Note: This page contains sample records for the topic aperture solar telescope from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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

2

Research on cooling technology for a large-aperture solar telescope's primary mirror  

NASA Astrophysics Data System (ADS)

The surface temperture of Open Large-Aperture Solar Telescope's primary mirror can vulnerablely be warmed too high by exposure to direct sunlight. If its temperature over the external environment is too high, it is likely to decline the mirror seeing. So generally keeping the surface temperture of primary mirror same as the environment's is very important by cooling technology researched. By using Ansys software to analyze a meniscus-shaped aluminum metal primary mirror with a diameter of 2.5m, and thickness of 4.45cm to gain the primary mirror's temperature distribution in order to verify the feasibility of methods of cooling. Furthermore form a more perfect cooling project. Thus it can provide a technical guidance for Large-Aperture primary mirror's development in the future.

Wang, Qingping; Zhang, Haiying

2009-05-01

3

Large aperture diffractive space telescope  

Microsoft Academic Search

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 \\

Hyde; Roderick A

2001-01-01

4

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

5

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

6

Application of research for metal primary mirror of large-aperture infrared solar telescope  

NASA Astrophysics Data System (ADS)

Metal is an early telescope mirror material, it was later replaced by glass which has lower thermal expansion coefficient. However, for observing the sun, these glass materials in the primary mirror are affected by the sun's intense radiation, its temperature rises rapidly, but which conducts heat slowly. The temperature difference between mirror and ambient air is so large that causing the air turbulence which has affected the observation precision. While the metal material has better thermal conductivity characteristics, it can greatly improve the problems caused by air turbulence. This paper analyzes the characteristics of the various mirror materials, and then makes a rust-proof aluminum alloy 5A05 as the mirror substrate material. For the major deficiencies of the soft aluminum surface which is not suitable for polishing, this paper presents a method of electroless nickel plating to improve its surface properties. After the mirror go through a thermal shock, the upper and lower levels of metal CTE don't match with each other, which leads to mirror deformation and warping. The bimetallic effect has been illustrated by the theory of beam element and give a result of elementary approximated. The analysis shows that the displacement deformation of the upper and lower layers of metal which is caused by thermal shock is smaller when the CTE is closer. In the experiments, a spherical aluminum mirrors with the substrate of 5A05 aluminum alloy, diameter of 110mm, the radius of curvature of 258.672mm is manufactured in classical technique. And it ultimately achieves optical mirror-polished precision. Besides, the long-term thermal stability experimental study of the aluminum mirrors proved that Al-infrared solar telescope primary mirror meets the needs of the long-term observation during use.

Meng, Xiaohui; Zhang, Haiying; Li, Xinnan

2010-05-01

7

Synthetic Aperture Technic in Astronomy Using Slit Aperture Telescope  

Microsoft Academic Search

The interest in a Rotating Slit-Aperture Telescope (RSAT) among other synthetic aperture telescopes is its capability of being\\u000a easily coupled with a spectrograph, in order to give reconstructed images of an astronomical object as a function of the light\\u000a wavelength. Each colored image is comparable with the others for fruitful astrophysical applications. The principle of image\\u000a reconstruction is well known:

H. Touma

1997-01-01

8

Very Large Aperture Diffractive Space Telescope  

SciTech Connect

A very large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary 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 magnifying glass 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 magnifying glass, 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.

Hyde, Roderick Allen

1998-04-20

9

Very Large Aperture Diffractive Space Telescope  

Microsoft Academic Search

A very large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary 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

Hyde; Roderick Allen

1998-01-01

10

Optical performance of synthetic aperture telescope configurations  

NASA Technical Reports Server (NTRS)

The diffraction-limited performances of synthetic aperture configuration arrays of four telescopes, used for coherent imaging or beam transmission, are calculated and compared. The optical performance of phased telescope arrays was found to be more sensitive to rms piston errors than to rms tilt errors. Image degradation due to pupil mapping errors imposes tight tolerances upon the structural integrity of the telescope. One part in 10,000 pupil mapping error limits the field-of-view to approximately 30 arcsec. Field curvature of the independent telescopes provides a fundamental limit to the field-of-view for phased arrays made up of two-mirror telescopes. These field-of-view limitations may profoundly affect target acquisition, tracking, or imaging applications.

Harvey, J. E.; Silverglate, P. R.; Wissinger, A. B.

1985-01-01

11

Optical performance of synthetic aperture telescope configurations  

NASA Astrophysics Data System (ADS)

The diffraction-limited performances of synthetic aperture configuration arrays of four telescopes, used for coherent imaging or beam transmission, are calculated and compared. The optical performance of phased telescope arrays was found to be more sensitive to rms piston errors than to rms tilt errors. Image degradation due to pupil mapping errors imposes tight tolerances upon the structural integrity of the telescope. One part in 10,000 pupil mapping error limits the field-of-view to approximately 30 arcsec. Field curvature of the independent telescopes provides a fundamental limit to the field-of-view for phased arrays made up of two-mirror telescopes. These field-of-view limitations may profoundly affect target acquisition, tracking, or imaging applications.

Harvey, J. E.; Silverglate, P. R.; Wissinger, A. B.

12

Apodized apertures for solar coronagraphy  

Microsoft Academic Search

An apodized aperture should make it possible to observe the solar corona without the need of a Lyot coronagraph. We show in this communication that Sonine functions are much better apodizers for the observation of the solar corona than the generalized prolate spheroidal functions previously proposed. For a perfect circular aperture of diameter unity operated in space, a simple Sonine

Alexis Carlotti; Claude Aime; Jean Arnaud; Marianne Faurobert; André Ferrari; Catherine Grec; Gilbert Ricort

2008-01-01

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

The solar optical telescope  

NASA Technical Reports Server (NTRS)

Objectives of the Solar Optical Telescope are to study the physics of the Sun on the scale at which many of the important physical processes occur and to attain a resolution of 73km on the Sun or 0.1 arc seconds of angular resolution. Topics discussed in this overview of the Solar Optical Telescope include: why is the Solar Optical Telescope needed; current picture of the Sun's atmosphere and convection zone; scientific problems for the Solar Optical Telescope; a description of the telescope; the facility - science management, contamination control, and accessibility to the instruments; the scientific instruments - a coordinated instrument package for unlocking the Sun's secrets; parameters of the coordinated instrument package; science operations from the Space Shuttle; and the dynamic solar atmosphere.

1990-01-01

15

DiffRACT: differential remapped aperture coronagraphic telescope  

NASA Astrophysics Data System (ADS)

We propose a new high dynamic imaging concept for the detection and characterization of extra-solar planets. DIFFRACT standing for DIFFerential Remapped Aperture Coronagraphic Telescope, uses a Wollaston prism to split the entrance pupil into two exit pupils. These exit pupils are then remapped with 2 apertures lenses of different diameters resulting in two separate rescaled focal images of the same star. Since the angular separation of a putative exoplanet orbiting around the star is independent of the angular resolution of the remapped output pupils they appear at the same linear location in the resulting images that differ in resolution proportional to the exit pupil sizes. Exoplanet detection is obtained by numerically rescaling the images at the same angular resolution and substracting them, so that, under aberration and photon noise free conditions the planet twin images appear as two positive and negative Airy patterns. In real conditions however and depending on the exoplanet separation normalized to the angular resolution of the input telescope detection performances depend strongly on the adaptive optics performances and the collecting surface of the telescope. In this study we present the formal expression of DIFFRACT optics concept with a complet set of numerical experiments to estimate the performances of the concept under real observing conditions including instrument and adaptive optics corrections.

Allouche, F.; Hadjara, M.; Kok, Y.; Vakili, F.; Abe, L.; Gori, P. M.

2012-09-01

16

The GREGOR Solar Telescope  

NASA Astrophysics Data System (ADS)

The 1.5-meter GREGOR solar telescope is a new facility for high-resolution observations of the Sun. The telescope is located at the Spanish Observatorio del Teide on Tenerife. The telescope incorporates advanced designs for a foldable-tent dome, an open steel-truss telescope structure, and active and passive means to minimize telescope and mirror seeing. Solar fine structure can be observed with a dedicated suite of instruments: a broad-band imaging system, the "GREGOR Fabry-Perot Interferometer", and the "Grating Infrared Spectrograph". All post-focus instruments benefit from a high-order (multi-conjugate) adaptive optics system, which enables observations close to the diffraction limit of the telescope. The inclusion of a spectrograph for stellar activity studies and the search for solar twins expands the scientific usage of the GREGOR to the nighttime domain. We report on the successful commissioning of the telescope until the end of 2011 and the first steps towards science verification in 2012.

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

2012-12-01

17

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

18

India's National Large Solar Telescope  

NASA Astrophysics Data System (ADS)

India's 2-m National Large Solar Telescope (NLST) is aimed primarily at carrying out observations of the solar atmosphere with high spatial and spectral resolution. A comprehensive site characterization program, that commenced in 2007, has identified two superb sites in the Himalayan region at altitudes greater than 4000-m that have extremely low water vapor content and are unaffected by monsoons. With an innovative optical design, the NLST is an on-axis Gregorian telescope with a low number of optical elements to reduce the number of reflections and yield a high throughput with low polarization. In addition, it is equipped with a high-order adaptive optics to produce close to diffraction limited performance. To control atmospheric and thermal perturbations of the observations, the telescope will function with a fully open dome, to achieve its full potential atop a 25 m tower. Given its design, NLST can also operate at night, without compromising its solar performance. The post-focus instruments include broad-band and tunable Fabry-Pérot narrow-band imaging instruments; a high resolution spectropolarimeter and an Echelle spectrograph for night time astronomy. 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 the ATST and EST come into operation. An international consortium has been identified to build the NLST. The facility is expected to be commissioned by 2016.

Hasan, S. S.

2012-12-01

19

Technology demonstration solar telescope  

NASA Astrophysics Data System (ADS)

The conceptual design of the Large Earth-based Solar Telescope (LEST) has evolved through the years. In 1995-97 it was discussed whether a technology demonstration telescope could be built at a lower cost than the LEST originally proposed. In 1997, a de-scoped LEST design, the so-called "Mini-LEST", was conceived and proposed to the LEST community. The telescope has an innovative design with a small field lens that makes the way for simple adaptive optics. The optical performance is excellent. It has a low-cost alt-az steel structure with a large slewing ring for the azimuth movement and direct-drive motors for simplicity. The telescope is open but can easily be modified to a Helium telescope to compare performance of Helium filled telescopes vs. open telescopes. The tower has also been simplified to reduce cost. It has a dome design that provides protection for wind and yet permits open-air observations. The budget shows an overall cost of 37.6 MSEK and an exectution time of less than four years.

Andersen, Torben; Engvold, Oddbjrn; Owner-Pedersen, Mette

20

Solar Rejection Filter for Large Telescopes  

NASA Technical Reports Server (NTRS)

To reject solar radiation photons at the front aperture for large telescopes, a mosaic of large transmission mode filters is placed in front of the telescope or at the aperture of the dome. Filtering options for effective rejection of sunlight include a smaller filter down-path near the focus of the telescope, and a large-diameter filter located in the front of the main aperture. Two types of large filters are viable: reflectance mode and transmittance mode. In the case of reflectance mode, a dielectric coating on a suitable substrate (e.g. a low-thermal-expansion glass) is arranged to reflect only a single, narrow wavelength and to efficiently transmit all other wavelengths. These coatings are commonly referred to as notch filter. In this case, the large mirror located in front of the telescope aperture reflects the received (signal and background) light into the telescope. In the case of transmittance mode, a dielectric coating on a suitable substrate (glass, sapphire, clear plastic, membrane, and the like) is arranged to transmit only a single wavelength and to reject all other wavelengths (visible and near IR) of light. The substrate of the large filter will determine its mass. At first glance, a large optical filter with a diameter of up to 10 m, located in front of the main aperture, would require a significant thickness to avoid sagging. However, a segmented filter supported by a structurally rugged grid can support smaller filters. The obscuration introduced by the grid is minimal because the total area can be made insignificant. This configuration can be detrimental to a diffraction- limited telescope due to diffraction effects at the edges of each sub-panel. However, no discernable degradation would result for a 20 diffraction-limit telescope (a photon bucket). Even the small amount of sagging in each subpanel should have minimal effect in the performance of a non-diffraction limited telescope because the part has no appreciable optical power. If the front aperture filter is integrated with the telescope dome, it will reject heat from the dome and will significantly reduce dome temperature regulation requirements and costs. Also, the filter will protect the telescope optics from dust and other contaminants in the atmosphere. It will be simpler to clean or replace this filter than the telescope primary mirror. It may be necessary to paint the support grid with a highly reflective material to avoid overheating.

