyadin, V.; Zarka, P.; Griessmeier, J.-M.; Litvinenko, G.; Sidorchuk, M.; Rucker, H.; Fischer, G.; Cecconi, B.; Coffre, A.; Denis, L.; Shevchenko, V.; Nikolaenko, V.

2012-09-01

298

The telescope and the double Fabry-Pérot interferometer for the ADAHELI solar space mission  

Microsoft Academic Search

ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for

V. Greco; F. Cavallini; F. Berrilli

2010-01-01

299

Design of the optics for an imaging classic mount multi-etalon spectro-polarimeter for the next generation of ground-based solar telescopes  

NASA Astrophysics Data System (ADS)

In designing the optics of an imaging classic mount multi-étalon spectro-polarimeter as a post-focus instrument for the next generation of ground-based solar telescopes (Advanced Technology Solar Telescope, European Solar Telescope), many constraints must be considered. The large entrance pupil diameter of the telescope (4 m), the demanded large field of view (>= 90 arcsec), high spectral resolving power (>= 200000), and limited field-dependent blue-shift of the instrumental profile (<= 3 FWHM) require Fabry-Pérot interferometers of large diameter (>= 200 mm), lighted by highly collimated beams. This implies large optical elements and long optical paths. Moreover, to use interference pre-filters, placed between the interferometers to reduce the inter-reflections in axial-mount, with a relatively small diameter (<= 70 mm), a "pupil adapter" should be included, with a further increase of the optical path length. Although a multi-étalon spectro-polarimeter works in quasi-monochromatic light, the Fraunhofer lines of interest cover a wide range of wavelengths (850 nm - 1650 nm), demanding a good chromatic aberration control. Finally, a low instrumental polarization (<= 0.5 %) is required to allow a high polarimetric precision. In this paper a diffraction limited optical solution is described, fulfilling all the above requirements in a relative small volume.

Greco, V.; Cavallini, F.

2011-09-01

300

Segmented telescopes for coronagraphs  

NASA Astrophysics Data System (ADS)

Use of a deployable telescope will be essential if the full science objectives of the Terrestrial Planet Finder mission are to be achieved with a visible coronagraph, since the largest monolithic mirrors that can be launched into space do not have the spatial resolution required to search the habitable zone around more than ~40 of the nearest stars. Current launch vehicle fairings limit the size of monolithic telescope mirrors to ~4 meters in diameter, or ~3.5-m x 10-m if the mirror is launched standing upright, and the telescope is unfolded after reaching orbit. By comparison, a telescope with two 3.5 x 7 meter segments could be launched and deployed autonomously to provide a 14-m elliptical aperture, and a telescope with six 4-m flat-flat hexagonal segments could be launched and deployed autonomously to provide a near-circular 12-m aperture with a single ring of segments (or 20-m if a second ring is added). Future NASA missions such as LifeFinder and planet imager will also require segmented, deployable telescopes to achieve the necessary collecting area. This paper discusses the issues associated with the use of segmented optics for coronagraphs and potential solutions.

Lillie, Charles F.; Flannery, Martin; Dailey, Dean

2004-10-01

301

Telescoping in on the Microscopic Origins of the Fast Solar Wind  

NASA Astrophysics Data System (ADS)

Despite many years of study, the basic physical processes that are responsible for producing the solar wind are not known (or at least not universally agreed upon). The fact that we have an overabundance of proposed ideas for solving the problems of coronal heating and wind acceleration can be seen as both a blessing and a curse. It is a blessing because it highlights the insight and creativity of the community, but it is a curse because we still do not know how to validate or falsify many of these ideas. Discerning the presence of any given proposed mechanism is difficult not only because measurements are limited, but also because many of the suggested processes act on a wide range of spatial scales (from centimeters to solar radii) with complex feedback effects that are not yet understood. This presentation will discuss a few key examples and controversies regarding the importance of small spatial and temporal scales in the regions where the solar wind is accelerated. For example, new observations have led to a revived debate about whether the hot plasma in the solar wind is injected dynamically from cooler regions below or whether it "evaporates" from the combined effects of radiation and conduction from above. There is also debate about how the open field lines are energized: Is the energy input from waves and turbulent eddies that propagate up from the Sun and dissipate, or is the constantly evolving magnetic carpet responsible for heating the plasma via reconnection? In some areas, traditional observational diagnostics of magnetohydrodynamic plasma properties may not be sufficient to distinguish between competing predictions. Thus, this presentation will also describe why it is probably wise to confront the truly microscopic (nonlinear, non-Maxwellian, collisionless) nature of the relevant particles and fields. Theories and measurements that "zoom in" to this level of kinetic detail have the greatest potential for improving our understanding of the origins of coronal heating and solar wind acceleration.

Cranmer, S. R.

2011-12-01

302

Webb Telescope Trailer  

NASA Video Gallery

Can you imagine seeing 13 billion years back in time, watching the first stars grow, galaxies evolve and solar systems form? When the James Webb Space Telescope launches, we will get that chance. Scheduled for launch in 2014, the Webb Telescope is the heir apparent to Hubble.

Robert Garner

2010-03-23

303

A portable solar adaptive optics system: software and laboratory developments  

Microsoft Academic Search

We present our recent process on a portable solar adaptive Optics system, which is aimed for diffraction-limited imaging in the 1.0 ~ 5.0-mum infrared wavelength range with any solar telescope with an aperture size up to 1.6 meters. The realtime wave-front sensing, image processing and computation are based on a commercial multi-core personal computer. The software is developed in LabVIEW.

Deqing Ren; Matt Penn; Claude Plymate; Haimin Wang; Xi Zhang; Bing Dong; Nathan Brown; Andrew Denio

2010-01-01

304

The Keck Solar Two gamma-ray telescope, and its observations of the Crab Nebula  

NASA Astrophysics Data System (ADS)

The Keck Solar Two gamma-ray observatory in Barstow, CA is a 32-channel, heliostat array detector. Data taken in the spring of 2002 indicate a statistically unambiguous gamma-ray signal from the Crab Nebula. Details of the detector and its performance are discussed here, as are observations of the Crab. Future prospects for the detector, after a planned expansion and upgrade, are also described.

Tripathi, S. M.; Bhattacharya, D.; Lizarazo, J.; Marleau, P.; Mohanty, G.; Mohideen, U.; Murray, P.; Tom, H.; Tumer, T.; Xing, G.; Zweerink, J.

2002-05-01

305

HILT: a heavy ion large area proportional counter telescope for solar and anomalous cosmic rays  

Microsoft Academic Search

The HILT sensor has been designed to measure heavy ion elemental abundances, energy spectra, and direction of incidence in the mass range from helium to iron and in the energy range 4-250 MeV\\/nucleon. With its large geometric factor of 60 cm2 sr the sensor is optimized to provide compositional and spectral measurements for low-intensity cosmic rays, i.e., for small solar

Berndt Klecker; Dietrich Hovestadt; M. Scholer; H. Arbinger; M. Ertl; H. Kaestle; E. Kuenneth; P. Laeverenz; E. Seidenschwang; J. B. Blake; N. Katz; D. Mabry

1993-01-01

306

Parabolic telescope and spectrometer combination  

NASA Astrophysics Data System (ADS)

The properties of a nonfocusing collimating parabolic telescope are studied in detail by a ray-tracing method. The best optical quality with respect to coma and astigmatism is calculated for rays close to the optical axis of the telescope. For rectangular fields of view the borders are not sharp because of the aberration. A combination of a parabolic telescope and an echelle-type spectrometer gives very high spectral resolution. Wadsworth, Ebert-Fastie, and other types of spectrometers are equally well suited to be combined with this telescope. For some cases spot diagrams demonstrate the optical performance. In addition, diffraction by the aperture and its implications are discussed.

Schmidtke, G.; Henneberg, P.; Hager, K.-H.; Busch, F.; Reinhardt, D.

1980-06-01

307

Parabolic telescope and spectrometer combination.  

PubMed

The properties of a nonfocusing collimating parabolic telescope are studied in detail by a ray-tracing method. The best optical quality with respect to coma and astigmatism is calculated for rays close to the optical axis of the telescope. For rectangular fields of view the borders are not sharp because of the aberration. A combination of a parabolic telescope and an echelle-type spectrometer gives very high spectral resolution. Wadsworth, Ebert-Fastie, and other types of spectrometers are equally well suited to be combined with this telescope. For some cases spot diagrams demonstrate the optical performance. In addition, diffraction by the aperture and its implications are discussed. PMID:20221130

Schmidtke, G; Henneberg, P; Hager, K H; Busch, F; Reinhardt, D

1980-06-01

308

Optical vortex coronagraphy with an elliptical aperture.  

PubMed

An optical vortex coronagraph that makes efficient use of a larger fraction of the clear aperture of a Cassegrain-type telescope is described. This design incorporates an elliptical subaperture rather than the conventional circular subaperture. We derive a new vortex phase mask that maintains the same theoretical contrast of a circularly symmetric vortex coronagraph. PMID:23314632

Ruane, Garreth J; Swartzlander, Grover A

2013-01-10

309

DEBRIS DISKS AROUND SOLAR-TYPE STARS: OBSERVATIONS OF THE PLEIADES WITH THE SPITZER SPACE TELESCOPE  

SciTech Connect

We present Spitzer MIPS observations at 24 {mu}m of 37 solar-type stars in the Pleiades and combine them with previous observations to obtain a sample of 71 stars. We report that 23 stars, or 32% +- 6.8%, have excesses at 24 {mu}m at least 10% above their photospheric emission. We compare our results with studies of debris disks in other open clusters and with a study of A stars to show that debris disks around solar-type stars at 115 Myr occur at nearly the same rate as around A-type stars. We analyze the effects of binarity and X-ray activity on the excess flux. Stars with warm excesses tend not to be in equal-mass binary systems, possibly due to clearing of planetesimals by binary companions in similar orbits. We find that the apparent anti-correlations in the incidence of excess and both the rate of stellar rotation and also the level of activity as judged by X-ray emission are statistically weak.

Sierchio, J. M.; Rieke, G. H.; Su, K. Y. L. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Plavchan, P. [Infrared Processing and Analysis Center, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Stauffer, J. R. [Spitzer Science Center, California Institute of Technology, MC 103-33, Pasadena, CA 91125 (United States); Gorlova, N. I., E-mail: jsierchi@email.arizona.ed [Instituut voor Sterrenkunde, K. U. Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium)

2010-04-01

310

HILT - A heavy ion large area proportional counter telescope for solar and anomalous cosmic rays  

NASA Astrophysics Data System (ADS)

The HILT sensor has been designed to measure heavy ion elemental abundances, energy spectra, and direction of incidence in the mass range from He to Fe and in the energy range 4 to 250 MeV/nucleon. With its large geometric factor of 60 sq cm sr the sensor is optimized to provide compositional and spectral measurements for low intensity cosmic rays (i.e. for small solar energetic particle events and for the anomalous component of cosmic rays). The instrument combines a large area ion drift chamber-proportional counter system with two arrays of 16 Li-drift solid state detectors and 16 CsI crystals. The multi dE/dx-E technique provides a low background mass and energy determination. The sensor also measures particle direction. Combining these measurements with the information on the spacecraft position and attitude in the low-altitude polar orbit, it will be possible to infer the ionic charge of the ions from the local cutoff of the Earth's magnetic field. The ionic charge in this energy range is of particular interest because it provides unique clues to the origin of these particles and has not been investigated systematically so far. Together with the other instruments on board SAMPEX (LEICA, MAST, and PET), a comprehensive measurement of the entire solar and anomalous particle population will be achieved.

Klecker, Berndt; Hovestadt, Dietrich; Scholer, M.; Arbinger, H.; Ertl, M.; Kaestle, H.; Kuenneth, E.; Laeverenz, P.; Seidenschwang, E.; Blake, J. B.

1993-05-01

311

The South Pole Telescope  

NASA Astrophysics Data System (ADS)

A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 meter diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over $\\sim 4000$ degrees for galaxy clusters using the Sunyaev-Zel'dovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

Ruhl, John; Ade, Peter A. R.; Carlstrom, John E.; Cho, Hsiao-Mei; Crawford, Thomas; Dobbs, Matt; Greer, Chris H.; Halverson, Nils w.; Holzapfel, William L.; Lanting, Trevor M.; Lee, Adrian T.; Leitch, Erik M.; Leong, Jon; Lu, Wenyang; Lueker, Martin; Mehl, Jared; Meyer, Stephan S.; Mohr, Joe J.; Padin, Steve; Plagge, T.; Pryke, Clem; Runyan, Marcus C.; Schwan, Dan; Sharp, M. K.; Spieler, Helmuth; Staniszewski, Zak; Stark, Antony A.

2004-10-01

312

The South Pole Telescope  

SciTech Connect

A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

Ruhl, J.E.; Ade, P.A.R.; Carlstrom, J.E.; Cho, H.M.; Crawford,T.; Dobbs, M.; Greer, C.H.; Halverson, N.W.; Holzapfel, W.L.; Lanting,T.M.; Lee, A.T.; Leitch, E.M.; Leong, J.; Lu, W.; Lueker, M.; Mehl, J.; Meyer, S.S.; Mohr, J.J.; Padin, S.; Plagge, T.; Pryke, C.; Runyan, M.C.; Schwan, D.; Sharp, M.K.; Spieler, H.; Staniszewski, Z.; Stark, A.A.