Hemmati, Hamid; Lesh, James

2009-01-01

21

Large diffractive/refractive apertures for space and airborne telescopes  

NASA Astrophysics Data System (ADS)

Recent work, specifically the Lawrence Livermore National Laboratory (LLNL) Eyeglass and the DARPA MOIRE programs, have evaluated lightweight, easily packaged and deployed, diffractive/refractive membrane transmissive lenses as entrance apertures for large space and airborne telescopes. This presentation describes a new, innovative approach to the theory of diffractive and refractive effects in lenses used as telescope entrance apertures and the fabrication of the necessary large membrane optics. Analyses are presented to indicate how a broadband, highly transmissive diffractive / refractive membrane lens can be developed and fabricated, and potential applications in defense and astronomy are briefly discussed.

MacEwen, Howard A.; Breckinridge, James B.

2013-05-01

22

Self-Referencing Hartmann Test for Large-Aperture Telescopes  

NASA Technical Reports Server (NTRS)

A method is proposed for end-to-end, full aperture testing of large-aperture telescopes using an innovative variation of a Hartmann mask. This technique is practical for telescopes with primary mirrors tens of meters in diameter and of any design. Furthermore, it is applicable to the entire optical band (near IR, visible, ultraviolet), relatively insensitive to environmental perturbations, and is suitable for ambient laboratory as well as thermal-vacuum environments. The only restriction is that the telescope optical axis must be parallel to the local gravity vector during testing. The standard Hartmann test utilizes an array of pencil beams that are cut out of a well-corrected wavefront using a mask. The pencil beam array is expanded to fill the full aperture of the telescope. The detector plane of the telescope is translated back and forth along the optical axis in the vicinity of the nominal focal plane, and the centroid of each pencil beam image is recorded. Standard analytical techniques are then used to reconstruct the telescope wavefront from the centroid data. The expansion of the array of pencil beams is usually accomplished by double passing the beams through the telescope under test. However, this requires a well-corrected, autocollimation flat, the diameter or which is approximately equal to that of the telescope aperture. Thus, the standard Hartmann method does not scale well because of the difficulty and expense of building and mounting a well-corrected, large aperture flat. The innovation in the testing method proposed here is to replace the large aperture, well-corrected, monolithic autocollimation flat with an array of small-aperture mirrors. In addition to eliminating the need for a large optic, the surface figure requirement for the small mirrors is relaxed compared to that required of the large autocollimation flat. The key point that allows this method to work is that the small mirrors need to operate as a monolithic flat only with regard to tip/tilt and not piston because in collimated space piston has no effect on the image centroids. The problem of aligning the small mirrors in tip/tilt requires a two-part solution. First, each mirror is suspended from a two-axis gimbal. The orientation of the gimbal is maintained by gravity. Second, the mirror is aligned such that the mirror normal is parallel to gravity vector. This is accomplished interferometrically in a test fixture. Of course, the test fixture itself needs to be calibrated with respect to gravity.

Korechoff, Robert P.; Oseas, Jeffrey M.

2010-01-01

23

Construction of the Advanced Technology 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 entered its construction phase. Major subsystems have been contracted. 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 4m 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 spectro-polarimeters. 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 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 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.; Keil, S.; McMullin, J.; Knölker, M.; Kuhn, J. R.; Goode, P. R.; Rosner, R.; Casini, R.; Lin, H.; Tritschler, A.; Wöger, F.; ATST Team

2012-12-01

24

Solar Sail Fresnel Zone Plate Lens for a Large Space Based Telescope.  

National Technical Information Service (NTIS)

A Fresnel zone plat lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by...

J. T. Early

2003-01-01

25

The scaling relationship between telescope cost and aperture size for very large telescopes  

NASA Technical Reports Server (NTRS)

Cost data for ground-based telescopes of the last century are analyzed for trends in the relationship between aperture size and cost. We find that for apertures built prior to 1980, costs scaled as aperture size to the 2.8 power, which is consistent with the precious finding of Meinel (1978). After 1980, 'traditional' monolithic mirror telescope costs have scaled as aperture to the 2.5 power. The large multiple mirror telescopes built or in construction during this time period (Keck, LBT, GTC) appear to deviate from this relationship with significant cost savings as a result, although it is unclear what power law such structures follow. We discuss the implications of the current cost-aperture size data on the proposed large telescope projects of the next ten to twenty years. Structures that naturally tend towards the 2.0 power in the cost-aperture relationship will be the favorable choice for future extremely large apertures; out expectation is that space-based structures will ultimately gain economic advantage over ground-based ones.

van Belle, Gerard T.; Meinel, Aden Baker; Meinel, Marjorie Pettit

2004-01-01

26

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

Microsoft Academic Search

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

T. D. Tarbell

2005-01-01

27

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.

28

Concepts for a Large-Aperture, High Dynamic Range Telescope  

NASA Astrophysics Data System (ADS)

This paper summarizes concept studies for a large telescope capable of wide-field imaging and of the highest possible dynamic range for photometry and angular resolution. Point-spread functions (PSFs) and scattered light levels at large offsets are computed and compared for four telescopes of the same light-gathering power but with different pupil functions:1. a reference monolithic mirror telescope with a 17.4 m primary,2. a segmented mirror telescope (SMT) with a hexagonally segmented primary,3. a hexagonal off-axis telescope (HOT) with a distributed aperture made of 6×6.5 m unobstructed circular mirrors that are identical off-axis sections of a parent 20 m mirror, and4. a square off-axis telescope (SOT) whose aperture is made of 4×8 m off-axis mirrors. The characteristics of the PSFs are examined in the diffraction- and seeing-limited regimes, assuming (1) perfect mirror figure and (2) realistic figure errors (edge defects). The implications of field rotation with an altitude-azimuth mounting are discussed in each case. The implementation of adaptive optics (AO) and the properties of AO-compensated PSFs having a Strehl ratio of 0.5, and of coronagraphic imaging, are also discussed for the four configurations. It is shown that, in the seeing-limited regime and as intuitively expected, the optical performance of all four telescopes is comparable. With higher order adaptive optics and for coronagraphic observations, the SOT and HOT are superior to the SMT. This distinction becomes larger with relaxed constraints on mirror edge-polishing requirements. A full optical design is presented for the novel HOT configuration, and optical fabrication issues are briefly addressed. Finally, science programs and possible instrumentation layouts with the HOT are briefly explored for different modes of operation. It appears that the natural ``optical bench'' configuration of the HOT can provide a remarkably versatile and convenient environment for instrument deployment.

Kuhn, J. R.; Moretto, G.; Racine, R.; Roddier, F.; Coulter, R.

2001-12-01

29

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

30

Solar energy apparatus with apertured shield  

NASA Technical Reports Server (NTRS)

A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

1989-01-01

31

Adaptive Optics for the 8 meter Chinese Giant Solar Telescope  

NASA Astrophysics Data System (ADS)

Solar ELTs enable diffraction limited imaging of the basic structure of the solar atmosphere. Magneto-hydrodynamic considerations limit their size to about 0.03 arcsec. To observe them in the near-infrared 8-meter class telescopes are needed. The Chinese Giant Solar Telescope, or CGST, is such a NIR solar ELT. It is a Ring Telescope with 8-meter outer diameter and a central clear aperture of about 6-meter diameter. At present various options for such a Gregorian type telescope are under study like a continuous ring made of segments or a multiple aperture ring made of 7 off-axis telescopes. The advantages of such a ring telescope is that its MTF covers all spatial frequencies out to those corresponding to its outer diameter, that its circular symmetry makes it polarization neutral, and that its large central hole helps thermal control and provides ample space for MCAO and Gregorian instrumentation. We present the current status of the design of the CGST. Our thinking is guided by the outstanding performance of the 1-meter vacuum solar telescope of the Yunnan Solar Observatory which like the CGST uses both AO and image reconstruction. Using it with a ring-shape aperture mask the imaging techniques for the CGST are being explored. The CGST will have Multi-Conjugate Adaptive Optics (MCAO). The peculiarities of Atmospheric Wavefront Tomography for Ring Telescopes are aided by the ample availability of guide stars on the Sun. IR MCAO-aided diffraction limited imaging offers the advantage of a large FOV, and high solar magnetic field sensitivity. Site testing is proceeding in western China, (e.g. northern Yunnan Province and Tibet). The CGST is a Chinese solar community project originated by the Yunnan Astronomical Observatory, the National Astronomical Observatories, the Purple Mountain Observatory, the Nanjing University, the Nanjing Institute of Astronomical Optics & Technology and the Beijing Normal University.

Beckers, Jacques; Liu, Zhong; Deng, Yuanyong; Ji, Haisheng

2013-12-01

32

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

33

Development of Large-Aperture, Light-Weight Fresnel Lenses for Gossamer Space Telescopes.  

National Technical Information Service (NTIS)

In order to examine more distant astronomical objects, with higher resolution, future space telescopes require objectives with significantly larger aperture than presently available. NASA has identified a progression in size from the 2.4m aperture objecti...

S. Dixit R. Hyde A. Weisberg J. Early M. Rushford J. Britten

2002-01-01

34

The New Solar Telescope (NST): What’s Next ?  

NASA Astrophysics Data System (ADS)

The 1.6 m, off-axis, clear aperture New Solar Telescope (NST) has been in regular operation in Big Bear Solar Observatory since 2009. The NST is the first facility class solar telescope built in the U.S. in a generation, which already offers a significant improvement in ground-based high angular resolution capabilities. This presentation reports the up-to-date progress on the NST and its 2nd generation instruments including the AO system (AO-308), the Near-InfraRed Imaging Spectro-polarimeter (NIRIS), the Visible Imaging Spectrometer (VIS), and the Cryogenic Infrared Spectrograph (CYRA).

Cao, Wenda; Goode, P. R.; NST Team

2013-07-01

35

Fast Imaging Solar Spectrograph System in New Solar Telescope  

NASA Astrophysics Data System (ADS)

In 2004, Big Bear Solar Observatory in California, USA launched a project for construction of the world's largest aperture solar telescope (D = 1.6m) called New Solar Telescope(NST). University of Hawaii (UH) and Korea Astronomy and Space Science Institute(KASI) partly collaborate on the project. NST is a designed off-axis parabolic Gregorian reflector with very high spatial resolution(0.07 arcsec at 5000A) and is equipped with several scientific instruments such as Visible Imaging Magnetograph (VIM), InfraRed Imaging Magnetograph IRIM), and so on. Since these scientific instruments are focused on studies of the solar photosphere, we need a post-focus instrument for the NST to study the fine structures and dynamic patterns of the solar chromosphere and low Transition Region (TR) layer, including filaments/prominences, spicules, jets, micro flares, etc. For this reason, we developed and installed a fast imaging solar spectrograph(FISS) system on the NST withadvantages of achieving compact design with high spectral resolution and small aberration as well as recording many solar spectral lines in a single and/or dual band mode. FISS was installed in May, 2010 and now we carry out a test observation. In this talk, we introduce the FISS system and the results of the test observation after FISS installation.

Park, Y.-D.; Kim, Y. H.; Chae, J.; Goode, P. R.; Cho, K. S.; Park, H. M.; Nah, J. K.; Jang, B. H.

2010-12-01

36

The New Solar Telescope in Big Bear  

NASA Astrophysics Data System (ADS)

The 1.6 m clear aperture, off-axis solar telescope (the "NST") in Big Bear Lake enjoyed first light in January 2009. In the Summer of 2009, high resolution, speckle corrected observations were made in TiO and Halpha. In the Summer of 2010, adaptive optics were implemented and the first magnetograms were obtained. The NST is first new U.S. facility class solar telescope in a generation. The NST has an off-axis Gregorian configuration consisting of a parabolic primary, heat-stop, elliptical secondary and diagonal flats. The focal ratio of the primary mirror is f/2.4, and the final ratio is f/50. The working wavelength range covers from 0.4 to 1.7 microns in the Coude Lab beneath the telescope and all wavelengths including the far infrared before the entrance window to the Coude Lab. Observational results will be introduced including revealing granular-scale chromospheric jets with their origin in the dark intergranular lanes, revealing bright lanes in granules, demonstration of equipartition between photospheric magnetic fields and plasma flow, and some unexpected results in the evolution of bright points.

Goode, Philip R.

2011-05-01

37

Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)  

NASA Technical Reports Server (NTRS)

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

2010-01-01

38

High resolution imaging with multilayer soft X-ray, EUV and FUV telescopes of modest aperture and cost  

NASA Technical Reports Server (NTRS)

The development of multilayer reflective coatings now permits soft X-ray, EUV and FUV radiation to be efficiently imaged by conventional normal incidence optical configurations. Telescopes with quite modest apertures can, in principle, achieve images with resolutions which would require apertures of 1.25 meters or more at visible wavelengths. The progress is reviewed which has been made in developing compact telescopes for ultra-high resolution imaging of the sun at soft X-ray, EUV and FUV wavelengths, including laboratory test results and astronomical images obtained with rocket-borne multilayer telescopes. The factors are discussed which limit the resolution which has been achieved so far, and the problems which must be addressed to attain, and surpass the 0.1 arc-second level. The application of these technologies to the development of solar telescopes for future space missions is also described.

Walker, Arthur B. C., Jr.; Lindblom, Joakim F.; Timothy, J. G.; Hoover, Richard B.; Barbee, Troy W., Jr.; Baker, Phillip C.; Powell, Forbes R.

1991-01-01

39

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

40

BLAST: The Balloon-Borne Large Aperture Submillimeter Telescope  

NASA Technical Reports Server (NTRS)

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 and 500 microns. By providing the first sensitive large-area (10 sq. deg.) sub-mm surveys at these wavelengths, BLAST will address some of the most important galactic and cosmological questions regarding the formation and evolution of stars, galaxies and clusters. Galactic and extragalactic BLAST surveys will: (1) identify large numbers of high-redshift galaxies; (2) measure photometric redshifts, rest-frame FIR luminosities and star formation rates thereby constraining the evolutionary history of the galaxies that produce the FIR and sub-mm background; (3) measure cold pre-stellar sources associated with the earliest stages of star and planet formation; (4) make high-resolution maps of diffuse galactic emission over a wide range of galactic latitudes. In addition to achieving the above scientific goals, the exciting legacy of the BLAST LDB experiment will be a catalogue of 3000-5000 extragalactic sub-mm sources and a 100 sq. deg. sub-mm galactic plane survey. Multi-frequency follow-up observations from SIRTF, ASTRO-F, and Herschel, together with spectroscopic observations and sub-arcsecond imaging from ALMA are essential to understand the physical nature of the BLAST sources.

Devlin, Mark; Ade, Peter; Bock, Jamie; Dicker, Simon; Griffin, Matt; Gunderson, Josh; Halpern, Mark; Hargrave, Peter; Hughes, David; Klein, Jeff

2004-01-01

41

The COronal Solar Magnetism Observatory (COSMO) Large Aperture Coronagraph  

NASA Astrophysics Data System (ADS)

The COSMO is a facility dedicated to observing coronal and chromospheric magnetic fields. It will be located on a mountaintop in the Hawaiian Islands and will replace the current Mauna Loa Solar Observatory (MLSO). COSMO will provide unique observations of the global coronal magnetic fields and its environment to enhance the value of data collected by other observatories on the ground (e.g. SOLIS, BBO NST, Gregor, ATST, EST, Chinese Giant Solar Telescope, NLST, FASR) and in space (e.g. SDO, Hinode, SOHO, GOES, STEREO, Solar-C, Solar Probe+, Solar Orbiter). COSMO will employ a fleet of instruments to cover many aspects of measuring magnetic fields in the solar atmosphere. The dynamics and energy flow in the corona are dominated by magnetic fields. To understand the formation of CMEs, their relation to other forms of solar activity, and their progression out into the solar wind requires measurements of coronal magnetic fields. The large aperture coronagraph, the Chromospheric and Prominence Magnetometer and the K-Coronagraph form the COSMO instrument suite to measure magnetic fields and the polarization brightness of the low corona used to infer electron density. The large aperture coronagraph will employ a 1.5 meter fuse silica singlet lens, birefringent filters, and a spectropolarimeter to cover fields of view of up to 1 degree. It will observe the corona over a wide range of emission lines from 530.3 nm through 1083.0 nm allowing for magnetic field measurements over a wide range of coronal temperatures (e.g. FeXIV at 530.3 nm, Fe X at 637.4 nm, Fe XIII at 1074.7 and 1079.8 nm. These lines are faint and require the very large aperture. NCAR and NSF have provided funding to bring the large aperture coronagraph to a preliminary design review state by the end of 2013. As with all data from Mauna Loa, the data products from COSMO will be available to the community via the Mauna Loa website: http://mlso.hao.ucar.edu

Tomczyk, Steve; Gallagher, Dennis; Wu, Zhen; Zhang, Haiying; Nelson, Pete; Burkepile, Joan; Kolinksi, Don; Sutherland, Lee

2013-04-01

42

Super Solar Neutron Telescope for the Next Solar Maximum  

Microsoft Academic Search

We propose a new type of solar neutron detector, the super Solar Neutron telescope, for the next solar cycle 24. The new detector should retain the function of the present solar neutron telescopes, i.e., the capability for energy measurement and determination of the arrival direction of solar neutrons with high detection efficiency. For this purpose the detector should be composed

T. Sako; Yasushi Muraki; Naoki Hirano; Harufumi Tsuchiya

2003-01-01

43

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

44

First steps in the development of a piston sensor for large aperture space telescopes  

NASA Astrophysics Data System (ADS)

Nowadays spaceborne missions for astronomy or Earth imaging need high resolution observation which implies the development of large aperture telescopes. This can be achieved by multi-aperture telescopes or large segmented telescopes. One of the major issues is the phasing of the sub-apertures or the segments of such telescopes. A cophasing sensor is therefore mandatory to achieve the ultimate resolution of these telescopes. In this framework, Liège Space Center (CSL) concern is the development of a compact cophasing sensor to phase new large lightweight segmented mirrors for future space telescopes. The sensor concept has its origins in new phase retrieval algorithms which have been recently developed. In this paper, we outline the concept and the experimental validation results of our piston sensor breadboard which is currently under development in our laboratory. Finally, future prospects and further developments of our experiment are presented.

Guerri, Géraldine; Roose, Stéphane; Stockman, Yvan; Mazzoli, Alexandra; Surdej, Jean; Defise, Jean-Marc

2010-07-01

45

Construction of the Advanced Technology Solar Telescope - A Progress Report.  

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 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 the first half of 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 summary 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, T. R.; Keil, S.; McMullin, J.; Goode, P. R.; Knoelker, M.; Kuhn, J. R.; Rosner, R.; ATST Team

2012-12-01

46

The Protoexist2 Advanced CZT Coded Aperture Telescope  

NASA Astrophysics Data System (ADS)

The ProtoEXIST program was conceived for the development of a scalable detector plane architecture utilizing pixilated CdZnTe (CZT) detectors for eventual deployment in a large scale (1-4 m2 active area) coded aperture X-ray telescope for use as a wide field ( 90° × 70° FOV) all sky monitor and survey instrument for the 5 up to 600 keV energy band. The first phase of the program recently concluded with the successful 6 hour high altitude (39 km) flight of ProtoEXIST1, which utilized a closely tiled 8 × 8 array of 20 mm × 20 mm, 5 mm thick Redlen CZT crystals each bonded to a RadNET asic via an interposer board. Each individual CZT crystal utilized a 8 × 8 pixilated anode for the creation of a position sensitive detector with 2.5 mm spatial resolution. Development of ProtoEXIST2, the second advanced CZT detector plane in this series, is currently under way. ProtoEXIST2 will be composed of a closely tiled 8 × 8 array of 20 mm × 20 mm, 5 mm thick Redlen CZT crystals, similar to ProtoEXIST1, but will now utilize the Nu-ASIC which accommodates the direct bonding of CZT detectors with a 32 × 32 pixilated anode with a 604.8 ?m pixel pitch. Characterization and performance of the ProtoEXIST2 detectors is discussed as well as current progress in the integration of the ProtoEXIST2 detector plane.

Allen, Branden; Hong, J.; Grindlay, J.; Barthelmy, S.; Baker, R.

2011-09-01

47

An optical technology study on large aperture telescopes  

NASA Technical Reports Server (NTRS)

The difficult and crucial problem of selecting a suitable telescope concept for an advanced space observatory was examined. To this end two and four mirror telescopes were analyzed and compared. Both configurations are very practical and structurally similar. Parabolic primary and spherical primary four mirror telescope were compared with respect to their performance and the alignment sensitivities of the three correction mirrors. A 1 meter class afocal telescope system with lag angle compensation, to be used in a LIDAR experiment, was examined.

Korsch, D.

1985-01-01

48

Parallel Image Reconstruction for New Vacuum Solar Telescope  

NASA Astrophysics Data System (ADS)

Many advanced ground-based solar telescopes improve the spatial resolution of observation images using an adaptive optics (AO) system. As any AO correction remains only partial, it is necessary to use post-processing image reconstruction techniques such as speckle masking or shift-and-add (SAA) to reconstruct a high-spatial-resolution image from atmospherically degraded solar images. In the New Vacuum Solar Telescope (NVST), the spatial resolution in solar images is improved by frame selection and SAA. In order to overcome the burden of massive speckle data processing, we investigate the possibility of using the speckle reconstruction program in a real-time application at the telescope site. The code has been written in the C programming language and optimized for parallel processing in a multi-processor environment. We analyze the scalability of the code to identify possible bottlenecks, and we conclude that the presented code is capable of being run in real-time reconstruction applications at NVST and future large aperture solar telescopes if care is taken that the multi-processor environment has low latencies between the computation nodes.

Li, Xue-Bao; Wang, Feng; Xiang, Yong Yuan; Zheng, Yan Fang; Liu, Ying Bo; Deng, Hui; Ji, Kai Fan

2014-04-01

49

Apodized Pupil Lyot Coronagraphs for Arbitrary Apertures. II. Theoretical Properties and Application to Extremely Large Telescopes  

Microsoft Academic Search

We study the application of Lyot coronagraphy to future Extremely Large Telescopes (ELTs), showing that Apodized Pupil Lyot Coronagraphs enable high-contrast imaging for exoplanet detection and characterization with ELTs. We discuss the properties of the optimal pupil apodizers for this application (generalized prolate spheroidal functions). The case of a circular aperture telescope with a central obstruction is considered in detail,

Rémi Soummer; Laurent Pueyo; André Ferrari; Claude Aime; Anand Sivaramakrishnan; Natalia Yaitskova

2009-01-01

50

High Performance Lyot and PIAA Coronagraphy for Arbitrarily Shaped Telescope Apertures  

NASA Astrophysics Data System (ADS)

Two high-performance coronagraphic approaches compatible with segmented and obstructed telescope pupils are described. Both concepts use entrance pupil amplitude apodization and a combined phase and amplitude focal plane mask to achieve full coronagraphic extinction of an on-axis point source. While the first concept, called Apodized Pupil Complex Mask Lyot Coronagraph (APCMLC), relies on a transmission mask to perform the pupil apodization, the second concept, called Phase-Induced Amplitude Apodization complex mask coronagraph (PIAACMC), uses beam remapping for lossless apodization. Both concepts theoretically offer complete coronagraphic extinction (infinite contrast) of a point source in monochromatic light, with high throughput and sub-?/D inner working angle, regardless of aperture shape. The PIAACMC offers nearly 100% throughput and approaches the fundamental coronagraph performance limit imposed by first principles. The steps toward designing the coronagraphs for arbitrary apertures are described for monochromatic light. Designs for the APCMLC and the higher performance PIAACMC are shown for several monolith and segmented apertures, such as the apertures of the Subaru Telescope, Giant Magellan Telescope, Thirty Meter Telescope, the European Extremely Large Telescope, and the Large Binocular Telescope. Performance in broadband light is also quantified, suggesting that the monochromatic designs are suitable for use in up to 20% wide spectral bands for ground-based telescopes.

Guyon, Olivier; Hinz, Philip M.; Cady, Eric; Belikov, Ruslan; Martinache, Frantz

2014-01-01

51

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

52

Space telescope: Solar array primary deployment mechanism  

NASA Technical Reports Server (NTRS)

The requirements, the design, and the test program which were carried out in producing the Space Telescope Solar Array (STSA) primary deployment mechanisms (PDM) are described. The PDM will be used to rotate the rolled solar array supporting boom from its launch position alongside the telescope housing, through 90 deg to its use position. After five years in space the array is to be rerolled and by use of the PDM swung back to its stowed position alongside the telescope housing for capture and return to Earth via the Space Shuttle.