2004-11-04

313

H? Line Impact Linear Polarization Observed in the 23 July 2002 Flare with the Large Solar Vacuum Telescope (LSVT)  

NASA Astrophysics Data System (ADS)

We present the results of studying the proton flare 2B/X4.8 on 23 July 2002, observed with the Large Solar Vacuum Telescope (LSVT) at the Baikal Astrophysical Observatory in spectropolarimetric mode with high spatial and spectral resolution. We have found some evidence for H? line impact linear polarization, predominantly during the initial moments of the flare. For the H? line 606 cuts were made along the dispersion in 53 spectrograms, and a polarization signal was found more or less confidently in 60 cuts (13 spectrograms). Polarization was mainly observed in one of the kernels of the flare. A particular feature of this kernel was that the H? line was observed to show a reversal in the central part of this kernel, which created a dip in the kernel center in the photometric cut. The size of these dips and the size of the sites with the linear polarization coincide and are equal to 3 - 6 arcsec. The maximum polarization degree in this kernel reached 15 %. The direction of the polarization in the kernel is radial, except for the first two frames, where the direction of the polarization was both radial and tangential. Furthermore, we found an analogy between the effects observed at the chromospheric level in this kernel (polarization and depression in H? line) and the temporal variation of the HXR sources.

Firstova, N. M.; Polyakov, V. I.; Firstova, A. V.

2012-08-01

314

The Telescope Array Experiment  

NASA Astrophysics Data System (ADS)

The Telescope Array (TA) is an ultra-high energy cosmic ray (UHECR) detector located in Millard County, Utah. The detector currently consists of a ground array of approximately 500 scintillator counters and three optical air-fluorescence stations. TA has now been fully operational for over two years and currently has the largest aperture for UHECRs in the Northern Hemisphere. Current analysis efforts will be discussed and recent findings will be presented.

Stokes, Benjamin

2010-10-01

315

The Spacewatch 1.8-meter Telescope  

NASA Astrophysics Data System (ADS)

The largest telescope in the world dedicated to the search for Earth-approaching asteroids and other previously unknown members of the solar system will soon be operational. Its 1.8-m aperture, large and sensitive CCD, and dedication to surveying will make it possible to find as many as 80,000 new asteroids per year. The mechanical design by Barr is optimized by finite-element analysis to provide high resonant frequencies. The mount is an altitude-azimuth type for compatibility with the mirror support cell contributed by the Multi-Mirror Telescope Observatory. Both axes are driven by DC servo motors directly coupled to friction rollers. The CCD instrument stage will also be rotated under computer control. The telescope was fabricated in the University Research Instrumentation Center (URIC). Construction of the building began on Kitt Peak on July 1, 1996. The optical configuration is f/2.7 folded prime focus with a flat secondary that locates the focal plane in the center of the optical truss near the altitude axis. This shortened the telescope enough to make the dome building affordable, and the flat secondary preserves the fast f/number of the primary mirror. The coma corrector designed by R. A. Buchroeder is a modified Klee design of 5 spherical lens elements plus a filter transmitting longward of the B bandpass. The filter greatly simplifies lens design and reduces sky background while not significantly reducing the brightness of asteroids. The distortion-free, flat, unvignetted field of view is 0.8 deg in diameter and the image scale is 1.0 arcsec/24 micron pixel. Construction of the Spacewatch Telescope has been funded by grants from the DoD Clementine Program, NASA, the University of Arizona Foundation, and other private and corporate donors.

Perry, M. L.; McMillan, R. S.; Barr, L. D.; Bressi, T. H.; Gehrels, T.

1996-09-01

316

Systematic Motion of Fine-scale Jets and Successive Reconnection in Solar Chromospheric Anemone Jet Observed with the Solar Optical Telescope/Hinode  

NASA Astrophysics Data System (ADS)

The Solar Optical Telescope (SOT) on board Hinode allows observations with high spatiotemporal resolution and stable image quality. A ?-shaped chromospheric anemone jet was observed in high resolution with SOT/Hinode. We found that several fine-scale jets were launched from one end of the footpoint to the other. These fine-scale jets (~1.5-2.5 Mm) gradually move from one end of the footpoint to the other and finally merge into a single jet. This process occurs recurrently, and as time progresses the jet activity becomes more and more violent. The time evolution of the region below the jet in Ca II H filtergram images taken with SOT shows that various parts (or knots) appear at different positions. These bright knots gradually merge into each other during the maximum phase. The systematic motion of the fine-scale jets is observed when different knots merge into each other. Such morphology would arise due to the emergence of a three-dimensional twisted flux rope in which the axial component (or the guide field) appears in the later stages of the flux rope emergence. The partial appearance of the knots could be due to the azimuthal magnetic field that appears during the early stage of the flux rope emergence. If the guide field is strong and reconnection occurs between the emerging flux rope and an ambient magnetic field, this could explain the typical feature of systematic motion in chromospheric anemone jets.

Singh, K. A. P.; Isobe, H.; Nishida, K.; Shibata, K.

2012-11-01

317

Zelenchukskaya Telescope.  

National Technical Information Service (NTIS)

The recently-constructed Russian ZELENTCHUKSKAYA telescope is described which is now the largest telescope in the world. Details are presented concerning the selection of its construction site, the construction of the telescope itself, and its dimensions....

1975-01-01

318

Synthetic Aperture Image Holography.  

National Technical Information Service (NTIS)

The paper describes the underwater imaging method of 'Synthetic Aperture Image Holography' which has real-time imaging capability. The method utilizes image holography and computer synthetic aperture techniques. The imaging system consists of the acoustic...

T. Sato J. S. Jaffe

1985-01-01

319

DAVINCI a Dilute Aperture Coronagraph  

NASA Astrophysics Data System (ADS)

The motivation for DAVINCI was originally to make use of the technology developed for space interferometers like SIM to build a coronagraph from four 1.1m telescopes that was dramatically lower in cost than a 4 5m filled aperture offaxis coronagraph. Our initial studies through team X have shown this cost savings to be real. But a more careful analysis showed that DAVINCI would have an inner working angle of 35mas a factor of 2 smaller than a 2 lambda/D 4 meter coronagraph or 70m external occulter, resulting in a 10X increase in the number of potential Earth-Clone targets. DAVINCI uses a nulling interferometer as a coronagraph, a nulling interferometer is one the few coronagraph architectures that are compatible with segmented and dilute aperture telescopes. Combined with a post coronagraph wavefront sensor several ultra-demanding tolerances of conventional coronagraphs can be relaxed by factors of 100. The post coronagraph wavefront sensor is also much less affected by local and exozodi background than wavefront sensors that use the science camera as the wavefront sensor. The post coronagraph interferometer is also used on ground based extreme AO coronagraphs, GPI, and P1640.

Shao, Michael

2009-01-01

320

The Green Bank Telescope  

NASA Astrophysics Data System (ADS)

Upon its completion in 1997, the Green Bank Telescope will be the world's largest fully steerable radio telescope. It is located at the National Radio Astronomy Observatory in Green Bank WV within the boundaries of the National Radio Quiet Zone, an area within which astronomers have some control over transmitters which might be harmful to radio astronomy. The GBT will be 100 meters in diameter, have a solid surface whose panels are accurate to nearly 100mu , and have motorized actuators supporting the panels which can be adjusted continually to compensate for gravitational and other distortions. The optics is that of an unblocked paraboloid whose focal point is outside of the aperture to reduce the effects of interference and standing waves. An innovative laser metrology system will monitor the position of many parts of the telescope to allow accurate focus and pointing. The initial suite of receivers will cover 25 MHz to 50 GHz.

Lockman, F. J.

1996-05-01

321

An Advanced Automatic Telescope Computer Control Program.  

National Technical Information Service (NTIS)

The report describes the major features of a modular, advanced, automatic telescope digital control program (TEST), used at the Mount Haleakala Observatory for automated, sampled-data control of one 60-in.- and two 48-in.-aperture telescopes, which may be...

J. D. Erickson P. Tanner C. Fujii

1970-01-01

322

Very wide field, very fast telescope  

NASA Astrophysics Data System (ADS)

A 1.3 meter aperture Cassegrain telescope with a very wide flat field has been completed and is now producing images. The field of view is a stunning 1.7 degrees while the focal ratio is a very fast F/4. The telescope is located at the United States Naval Observatory Flagstaff Station in Arizona, USA.

Melsheimer, Frank M.; MacFarlane, Malcolm J.

2000-07-01

323

Very wide field, very fast telescope  

Microsoft Academic Search

A 1.3 meter aperture Cassegrain telescope with a very wide flat field has been completed and is now producing images. The field of view is a stunning 1.7 degrees while the focal ratio is a very fast F\\/4. The telescope is located at the United States Naval Observatory Flagstaff Station in Arizona, USA.

Frank M. Melsheimer; Malcolm J. MacFarlane

2000-01-01

324

Synthetic Aperture Sonar.  

National Technical Information Service (NTIS)

The report discusses synthetic-aperture imagery applied to the Seabed Treaty verification problem. It presents the basic theory of the synthetic-aperture side-looking sonar and shows the transition region from real to synthetic aperture in terms of resolu...

J. N. Bucknam A. M. Chwastyk H. D. Black F. C. Paddison

1971-01-01

325

Alignment telescope for Antares  

SciTech Connect

The Antares Automatic Alignment System employs a specially designed telescope for alignment of its laser beamlines. There are two telescopes in the system, and since each telescope is a primary alignment reference, stringent boresight accuracy and stability over the focus range were required. Optical and mechanical designs, which meet this requirement as well as that of image quality over a wide wavelength band, are described. Special test techniques for initial assembly and alignment of the telescope are also presented. The telescope, which has a 180-mm aperture FK51-KZF2 type glass doublet objective, requires a boresight accuracy of 2.8 ..mu..rad at two focal lengths, and object distances between 11 meters and infinity. Travel of a smaller secondary doublet provides focus from 11 m to infinity with approximately 7.8 m effective focal length. By flipping in a third doublet, the effective focal length is reduced to 2.5 m. Telescope alignment was accomplished by using a rotary air bearing to establish an axis in front of the system and placing the focus of a Laser Unequal Path Interferometer (LUPI) at the image plane.

Appert, Q.D.; Swann, T.A.; Ward, J.H.; Hardesty, C.; Wright, L.

1983-01-01

326

Alignment telescope for Antares  

NASA Astrophysics Data System (ADS)

The Antares Automatic Alignment System employs a specially designed telescope for alignment of its laser beamlines. There are two telescopes in the system, and since each telescope is a primary alignment reference, stringent boresight accuracy and stability over the focus range were required. Optical and mechanical designs, which meet this requirements as well as that of image quality over a wide wavelength band, are described. Special test techniques for initial assembly and alignment of the telescope are also presented. The telescope, which has a 180-mm aperture FK51-KZF2 type glass doublet objective, requires a boresight accuracy of 2.8 (SIGMA)rad at two focal lengths, and object distances between 11 meters and infinity. Travel of a smaller secondary doublet provides focus from 11 m to infinity with approximately 7.8 m effective focal length. By flipping in a third doublet, the effective focal length is reduced to 2.5 m. Telescope alignment was accomplished by using a rotary air bearing to establish an axis in front of the system and placing the focus of a Laser Unequal Path Interferometer (LUPI) at the image plane.

Appert, Q. D.; Swann, T. A.; Ward, J. H.; Hardesty, C.; Wright, L.

327

Apodized phase mask coronagraphs for arbitrary apertures  

NASA Astrophysics Data System (ADS)

Context. Phase-mask coronagraphs can be seen as linear systems that spatially redistribute in the pupil plane the energy collected by the telescope. Most of the on-axis light must ideally be rejected outside the aperture so as to be blocked with a Lyot stop, while almost all of the off-axis light must go through it. The unobstructed circular apertures of off-axis telescopes make this possible but all of the major telescopes are on-axis, however, and the performance of these coronagraphs is dramatically reduced by their central obstructions. Aims: Their performance can be restored by using an additional optimally designed apodizer that changes the amplitude in the first pupil plane so that the on-axis light is rejected outside the obstructed aperture of the on-axis telescope. Methods: An apodizer is assumed to be located in a pupil plane, a phase mask in a subsequent image plane, and a Lyot stop in a reimaged pupil plane. The numerical optimization model is built by maximizing the apodizer's transmission while setting constraints on the extremum values of the electric field that the Lyot stop does not block. The coronagraphic image is compared to what a non-apodized phase mask coronagraph provides and an analysis is made of the trade-offs that exist between the transmission of the apodizer and the properties of the Lyot stop. Results: The existence of a solution and the transmission of the mask depend on the geometries of the aperture and of the Lyot stop, and on the constraints that are set on the on-axis attenuation. The system's throughput is a concave function of the Lyot stop transmission. In the case of a VLT-like aperture, optimal apodizers with a transmission of 16% to 92% associated with a four-quadrant phase mask provide contrast as low as a few 10-10 at 1 ?/D from the star. The system's maximum throughput is about 64% for an apodizer with an 88% transmission and a Lyot stop with a 69% transmission. It is shown that optimizing apodizers for a vortex phase mask requires computation times much longer than in the previous case, and no result is presented for this mask. Conclusions: It is demonstrated that apodizers can be successfully optimized to allow phase mask coronagraphs to be used with the full aperture of on-axis telescopes while delivering contrast as low as, or even lower than what they could provide by themselves with off-axis telescopes.