Chandler, D. P.; Veit, A.

1983-01-01

53

A parametric study of various synthetic aperture telescope configurations for coherent imaging applications  

NASA Astrophysics Data System (ADS)

The comparative advantages of synthetic aperture telescopes (SATs) of segmented primary mirror and common secondary mirror type, on the one hand, and on the other those employing an array of independent telescopes, are discussed. The diffraction-limited optical performance of both redundant and nonredundant subaperture configurations are compared in terms of point spread function characteristics and encircled energy plots. Coherent imaging with afocal telescope SATs involves a pupil-mapping operation followed by a Fourier transform one. A quantitative analysis of the off-axis optical performance degradation due to pupil-mapping errors is presented, together with the field-dependent effects of residual design aberrations of independent telescopes.

Harvey, James E.; Wissinger, Alan B.; Bunner, Alan N.

1986-01-01

54

The 100 cm solar telescope primary mirror study  

NASA Technical Reports Server (NTRS)

The manufacturing impact of primary mirror configuration on the performance of a 100 cm aperture solar telescope was studied. Three primary mirror configurations were considered: solid, standard lightweight, and mushroom. All of these are of low expansion material. Specifically, the study consisted of evaluating the mirrors with regard to: manufacturing metrology, manufacturing risk factors and ultimate quality assessment. As a result of this evaluation, a performance comparison of the configurations was made, and a recommendation of mirror configuration is the final output. These evaluations, comparisons and recommendations are discussed in detail. Other investigations were completed and are documented in the appendices.

1975-01-01

55

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.

56

Effect of misalignment errors on the optical transfer function of the synthetic aperture telescopes  

NASA Astrophysics Data System (ADS)

A segmented or diluted aperture optical system will undergo phase errors due to errors in the positing of the segments. The errors associated with a segmented primary mirror limit the image quality obtainable with the synthetic aperture telescopes. Here, we study the effects of segmentation errors on image quality considering both the phase angle and amplitude of the OTF. We show that, in these kind telescopes, the phasing and alignment errors among segments reduce the amplitude and distort the phase angle of the OTF.

Flores, Jorge L.; Paez, Gonzalo; Strojnik, Marija; Garcia, Guillermo

2003-12-01

57

The application of wavefront coding technology to a large segmented synthetic aperture telescope  

NASA Astrophysics Data System (ADS)

The utilization of a telescope with a large single aperture is limited by the manufacturing technique, cost, volume and weight of a monolithic mirror. In order to solve these problems, the technology of the segmented synthetic aperture was introduced. The primary mirror of a large segmented synthetic aperture telescope consists of several segmented mirrors, whose misalignment errors make the wavefront change drastically and influence the MTF of the optical system badly. The wavefront coding technology (WFC) is an innovative technology that joints the optical design and digital image processing together. By adding a phase mask close to the pupil of an optical system and modulating the wavefront, the WFC system becomes very insensitive to defocus and other aberrations based on defocus. The theoretical analysis of characteristics of the WFC system was done in the form of PSF. The application of WFC to a segmented three mirror anastigmat (TMA) was presented. A space telescope with an effective focal length as 40m, a F number as 10, a field of view as 0.5°x0.05° was designed, whose primary mirror consisted of seven segmented mirrors. The influence of defocus and misalignment errors on the telescope was discussed. The imaging process of the WFC system and following image restoration were simulated. As a result, sharp images were obtained and the large segmented synthetic aperture telescope had looser misalignment tolerance and extended depth of focus.

Feng, Litong; Meng, Junhe; Dun, Xiong; Tao, Yu; Zhu, Lixin; Wu, Xiaojing; Zhang, Zhen; Zhang, Chenzhong; Chen, Xin; Lei, Li; Zhao, Kan

2010-05-01

58

Low-cost Large Aperture Telescopes for Optical Communications  

NASA Technical Reports Server (NTRS)

Low-cost, large-aperture optical receivers are required to form an affordable optical ground receiver network for laser communications. Among the ground receiver station's multiple subsystems, here, we only discuss the ongoing research activities aimed at reducing the cost of the large-size optics on the receiver. Experimental results of two different approaches for fabricating low-cost mirrors of wavefront quality on the order of 100-200X the diffraction limit are described. Laboratory-level effort are underway to improve the surface figure to better than 20X the diffraction limit.

Hemmati, Hamid

2006-01-01

59

Layered synthetic microstructures for solar EUV telescopes  

NASA Technical Reports Server (NTRS)

The application of layered synthetic microstructures (LSMs) to figured mirrors suitable for normal incidence solar EUV telescopes is considered, and initial studies for a single mirror telescope consisting of an f/18, 200-cm focal length off-axis paraboloid demonstrate the feasibility of LSM coatings for moderate sized mirrors. Analytical studies on broadband designs comprised of five layers show a seven percent reflectance at 256 A and reflectivities of over 12 percent for wavelengths above 300 A. Deposition considerations are also discussed.

Keski-Kuha, R. A. M.; Thomas, R. J.; Epstein, G. L.; Osantowski, J. F.

1985-01-01

60

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

61

Thermal analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8-meter primary mirror  

Microsoft Academic Search

The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 point and will experience constant exposure to the sun. The insulation on the optical tube and sunshade

Linda Hornsby; Randall C. Hopkins; H. Philip Stahl

2010-01-01

62

Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers and Technology Developments.  

National Technical Information Service (NTIS)

The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astro...

D. Calzetti H. P. Stahl J. Tumlinson K. Sembach K. Stapelfeldt M. Giavalisco M. Mountain M. Postman R. Soummer R. M. Rich T. Brown T. Hyde W. Oegerle W. Traub

2011-01-01

63

Position measurement of the direct drive motor of Large Aperture Telescope  

NASA Astrophysics Data System (ADS)

Along with the development of space and astronomy science, production of large aperture telescope and super large aperture telescope will definitely become the trend. It's one of methods to solve precise drive of large aperture telescope using direct drive technology unified designed of electricity and magnetism structure. A direct drive precise rotary table with diameter of 2.5 meters researched and produced by us is a typical mechanical & electrical integration design. This paper mainly introduces position measurement control system of direct drive motor. In design of this motor, position measurement control system requires having high resolution, and precisely aligning the position of rotor shaft and making measurement, meanwhile transferring position information to position reversing information corresponding to needed motor pole number. This system has chosen high precision metal band coder and absolute type coder, processing information of coders, and has sent 32-bit RISC CPU making software processing, and gained high resolution composite coder. The paper gives relevant laboratory test results at the end, indicating the position measurement can apply to large aperture telescope control system. This project is subsidized by Chinese National Natural Science Funds (10833004).

Li, Ying; Wang, Daxing

2010-07-01

64

Performance predictions for spaceborne, long-lifetime helium dewars containing large-aperture telescopes  

NASA Technical Reports Server (NTRS)

The evolution of design approaches for high-performance superfluid helium dewars containing large-aperture telescopes are discussed. Particular attention is given to thermal-math modeling for the IRAS and the Cosmic Background Explorer (COBE) dewars. Correlation of the recent COBE flight data with the dewar thermal-math model is presented, and apparent predictive deficiencies of the model are discussed.

Hopkins, Richard A.; Nieczkoski, Stephen J.; Volz, Stephen M.

1990-01-01

65

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.

66

Detection and initial characterisation of an exoplanet atmosphere with small aperture telescopes  

NASA Astrophysics Data System (ADS)

In the recent years atmospheres of exoplanets have been studied with space-based telescopes like the HST or large aperture ground-based telescopes like the Gran Telescopio Canarias. But as the number of suitable exoplanets is rising, comparative studies of atmospheres with a statistically meaningful amount of targets will follow, for which the observational time with large telescopes is limited and expensive. Our aim is to investigate whether it is possible to detect and initially characterise the atmosphere of an exoplanet with small aperture telescopes using chromatic variations in transit depths. We collected multi-color transits in the years 2011 to 2013 using the robotic 1.2m-telescope STELLA on Tenerife as well as the Nordic Optical Telescope and the 70cm-telescope at the Leibniz Institute for Astrophysics Potsdam. The highly inflated Hot Jupiter HAT-P-32 b was chosen as target for our pilot study for its favorable large atmospheric scale height and therefore enhanced atmospheric detectability. Models of the atmospheric spectra of HAT-P-32 b indicate that the STELLA-data can be used to distinguish between a dusty and a cloud-free atmosphere using the gradient in transit depth of the observations in the blue band and in the visible band. Here we want to present our project together with the first results of the transit depth analysis.

Bernt, I.; Müller, M.; Strassmeier, K. G.; Granzer, T.

2013-09-01

67

Thermal Analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8 Meter Primary Mirror  

NASA Technical Reports Server (NTRS)

The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The primary mirror will be maintained at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop(R) SINDA/FLUINT(R) was used for the thermal analysis and the radiation environment was analyzed using RADCAD(R). A XX node model was executed in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew or 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the environment which influences the thermal performance. All assumptions that were used in the analysis are also documented. Parametric analyses are summarized for design parameters including primary mirror coatings and sunshade configuration. Estimates of mirror heater power requirements are reported. The thermal model demonstrates results for the primary mirror heated from the back side and edges using a heater system with multiple independently controlled zones.

Hornsby, Linda; Stahl, H. Philip; Hopkins, Randall C.

2010-01-01

68

New telescopes for ground-based solar observations at submillimeter and mid-infrared  

Microsoft Academic Search

The solar submillimeter-wave telescope (SST) is the only one of its kind dedicated to solar continuous observations. Two radiometers at 0.740 mm (405 GHz), and four at 1.415 mm (212 GHz) are placed in the Cassegrain focal plane of the 1.5-m dish at El Leoncito high altitude site, San Juan, Argentina. The aperture efficiencies are close to design predictions: 20%

Pierre Kaufmann; Hugo Levato; Marta M. Cassiano; Emilia Correia; Joaquim E. R. Costa; C. Guillermo Giménez de Castro; Rodolfo Godoy; Robert K. Kingsley; Jeffrey S. Kingsley; Amauri S. Kudaka; Rogério Marcon; Robert Martin; Adolfo Marun; Arline M. Melo; Pablo Pereyra; Jean-Pierre Raulin; Thomas Rose; Adriana Silva Valio; Achim Walber; Patrick Wallace; Azriel Yakubovich; Maria Beny Zakia

2008-01-01

69

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

70

Engineering Specification for Large-aperture UVO Space Telescopes Derived from Science Requirements  

NASA Technical Reports Server (NTRS)

An advanced large aperture UV/optical UVO space telescope is required for the next generation of astrophysics and exoplanet science. The science requirements of proposed exoplanet and astrophysics missions were used to determine the encircled energy, point spread function stability and thermal environment requirements. These requirements then determine the optical wavefront specification for potential telescope assemblies which can fit inside current and planned launch vehicles. The optical wavefront specification becomes the top level of the error budget that is split into various sources that control the structural, thermal and optical design.

Stahl, H. Philip; Arnold, William; Bevan, Ryan M.; Smith, W. Scott.; Kirk, Charles S.; Postman, Mark

2013-01-01

71

ATLAST-9.2m: a Large-Aperture Deployable Space Telescope  

NASA Technical Reports Server (NTRS)

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.

Oergerle, William; Feinberg, Lee D.; Purves, Lloyd R.; Hyde, T. Tupper; Thronson, Harley A.; Townsend, Jacqueline A.; Postman, Marc; Bolear, 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.

2010-01-01

72

Design of a large low-scattered light telescope for solar observations  

NASA Astrophysics Data System (ADS)

This paper is an interim report of a feasibility study which is in progress for a large 400 cm aperture solar telescope (`CLEAR'). Unlike other large solar telescopes constructed in the last three decades, CLEAR does not use the concept of evacuated telescopes to eliminate internal seeing. The requirement for full access to the far infrared spectral region (> 2.5 micrometers ), and for low scattered light, eliminates the use of the entrance window which evacuated telescopes require. Instead, CLEAR avoids internal seeing by carefully controlling the internal thermal environment of the telescope by a number of means: (1) thermal control of the primary mirror; (2) flow of ambient air over the primary mirror surface and in the telescope; (3) locating the primary focus outside the telescope beam and enclosure where the heating resulting in concentrated sunlight can be managed better (this requires the use of an off-axis primary mirror); and (4) the use of a prime focus heat stop/absorber. In addition to controlling the internal seeing, such a configuration produces a telescope with very low scattered light characteristics, allowing quality observation of regions outside the solar limb and of sunspots. By eliminating the need for a large entrance window, the CLEAR concept therefore opens up the possibility of larger aperture solar telescopes. Notwithstanding its off-axis configuration, the Gregorian telescope produces excellent images (< 0.1 arcsec) over a 5 arcminute diameter field-of-view at the f/130 Gregorian focus. In addition to the four instrumentation stations near the Gregorian focus (i.e., direct Gregorian, Nasmyth, two `folded Gregorian'), the design provides for extensive instrumentation locations in a coude area. By means of a 3- level rotating coude platform, large instruments can be located at respectively f/30, f/45 and f/60 foci.