Carlotti, A.

2013-03-01

328

A Lithium Abundance Study of Solar-type Stars in Blanco 1 using the 2.1m McDonald Telescope: Developing Undergraduate Research Experiences.  

NASA Astrophysics Data System (ADS)

We present a new catalog of lithium equivalent widths for 20 solar-type stars in the young (60-100 Myr), nearby (250 pc) open cluster Blanco 1, measured from high-resolution spectra (R 30,000), taken during an observing run on the 2.1m telescope at McDonald Observatory. These new lithium data, coupled with the 20 or so extant measurements in the literature, are used in combination with the results of a recently completed standardized BVIc CCD survey, and corresponding 2MASS near-infrared colors, to derive precise lithium abundances for solar-type stars in Blanco 1. Comparing these new results with the existing lithium dataset for other open clusters, we investigate the mass- and age-dependent lithium depletion distribution among early-epoch (< 1Gyr) solar-type stars, and specifically, the lithium abundance scatter as a function of mass in Blanco 1. Our scientific project is highly synergystic with a pedagogical philosophy. We have instituted a program whereby undergraduate students - typically majoring in Liberal Arts and performing an independent study in Astronomy - receive hands-on research experience observing with the 2.1m telescope at the McDonald Observatory. After their observing run, these undergraduates take part in the reduction and analysis of the acquired spectra, and their research experience typically culminates in writing an undergraduate thesis and/or giving a professional seminar to the Astronomy group at Vanderbilt University.

Cargile, Phillip; James, D. J.; Villalon, K.; Girgenti, S.; Mermilliod, J.

2007-12-01

329

Neutrino Telescopes  

SciTech Connect

Neutrino telescopes complement gamma ray telescopes in the observations of energetic astronomical sources as well as in searching for the dark matter. This paper gives the status of the current generation neutrino telescopes projects: Baikal, AMANDA, NESTOR, NEMO and ANTARES with particular emphasis on the ANTARES telescope in the Mediterranean Sea.

Carr, John [Centre de Physiques des Particules de Marseille, IN2P3/CNRS (France)

2005-02-21

330

Space Telescope.  

ERIC Educational Resources Information Center

This pamphlet describes the Space Telescope, an unmanned multi-purpose telescope observatory planned for launch into orbit by the Space Shuttle in the 1980s. The unique capabilities of this telescope are detailed, the major elements of the telescope are described, and its proposed mission operations are outlined. (CS)

National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

331

Thermal Performance of the Hubble Space Telescope (HST) Solar Array-3 During the Disturbance Verification Test (DVT).  

National Technical Information Service (NTIS)

The Hubble Space Telescope (HST) is one of NASA's most productive astronomical observatories. Launched in 1990, the HST continues to gather scientific data to help scientists around the world discover amazing wonders of the universe. To maintain HST in th...

D. H. Nguyen L. M. Skladany B. D. Prats

2001-01-01

332

Balloon-borne stratospheric far-IR spectral absorption measurements: the design of a solar telescope and high-resolution Michelson interferometer combination.  

PubMed

The design, construction, and performance of a combined solar telescope and Michelson interferometer for balloon-borne stratospheric far-IR absorption studies is discussed in terms of the relevant parameters and precautions necessary to obtain high resolution radiometrically calibrated spectra of the stratosphere between 20 and 100 cm(-1). Preliminary data are presented to indicate that the system performed as designed and provided constituent concentration values for H(2)O and O(3) from measurements of strong absorption lines in this spectrum. PMID:20309276

Naylor, D A; Clark, T A; Boreiko, R T

1981-04-01

333

Multiple instrument distributed aperture sensor (MIDAS) testbed  

NASA Astrophysics Data System (ADS)

Lockheed Martin is developing an innovative and adaptable optical telescope comprised of an array of nine identical afocal sub-telescopes. Inherent in the array design is the ability to perform high-resolution broadband imaging, Fizeau Fourier transform spectroscopy (FTS) imaging, and single exposure multi-spectral and polarimetric imaging. Additionally, the sensor suite's modular design integrates multiple science packages for active and passive sensing from 0.4 to 14 microns. We describe the opto-mechanical design of our concept, the Multiple Instrument Distributed Aperture Sensor (MIDAS), and a selection of passive and active remote sensing missions it fulfills.

Smith, Eric H.; de Leon, Erich; Dean, Peter; Deloumi, Jake; Duncan, Alan; Hoskins, Warren; Kendrick, Richard; Mason, James; Page, Jeff; Phenis, Adam; Pitman, Joe; Pope, Christine; Privari, Bela; Ratto, Doug; Romero, Enrique; Shu, Ker-Li; Sigler, Robert; Stubbs, David; Tapos, Francisc; Yee, Albert

2005-08-01

334

Design of a 50-m pulsar radio telescope  

Microsoft Academic Search

A radio telescope is to be built at National Astronomical Observatory of China, which is designed to receive signal from pulsars for timing and relevant usage. The telescope will have an aperture of 50 m in diameter working at multi-wave bands of which the shortest wavelength is down to 13 cm. A fully steerable exposed scheme of the telescope within

Dehua Yang; Shuangshuo Xue; Daxing Wang; Wenzhi Lu; Jingquan Cheng

2003-01-01

335

Design of large aperture focal plane shutter  

NASA Astrophysics Data System (ADS)

To satisfy the requirement of large telescope, a large aperture focal plane shutter with aperture size of ?200mm was researched and designed to realize, which could be started and stopped in a relative short time with precise position, and also the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the PWM pulse generated by DSP. Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2s, which meets the performance requirements of large telescope properly.

Hu, Jia-wen; Ma, Wen-li; Huang, Jin-long

336

CRTF Real-Time Aperture Flux system  

SciTech Connect

The Real-Time Aperture Flux system (TRAF) is a test measurement system designed to determine the input power/unit area (flux density) during solar experiments conducted at the Central Receiver Test Facility, Sandia National Laboratories, Albuquerque, New Mexico. The RTAF is capable of using both thermal sensors and photon sensors to determine the flux densities in the RTAF measuring plane. These data are manipulated in various ways to derive input power and flux density distribution to solar experiments.

Davis, D.B.

1980-01-01

337

The Spitzer Space Telescope Mission  

Microsoft Academic Search

The Spitzer Space Telescope, NASA's Great Observatory for infrared astronomy, was launched 2003 August 25 and is returning excellent scientific data from its Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity achievable with a cryogenic telescope in space with the great imaging and spectroscopic power of modern detector arrays to provide the user community with huge gains in capability for

M. W. Werner; T. L. Roellig; F. J. Low; G. H. Rieke; M. Rieke; W. F. Hoffmann; E. Young; J. R. Houck; B. Brandl; G. G. Fazio; J. L. Hora; R. D. Gehrz; G. Helou; B. T. Soifer; J. Stauffer; J. Keene; P. Eisenhardt; D. Gallagher; T. N. Gautier; W. Irace; C. R. Lawrence; L. Simmons; J. E. Van Cleve; M. Jura; E. L. Wright; D. P. Cruikshank

2004-01-01

338

The spitzer space telescope mission  

Microsoft Academic Search

The Spitzer Space Telescope, NASA’s Great Observatory for infrared astronomy, was launched 2003 August 25 and is returning excellent scientific data from its Earth-trailing solar orbit. Spitzer combines the intrinsic sensitivity achievable with a cryogenic telescope in space with the great imaging and spectroscopic power of modern detector arrays to provide the user community with huge gains in capability for

M. W. Werner

2005-01-01

339

Adaptive coded aperture projection  

Microsoft Academic Search

With adaptive coded aperture projection, we present solutions for taking projectors to the next level. By placing a programmable liquid crystal array at a projectors aperture plane we show how the depth of field (DOF) of a projection can be greatly enhanced. This allows focussed imagery to be shown on complex screens with varying distances to the projectors focal plane,

Max Grosse; Gordon Wetzstein; Oliver Bimber; Anselm Grundhöfer

2009-01-01

340

Electron Microscope Aperture System.  

National Technical Information Service (NTIS)

An electron microscope is described, which includes an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the speci...

K. Heinemann

1972-01-01

341

Electron Microscope Aperture System.  

National Technical Information Service (NTIS)

An electron microscope is described which includes an electron source, a condenser lens having either a circular aperture for focusing a solid cone of electrons onto a specimen or an annular aperture for focusing a hollow cone of electrons onto the specim...

K. Heinemann

1973-01-01

342

Beam combination with a large number of apertures  

NASA Astrophysics Data System (ADS)

The design of a space-based interferometer with a large number of apertures has been a subject of much discussion. In this paper, we argue in favor of using a Michelson beam combiner for the case where a small field of view is acceptable. We address the normal criticism that a Michelson combiner is too complicated by presenting an optical design for a 90-aperture, laboratory prototype. Coupling this device to a large, ground-based telescope with a coherent fiber array forms an imaging system that is a significant improvement over aperture masking.

Mozurkewich, D.

2008-07-01

343

Design and fabrication of three 1.6-meter telescopes for the Korea Microlensing Telescope Network (KMTNet)  

NASA Astrophysics Data System (ADS)

The KMTNet telescope Project, sponsored by The Korea Astronomy and Space Science Institute (KASI), is fabricating three wide-field equatorial mount telescopes of 1.6 meter aperture to conduct continuous observations of the Galactic bulge region to search for extra-solar planets. Southern latitude sites secured for these telescopes are SAAO (South Africa), CTIO (Chile), and SSO (Australia). A prime-focus configuration, along with a four-lens corrector achieves the 2.8 degree diagonal FOV. The basic mechanical design utilizes a scaled-up version of the successful 2MASS Telescopes built by the authors in the late 1990's. Scaling up of components has presented challenges requiring several iterations of the detailed mechanical analysis as well as the optical analysis due to interaction with mounting assemblies for the optical components. A flexure-style focus mechanism, driven by three precision actuators, moves the entire headring assembly and provides real-time focus capability, and active primary mirror cooling is implemented for the Zerodur primary. KMTNet engineering specifications are met with the current design, which uses Comsoft's Legacy PCTCS for control. A complete operational telescope and enclosure are scheduled for installation in Tucson, AZ prior to shipping the first hardware to CTIO in order to verify tracking, optical characteristics at various attitudes, and overall observatory functionality. The cameras, being fabricated by The Ohio State University Department of Astronomy, Imaging Sciences Laboratory (ISL), are proceeding in parallel with the telescope fabrication, and that interface is now fixed. Specifics of the mechanical and optical design are presented, along with the current fabrication progress and testing protocols.

Poteet, W. M.; Cauthen, H. K.; Kappler, N.; Kappler, L. G.; Park, Byeong-Gon; Lee, Chung-Uk; Kim, Seung-Lee; Cha, Sang-Mok

2012-09-01

344

The High-resolution Lightweight Telescope for the EUV (HiLiTE)  

NASA Astrophysics Data System (ADS)

The highly-structured and extremely dynamic interface between the photosphere and the corona is of crucial importance in understanding solar activity and space weather. Recent high-resolution observations with Hinode have shown that understanding this interface requires the ability to study the transition region by imaging plasma around 500,000 K on spatial scales of ~0.2 arc seconds, at cadences of ~5 seconds or less. We have completed a preliminary design of a telescope capable of meeting all three of these requirements - thermal, spatial, and temporal, called the High-resolution Lightweight Telescope for the EUV (HiLiTE). HiLiTE is a Cassegrain telescope with an aperture of 30 cm, angular resolution of ~0.2 arc seconds, and a mass that is about 1/4 that of one of the 20 cm aperture telescopes on SDO/AIA. The instrument bandpass will be tuned to the 46.5 nm Ne VII emission line formed in plasma at ~500,000 K. HiLiTE, including both mirrors and the metering structure, will be constructed entirely from lightweight, thermally stable, high-stiffness advanced Silicon Carbide (SiC) material. While SiC is an extremely promising material for space telescopes, SiC optics with the figure and surface finish required for normal-incidence multilayers have not yet been demonstrated. Upon integrating this instrument with an Advanced CMOS detector (in parallel development at Lockheed Martin via another internally funded program) and on board electronics, HiLiTE can easily be retrofitted to fly on board a sounding rocket, acting as a path finder to a post-AIA, Explorer-class mission. Herein, we give an update of the HiLiTE instrument development program, discussing expected instrument performance as well as the advantages of using SiC for EUV/Soft X-ray imaging in solar physics.

Martínez-Galarce, D.; Boerner, P.; de Pontieu, B.; Katz, N.; Title, A.; Soufli, R.; Gullikson, E.

2007-12-01

345

Design of the Discovery Channel Telescope enclosure  

NASA Astrophysics Data System (ADS)

The Discovery Channel Telescope (DCT) is a project of Lowell Observatory in conjuction with the Discovery Channel to design and construct a 4.2-meter clear aperture telescope and support facility on a site approximately 40 miles southeast of Flagstaff, Arizona, USA. The site is an undisturbed mountain top at an altitude of 7800-feet. Design and construction of the telescope enclosure includes all of the site utilities, access road to the site along with the fixed base enclosure, telescope pier and rotating dome structure. The details covered in this paper are the decisions and rationale of the DCT enclosure conceptual design completed by M3 Engineering & Technology Corporation (M3).

Terán U., José; Sebring, Thomas A.; Neff, Daniel H.; de Kock, Mariana

2004-10-01

346

Imaging interplanetary CMEs at radio frequency from solar polar orbit  

NASA Astrophysics Data System (ADS)

Coronal mass ejections (CMEs) represent a great concentration of mass and energy input into the lower corona. They have come to be recognized as the major driver of physical conditions change in the Sun-Earth system. Consequently, observations of CMEs are important for understanding and ultimately predicting space weather conditions. This paper discusses a proposed mission, the Solar Polar Orbit Radio Telescope (SPORT) mission, which will observe the propagation of interplanetary CMEs to distances of near 0.35 AU from the Sun. The orbit of SPORT is an elliptical solar polar orbit. The inclination angle between the orbit and ecliptic plane should be about 90°. The main payload on board SPORT will be an imaging radiometer working at the meter wavelength band (radio telescope), which can follow the propagation of interplanetary CMEs. The images that are obtained by the radio telescope embody the brightness temperature of the objectives. Due to the very large size required for the antenna aperture of the radio telescope, we adopt interferometric imaging technology to reduce it. Interferometric imaging technology is based on indirect spatial frequency domain measurements plus Fourier transformation. The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind ion instrument, an energetic particle detector, a magnetometer, a wave detector and a solar radio burst spectrometer.

Wu, Ji; Sun, Weiying; Zheng, Jianhua; Zhang, Cheng; Liu, Hao; Yan, Jingye; Wang, Chi; Wang, Chuanbing; Wang, Shui

2011-09-01

347

Monolithic versus segmented primary mirror concepts for space telescopes  

NASA Astrophysics Data System (ADS)

A number of ongoing astrophysical mission concept studies are based on large aperture spaceborne telescopes. As optics get larger, both manufacturing and engineering trades come into consideration and must be balanced with the science goals and requirements. One of the top-level telescope trades examines the impact of a large monolithic primary mirror versus an array of smaller mirror segments to either fully or sparsely populate the same aperture. The first consideration is the scientific impact. Should the scattered edge effects and diffraction of a segmented design be acceptable, it then becomes a fabrication, test, and cost trade along with any associated risks. This paper will examine some of the key factors that go into such a trade and looks at manufacturing breakpoints. Examples such as the 4-m aperture New World Observer (NWO) and the 8-m aperture Advanced Technology Large Aperture Space Telescope (ATLAST) will be presented.

Kendrick, Stephen E.

2009-08-01

348

A balloon-borne imaging gamma-ray telescope  

Microsoft Academic Search

A balloon-borne coded-aperture gamma-ray telescope for galactic and extragalactic astronomy observations is described. The instrument, called Gamma Ray Imaging Payload (GRIP), is designed for measurements in the energy range from 30 keV to 5 MeV with an angular resolution of 0.6 deg over a 20 deg field of view. Distinguishing characteristics of the telescope are a rotating hexagonal coded-aperture mask

W. E. Althouse; W. R. Cook; A. C. Cummings; M. H. Finger; T. A. Prince; S. M. Schindler; C. H. Starr; E. C. Stone

1985-01-01

349

A comparison between using incoherent or coherent sources to align and test an adaptive optical telescope  

Microsoft Academic Search

The concept in the initial alignment of the segmented mirror adaptive optics telescope called the phased array mirror extendable large aperture telescope (Pamela) is to produce an optical transfer function (OTF) which closely approximates the diffraction limited value which would correspond to a system pupil function that is unity over the aperture and zero outside. There are differences in the

Richard Anderson

1994-01-01

350

New homes for monster telescopes  

Microsoft Academic Search

In anticipation of telescope apertures in the 8-15 m range, the astronomical community has begun to reexamine the criteria for choosing near-ideal observatory sites and to consider new sites in light of these criteria. The best sites are in principle located away from the lights of large cities and major sources of natural or man-made atmospheric pollution. Major site categories

D. H. Smith

1985-01-01

351

The solar transition region: High resolution FUV-EUV imaging and modeling of unresolved coronal funnels as observed with the multi-spectral solar telescope array II: MSSTA II, the second flight  

NASA Astrophysics Data System (ADS)

The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne observatory composed of a set of normal-incidence, multilayer-coated telescopes that obtained selected bandpass spectroheliograms (44Å-1550Å) of the Solar atmosphere. These images were recorded on specially fabricated XUV and FUV 70mm Kodak film. Rocket launches of this instrument payload took place in 1991 (MSSTA I) and 1994 (MSSTA II) at the White Sands Missile Test Range in New Mexico. Immediately prior to the 1994 launch, visible light focusing tests of each telescope were performed in-situ using a 1951 Standard Air Force High Resolution Test-target to measure optical resolution performance. We determined that the MSSTA II telescopes performed at diffraction limited resolutions down to 0.70 arcsecond at visible wavelengths, and, based on these measurements, we calculate an upper-bound to the focusing errors that incorporate the sum of all uncorrelated system resolution errors that affect resolution performance. Coupling these upper-bound estimates with the in-band diffraction limits, surface scattering errors, and payload pointing jitter, I demonstrate that eleven of nineteen MSSTA II telescopes-having negligible figures of focus errors in comparison to the corresponding visible diffraction limits-performed at sub arcsecond resolution at their operational FUV/EUV/XUV wavelengths during flight. I estimate the in- band performance down to 0.14 +/- 0.08 second of arc. Careful digitizations were then made of selected spectroheliograms, noise-reduced and calibrated to yield energy flux measurements (171 Å) and then deconvolved using a blind form of the Richardson- Lucy algorithm to recover the highest angular resolution possible. Using the 1550 Å (C IV) and 171 Å (Fe IX/X) images, a funnel model that is based on coronal back-heating was constructed and tested against the data. The analysis demonstrates that funnels can account for the quiescent, globally diffuse emission seen in 171 Å spectroheliograms, suggesting this emission is mostly of upper transition region origin (T ~ 650,000 K), and, simultaneously satisfy areal coverage constraints observed at both 171 (60-90%) and 1550 Å (<=45%) wavelengths.

Martinez-Galarce, Dennis Stanley

352

Large Ground-Based Telescopes with High Order Adaptive Optics for Imaging Faint Objects and ExtraSolar Planets  

Microsoft Academic Search

\\u000a The new 6-8 m class ground based telescopes equiped with very high-resolution adaptive optics have the potential to detect\\u000a Jupiter-like planets around nearby stars. Direct detection will allow discoveries of planets, beyond the angular radius where\\u000a Doppler spectroscopy achieves maximum sensitivity. In addition, direct imaging (and spectroscopy) will allow confirmation\\u000a for those indirect detections which lie within 0.3–2 arcseconds in

M. Langlois; D. Sandler; D. McCarthy

1999-01-01

353

Fluorescence and hybrid detection aperture of the Pierre Auger Observatory  

SciTech Connect

The aperture of the Fluorescence Detector (FD) of the Pierre Auger Observatory is evaluated from simulated events using different detector configurations: mono, stereo, 3-FD and 4-FD. The trigger efficiency has been modeled using shower profiles with ground impacts in the field of view of a single telescope and studying the trigger response (at the different levels) by that telescope and by its neighbors. In addition, analysis cuts imposed by event reconstruction have been applied. The hybrid aperture is then derived for the Auger final extension. Taking into account the actual Surface Detector (SD) array configuration and its trigger response, the aperture is also calculated for a typical configuration of the present phase.

Bellido, J.A.; D'Urso, D.; Geenen, H.; Guarino, F.; Perrone, L.; Petrera, Sergio; Prado, L., Jr.; Salamida, F.

2005-07-01

354

Optimum synthetic-aperture imaging of extended astronomical objects.  

PubMed

In optical aperture-synthesis imaging of stellar objects, different beam combination strategies are used and proposed. Coaxial Michelson interferometers are very common and a homothetic multiaxial interferometer is recently realized in the Large Binocular Telescope. Laboratory experiments have demonstrated the working principles of two new approaches: densified pupil imaging and wide field-of-view (FOV) coaxial imaging using a staircase-shaped mirror. We develop a common mathematical formulation for direct comparison of the resolution and noise sensitivity of these four telescope configurations for combining beams from multiple apertures for interferometric synthetic aperture, wide-FOV imaging. Singular value decomposition techniques are used to compare the techniques and observe their distinct signal-to-noise ratio behaviors. We conclude that for a certain chosen stellar object, clear differences in performance of the imagers are identifiable. PMID:17361290

van der Avoort, Casper; Pereira, Silvania F; Braat, Joseph J M; den Herder, Jan-Willem

2007-04-01

355

Telescope Landscapes.  

ERIC Educational Resources Information Center

Describes an art lesson in which first grade students learned to reproduce the three-dimensional world on two-dimensional paper, creating a landscape through a telescopic perspective. Explains that students first learn about landscapes. Discusses the process of making telescopic drawings. (CMK)

Smith, Gay Lynn

1999-01-01

356

Telescopic Alidade  

USGS Multimedia Gallery

A high standard alidade; this type of alidade permits direct viewing through the telescope. The level is mounted below the inverting telescope and the base (blade) is solid brass with circular voids. Manufactured by Keuffel & Esser, New York & New Jersey. Object ID: USGS-000165...

2009-07-22

357

Construction Milestone Announced on Green Bank Telescope  

NASA Astrophysics Data System (ADS)

The National Radio Astronomy Observatory announces completion of a major construction milestone on the world's largest fully steerable radio telescope - the National Science Foundation's Green Bank Telescope (GBT). The last of 2,004 aluminum surface panels was recently installed on the GBT's two-acre (100 m x 110 m) collecting dish. The telescope is located at NRAO's Green Bank site, in rural Pocahontas County, West Virginia. The GBT will be used to study everything from the formation of galaxies in the early universe, to the chemical make-up of the dust and gas inside galaxies and in the voids that separate them, to the birth processes of stars. In conjunction with other instruments, it will help make highly accurate radar maps of some familiar objects in our own solar system. The GBT is an engineering marvel. At 485 feet tall, it is comparable in height to the Washington Monument. It weighs 16 million pounds, yet by swiveling the dish in both azimuth and elevation, it can be pointed to any point in the sky with exquisite accuracy. Additionally, the telescope's two-acre collecting dish has many novel features. Most radio telescopes in use today use receivers suspended above the dish by four struts. These struts block some of the surface of the dish, scattering some of the incoming radio waves from celestial objects under study. The GBT's offset feedarm has no struts to block incoming radio waves. The GBT also boasts an active surface. The surface of the dish is composed of 2,004 panels. On the underside of the dish, actuators are located at each corner (i.e., intersection of four panels). These actuators are motors that move the surface panels up and down, keeping the (paraboloid) shape of the dish precisely adjusted, no matter what the tilt of the telescope. The combination of its unblocked aperture and active surface promise that the GBT will display extremely high sensitivity to faint radio signals. The GBT itself is not the only precious national resource in Green Bank. The Observatory also administers the National Radio Quiet Zone, which is centered on the NRAO Green Bank site. The Zone extends outward from there, enclosing a land area of approximately 13,000 square miles. This zone is the only one of its kind in the world. Inside it, anything that might interfere with a radio telescope's sensitive receivers - like cellular phones and radio stations - are strictly regulated. This will ensure the GBT clearer reception of radio waves from distant galaxies and the other celestial objects it will study. What remains before the GBT will begin probing the heavens for new discoveries? First, the contractor building the telescope will complete several tasks, including tests of the systems that move the dish. Following successful completion of these tasks, NRAO can begin outfitting the telescope with the sensitive radio-wave receivers it designed and built especially for the GBT If all goes according to the current plan, astronomers should be doing exciting new science with the GBT by the first quarter of 2001. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

2000-04-01

358

Solar Meridional Circulation from Doppler Shifts of the Fe I Line at 5250 Å as Measured by the 150-foot Solar Tower Telescope at the Mt. Wilson Observatory  

NASA Astrophysics Data System (ADS)

Doppler shifts of the Fe I spectral line at 5250 Å from the full solar disk obtained over the period 1986 to 2009 are analyzed to determine the circulation velocity of the solar surface along meridional planes. Simultaneous measurements of the Zeeman splitting of this line are used to obtain measurements of the solar magnetic field that are used to select low field points and impose corrections for the magnetically induced Doppler shift. The data utilized is from a new reduction that preserves the full spatial resolution of the original observations so that the circulation flow can be followed to latitudes of 80° N/S. The deduced meridional flow is shown to differ from the circulation velocities derived from magnetic pattern movements. A reversed circulation pattern is seen in polar regions for three successive solar minima. A surge in circulation velocity at low latitudes is seen during the rising phases of cycles 22 and 23.

Ulrich, Roger K.