Beckers, Jacques M.

1998-08-01

73

Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC  

NASA Technical Reports Server (NTRS)

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 in improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (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; Burdine, Robert (Technical Monitor)

2001-01-01

74

Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC  

NASA Technical Reports Server (NTRS)

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, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (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; Montgomery, Edward E.; Lindner, Jeff

2000-01-01

75

Adaptive optics system application for solar telescope  

NASA Astrophysics Data System (ADS)

The possibility of applying adaptive correction to ground-based solar astronomy is considered. Several experimental systems for image stabilization are described along with the results of their tests. Using our work along several years and world experience in solar adaptive optics (AO) we are assuming to obtain first light to the end of 2008 for the first Russian low order ANGARA solar AO system on the Big Solar Vacuum Telescope (BSVT) with 37 subapertures Shack-Hartmann wavefront sensor based of our modified correlation tracker algorithm, DALSTAR video camera, 37 elements deformable bimorph mirror, home made fast tip-tip mirror with separate correlation tracker. Too strong daytime turbulence is on the BSVT site and we are planning to obtain a partial correction for part of Sun surface image.

Lukin, V. P.; Grigor'ev, V. M.; Antoshkin, L. V.; Botugina, N. N.; Emaleev, O. N.; Konyaev, P. A.; Kovadlo, P. G.; Krivolutskiy, N. P.; Lavrionova, L. N.; Skomorovski, V. I.

2008-07-01

76

First light of the 1.6 meter off-axis New Solar Telescope at Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

New Jersey Institute of Technology, in collaboration with the University of Hawaii and the Korea Astronomy & Space Science Institute, has successfully developed and installed a 1.6 m clear aperture, off-axis New Solar Telescope (NST) at the Big Bear Solar Observatory. The NST will be the largest aperture solar telescope in the world until the 4 m Advanced Technology Solar Telescope (ATST) and 4 m European Solar Telescope (EST) begin operation in the next decade. Meanwhile, the NST will be the largest off-axis telescope before the 8.4 m segmented Giant Magellan Telescope (GMT) comes on-line. The NST is configured as an off-axis Gregorian system consisting of a parabolic primary, prime focus field stop and heat reflector, elliptical secondary and diagonal flats. The primary mirror is made of Zerodur from Schott and figured to a final residual error of 16 nm rms by Steward Observatory Mirror Lab. The final focal ratio is f/52. The 180 circular opening in the field stop defines the maximal square field-of-view. The working wavelength range will cover 0.4 to 1.7 ?m in the Coud´e Lab two floors beneath the telescope, and all wavelengths including far infrared at the Nasmyth focus on an optical bench attached to the side of the telescope structure. First-light scientific observations have been attained at the Nasmyth focus and in the Coud´e Lab. This paper presents a detailed description of installation and alignment of the NST. First-light observational results are also shown to demonstrate the validity of the NST optical alignment.

Cao, Wenda; Gorceix, Nicolas; Coulter, Roy; Coulter, Aaron; Goode, Philip R.

2010-07-01

77

The solar polar radio telescope mission: an overview  

NASA Astrophysics Data System (ADS)

: The solar polar orbit telescope (SPORT) is a mission proposed for the observation of ICMEs. The main payload is a synthetic aperture radiometer working at meter wave band taking images of the high density interplanetary plasma clouds formed by ICMEs and follows the propagation if it from the surface of the Sun all the way to as far as 0.5 AU or even further. With such a capability of observation, also the SPORT will study transient high energy phenomenon, the magnetic topology, temperature and density as well as velocity of the solar wind in the inner interplanetary heliosphere. In the practical part, the mission is also very useful for space weather forecast in advance of the geo-storm events. Other instruments are also selected to be on board of the solar polar orbit mission for in-situ measurement, such as fluxgate magnetometer, solar wind ion detector and high energy particle detectors. In this paper, we describe the scientific objective, basic principles and feasibility of the interferometric radiometer, general mission design and the status of the SPORT mission.

Sun, Weiying; Zhang, Cheng; Zheng, Jianhua; Wu, Ji; Wang, C. B.; Wang, Chi; Wang, S.

78

Observation System of Solar Flare Telescope  

NASA Astrophysics Data System (ADS)

SOFT(Solar Flare Telescope) installed at BOAO(Bohyunsan Optical Astronomy Observatory) is purposed for observing solar active regions using four refractors on a single mount with a 400" x 300" field of view: Two refractors with a diameter of 15cm(f15) observe the white light and H?, and the other two refractors with a diameter of 20cm(f8) observe the magnetic field distribution and Doppler shifts at the solar chromosphere. Three Lyot filters, one of the most important observational instruments, are installed on the optical rails for VMG, LMG, and H? that possible to very narrow pass band observation under high precision stability of temperature. From the combination of KD*P and quarter wave plate in the Lyot filter possible observe the magnetic fields strength and doppler shifts by using the characteristics of polarization components. In this paper, we introduce the basic characteristics, optical system, and monitor system of the SOFT.

Park, Young Deuk; Moon, Yong-Jae; Jang, Be-Ho; Sim, Kyung Jin

1997-12-01

79

Mechanical design of the solar telescope GREGOR  

NASA Astrophysics Data System (ADS)

The mechanical structure of the GREGOR telescope was installed at the Observatorio del Teide, Tenerife, in 2004. New concepts for mounting and cooling of the 1.5-meter primary mirror were introduced. GREGOR is an open telescope, therefore the dome is completely open during observations to allow for air flushing through the open, but stiff telescope structure. Backside cooling system of the primary mirror keeps the mirror surface close to ambient temperature to prevent mirror seeing. The large collecting area of the primary mirror results in high energy density at the field stop at the prime focus of the primary which needs to be removed. The optical elements are supported by precision alignment systems and should provide a stable solar image at the optical lab. The coudé train can be evacuated and serves as a natural barrier between the outer environmental conditions and the air-conditioned optical laboratory with its sensitive scientific instrumentation. The telescope was successfully commissioned and will start its nominal operation during 2013.

Volkmer, R.; Eisenträger, P.; Emde, P.; Fischer, A.; von der Lühe, O.; Nicklas, H.; Soltau, D.; Schmidt, W.; Weis, U.

2012-11-01

80

Beam Patterns of the Five-hundred-metre Aperture Spherical Telescope  

NASA Astrophysics Data System (ADS)

The Five-hundred-metre Aperture Spherical Telescope (FAST) is being constructed in China. With an illuminated aperture of 300-m diameter, it will be the most sensitive single-dish radio telescope in the world. We calculate the beam patterns, gains, and efficiencies of the FAST at 200 MHz, 1.4 GHz, and 3 GHz. A program is developed to calculate the structural parameters and construct the FAST models. The three-dimensional beam patterns are calculated by utilising the shooting and bouncing ray method. We show that, with a coaxial horn feed, the FAST has a beam pattern of high gain and reasonably low first sidelobe over the frequency range of 200 MHz to 3 GHz. Compared with an ideal 300-m parabolic reflector, the un-illuminated spherical part of the FAST would make the power level near both sides of the main beam rise by at least 20 dB and the efficiency tends to decrease at high frequencies. At a zenith angle of 0°, its efficiencies at 200 MHz, 1.4 GHz, and 3 GHz are 71.72%, 66.94%, and 57.55%, respectively. We conclude that the FAST is an excellent telescope at low frequencies. At high frequencies, the triangular spherical panels and the gaps between panels are important factors that affect the performance of the FAST.

Dong, B.; Han, J. L.

2013-04-01

81

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

NASA Astrophysics Data System (ADS)

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 various sites are used in the calculations. Modal phase correction is considered to large aperture ground-based telescope with multi-guide stars. Wave aberrations presented in the in terms of Zernike polynomials are used to calculate the angular correlation of modal components of phase fluctuations of optical radiation propagating in the turbulent atmosphere. The size of the isoplanatic area in an adaptive optical system is studied. The influence of the model of vertical profile of the structure parameter of atmospheric refractive index fluctuations, the outer scale of atmospheric turbulence, and the size of receiving aperture of a telescopic system are analyzed. Requirements on bandwidth of adaptive optical system for effective correction are formulated.

Bolbasova, Lidia A.; Lukin, Vladimir P.

2009-09-01

82

Dynamic Aperture-based Solar Loop Segmentation  

NASA Technical Reports Server (NTRS)

A new method to automatically segment arc-like loop structures from intensity images of the Sun's corona is introduced. The method constructively segments credible loop structures by exploiting the Gaussian-like shape of loop cross-sectional intensity profiles. The experimental results show that the method reasonably segments most of the well-defined loops in coronal images. The method is only the second published automated solar loop segmentation method. Its advantage over the other published method is that it operates independently of supplemental time specific data.

Lee, Jon Kwan; Newman, Timothy S.; Gary, G. Allen

2006-01-01

83

Beam Patterns of the Five-hundred-metre Aperture Spherical Telescope: Optimisation  

NASA Astrophysics Data System (ADS)

The Five-hundred-metre Aperture Spherical Telescope (FAST) uses adaptive spherical panels to achieve a huge collecting area for radio waves. In this paper, we try to explore the optimal parameters for the curvature radius of spherical panels and the focal distance by comparison of the calculated beam patterns. We show that to get the best beam shape and maximum gain, the optimal curvature radius of panels is around 300 m, and a small shift in the focal distance of a few cm is needed. The aperture efficiency can be improved by ~10% at 3 GHz by this small shift. We also try to optimise the panel positioning for the best beam, and find that panel shifts of a few mm can improve the beam pattern by a similar extent. Our results indicate that accurate control of the feed and panel positions to the mm level is very crucial for the stability of FAST's observational performance.

Dong, B.; Han, J. L.

2013-07-01

84

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

85

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

86

The Five-hundred-meter Aperture Spherical radio Telescope project and its early science opportunities  

NASA Astrophysics Data System (ADS)

The National Astronomical Observatories, Chinese Academy of Science (NAOC), has started building the largest antenna in the world. Known as FAST, the Five-hundred-meter Aperture Spherical radio Telescope is a Chinese mega-science project funded by the National Development and Reform Commission (NDRC). FAST also represents part of Chinese contribution to the international efforts to build the square kilometer array (SKA). Upon its finishing around September of 2016, FAST will be the most sensitive single-dish radio telescope in the low frequency radio bands between 70 MHz and 3 GHz. The design specifications of FAST, its expected capabilities, and its main scientific aspirations were described in an overview paper by Nan et al. (2011). In this paper, we briefly review the design and the key science goals of FAST, speculate the likely limitations at the initial stages of FAST operation, and discuss the opportunities for astronomical discoveries in the so-called early science phase.

Li, Di; Nan, Rendong; Pan, Zhichen

2013-03-01

87

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

88

Optical design and testing of a fast, large aperture, infrared space telescope  

NASA Technical Reports Server (NTRS)

An optical design study for a next generation infrared space telescope has been performed. The concept is that of a passively cooled telescope of minimum aperture 2.5 m with an F/1.2 primary and wavelength coverage from 2 to as least 40 microns, and possibly to 100 microns. Compactness, low thermal emission from the optics and structure, diffraction limited imaging at 2 microns, and sensitivity to misalignment aberrations and manufacturing errors were the main considerations for this study. Ray tracing results are presented showing the characteristics of the various designs considered. A preliminary investigation of stray light properties is also given. Special emphasis has been placed on the testing of such a fast primary, and optical systems using a lateral shearing interferometer are described for testing both the primary and the primary/secondary combination.

Humphries, C. M.; Nevo, Y.; Ettedgui-Atad, E.; Harris, J. W.