2010-12-01

359

Scanning holographic lidar telescope  

NASA Astrophysics Data System (ADS)

We have developed a unique telescope for lidar using a holographic optical element (HOE) as the primary optic. The HOE diffracts 532 nm laser backscatter making a 43 deg angle with a normal to its surface to a focus located 130 cm along the normal. The field of view scans a circle as the HOE rotates about the normal. The detector assembly and baffling remain stationary, compared to conventional scanning lidars in which the entire telescope and detector assembly require steering, or which use a large flat steerable mirror in front of the telescope to do the pointing. The spectral bandpass of our HOE is 50 nm (FWHM). Light within that bandpass is spectrally dispersed at 0.6 nm/mm in the focal plane. An aperture stop reduces the bandpass of light reaching the detector from one direction to 1 nm while simultaneously reducing the field of view to 1 mrad. Wavelengths outside the 50 nm spectral bandpass pass undiffracted through HOE to be absorbed by a black backing. Thus, the HOE combines three functions into one optic: the scanning mirror, the focusing mirror, and a narrowband filter.

Schwemmer, Geary K.; Wilkerson, Thomas D.

360

Report on the Conference Future Ground-based Solar System Research: Synergies with Space Probes and Space Telescopes  

Microsoft Academic Search

An interdisciplinary workshop bringing together Solar System researchers, space mission engineers and scientists, ground- and space-based observers and theoreticians is summarised. The broad scope of the meeting covered current and future space missions, planned ground-based facilities and their closer interaction.

Hans Ulrich Käufl; Gian Paolo Tozzi

2008-01-01

361

Study of Rapid Formation of a ? Sunspot Associated with the 2012 July 2 C7.4 Flare Using High-resolution Observations of the New Solar Telescope  

NASA Astrophysics Data System (ADS)

Rapid, irreversible changes of magnetic topology and sunspot structure associated with flares have been systematically observed in recent years. The most striking features include the increase of the horizontal field at the polarity inversion line (PIL) and the co-spatial penumbral darkening. A likely explanation of the above phenomenon is the back reaction to the coronal restructuring after eruptions: a coronal mass ejection carries the upward momentum while the downward momentum compresses the field lines near the PIL. Previous studies could only use low-resolution (above 1'') magnetograms and white-light images. Therefore, the changes are mostly observed for X-class flares. Taking advantage of the 0.''1 spatial resolution and 15 s temporal cadence of the New Solar Telescope at the Big Bear Solar Observatory, we report in detail the rapid formation of sunspot penumbra at the PIL associated with the C7.4 flare on 2012 July 2. It is unambiguously shown that the solar granulation pattern evolves to an alternating dark and bright fibril structure, the typical pattern of penumbra. Interestingly, the appearance of such a penumbra creates a new ? sunspot. The penumbral formation is also accompanied by the enhancement of the horizontal field observed using vector magnetograms from the Helioseismic and Magnetic Imager. We explain our observations as being due to the eruption of a flux rope following magnetic cancellation at the PIL. Subsequently, the re-closed arcade fields are pushed down toward the surface to form the new penumbra. NLFFF extrapolation clearly shows both the flux rope close to the surface and the overlying fields.

Wang, Haimin; Liu, Chang; Wang, Shuo; Deng, Na; Xu, Yan; Jing, Ju; Cao, Wenda

2013-09-01

362

High-contrast Imaging with an Arbitrary Aperture: Active Compensation of Aperture Discontinuities  

NASA Astrophysics Data System (ADS)

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential deformable mirrors (DMs) to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of DM surfaces that yield high-contrast point-spread functions is not linear, and nonlinear methods are needed to find the true minimum in the optimization topology. We solve the highly nonlinear Monge-Ampere equation that is the fundamental equation describing the physics of phase-induced amplitude modulation. We determine the optimum configuration for our two sequential DM system and show that high-throughput and high-contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to the James Webb Space Telescope, ACAD can attain at least 10-7 in contrast and an order of magnitude higher for both the future extremely large telescopes and on-axis architectures reminiscent of the Hubble Space Telescope. We show that the converging nonlinear mappings resulting from our DM shapes actually damp near-field diffraction artifacts in the vicinity of the discontinuities. Thus, ACAD actually lowers the chromatic ringing due to diffraction by segment gaps and struts while not amplifying the diffraction at the aperture edges beyond the Fresnel regime. This outer Fresnel ringing can be mitigated by properly designing the optical system. Consequently, ACAD is a true broadband solution to the problem of high-contrast imaging with segmented and/or on-axis apertures. We finally show that once the nonlinear solution is found, fine tuning with linear methods used in wavefront control can be applied to further contrast by another order of magnitude. Generally speaking, the ACAD technique can be used to significantly improve a broad class of telescope designs for a variety of problems.

Pueyo, Laurent; Norman, Colin

2013-06-01

363

Confocal coded aperture imaging  

DOEpatents

A method for imaging a target volume comprises the steps of: radiating a small bandwidth of energy toward the target volume; focusing the small bandwidth of energy into a beam; moving the target volume through a plurality of positions within the focused beam; collecting a beam of energy scattered from the target volume with a non-diffractive confocal coded aperture; generating a shadow image of said aperture from every point source of radiation in the target volume; and, reconstructing the shadow image into a 3-dimensional image of the every point source by mathematically correlating the shadow image with a digital or analog version of the coded aperture. The method can comprise the step of collecting the beam of energy scattered from the target volume with a Fresnel zone plate.

Tobin, Jr., Kenneth William (Harriman, TN); Thomas, Jr., Clarence E. (Knoxville, TN)

2001-01-01

364

Optimization of 100-Meter Green Bank Telescope.  

National Technical Information Service (NTIS)

Candidate designs for NRAO's 100-m clear-aperture radio telescope were evaluated and optimized by JPL using JPL-developed structural optimization and analysis software. The weight of a non-optimum design was reduced from 9.4 million pounds to 9.2 million ...

D. Strain

1994-01-01

365

A balloon borne telescope for infrared astronomy  

Microsoft Academic Search

A balloon borne telescope with an aperture of 50 cm has been built for infrared astronomical observations. A Nasmyth focus is added to the conventional Cassegrain focus to provide a stable platform for delicate instruments as cryogenically cooled spectrometers. Pointing and tracking accuracies as good as 15 arcsec are achieved in cooperation of a control momentum gyro (C.M.G.) torquer and

H. Okuda; H. Shibai; T. Yamagami; Y. Koma; Y. Matsuzaka

1984-01-01

366

Perception for a large deployable reflector telescope  

NASA Astrophysics Data System (ADS)

Optical science and technology concepts for a large deployable reflector for far-infrared and submillimeter astronomy from above the earth's atmosphere are discussed. Requirements given at the Asilomar Conference are reviewed. The technical challenges of this large-aperture (about 20-meter) telescope, which will be diffraction limited in the infrared, are highlighted in a brief discussion of one particular configuration.

Breckinridge, J. M.; Swanson, P. N.; Meinel, A. B.; Meinel, M. P.

1984-01-01

367

Design of the Discovery Channel Telescope mount  

NASA Astrophysics Data System (ADS)

The Discovery Channel Telescope is a 4.2-meter clear aperture telescope undertaken by the Lowell Observatory in Flagstaff, Arizona. It will feature an interchangeable secondary assembly to allow the use of either a prime focus instrument or a secondary mirror. In addition, it will have an active optical system and provisions for a wide range of instruments. This paper describes the design of the telescope mount and drive systems. Particular challenges associated with the design include: consideration for the weight of the 3500 lb Prime Focus Assembly (PFA) instrument; interchangeable secondary assemblies; and providing thermal and mechanical stability in between updates to maintain alignment between optical elements.

Finley, David T.; Squires, Chuck; McCreight, Brad A.; Smith, Byron W.; Chylek, Tomas; Venetiou, Alexander

2008-08-01

368

Green Bank Telescope and the Millimeter Array  

NASA Astrophysics Data System (ADS)

The National Radio Astronomy Observatory is engaged in two major new telescope projects. Each requires technological advances to meet the scientific requirements. The Green Bank Telescope is a fully steerable 100 m diameter filled aperture telescope for operation over the frequency range 300 MHz to 100 GHz. The Millimeter Array is a forty element interferometer of 8 m diameter antennas, with a goal of using 10 m or even 12 m antennas, for operation over the frequency range 30 - 850 GHz. The technical features being used to achieve the performance specifications are presented together with examples of the science that calls for these specifications. The current status of each project is also discussed.

Vanden Bout, Paul A.

1998-07-01

369

Teaching Telescopes  

ERIC Educational Resources Information Center

|Discusses experience of teaching optical experiments with emphasis upon the student's design and construction of refracting and reflecting telescopes. Concludes that the student's interest and acquired knowledge are greatly enhanced through the use of realistic experiments. (CC)|

Reid, John S.

1974-01-01

370

Telescoping Columns.  

National Technical Information Service (NTIS)

A power operated telescoping column is described for the deployment and retraction of a large parabolic antenna for space applications. The column consists of several axially elongated rigid structural sections nested within one another. The outermost and...

J. T. Mazur

1978-01-01

371

Galilean Telescope  

NASA Astrophysics Data System (ADS)

A refracting telescope that uses a long focal length converging lens and a short-focus diverging lens to produce a magnified image of a distant object. Named after the Italian scientist Galileo Galilei (1564-1642), who designed and built a telescope of this type in 1609, the Galilean refractor produces an upright image but suffers from having a very small field of view. This particular optical sy...

Murdin, P.

2000-11-01

372

Aperture averaging analysis and aperture shape invariance of received scintillation in free-space optical communication links  

NASA Astrophysics Data System (ADS)

Intensity scintillation and beam wander caused by atmospheric turbulence are two significant phenomena that affect free space optical (FSO) communication links. We have constructed an imaging system for measuring the effects of atmospheric turbulence and obscuration on FSO links. A He-Ne laser beam propagates over a range of 863 meters in atmospheric turbulence conditions that vary diurnally and seasonally from weak to strong. A high performance digital camera with a frame-grabbing computer interface is used to capture received laser intensity distributions at rates up to 30 frames per second and various short shutter speeds, down to 1/16,000s per frame. The captured image frames are analyzed in Labview to evaluate the turbulence index parameter, temporal and spatial intensity variances, and aperture averaging. The aperture averaging results demonstrate the expected reduction in intensity fluctuations with increasing aperture diameter, and show quantitatively the differences in behavior between various strengths of turbulence. This paper will present the most accurate empirical data to date for the weak and intermediate turbulence regime. Such results can help build upon existing empirical data and lead to the development of new theories. Aperture averaging of the received irradiance is also shown to be independent of the shape of the receiver aperture, and depends only on its area. This finding allows the use of refractive or catadioptric receivers, whichever is convenient, and the same amount of aperture averaging will be achieved for equal unobscured aperture areas. This can make the telescope design for an FSO receiver more compact.

Yuksel, Heba; Davis, Christopher C.

2006-09-01

373

Bistatic synthetic aperture radar  

Microsoft Academic Search

Synthetic aperture radar (SAR) is becoming increasingly important in many military ground surveillance and targeting roles because of its ability to operate in all weather, day and night, and to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and receiver are on separate platforms, is seen as a potential means of countering vulnerability. This

A. M. Horne; G. Yates

2002-01-01

374

Piezoceramic actuated aperture antennae  

Microsoft Academic Search

Recently, it has been demonstrated that aperture antennae can have their performance improved by employing shape control on the antenna surface. The antennae previously studied were actuated utilizing polyvinylidene fluoride (PVDF). Since PVDF is a polymer with limited control authority, these antennae can only be employed in space based applications. This study examines more robust antenna structures devised of a

Hwan-Sik Yoon; Gregory Washington

1998-01-01

375

The Origin of Solar and Stellar Image Aureole  

NASA Astrophysics Data System (ADS)

The extended wings of the telescope point-spread-function affect the performance of solar and stellar reflecting coronagraphs used to study the faint envelopes of bright objects like the sun, planets, and stars. We are expanding an initial examination of the origin of these wings (Beckers, ``Scientific and Engineering Frontiers for 8 - 10 m Telescopes", Eds. M. Iye and T. Nishimura, 1995, 303 - 312) in order to obtain a quantitative evaluation of the observed point-spread-function and to derive the technical specifications for solar and stellar coronagraphs. We include the following factors contributing to the point-spread-function wings : (i) the atmospheric seeing, including the effects of the finite inner scale of turbulence, (ii) the scattering by atmospheric aerosol particles, (iii) the atmospheric Rayleigh scattering, (iv) the scattering by small scale surface irregularities in the telescope optics (micro-ripple), (v) the scattering by dust in the telescope, (vi) the diffraction on the telescope aperture, and (vii) diffraction on objects partially obscuring the aperture (e.g. spiders). It is assumed that care is taken not to increase the point-spread-function wings by ghosting and scattering in the astronomical instrument and in its detector(s). Using the resulting algorithms, we interpret observed stellar and solar image aureolae. The wavelength dependence of the point-spread-function wings is evaluated and applied to the performance estimates and technical specification definition of the CLEAR facility (CLEAR = ``Coronagraphic and Low Emissivity Astronomical Reflector"), a 4 meter class solar/stellar coronagraph presently under study.

Beckers, J. M.; Ftaclas, C.

1996-05-01

376

Adaptive optics for Extremely Large Telescopes  

NASA Astrophysics Data System (ADS)

Adaptive Optics (AO) will be essential for accomplishing many, if not most, of the science objectives currently planned for Extremely Large Telescopes including GMT, OWL, and TMT. AO will be needed to support a range of instrumentation, including near infrared (IR) imagers and spectrometers, mid IR imagers and spectrometers, “planet finding” instrumentation and wide-field optical spectrographs. Multiple advanced AO systems, utilizing the full range of concepts currently under development, will need to be combined into an integrated architecture to meet a broad range of requirements for field-of-view, spatial resolution and spectral bandpass.In this paper, we describe several of the possible options for these systems and outline the range of issues, trade studies and component development activities which must be addressed. Some of these challenges include very high-order, large-stroke wavefront correction, tip-tilt sensing with faint natural guide stars to maximize sky coverage, laser guide star wavefront sensing on a very large aperture and achieving extremely high contrast ratios for the detection of extra-solar planet and other faint companions of nearby bright stars.

Hubin, Norbert; Ellerbroek, Brent L.; Arsenault, Robin; Clare, Richard M.; Dekany, Richard; Gilles, Luc; Kasper, Markus; Herriot, Glen; Le Louarn, Miska; Marchetti, Enrico; Oberti, Sylvain; Stoesz, Jeff; Veran, Jean Pierre; Vérinaud, Christophe

377

Real-time correction of atmospherically degraded telescope images through image sharpening  

Microsoft Academic Search

A new technique for the correction of atmospheric distortion in a telescope is presented. Most of this distortion arises from a random phase variation in the incoming light across the telescope aperture. This variation limits the resolving power of even large telescopes to about one second of arc. If one defines the sharpness value of the images in a suitable

R. A. Muller; Andrew Buffington

1974-01-01

378

Improving imaging through turbulence via aperture partitioning  

NASA Astrophysics Data System (ADS)

Speckle imaging techniques make it possible to do high-resolution imaging through the turbulent atmosphere by collecting and processing a large number of short-exposure frames, each of which effectively freezes the atmosphere. In severe seeing conditions, when the characteristic scale of atmospheric fluctuations is much smaller than the diameter of the telescope, the reconstructed image is dominated by "turbulence noise" caused by redundant baselines in the pupil. I describe a generalization of aperture masking interferometry that dramatically improves imaging performance in this regime. The approach is to partition the aperture into annuli, form the bispectra of the focal plane images formed from each annulus, and recombine them into a synthesized bispectrum from which the object may be retrieved. This may be implemented using multiple cameras and special mirrors, or with a single camera and a suitable pupil phase mask. I report results from simulations as well as experimental results using telescopes at the Air Force Research Lab's Maui Space Surveillance Site.

Calef, Brandoch

2010-04-01

379

ON THE ABSENCE OF PHOTOSPHERIC NET CURRENTS IN VECTOR MAGNETOGRAMS OF SUNSPOTS OBTAINED FROM HINODE (SOLAR OPTICAL TELESCOPE/SPECTRO-POLARIMETER)  

SciTech Connect

Various theoretical and observational results have been reported regarding the presence/absence of net electric currents in the sunspots. The limited spatial resolution of the earlier observations perhaps obscured the conclusions. We have analyzed 12 sunspots observed from Hinode (Solar Optical Telescope/Spectro-polarimeter) to clarify the issue. The azimuthal and radial components of magnetic fields and currents have been derived. The azimuthal component of the magnetic field of sunspots is found to vary in sign with azimuth. The radial component of the field also varies in magnitude with azimuth. While the latter pattern is a confirmation of the interlocking combed structure of penumbral filaments, the former pattern shows that the penumbra is made up of a 'curly interlocking combed' magnetic field. The azimuthally averaged azimuthal component is seen to decline much faster than 1/piv in the penumbra, after an initial increase in the umbra, for all the spots studied. This confirms the confinement of magnetic fields and absence of a net current for sunspots as postulated by Parker. The existence of a global twist for a sunspot even in the absence of a net current is consistent with a fibril-bundle structure of the sunspot magnetic fields.

Venkatakrishnan, P.; Tiwari, Sanjiv Kumar, E-mail: pvk@prl.res.i, E-mail: stiwari@prl.res.i [Udaipur Solar Observatory, Physical Research Laboratory, Dewali, Bari Road, Udaipur-313 001 (India)

2009-11-20

380

Resolution enhanced sparse aperture imaging  

Microsoft Academic Search

The resolution of a conventional diffraction limited imaging system is proportional to its entrance pupil diameter. The primary goal of multiple aperture imaging is to enhance resolution by increasing the effective aperture diameter, while also minimizing the total image collection area, the latter being desirable because of the cost and weight of large single aperture imaging systems. Provided is a

Nick Miller; Bradley Duncan; Matthew P. Dierking

2006-01-01

381

Eyelid system for telescope protection  

NASA Astrophysics Data System (ADS)

By the end of the XXth century, the development of new technologies, such as segmented mirrors and adaptive optics, allowed an increase in the maximum feasible diameter of telescopes with diffraction limited resolution. The technological limit for the diameter of new generation telescopes is not clear yet and several feasibility studies have been carried out. In Europe, after some previous studies performed by the ESO (OWL) and the University of Lund in Sweden (EURO50), the design study for the European Extremely Large Telescope has been launched supported by the European Community (Framework Programme 6, ELT Design Study, contract No 011863). In the context of this design study, the IAC (Instituto Astrofisico de Canarias) as responsible for the design of the enclosure of the giant telescope, organized a call for ideas in order to find a third alternative for this system (to the two previously developed EURO50 and OWL), in which enterprises and individuals were invited to participate. This paper presents the enclosure concept presented to the contest by IDOM, the Eyelid System for Telescope Protection, which was one of the two ideas selected by the jury. The system basically consists of two structures that can be kept apart during observation - providing the required aperture for light gathering - and closed (joined) when the observation is finished.

Murga, Gaizka; Ruiz, José L.; Vizcargüenaga, Alberto; Zarraoa, Amaia; Pan, Jorge

2006-07-01

382

The Green Bank Telescope  

NASA Astrophysics Data System (ADS)

The Green Bank Telescope The 100-m NRAO Green Bank Telescope will be completed in early 2000. The GBT has a large number of unique design and performance features that will give it unprecedented scientific capability. This poster display will review those features, which include an offset feed (clear aperture) design, an active surface, a closed-loop laser metrology system for surface figure and pointing control, broad frequency coverage from 100 MHz to 115 GHz, a versatile receiver selection mechanism, and a new multi-input, 256k-channel autocorrelation spectrometer. The status of the project, the commissioning schedule, plans for early operations, the initial instrumentation suite, and plans for future instrumentation will be reviewed. Scientific areas for which the GBT will have a large impact will be discussed, including observations of young galaxies at extreme redshifts, pulsars, HI and molecular spectroscopy, VLBI work, and millimeter-wave spectroscopy and continuum studies. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Jewell, P. R.

1999-12-01

383

Selecting Your First Telescope.  

ERIC Educational Resources Information Center

Designed for first-time telescope purchasers, provides information on how a telescope works; major telescope types (refractors, reflectors, compound telescopes); tripod, pier, altazimuth, and equatorial mounts; selecting a telescope; visiting an astronomy club; applications/limitations of telescope use; and tips on buying a telescope. Includes a…

Harrington, Sherwood

1982-01-01

384

Did the 28 October 2003 solar flare accelerate protons to (greater-or-similar sign)20 GeV? A study of the subsequent Forbush decrease with the GRAPES-3 tracking muon telescope  

SciTech Connect

Solar flares accelerate charged particles through a variety of mechanisms, which may be constrained through observations at high energies (>10 GeV). We report here a search for direct emission of protons of energy (greater-or-similar sign)20 GeV in association with an X17 class solar flare that occurred on 28 October 2003, using a large area tracking muon telescope of the GRAPES-3 experiment at Ooty. Some features of the telescope, including its novel capability of high sensitivity search for the directional enhancement of the solar protons are also described. A 99% C.L. upper limit on the flux of protons due to the solar flare has been placed at 1.4x10{sup -6} cm{sup -2} s{sup -1} sr{sup -1}. A separate upper limit on the narrow solid angle flux of protons at 4x10{sup -6} cm{sup -2} s{sup -1} sr{sup -1} is also placed. Solar flares are also associated with coronal mass ejections, which propagate through the interplanetary space producing geomagnetic storms and Forbush decrease (Fd) events, upon their arrival at the Earth. New information on the structure and time evolution of the large Fd observed on 29 October 2003 by GRAPES-3 is presented. The onset of Fd in nine different solid angle bins ({approx}0.3 sr) shows a remarkably similar behavior, with an evolution on a time scale of {approx}1 h. A power law dependence of the magnitude of the Fd on the cutoff rigidity has been derived, using the data from tracking muon telescope, over a narrow range of cutoff rigidity 14.3-24.0 GV, which shows a spectral slope ''{gamma}=0.53{+-}0.04,'' in agreement with earlier measurements.

Nonaka, T.; Hayashi, Y.; Ito, N.; Kawakami, S.; Matsuyama, T.; Oshima, A.; Tanaka, H.; Yoshikoshi, T.; Gupta, S. K.; Jain, A.; Karthikeyan, S.; Mohanty, P. K.; Morris, S. D.; Rao, B. S.; Ravindran, K. C.; Sivaprasad, K.; Sreekantan, B. V.; Tonwar, S. C.; Viswanathan, K.; Kojima, H. [Graduate School of Science, Osaka City University, Osaka 558-8585 (Japan); Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005 (India); Nagoya Women's University, Nagoya 467-8610 (Japan)

2006-09-01

385

Telescope revolution  

NASA Astrophysics Data System (ADS)

The scientific and technical challenges facing the astronomical community during the next decade are discussed within the framework of new technology and technical management issues. The astronomical telescope and instrument communities of industry, academia and government need to be prepared to meet the challenges of 21st century Astronomy. Emphasis is given to ground-based optical and infrared astronomy.

Breckinridge, James B.

2000-10-01

386

Aperture weighting technique for video synthetic aperture radar  

NASA Astrophysics Data System (ADS)

We present a technique for aperture weighting for use in video synthetic aperture radar (SAR). In video SAR the aperture required to achieve the desired cross range resolution typically exceeds the frame rate period. As a result, there can be a significant overlap in the collected phase history used to form consecutive images in the video. Video SAR algorithms seek to exploit this overlap to avoid unnecessary duplication of processing. When no aperture weighting or windowing is used one can simply form oversampled SAR images from the non-overlapping sub-apertures using coherent back projection (or other similar techniques). The resulting sub-aperture images may be coherently summed to produce a full resolution image. A simple approach to windowing for sidelobe control is to weight the sub-apertures during summation of the images. Our approach involves producing two or more weighted images for each sub-aperture which can be linearly combined to approximate any desired aperture weighting. In this method we achieve nearly the same sidelobe control as weighting the phase history data and forming a new image for each frame without losing the computation savings of the sub-aperture image combining approach.

Hawley, Robert W.; Garber, Wendy L.

2011-05-01

387

High-resolution mesospheric sodium observations for extremely large telescopes  

NASA Astrophysics Data System (ADS)

Variations in density structure and altitude of mesospheric sodium impact the performance of adaptive optics systems employing sodium laser guide stars. The associated wave-front errors grow as the square of the telescope aperture and will be very significant for the next generation of large-aperture ground-based optical/infrared telescopes. To support the adaptive optics program for the Thirty Meter Telescope and European Extremely Large Telescope, we are conducting a program of sodium monitoring using a high-resolution sodium lidar system on the 6-meter Large Zenith Telescope (LZT). Located at 49°N latitude, the LZT lidar system provides density profiles with spatial and temporal resolution sampling of 4.8 m and 20 ms. In this paper we report highlights of results obtained over two years of observations.

Pfrommer, Thomas; Hickson, Paul

2010-07-01

388

The Discovery Channel Telescope: A Wide-field Telescope in Northern Arizona  

NASA Astrophysics Data System (ADS)

The Discovery Channel Telescope (DCT) is a 4.2-meter clear aperture telescope that is currently in its design phase. It features a prime focus camera with a 2° field of view and a standard Ritchey-Chrétien focus for infrared imaging and optical and infrared spectroscopy. The prime focus will be occupied by a mosaic camera containing 40 2Kx4K CCDs. The camera will incorporate guiding and wavefront sensing functions. The DCT will be located at a site southeast of Flagstaff, Arizona that exhibits 0.6 arcsec FWHM first quartile seeing. Lowell Observatory and Discovery Communications, Inc. are the partners currently developing the telescope.

Dunham, E. W.; Millis, R. L.; Smith, B.; Sebring, T. A.

2005-10-01

389

Cryogenic system for the infrared space telescope SPICA  

NASA Astrophysics Data System (ADS)

The SPICA mission has been proposed to JAXA as the second Japanese IR space telescope to be launched in 2017. The SPICA spacecraft, launched with an H-IIA launch vehicle, is to be transferred into a halo orbit around the Sun-Earth L2, where effective radiant cooling is feasible owing to solar rays and radiant heat fluxes from the Earth constantly coming from the same direction. That optimal thermal environment enables this IR space telescope to use a large 3.5-mdiameter- single-aperture primary mirror cooled to 4.5 K with advanced mechanical cryocoolers and effective radiant cooling instead of a massive and short-lived cryogen. As a result of thermal and structural analyses, the thermal design of cryogenic system was obtained. Then, mechanical cryocoolers have been developed to meet cooling requirement at 1.7 K, 4.5 K and 20 K. The latest results of upgrading of the 20 K-class two-stage Stirling cooler, the 4K-class JT cooler, and the 1K-class JT cooler indicate that all cryocoolers gain a sufficient margin of cooling capacity with unprecedentedly low power consumption for the cooling requirement. It is concluded that the feasibility of the SPICA mission was confirmed for the critical cryogenic system design, while some attempts to achieve higher reliability, higher cooling capacity and less vibration have been continued for stable operations throughout the entire mission period.