1992-01-01

89

A large-aperture space telescope for infrared and submillimeter astronomy  

NASA Technical Reports Server (NTRS)

The Large Aperture Telescope (LAT), which will have a diameter of 10-30 m and will operate in the 2-1000 micron wavelength range, is described. It is noted that the LAT could be carried into orbit with a single launch of the Space Transportation System and semiautomatically deployed as a free flyer with a nominal 10-yr mission duration. Servicing and instrument changes would be made at 2-yr intervals. It is pointed out that the LAT would have to be placed above the earth's atmosphere to avoid both the absorption that occurs through much of the infrared and submillimeter and the turbulence which limits spatial resolution. Important technical considerations for the LAT are discussed; they include the telescope optical form, the primary mirror material, figure control techniques, the deployment techniques, and thermal control. The science objectives and rationale for the LAT are discussed and various hardware techniques and concepts for its implementation are described.

Murphy, J. P.; Kiya, M. K.; Werner, M.; Swanson, P. N.; Kuiper, T. B. H.; Batelaan, P. D.

1980-01-01

90

SAINT, Small Aperture Imaging Network Telescope for studying variability of cosmic objects  

NASA Astrophysics Data System (ADS)

We present a project of a multi-channel wide-field instrument, Small Aperture Imaging Network Telescope (SAINT), consisting of a number of 20--40-cm objectives with independent pointings, whose performance in narrow-field mode is comparable to one of a 4-meter-class telescope. Such an instrument, however, provides a great possibility of detecting and observing the fast variable targets, stable and moving, in various modes - photometric, polarimetric, spectroscopic - simultaneously, as well as to solve a wide-field monitoring tasks. Also, its advantages include much simpler construction, optics and maintenance than the ones required for a larger, monolithic design of the same performance, and, due to much smaller weight and size of each channel, a very fast repointing time of the whole system, which is critical for follow-up observations of detected explosive transient events.

Beskin, G.; Bondar, S.; Karpov, S.; Perkov, A.; Greco, G.; Sasyuk, V.

91

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

92

Lightweight ZERODUR®: A Candidate Material for Affordable Future UVOIR Space Telescopes of All Apertures  

NASA Astrophysics Data System (ADS)

Recent Developments now make available for spaceborne applications highly lightweighted mirrors in ZERODUR®, regarded to be the “gold standard” material for thermal stability. ZERODUR® has flown on over 30 missions, including two great observatories, but not previously to this high degree of lightweighting. Now highly lightweighted mirror substrates can be made from a single billet of low expansion glass which exhibits remarkably low thermal expansion, anisotropy and inhomogeneity. This staility has the potential to simplify every aspect of a mission payload cost. A 1.2m open-back isogrid lightweighted mirror substrate has been made by SCHOTT exhibiting 88% lightweighting and a first Eigenfrequency over 200Hz. Also a recently made 0.3m isogrid lightweighted mirror exhibits ribs thinner than 0.9mm. Mirror or mirror segment substrates can be cost-effectively manufactured from monolithic blanks in apertures as small as 0.3m aperture to over 4m aperture (until recently SCHOTT maintained a line to make 8m ZERODUR® billets). We will describe this technology, the attributes of isogrid lightweighted mirror blanks, and the relevance of this material and manufacturing approach to upcoming UVOIR missions from suborbital to Explorer class to next generation Great Observatory. Lightweight ZERODUR® supports optical telescope systems requiring great stability, even in the presence of payload and scene thermal perturbations. Furthermore, mirrors or mirror segments made with the approach described can be made to remarkably short schedule, cost effectively and with little risk.

Hull, Anthony B.; Westerhoff, T.; Leys, A.

2014-01-01

93

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

94

Aperture Shield Materials Characterized and Selected for Solar Dynamic Space Power System  

NASA Technical Reports Server (NTRS)

The aperture shield in a solar dynamic space power system is necessary to prevent thermal damage to the heat receiver should the concentrated solar radiation be accidentally or intentionally focused outside of the heat receiver aperture opening and onto the aperture shield itself. Characterization of the optical and thermal properties of candidate aperture shield materials was needed to support the joint U.S./Russian solar dynamic space power effort for Mir. The specific objective of testing performed at the NASA Lewis Research Center was to identify a high-temperature material with a low specular reflectance, a low solar absorptance, and a high spectral emittance so that during an off-pointing event, the amount of solar energy reflecting off the aperture shield would be small, the ratio of solar absorptance to spectral emittance would provide the lowest possible equilibrium temperature, and the integrity of the aperture shield would remain intact.

1995-01-01

95

Image stabilization system on SOLAR-B Solar Optical Telescope  

NASA Astrophysics Data System (ADS)

Extremely stable pointing of the telescope is required for images on the CCD cameras to accurately measure the nature of magnetic field on the sun. An image stabilization system is installed to the Solar Optical Telescope onboard SOLAR-B, which stabilizes images on the focal plane CCD detectors in the frequency range lower than about 20Hz. The system consists of a correlation tracker and a piezo-based tip-tilt mirror with servo control electronics. The correlation tracker is a high speed CCD camera with a correlation algorithm on the flight computer, producing a pointing error from series of solar granule images. Servo control electronics drives three piezo actuators in the tip-tilt mirror. A unique function in the servo control electronics can put sine wave form signals in the servo loop, allowing us to diagnose the transfer function of the servo loop even on orbit. The image stabilization system has been jointly developed by collaboration of National Astronomical Observatory of Japan/Mitsubishi Electronic Corp. and Lockheed Martin Advanced Technology Center Solar and Astrophysics Laboratory. Flight model was fabricated in summer 2003, and we measured the system performance of the flight model on a laboratory environment in September 2003, confirming that the servo stability within 0-20 Hz bandwidth is 0.001-0.002 arcsec rms level on the sun.

Shimizu, Toshifumi; Nagata, Shin'ichi; Edwards, Chris; Tarbell, Theodore; Kashiwagi, Yasuhiro; Kodeki, Kazuhide; Ito, Osamu; Miyagawa, Hiroyuki; Nagase, Masayuki; Inoue, Syunsaku; Kaneko, Kazumasa; Sakamoto, Yasushi; Ichimoto, Kiyoshi; Tsuneta, Saku; Miki, Shiro; Endo, Makoto; Tabata, Masaki; Nakaoji, Toshitaka; Matsuzaki, Keiichi; Kobayashi, Ken; Otsubo, Masashi; Suematsu, Yoshinori; Kumagai, Kazuyoshi; Noguchi, Motokazu; Tamura, Tomonori; Nakagiri, Masao

2004-10-01

96

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

97

GREGOR solar telescope: Design and status  

NASA Astrophysics Data System (ADS)

The integration and verification phase of the GREGOR telescope reached an important milestone with the installation of the interim 1 m SolarLite primary mirror. This was the first time that the entire light path had seen sunlight. Since then extensive testing of the telescope and its subsystems has been carried out. The integration and verification phase will culminate with the delivery and installation of the final 1.5 m Zerodur primary mirror in the summer of 2010. Observatory level tests and science verification will commence in the second half of 2010 and in 2011. This phase includes testing of the main optics, adaptive optics, cooling and pointing systems. In addition, assuming the viewpoint of a typical user, various observational modes of the GREGOR Fabry-Pérot Interferometer (GFPI), the Grating Infrared Spectrograph (GRIS), and high-speed camera systems will be tested to evaluate if they match the expectations and science requirements. This ensures that GREGOR will provide high-quality observations with its combination of (multi-conjugate) adaptive optics and advanced post-focus instruments. Routine observations are expected for 2012.

Volkmer, R.; von der Lühe, O.; Denker, C.; Solanki, S. K.; Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Klva?a, M.; Kneer, F.; Lagg, A.; Popow, E.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier, K. G.

2010-06-01

98

THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2006: CALIBRATION AND FLIGHT PERFORMANCE  

SciTech Connect

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 250 hr flight over Antarctica in 2006 December (BLAST06). As part of the calibration and pointing procedures, the red hypergiant star VY CMa was observed and used as the primary calibrator. Details of the overall BLAST06 calibration procedure are discussed. The 1sigma uncertainty on the absolute calibration is accurate to 9.5%, 8.7%, and 9.2% at the 250, 350, and 500 mum bands, respectively. The errors are highly correlated between bands resulting in much lower errors for the derived shape of the 250-500 mum continuum. The overall pointing error is < 5'' rms for the 36'', 42'', and 60'' beams. The performance of optics and pointing systems is discussed.

Truch, Matthew D. P.; Devlin, Mark J.; Dicker, Simon R.; Klein, Jeff [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States); Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Mauskopf, Philip; Moncelsi, Lorenzo; Pascale, Enzo [Department of Physics and Astronomy, Cardiff University, 5 The Parade, Cardiff, CF24 3AA (United Kingdom); Bock, James J. [Jet Propulsion Laboratory, Pasadena, CA 91109-8099 (United States); Chapin, Edward L.; Halpern, Mark; Marsden, Gaelen [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Gundersen, Joshua O. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Hughes, David H. [Instituto Nacional de AstrofIsica Optica y Electronica (INAOE), Aptdo. Postal 51 y 72000 Puebla (Mexico); Martin, Peter G. [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Netterfield, C. Barth [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Olmi, Luca [Physics Department, University of Puerto Rico, Rio Piedras Campus, Box 23343, UPR Station, San Juan (Puerto Rico); Patanchon, Guillaume, E-mail: matthew@truch.ne [Universite Paris Diderot, Laboratoire APC, 10 rue Alice Domon et Leonie Duquet 75205 Paris (France)

2009-12-20

99

Advanced Technology Large-Aperture Space Telescope: Science Drivers and Technology Developments  

NASA Technical Reports Server (NTRS)

The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8- to 16-m ultraviolet optical near Infrared space observatory for launch in the 2025 to 2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including: Is there life elsewhere in the Galaxy? We present a range of science drivers and the resulting performance requirements for ATLAST (8- to 16-marcsec angular resolution, diffraction limited imaging at 0.5 micron wavelength, minimum collecting area of 45 sq m, high sensitivity to light wavelengths from 0.1 to 2.4 micron, high stability in wavefront sensing and control). We also discuss the priorities for technology development needed to enable the construction of ATLAST for a cost that is comparable to that of current generation observatory-class space missions.

Postman, Marc; Brown, Tom; Sembach, Kenneth; Glavallsco, Mauro; Traub, Wesley; Stapelfeldt, Karl; Calzetti, Daniela; Oegerle, William; Rich, R. Michael; Stahl, H. Phillip; Tumlinson, Jason; Mountain, Matt; Soummer, Remi; Hyde, Tupper

2012-01-01

100

The New Solar Telescope in Big Bear: Polarimetry I  

NASA Astrophysics Data System (ADS)

We present here the near-term polarimetry plans for the 1.6 m clear aperture, off-axis telescope in Big Bear. The first scientific data were taken in the Summer of 2009 at the Nasmyth focus, and first observations corrected by adaptive optics were taken in the Summer of 2010. The first polarimetry for this telescope will be done in the near infrared at 1.56 ?m, which is close to the photospheric opacity minimum. We show and explain reasons for the general layout of the polarimetric hardware for the telescope.

Goode, P. R.; Cao, W.; Ahn, K.; Gorceix, N.; Coulter, R.

2011-04-01

101

Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope  

SciTech Connect

A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.

Early, J T

2002-02-13

102

New vacuum solar telescope and observations with high resolution  

NASA Astrophysics Data System (ADS)

The New Vacuum Solar Telescope (NVST) is a one meter vacuum solar telescope that aims to observe fine structures on the Sun. The main goals of NVST are high resolution imaging and spectral observations, including measurements of the solar magnetic field. NVST is the primary ground-based facility used by the Chinese solar research community in this solar cycle. It is located by Fuxian Lake in southwest China, where the seeing is good enough to perform high resolution observations. We first introduce the general conditions at the Fuxian Solar Observatory and the primary science cases of NVST. Then, the basic structures of this telescope and instruments are described in detail. Finally, some typical high resolution data of the solar photosphere and chromosphere are also shown.

Liu, Zhong; Xu, Jun; Gu, Bo-Zhong; Wang, Sen; You, Jian-Qi; Shen, Long-Xiang; Lu, Ru-Wei; Jin, Zhen-Yu; Chen, Lin-Fei; Lou, Ke; Li, Zhi; Liu, Guang-Qian; Xu, Zhi; Rao, Chang-Hui; Hu, Qi-Qian; Li, Ru-Feng; Fu, Hao-Wen; Wang, Feng; Bao, Men-Xian; Wu, Ming-Chan; Zhang, Bo-Rong

2014-06-01

103

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

104

New solar telescope in Big Bear: evidence for super-diffusivity and small-scale solar dynamos?  