Sugita, Hiroyuki; Sato, Yoichi; Nakagawa, Takao; Murakami, Hiroshi; Kaneda, Hidehiro; Enya, Keigo; Murakami, Masahide; Tsunematsu, Shoji; Hirabayashi, Masayuki

2008-08-01

390

Astronomical measurements using amateur telescopes  

NASA Astrophysics Data System (ADS)

We show, with three example experiments, how to measure the Earth precession, the speed of light, and the orbital parameters of the Moon by using only unexpensive amateur material (a telescope with small aperture, a digital camera, and a quartz clock). These experiments do not require a high-level mathematical background, and can be performed by high-school and/or university students. We also provide allthe necessary ephemerides information for the reader to be able to perform all the observations and data analysis by him/herself.

Martí-Vidal, I.; Jiménez-Monferrer, S.; Cruz-Molina, C.

2011-11-01

391

New homes for monster telescopes  

NASA Astrophysics Data System (ADS)

In anticipation of telescope apertures in the 8-15 m range, the astronomical community has begun to reexamine the criteria for choosing near-ideal observatory sites and to consider new sites in light of these criteria. The best sites are in principle located away from the lights of large cities and major sources of natural or man-made atmospheric pollution. Major site categories by which these conditions are best approximated include isolated volcanic islands, coastal mountains on the western sides of continental land masses, and exceptionally high inland peaks.

Smith, D. H.

1985-07-01

392

Future Plans of Telescope Array  

SciTech Connect

The Telescope Array (TA) experiment is the only ultra high energy cosmic ray observatory in the northern hemisphere. In addition, it will be the world's first air shower detector to be directly calibrated by an on-site accelerator beam. For wider and deeper understanding of cosmic rays by via high precision measurements, we have undertaken the study of extension plans for TA. One extension plan will extend the sensitive energy range of TA down to 10{sup 17} eV. A second plan would extend of the aperture area of the SD array. These plans are described in this note.

Ogio, Shoichi [Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585 (Japan)

2011-09-22

393

Synchronous network of distant telescopes  

NASA Astrophysics Data System (ADS)

The Synchronous Network of distant Telescopes (SNT) represents an innovative approach in observational astrophysics. The authors present an unique existing realization of the SNT-conception. It was founded within the international collaboration between astronomical observatories of Ukraine, Russia, Bulgaria and Greece. All the telescopes of the Network are equipped with standardized photometric systems (based on photo-multipliers). The unified timing systems (based on GPS-receivers) synchronize all the apertures to UTC with an accuracy of 1 microsecond and better. The essential parts of the SNT are the original software for operating and data processing. The described international Network successfully works for more than 10 years. The obtained unique observational data made it possible to discover new fine-scale features and flare-triggered phenomena in flaring red dwarfs, as well as the recently found high-frequency variability in some chromospherically active stars.

Zhilyaev, B.; Svyatogorov, O.; Verlyuk, I.; Andreev, M.; Sergeev, A.; Lovkaya, M.; Antov, A.; Konstantinova-Antova, R.; Bogdanovski, R.; Avgoloupis, S.; Seiradakis, J.; Contadakis, M. E.

394

High efficiency solar heater  

Microsoft Academic Search

This patent describes a solar oven comprising canted side-walls defining a heating chamber of inverted pyramidal configuration having a rectangular upper aperture for admitting solar radiation into the chamber, and a closed bottom, the side walls having four blackened non-reflective interior surfaces and translucent means closing the upper aperture for containing heated air with the chamber. The four interior surfaces

J. A. Varney; F. M. Varney

1987-01-01

395

The chaotic dynamical aperture  

SciTech Connect

Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator design have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipoles should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take tremendous amount of computing time. In this paper, we try to apply the existing method in the nonlinear dynamics to study the possible alternative solution. When the Hamiltonian motion becomes chaotic, the tune of the machine becomes undefined. The aperture related to the chaotic orbit can be identified as chaotic dynamical aperture. We review the method of determining chaotic orbit and apply the method to nonlinear problems in accelerator physics. We then discuss the scaling properties and effect of random sextupoles.

Lee, S.Y.; Tepikian, S.

1985-10-01

396

Total-light imager with flat spectral response for solar photometric measurements.  

PubMed

Certain applications in imaging photometry and radiometry require a telescope-detector system with (preferably constant) response over a wide spectral range from the ultraviolet through the infrared. We describe the design and characterization of the Solar Bolometric Imager (SBI), a 30-cm-aperture Dall-Kirkham telescope combined with a gold-blacked, 80, 000-element thermal array detector. Our SBI prototype provides spectrally uniform imaging in total solar light (0.28-2.6 mum) of heat-flow inhomogeneities at the solar photosphere, with better than 5-arc sec angular resolution over a 6.5 x 13 arc min field of view. A balloon-borne SBI would avoid most atmospheric transmission variation over this spectral range, enabling accurate study of the sources of total irradiance variation. PMID:18357099

Foukal, P; Libonate, S

2001-03-01

397

Optimal aperture geometry for high transmission through subwavelength aperture arrays  

NASA Astrophysics Data System (ADS)

The optical transmission through a periodic aperture array in a metal film is strongly enhanced by a resonance of the incident light with surface plasmon polaritons on one or both of the metal surfaces. The efficiency of the coupling, and thus the strength of the transmission enhancement, depends sensitively on the geometry of the apertures close to the metal surface. We show that this holds for the case of a single aperture surrounded by a surface corrugation as well as for an array of apertures. URL:http://www.neci.nj.nec.com/homepages/thio/arrays.html *Present address: Physics Department, Univ. of Wisconsin at Madison

Thio, Tineke; Pellerin, K. M.

2003-03-01

398

Membrane photon sieve telescope  

NASA Astrophysics Data System (ADS)

We are currently constructing FalconSAT-7 for launch in late 2013. The low-Earth, 3U CubeSat solar telescope incorporates a 0.2m deployable membrane photon sieve with over 2.5 billion holes. The aim of the experiment is to demonstrate diffraction limited imaging of a collapsible, diffractive primary over a narrow bandwidth. As well as being simpler to manufacture and deploy than curved, polished surfaces, the sheets do not have to be optically flat, greatly reducing many engineering issues. As such, the technology is particularly promising as a means to achieve extremely large optical primaries from compact, lightweight packages.

Andersen, Geoff; Dearborn, Michael E.; McHarg, Matthew G.; Harvey, Jeff

2012-05-01

399

The Astronomical Telescope of New York: a new 12-meter astronomical telescope  

NASA Astrophysics Data System (ADS)

The Astronomical Corporation of New York has commissioned a study of a 12-meter class telescope to be developed by a group of NY universities. The telescope concept builds on the basic principles established by the Keck telescopes; segmented primary mirror, Ritchey Chretien Nasmyth instrument layout, and light weight structures. New, lightweight, and low cost approaches are proposed for the primary mirror architecture, dome structure and mechanisms, telescope mount approach, and adaptive optics. Work on the design is supported by several NY based corporations and universities. The design offers a substantially larger aperture than any existing Visible/IR wavelength telescope at historically low cost. The concept employs an adaptive secondary mirror and laser guide star adaptive optics. Two First Light instruments are proposed; A High resolution near infrared spectrograph and a near infrared Integral field spectrograph/imager.

Sebring, T.; Junquist, R.; Stutzki, C.; Sebring, P.; Baum, S.

2012-09-01

400

Nanolithography using nanoscale ridge apertures  

NASA Astrophysics Data System (ADS)

There is a continuous effort to develop techniques for nanoscale feature definition below the diffraction limit. Nanolithography has been a key technique because of its precision and cost effective. A sub-wavelength hole in an opaque screen can be used to provide a small light source with the optical resolution beyond the diffraction limit in the near field. However, a nanometer-sized hole in circular or square shapes is plagued by low transmission and poor contrast. This drawback limits the nanoscale apertures from being employed in nanolithography applications. Ridge apertures in C, H and bowtie shapes, on the other hand, have been numerically and experimentally demonstrated to show the ability of achieving both enhanced light transmission and sub-wavelength optical resolution down to nanometer domain benefiting from the existence of waveguide propagation mode confined in the gap between the ridges. In this report, the detailed field distributions in contact nanolithography are analyzed using finite difference time domain (FDTD) simulations. It was found that the high imaging contrast, which is necessary for successful lithography, is achieved close to the mask exit plane and decays quickly with the increase of the distance from the mask exit plane. Simulations are also performed for comparable regular shaped apertures and different shape bowtie apertures. Design rules are proposed to optimize the bowtie aperture for producing a sub-wavelength, high transmission field with high imaging contrast. High resolution contact nanolithography was carried on a home constructed lithography setup. It has been experimentally demonstrated that nanoscale bowtie and C apertures can be used for contact lithography to achieve nanometer scale resolution due to its intrinsic advantages of achieving enhanced optical transmission and concentrating light far beyond the diffraction limit. It also has shown the advantages of bowtie and C apertures over conventional apertures in both transmission enhancement and nanoscale light concentration. Lithographic holes as small as 40 nm x 50 nm and 50 nm x 60 nm for bowtie and C apertures, respectively, has been achieved. To study the properties of nanoscale bowtie apertures, a home-made near-field scanning optical microscope (NSOM) is developed. AFM images of standard calibration samples are used to calibrate the piezoelectric stage and topography resolution. NSOM results of bowtie apertures are also presented to study their transmission enhancement and field localization. Near-field scanning optical microscopy (NSOM) probe integrated with nanometer scale bowtie aperture for enhanced optical transmission is demonstrated. The bowtie-shape aperture allows waveguide propagating mode in the bowtie gap region, which enables simultaneous nanoscale optical resolution and enhanced optical transmission. These unique optical characteristics of bowtie aperture are demonstrated by measuring optical near fields produced by apertures in metal film. It is shown that bowtie aperture probes have one order of magnitude increase in transmission over probes with a regular shape aperture. The imaging results using bowtie aperture are in agreement with those obtained from numerical calculations. Spectroscopic measurements of transmitted field through bowtie shaped nanoscale apertures in visible wavelength region were used to further calibrate the aperture. Resonance in these apertures and its relation with the aperture geometry are investigated. The near-field spectral response is also investigated using Finite Difference Time Domain (FDTD) computation and compared with the spectroscopic measurements. The dependences of the peak wavelength and peak amplitude on the geometry of the bowtie aperture are illustrated. Design rules are proposed to optimize the bowtie aperture for producing a sub-wavelength, high transmission field.

Wang, Liang

401

The new 800mm reflecting telescope  

NASA Astrophysics Data System (ADS)

The design and capabilities of the 800-mm Ritchey-Chretien system are described. The optical system of the telescope has an aperture ratio of 1:8; is suitable for photography in a 1.5 deg field with photoplates of 16 x 16 cm; and consists of primary and secondary hyperbolically deformed mirrors. The attachment of the mirrors, position rotator, and offset guider to the tube, which is a truss structure, is examined. The mount for the telescope is an equatorial fork type. The electronic control system is a 16-bit microcomputer system; the functions of the control system are discussed. The 8-m polyester dome of the telescope consists of a supporting steel structure carrying shell elements of glass fiber-reinforced polyester resins. Consideration is given to the auxiliary devices of the telescope.

Teske, Hans-Joachim

402

Equivalent circuit for aperture antennas  

NASA Astrophysics Data System (ADS)

The commonly used equivalent circuit based on a constant-voltage generator does not correctly characterize scattering by an aperture antenna, nor does its dual, the constant-current generator. This long-standing dilemma has been resolved by combining voltage and current sources to form a constant-power source. The power generated by this source is equated to the available power in a plane wave incident on the aperture. The voltage and current of the two sources and their respective internal impedances are then completely determined from the aperture area, the impedance, the aperture efficiency, and the relative power pattern of the antenna.

Love, A. W.

1987-06-01

403

Intensity Masking to Get High Resolution Images from Low Quality Apertures  

SciTech Connect

The effort and expense required to build and maintain an optical-quality telescope increases dramatically with the size of the telescope aperture, and this is especially so in space. But scenarios have been proposed for deploying (for instance, inflatable) telescopes with very large but considerably lecithin optical-quality apertures. Our interest is in ameliorating the effects of the low quality aperture in order to exploit the raw size of the aperture to obtain high resolution images. We describe an algorithm for generating an adaptive binary mask to correct the time-varying aberrations of very large apertures which are many (possibly hundreds of) wavelengths out of figure. The technique is limited to monochromatic imagery, though the wavelength at which observations are taken can be readily changed on the fly, and for earth-pointing applications, the limited light-gathering power imposed by the monochromatic filter is not a problem. The mask itself can be placed at the exit pupil of the telescope, which permits implementation on a large scale. A similar approach, in which the pixels of the mask are half-wave phase shifters instead of opaque optical elements, was described by Love et al.

Theiler, J.P., Priedhorsky, W.C.