NASA Astrophysics Data System (ADS)

The 1.6 m clear aperture New Solar Telescope (NST) in Big Bear Solar Observatory (BBSO) is now providing the highest resolution solar data ever. These data have revealed surprises about the Sun on small-scales including the observation that bright points (BPs), which can be used as proxies for the intense, compact magnetic elements that are apparent in photospheric intergranular lanes. The BPs are ever more numerous on ever smaller spatial scales as though there were no limit to how small the BPs can be. Here we discuss high resolution NST data on BPs that provide support for the ideas that a turbulent regime of super-diffusivity dominates in the quiet Sun, and there are local dynamos operating near the solar surface.

Goode, Philip R.; Abramenko, Valentyna; Yurchyshyn, Vasyl

2012-07-01

105

Progress and development status of the Space Telescope solar array  

NASA Astrophysics Data System (ADS)

The development status of the Space Telescope solar array flexible solar cell blanket deployment mechanism, primary deployment mechanism and array orientation subsystems are reviewed. The array has a life time requirement of 5 yr. Design features include the ability to be operated manually in space and replaced as a complete unit in-orbit. Since the Space Telescope itself is too large to test in a conventional, satellite manner, thermal and dynamic analyses were used to prove the design. The deployed array inertia of 700 kg/sqm per wing and the extreme pointing accuracy requirement of the Space Telescope require an extremely sophisticated array orientation subsystem.

Fox, R. H. W.

1982-06-01

106

Initial Results of Aperture Area Comparisons for Exo-Atmospheric Total Solar Irradiance Measurements  

NASA Technical Reports Server (NTRS)

In the measurement of exo-atmospheric total solar irradiance (TSI), instrument aperture area is a critical component in converting solar radiant flux to irradiance. In a May 2000 calibration workshop for the Total Irradiance Monitor (TIM) on the Earth Observing System (EOS) Solar Radiation and Climate Experiment (SORCE), the solar irradiance measurement community recommended that NASA and NISI coordinate an aperture area measurement comparison to quantify and validate aperture area uncertainties and their overall effect on TSI uncertainties. From May 2003 to February 2006, apertures from 4 institutions with links to the historical TSI database were measured by NIST and the results were compared to the aperture area determined by each institution. The initial results of these comparisons are presented and preliminary assessments of the participants' uncertainties are discussed.

Johnson, B. Carol; Litorja, Maritoni; Fowler, Joel B.; Butler, James J.

2009-01-01

107

Update on the 18m aperture multi-mirror telescope concept  

NASA Astrophysics Data System (ADS)

Progress is reported on the development of the finite element programs and models which permit the stresses and deflections of complex refractive elements, and of honeycomb and homogeneous primary mirrors of the 18 m aperture multimirror telescope to be determined. The axisymmetric finite element models for calculating stresses and deflections within the material of a 7.5 m primary mirror and for determining initial radial positions and forces required for the axial supports are discussed. The large three-dimensional finite element models used in an analysis to determine the deflections of the front element of the 4.2 m William Herschel prime focus corrector are briefly described and the analytical results are given. The analysis of a borosilicate honeycomb mirror is described, and results on local deflections within the honeycomb structure are presented. Proposals for the design of the support system of a 7.5 m primary mirror are described along with the development of a finite element model for computing the structural and thermal deflections.

Mack, B.; Harman, D. J.

108

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

109

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

110

8 Meter Advanced Technology Large-Aperture Space Telescope (ATLAST-8m)  

NASA Technical Reports Server (NTRS)

ATLAST-8m (Advanced Technology Large Aperture Space Telescope) is a proposed 8-meter monolithic UV/optical/NIR space observatory (wavelength range 110 to 2500 nm) to be placed in orbit at Sun-Earth L2 by NASA's planned Ares V heavy lift vehicle. Given its very high angular resolution (15 mas @ 500 nm), sensitivity and performance stability, ATLAST-8m is capable of achieving breakthroughs in a broad range of astrophysics including: Is there life elsewhere in the Galaxy? An 8-meter UVOIR observatory has the performance required to detect habitability (H2O, atmospheric column density) and biosignatures (O2, O3, CH4) in terrestrial exoplanet atmospheres, to reveal the underlying physics that drives star formation, and to trace the complex interactions between dark matter, galaxies, and intergalactic medium. The ATLAST Astrophysics Strategic Mission Concept Study developed a detailed point design for an 8-m monolithic observatory including optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; mass and power budgets; and system cost. The results of which were submitted by invitation to NRC's 2010 Astronomy & Astrophysics Decadal Survey.

Stahl, H. Philip

2010-01-01

111

Be Star Monitoring Using a Small Aperture Telescope and Fiber-fed Spectrograph  

NASA Astrophysics Data System (ADS)

Initial results are reported from a Be star monitoring project developed for undergraduate student research involvement at a small undergraduate university using a small aperture telescope and a custom-built fiber-fed spectrograph. Beginning in 2003 June, 0.8 Angstrom/pixel resolution spectra of the H-alpha line for over forty Be stars (Omi Aqr, 4 Aql, V923 Aql, V1294 Aql, Nu 2 Boo, 24 CVn, Gamma Cas, 4 CrB, Beta Cyg, 11 Cyg, 28 Cyg, 55 Cyg, 59 Cyg, 66 Cyg, V2136 Cyg, 1 Del, CX Dra, Omi Her, Sigma Her, 4 Her, 11 Her, 88 Her, 48 Lib, Chi Oph, Zeta Oph, 51 Oph, 66 Oph, Eta PsA, V4024 Sgr, 64 Ser, Delta Sco, QR Vul, 12 Vul, 20 Vul, 25 Vul, HD142184, HD165174, HD169033, HD170235, HD174179, HD181615, HD184279, HD195554, HD201733) have been obtained. H-alpha line profile velocities and evolution are shown. Funding has been provided by the UCA University Research Council and the Arkansas Space Grant Consortium.

Austin, S. J.

2003-12-01

112

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

113

The New Solar Telescope in Big Bear: Polarimetry II  

Microsoft Academic Search

IRIM (Infrared Imaging Magnetograph) is one of the first imaging solar spectro-polarimeters working in the near infrared (NIR). IRIM is being installed and commissioned in the Coudé Lab of the 1.6-meter New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO). This innovative system, which includes a 2.5 nm interference filter, a unique 0.25 nm birefringent Lyot filter, and a

W. Cao; K. Ahn; P. R. Goode; S. Shumko; N. Gorceix; R. Coulter

2011-01-01

114

Spillage and flux density on a receiver aperture lip. [of solar thermal collector  

NASA Technical Reports Server (NTRS)

In a dish-type point-focusing solar thermal collector, the spillage and the flux density on the receiver aperture lip are related in a very simple way, if the aperture is circular and centered on the optical axis. Specifically, the flux density on the lip is equal to the spillage times the peak flux density in the plane of the lip.

Jaffe, L. D.

1985-01-01

115

The National Large Solar Telescope (NLST) of India  

NASA Astrophysics Data System (ADS)

The Indian National Large Solar Telescope (NLST) will be a state-of-the-art 2-m class telescope for carrying out high-resolution studies in the solar atmosphere. Recent numerical simulations suggest that crucial physical processes like vortex flow, dissipation of magnetic fields and the generation of MHD waves can occur efficiently over length scales of tens of kilometers. Current telescopes are unable to resolve solar feature to this level at visible wavelengths. NLST will not only achieve good spatial resolution, but will also have a high photon throughput in order to carry out spectropolarimetric observations to accurately measure vector magnetic fields in the solar atmosphere with a good signal to noise ratio. The main science goals of NLST include: a) Magnetic field generation and the solar cycle; b) Dynamics of magnetized regions; c) Helioseismology; d) Long term variability; e) Energetic phenomena and Activity; and f) Night time astronomy. The optical design of the telescope is optimized for high optical throughput and uses a minimum number of optical elements. A high order adaptive optics system is integrated as part of the design that works with a modest Fried's 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. NLST will also be used for carrying out stellar observations during the night. The mechanical design of the telescope, building, and the innovative dome takes advantage of the natural air flush which will help to keep the open telescope in temperature equilibrium. Critical to the successful implementation of NLST is the selection of a site with optimum atmospheric properties, such as the number of sunshine hours and good "seeing" over long periods. A site characterization programme carried over several years has established the existence of suitable sites in the Ladakh region. After its completion, currently planned for 2016, NLST will fill a gap in longitude between the major solar facilities in the world and will be for some years the largest solar telescope in the world.

Hasan, S. S.

2012-12-01

116

Statistical Distribution of Size and Lifetime of Bright Points Observed with the New Solar Telescope  

NASA Astrophysics Data System (ADS)

We present results of 2 hr non-interrupted observations of solar granulation obtained under excellent seeing conditions with the largest aperture ground-based solar telescope—the New Solar Telescope (NST)—of Big Bear Solar Observatory. Observations were performed with adaptive optics correction using a broadband TiO filter in the 705.7 nm spectral line with a time cadence of 10 s and a pixel size of 0farcs0375. Photospheric bright points (BPs) were detected and tracked. We find that the BPs detected in NST images are cospatial with those visible in Hinode/SOT G-band images. In cases where Hinode/SOT detects one large BP, NST detects several separated BPs. Extended filigree features are clearly fragmented into separate BPs in NST images. The distribution function of BP sizes extends to the diffraction limit of NST (77 km) without saturation and corresponds to a log-normal distribution. The lifetime distribution function follows a log-normal approximation for all BPs with lifetime exceeding 100 s. A majority of BPs are transient events reflecting the strong dynamics of the quiet Sun: 98.6% of BPs live less than 120 s. The longest registered lifetime was 44 minutes. The size and maximum intensity of BPs were found to be proportional to their lifetimes.

Abramenko, Valentyna; Yurchyshyn, Vasyl; Goode, Philip; Kilcik, Ali

2010-12-01

117

Prototype Spectro-Polarimeter for the India's National Large Solar Telescope  

NASA Astrophysics Data System (ADS)

India's National Large Solar Telescope (NLST) of two meter aperture size is proposed to be set up in Ladakh region of Himalayas at a height of around 4300 meters. A high resolution spectrograph along with a polarimeter is planned as one of the backend instruments for NLST. Prototype development of the NLST Spectro-Polarimeter (SP) is proposed to be designed and developed for usage at the back focal plane of the Multi-Application Solar Telescope (MAST) recently installed at the Udaipur Solar Observatory. Design of the prototype SP is discussed in detail along with the scientific goals. The SP is designed to be operated in three wavelengths to observe photospheric and chromospheric layers of the solar atmosphere simultaneously. Vector magnetic fields will be calculated in these layers. High resolution of the designed SP will provide accurate estimates of velocities. Highly resolved polarized line profiles will allow us to obtain the height variation of vector magnetic fields when used along with suitable inversion codes (like SPINOR or SIR).

Elayavalli Rangarajan, Komandur; Sankarasubramanian, Kasiviswanathan; Srivastava, Nandita; Venkatakrishnan, Parameswaran; Mathew, Shibu; Bayanna, Raja; Hasan, Sirajul; Prabhu, Kesavan

2013-04-01

118

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

119

G-133: A soft x ray solar telescope  

NASA Technical Reports Server (NTRS)

The GOLDHELOX Project, NASA payload number G-133, is a robotic soft x ray solar telescope designed and built by an organization of undergraduate students. The telescope is designed to observe the sun at a wavelength of 171 to 181 A. Since we require observations free from atmospheric interference, the telescope will be launched in a NASA Get-Away-Special (GAS) canister with a Motorized Door Assembly (MDA). In this paper we primarily discuss the most important elements of the telescope itself. We also elaborate on some of the technical difficulties associated with doing good science in space on a small budget (about $100,000) and mention ways in which controlling the instrument environment has reduced the complexity of the system and thus saved us money.

Williams, Memorie K.; Campbell, Branton; Roming, Peter W. A.; Spute, Mark K.; Moody, J. Ward

1992-01-01

120

G-133: A soft X ray solar telescope  

NASA Astrophysics Data System (ADS)

The GOLDHELOX Project, NASA payload number G-133, is a robotic soft x ray solar telescope designed and built by an organization of undergraduate students. The telescope is designed to observe the sun at a wavelength of 171 to 181 A. Since we require observations free from atmospheric interference, the telescope will be launched in a NASA Get-Away-Special (GAS) canister with a Motorized Door Assembly (MDA). In this paper we primarily discuss the most important elements of the telescope itself. We also elaborate on some of the technical difficulties associated with doing good science in space on a small budget (about $100,000) and mention ways in which controlling the instrument environment has reduced the complexity of the system and thus saved us money.