1997-12-31

404

Novel Adaptive Optics concepts : wavefront sensing with sodium laser guide stars at Extemely Large Telescopes and simultaneous differential imaging  

Microsoft Academic Search

Since more than 15 years, Adaptive Optics (AO) is a proven concept to reach diffraction limited imaging at modern astronomical telescopes. In the case of next generation telescopes (Extremely Large Telescopes (ELTs)) with aperture diameters of up to 100m, sodium laser guide star based multi-conjugated-AO systems will be a basic requirement to exploit their full capability in terms of resolution

Stephan Albert Kellner

2005-01-01

405

Test method for telescopes using a point source at a finite distance  

NASA Astrophysics Data System (ADS)

A test method for telescopes that makes use of a focused ring formed by an annular aperture when using a point source at a finite distance is evaluated theoretically and experimentally. The results show that the concept can be applied to near-normal, as well as grazing incidence. It is particularly suited for X-ray telescopes because of their intrinsically narrow annular apertures, and because of the largely reduced diffraction effects.

Griner, D. B.; Zissa, D. E.; Korsch, D.

1985-09-01

406

The new 800mm reflecting telescope  

Microsoft Academic Search

The design and capabilities of the 800-mm Ritchey-Chretien system are described. The optical system of the telescope has an aperture ratio of 1:8; is suitable for photography in a 1.5 deg field with photoplates of 16 x 16 cm; and consists of primary and secondary hyperbolically deformed mirrors. The attachment of the mirrors, position rotator, and offset guider to the

Hans-Joachim Teske

1986-01-01

407

Synthetic aperture active sonar imaging  

Microsoft Academic Search

The main problems involved in synthetic aperture sonar imaging are medium instability, slow mapping rate, and platform motion. Proposed solutions to these problems are reviewed, and a new technique for synthetic aperture sonar imaging is presented which allows a fast mapping rate and improved motion compensation. This technique involves using multiple receivers to form a complex-valued preliminary image for each

Bretton L. Douglas; Hua Lee

1992-01-01

408

Reconfigurable aperture decade bandwidth array  

Microsoft Academic Search

A variety of military systems employ multiple antenna apertures on a single platform such as a ship or an aircraft. In order to reduce cost and improve performance characteristics such as the radar cross section (RCS), it is desirable to combine multiple functions into a single aperture. Wide (10:1) bandwidth phased array antennas are needed to accomplish this goal. To

J. C. Veihl; R. E. Hodges; D. McGrath; C. Monzon

2000-01-01

409

Feasibility studies to upgrade the Canada-France-Hawaii Telescope site for the next generation Canada-France-Hawaii Telescope  

NASA Astrophysics Data System (ADS)

The Next Generation Canada-France-Hawaii Telescope is a dedicated, 10m aperture, wide-field, fiber-fed multiobject spectroscopic facility proposed as an upgrade to the existing Canada-France-Hawaii Telescope on the summit of Mauna Kea. The Next Generation Canada-France-Hawaii Telescope baseline concept assumes the new facility is built on the existing Canada-France-Hawaii Telescope telescope pier and enclosure pier and occupies the same three dimensional exterior “footprint”. Three technical studies have been planned to examine the validity of these assumptions. The technical studies are executed in series as they represent technical decision points in a logical sequence. The three technical studies in succession are: 1. Telescope Pier Study - Load Capacity and Structural Interface, 2. Enclosure Fixed Base Study - Telescope and Enclosure Configuration and Load Capacity and 3. Aero- Thermal Study - Dome Thermal Seeing and Air Flow Attenuation over the Enclosure Aperture Opening. The paper outlines the baseline facility (telescope, spectrograph and enclosure) concept and the status of these studies, and discusses the proposed telescope and enclosure configuration in terms of the redevelopment assumptions. A consolidated feasibility study report will be submitted to the CFHT Board and Science Advisory Committee in the Fall of 2012, with first light for the facility aiming to be in the early 2020s.

Szeto, Kei; Angers, Mathieu; Breckenridge, Craig; Bauman, Steven; Loewen, Nathan; Loop, David; McConnachie, Alan; Pazder, Jonh; Salmon, Derrick; Spano, Paolo; Stiemer, Siegfried; Veillet, Christian

2012-09-01

410

OBSERVING THE FINE STRUCTURE OF LOOPS THROUGH HIGH-RESOLUTION SPECTROSCOPIC OBSERVATIONS OF CORONAL RAIN WITH THE CRISP INSTRUMENT AT THE SWEDISH SOLAR TELESCOPE  

SciTech Connect

Observed in cool chromospheric lines, such as H{alpha} or Ca II H, coronal rain corresponds to cool and dense plasma falling from coronal heights. Considered as a peculiar sporadic phenomenon of active regions, it has not received much attention since its discovery more than 40 years ago. Yet, it has been shown recently that a close relationship exists between this phenomenon and the coronal heating mechanism. Indeed, numerical simulations have shown that this phenomenon is most likely due to a loss of thermal equilibrium ensuing from a heating mechanism acting mostly toward the footpoints of loops. We present here one of the first high-resolution spectroscopic observations of coronal rain, performed with the CRisp Imaging Spectro Polarimeter (CRISP) instrument at the Swedish Solar Telescope. This work constitutes the first attempt to assess the importance of coronal rain in the understanding of the coronal magnetic field in active regions. With the present resolution, coronal rain is observed to literally invade the entire field of view. A large statistical set is obtained in which dynamics (total velocities and accelerations), shapes (lengths and widths), trajectories (angles of fall of the blobs), and thermodynamic properties (temperatures) of the condensations are derived. Specifically, we find that coronal rain is composed of small and dense chromospheric cores with average widths and lengths of {approx}310 km and {approx}710 km, respectively, average temperatures below 7000 K, displaying a broad distribution of falling speeds with an average of {approx}70 km s{sup -1}, and accelerations largely below the effective gravity along loops. Through estimates of the ion-neutral coupling in the blobs we show that coronal rain acts as a tracer of the coronal magnetic field, thus supporting the multi-strand loop scenario, and acts as a probe of the local thermodynamic conditions in loops. We further elucidate its potential in coronal heating. We find that the cooling in neighboring strands occurs simultaneously in general suggesting a similar thermodynamic evolution among strands, which can be explained by a common footpoint heating process. Constraints for coronal heating models of loops are thus provided. Estimates of the fraction of coronal volume with coronal rain give values between 7% and 30%. Estimates of the occurrence time of the phenomenon in loops set times between 5 and 20 hr, implying that coronal rain may be a common phenomenon, in agreement with the frequent observations of cool downflows in extreme-ultraviolet lines. The coronal mass drain rate in the form of coronal rain is estimated to be on the order of 5 Multiplication-Sign 10{sup 9} g s{sup -1}, a significant quantity compared to the estimate of mass flux into the corona from spicules.

Antolin, P. [Also at Center of Mathematics for Applications, University of Oslo, P.O. Box 1053, Blindern, NO-0316 Oslo, Norway. (Norway); Rouppe van der Voort, L., E-mail: patrick.antolin@astro.uio.no, E-mail: v.d.v.l.rouppe@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)

2012-02-01

411

Observing the Fine Structure of Loops through High-resolution Spectroscopic Observations of Coronal Rain with the CRISP Instrument at the Swedish Solar Telescope  

NASA Astrophysics Data System (ADS)

Observed in cool chromospheric lines, such as H? or Ca II H, coronal rain corresponds to cool and dense plasma falling from coronal heights. Considered as a peculiar sporadic phenomenon of active regions, it has not received much attention since its discovery more than 40 years ago. Yet, it has been shown recently that a close relationship exists between this phenomenon and the coronal heating mechanism. Indeed, numerical simulations have shown that this phenomenon is most likely due to a loss of thermal equilibrium ensuing from a heating mechanism acting mostly toward the footpoints of loops. We present here one of the first high-resolution spectroscopic observations of coronal rain, performed with the CRisp Imaging Spectro Polarimeter (CRISP) instrument at the Swedish Solar Telescope. This work constitutes the first attempt to assess the importance of coronal rain in the understanding of the coronal magnetic field in active regions. With the present resolution, coronal rain is observed to literally invade the entire field of view. A large statistical set is obtained in which dynamics (total velocities and accelerations), shapes (lengths and widths), trajectories (angles of fall of the blobs), and thermodynamic properties (temperatures) of the condensations are derived. Specifically, we find that coronal rain is composed of small and dense chromospheric cores with average widths and lengths of ~310 km and ~710 km, respectively, average temperatures below 7000 K, displaying a broad distribution of falling speeds with an average of ~70 km s-1, and accelerations largely below the effective gravity along loops. Through estimates of the ion-neutral coupling in the blobs we show that coronal rain acts as a tracer of the coronal magnetic field, thus supporting the multi-strand loop scenario, and acts as a probe of the local thermodynamic conditions in loops. We further elucidate its potential in coronal heating. We find that the cooling in neighboring strands occurs simultaneously in general suggesting a similar thermodynamic evolution among strands, which can be explained by a common footpoint heating process. Constraints for coronal heating models of loops are thus provided. Estimates of the fraction of coronal volume with coronal rain give values between 7% and 30%. Estimates of the occurrence time of the phenomenon in loops set times between 5 and 20 hr, implying that coronal rain may be a common phenomenon, in agreement with the frequent observations of cool downflows in extreme-ultraviolet lines. The coronal mass drain rate in the form of coronal rain is estimated to be on the order of 5 × 109 g s-1, a significant quantity compared to the estimate of mass flux into the corona from spicules.

Antolin, P.; Rouppe van der Voort, L.

2012-02-01

412

Research on reflective optical telescope system's wavefront aberration compensation method  

NASA Astrophysics Data System (ADS)

Wavefront aberration measurement of the image quality of reflective telescope system which has a large aperture and long focal length is one of the frequently-used methods of high-precision test and alignment. It was widely used during the large aperture telescope manufacturing process. The influences of surface shape error of the reflective optical telescope system components were simulated and analyst by input the actual measuring data into the optical design software CODE V in this article. According to the test results compared to the alignment process, the accuracy of the simulation method was indicated. At the same time, the wavefront aberration optical compensation principle of the reflective optical telescope system was proved by the simulation of alignment. And in this article, the feasibility of the application of optical phase compensation alignment method was investigated.

Duan, Xueting

413

Very large telescopes, their instrumentation and programs; Proceedings of the Colloquium, Garching, West Germany, April 9-12, 1984  

NASA Astrophysics Data System (ADS)

The present conference discusses the construction and properties of very large telescope mirrors, domes, and mountings, as well as instrumentation components and their capabilities, astronomical programs for very large telescopes, the development status of current very large telescope projects, and the relationships among atmospheric seeing, interferometry, and the operation of multiple mirror telescopes. Specific attention is given to 8-m aperture honeycomb structure mirror blanks, passive and active telescope support systems, the fabrication, processing, and testing of large telescope mirrors, testing of liquid mirrors, wind loads on large telescopes, adaptive optics, large telescope interferometry, IR speckle methods, active image stabilization, the ESO's 16-m telescope project, high resolution and imaging spectroscopy for very large telescopes, fiber-optics in future telescope instrumentation, star formation and interstellar matter studies, galaxy research, and the development status of the 15-m National New Technology Telescope.

Ulrich, M.-H.; Kjaer, K.

414

A Wide Field of View Air Cherenkov Imaging Telescope  

Microsoft Academic Search

The existing imaging air Cherenkov Telescopes (IACT) are using imaging cameras of aperture 2-4 degrees. These telescopes have F\\/0.7 to F\\/1.2 optics. The best optical resolution that one can obtain with these optical designs is in the range of 3 minutes of arc, and that only in the central region of the imaging camera. There are indications from simulations that

Razmick Mirzoyan; Michael I. Andersen

2008-01-01

415

The 15-Meter National New Technology Telescope - A progress report  

NASA Astrophysics Data System (ADS)

A brief review of current technical activities related to the 15-Meter NNTT is given along with a listing of tentative design goals specified by astronomers. A general comparison is made of filled versus unfilled aperture characteristics. These characteristics will influence the final NNTT concept selection to be made in 1983 between a Segmented-Mirror-Telescope (SMT) and a Multiple-Mirror-Telescope (MMT).

Barr, L. D.

416

SiC lightweight telescope for the GEO mission  

Microsoft Academic Search

Many satellite-borne measurement applications require lightweight, reflective near diffraction limited telescopes with wide spectral bands (UV\\/visible to LWIR), for operation in space environments and over wide temperature ranges. Emerging silicon carbide (SiC) technology provides an attractive material for these telescope applications. The present paper describes the design and analysis of a 50 cm dia. aperture on-axis three mirror re-imaging SiC

Michael I. Anapol; Leo R. Gardner; Richard R. Glasheen; Peter Hadfield; Theodore W. Tucker

1993-01-01

417

Optimized Wide-Field Survey Telescope Using Adaptive Optics  

Microsoft Academic Search

We describe a new technique for ground-based telescopic surveys that can deliver a wide field of view and nearly diffraction-limited image quality. We discuss a very low cost, yet sensitive and efficient, concept to perform science previously considered from space. For ground-based telescopes with small D\\/r0 (aperture over turbulence cell diameter) a significant improvement in point source sensitivity can be

Bernhard R. Brandl; Richard G. Dekany; Riccardo Giovanelli

2002-01-01