Williams, Memorie K.; Campbell, Branton; Roming, Peter W. A.; Spute, Mark K.; Moody, J. Ward

1992-10-01

121

Latest results and prospects of the CERN Axion Solar Telescope  

Microsoft Academic Search

The CERN Axion Solar Telescope (CAST) experiment searches for axions from the Sun converted into few keV photons via the inverse Primakoff effect in the high magnetic field of a superconducting Large Hadron Collider (LHC) decommissioned test magnet. After results obtained with vacuum in the magnet pipes (phase I of the experiment) as well as with 4He the collaboration is

I. G. Irastorza; S. Aune; K. Barth; A. Belov; S. Borghi; H. Bräuninger; G. Cantatore; J. M. Carmona; S. A. Cetin; J. I. Collar; T. Dafni; M. Davenport; C. Eleftheriadis; N. Elias; C. Ezer; G. Fanourakis; E. Ferrer-Ribas; P. Friedrich; J. Galán; A. Gardikiotis; E. N. Gazis; T. Geralis; I. Giomataris; S. Gninenko; H. Gómez; E. Gruber; T. Guthörl; R. Hartmann; F. Haug; M. D. Hasinoff; D. H. H. Hoffmann; F. J. Iguaz; J. Jacoby; K. Jakovcic; M. Karuza; K. Königsmann; R. Kotthaus; M. Krcmar; M. Kuster; B. Lakic; J. M. Laurent; A. Liolios; A. Ljubicic; V. Lozza; G. Lutz; G. Luzón; J. Morales; T. Niinikoski; A. Nordt; T. Papaevangelou; M. J. Pivovaroff; G. Raffelt; T. Rashba; H. Riege; A. Rodríguez; M. Rosu; J. Ruz; I. Savvidis; P. S. Silva; S. K. Solanki; R. Soufli; L. Stewart; A. Tomás; M. Tsagri; K. van Bibber; T. Vafeiadis; J. Villar; J. K. Vogel; S. C. Yildiz; K. Zioutas

2011-01-01

122

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

123

Investigation of small solar system objects with the space telescope  

NASA Technical Reports Server (NTRS)

The application of the space telescope (ST) to study small objects in the solar system in order to understand the birth and the early evolution of the solar system is discussed. The upper size limit of the small bodies is defined as approximately 5000 km and includes planetary satellites, planetary rings, asteroids, and comets.The use of the astronomical instruments aboard the ST, such as the faint object camera, ultraviolet and infrared spectrometers, and spectrophotometers, to study the small solar system objects is discussed.

Morrison, D.

1979-01-01

124

A large aperture balloon-borne telescope for a submillimeter wavelength survey of the galactic plane  

NASA Technical Reports Server (NTRS)

A balloon-borne, 1.2 meter Cassegrain telescope with a servo-controlled chopping secondary mirror has been developed and used to survey the Galactic Plane at submillimeter wavelengths. The telescope pointing system uses a gyroscope as the primary stabilization reference and makes use of microprocessors for pointing control, on-board data collection, and telemetry formatting. A description of the telescope, multi-channel liquid-helium-cooled focal plane and the aspect and orientation subsystems are presented.

Silverberg, R. F.; Hauser, M. G.; Walser, D. W.; Flanick, A.; Silver, A. D.; Smith, J.; Gezari, D. Y.; Kelsall, T.; Cheung, L. H.; Skillman, T. L., Jr.

1983-01-01

125

Fabrication of and performance studies on a low cost solar cooker having an inclined aperture plane  

Microsoft Academic Search

A low cost box-type solar cooker made of two paper carton boxes with crumpled newspaper balls as insulation has been fabricated with a tilted aperture plane. Comparative tests of this cooker have been conducted against a normal type costlier solar cooker with 1000 ml load of water in each of the cookers. It has been observed that on a sunny

M. Hussain; Sirajul Islam Khan

1996-01-01

126

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

127

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

128

Facility level thermal systems for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The management and control of the local aero-thermal environment is critical for success of the Advanced Technology Solar Telescope (ATST). In addition to minimizing disturbances to local seeing, the facility thermal systems must meet stringent energy efficiency requirements to minimize impact on the surrounding environment and meet federal requirements along with operational budgetary constraints. This paper describes the major facility thermal equipment and systems to be implemented along with associated energy management features. The systems presented include the central plant, the climate control systems for the computer room and coudé laboratory, the carousel cooling system which actively controls the surface temperature of the rotating telescope enclosure, and the systems used for active and passive ventilation of the telescope chamber.

Phelps, LeEllen; Murga, Gaizka; Fraser, Mark; Climent, Tània

2012-09-01

129

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

130

Thermal response of solar receiver aperture plates during sun walk-off  

NASA Technical Reports Server (NTRS)

The tracking mechanism for a point-focusing concentrator may be subject to failure. If this should occur, the solar image will travel across the aperture plate, and it may also impinge on the adjacent support structure. Such an event is called 'sun walk-off'. The present investigation is concerned with the transient response of different aperture plate materials to the intense heating produced in a typical walk-off situation for parabolic dish concentrators. Receivers for two solar module systems are considered, including a high-temperature receiver that utilizes a 2-milliradian (mrad) concentrator, and a lower-temperature receiver which is coupled with a 4-mrad concentrator. It is found that during a walk-off situation the solar image travels in a straight line in the radial direction. The results obtained for a copper aperture plate were disappointing. It appears that passive metallic plates without cooling or other protective support cannot withstand the intense heating.

Wen, L.; Roschke, J.

1982-01-01

131

Thermal characteristics of a classical solar telescope primary mirror  

NASA Astrophysics Data System (ADS)

We present a detailed thermal and structural analysis of a 2 m class solar telescope mirror which is subjected to a varying heat load at an observatory site. A 3-dimensional heat transfer model of the mirror takes into account the heating caused by a smooth and gradual increase of the solar flux during the day-time observations and cooling resulting from the exponentially decaying ambient temperature at night. The thermal and structural response of two competing materials for optical telescopes, namely Silicon Carbide - best known for excellent heat conductivity and Zerodur - preferred for its extremely low coefficient of thermal expansion, is investigated in detail. The insight gained from these simulations will provide a valuable input for devising an efficient and stable thermal control system for the primary mirror.

Banyal, Ravinder K.; Ravindra, B.

2011-08-01

132

High-aperture ratio optical system for observation of telescopic meteors and comets  

Microsoft Academic Search

Use of television equipment and an electrooptical converter in combination with a high-aperture-ratio optical system makes possible a significant increase in the capabilities of the optical method of observing giant meteors and comets. An optical system similar to a Schwarzschild (1905) system was calculated with an aspherical main mirror and a spherical secondary mirror. It is shown that such a

S. Mukhamednazarov; O. G. Ovezgeldyev; G. M. Popov; E. G. Popova

1986-01-01

133

The Advanced Technology Solar Telescope: design and early construction  

NASA Astrophysics Data System (ADS)

The National Solar Observatory’s (NSO) Advanced Technology Solar Telescope (ATST) is the first large U.S. solar telescope accessible to the worldwide solar physics community to be constructed in more than 30 years. The 4-meter diameter facility will operate over a broad wavelength range (0.35 to 28 ?m ), employing adaptive optics systems to achieve diffraction limited imaging and resolve features approximately 20 km on the Sun; the key observational parameters (collecting area, spatial resolution, spectral coverage, polarization accuracy, low scattered light) enable resolution of the theoretically-predicted, fine-scale magnetic features and their dynamics which modulate the radiative output of the sun and drive the release of magnetic energy from the Sun’s atmosphere in the form of flares and coronal mass ejections. In 2010, the ATST received a significant fraction of its funding for construction. In the subsequent two years, the project has hired staff and opened an office on Maui. A number of large industrial contracts have been placed throughout the world to complete the detailed designs and begin constructing the major telescope subsystems. These contracts have included the site development, AandE designs, mirrors, polishing, optic support assemblies, telescope mount and coudé rotator structures, enclosure, thermal and mechanical systems, and high-level software and controls. In addition, design development work on the instrument suite has undergone significant progress; this has included the completion of preliminary design reviews (PDR) for all five facility instruments. Permitting required for physically starting construction on the mountaintop of Haleakal?, Maui has also progressed. This paper will review the ATST goals and specifications, describe each of the major subsystems under construction, and review the contracts and lessons learned during the contracting and early construction phases. Schedules for site construction, key factory testing of major subsystems, and integration, test and commissioning activities will also be discussed.

McMullin, Joseph P.; Rimmele, Thomas R.; Keil, Stephen L.; Warner, Mark; Barden, Samuel; Bulau, Scott; Craig, Simon; Goodrich, Bret; Hansen, Eric; Hegwer, Steve; Hubbard, Robert; McBride, William; Shimko, Steve; Wöger, Friedrich; Ditsler, Jennifer

2012-09-01

134

The Lyman-alpha Imager onboard Solar Polar Orbit Telescope  

NASA Astrophysics Data System (ADS)

Solar Polar ORbit Telescope (SPORT) was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences, which is currently being under background engineering study phase in China. SPORT will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. The Lyman-alpha Imager (LMI) is one of the key remotesensing instruments onboard SPORT with 45arcmin FOV, 2000mm effective focal length and 1.4arcsec/pixel spatial resolution . The size of LMI is ?150×1000mm, and the weight is less than10kg, including the 7kg telescope tube and 3kg electronic box. There are three 121.6nm filters used in the LMI optical path, so the 98% spectral purity image of 121.6nm can be achieved. The 121.6nm solar Lyman-alpha line is produced in the chromosphere and very sensitive to plasma temperature, plasma velocity and magnetism variation in the chromosphere. Solar Lyman-alpha disk image is an ideal tracker for corona magnetism variation.

Li, Baoquan; Li, Haitao; Zhou, Sizhong; Jiang, Bo

2013-12-01

135

Thermal design features of the solar telescope GREGOR  

NASA Astrophysics Data System (ADS)

The optical performance and pointing accuracy of the 1.5 m solar telescope GREGOR depend on the passive and active temperature control design features. Stringent thermal requirements are given in the technical specification for the passive thermal control of telescope structure and the main mirror air cooling system under operational conditions. The telescope structure has to be kept within a range of -0.5K through +0.2K against the ambient temperature. The main mirror temperature has to be kept up to a temperature difference of less than 2K under the ambient temperature with an accuracy of +/-0.1K. The temperature difference across the main mirror surface has to be smaller than +/-0.1K. Another thermal requirement asks for a main mirror safety cover to prevent the wandering of focused sunlight over the telescope structure in case of control system malfunction or power loss. Features of the chosen passive thermal concept for the telescope structure and the active main mirror air cooling system as well as the primary mirror safety cover system are presented together with the finite element analyses results and tests performed in order to find and verify the chosen design.

Emde, Peter; Kühn, Jürgen; Weis, Ulrich; Bornkessel, Thomas

2004-09-01

136

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

137

On the co-alignment of solar telescopes. A new approach to solar pointing  

NASA Astrophysics Data System (ADS)

Helioseismological measurements require long observing times and thus may be adversely affected by lateral image drifts as caused by pointing instabilities. At the Vacuum Tower Telescope VTT, Tenerife we have recorded drift values of up to 5" per hour under unstable thermal conditions (dome opening, strong day-to-day thermal gradients). Typically drifts of 0.5" - 1.0" per hour may be encountered under more favorable conditions. Past experience has shown that most high-resolution solar telescopes may be affected by this problem to some degree. This inherent shortcoming of solar pointing is caused by the fact that the guiding loop can be closed only within the guiding beam but not within the telescope's main beam. We have developed a new approach to this problem. We correlate continuum brightness patterns observed from within the telescope main beam with patterns originating from a full disk telescope. We show that brightness patterns of sufficient size are unique with respect to solar location at any instant of time and may serve as a location identifier. We make use of the fact that averaged location information of solar structures is invariant with respect to telescope resolution. We have carried out tests at the VTT together with SDO. We have used SDO as a full disk reference. We were able to reduce lateral image drifts by an order of magnitude.

Staiger, J.

2013-06-01

138

Solar Adaptive Optics System for 1-m New Vacuum Solar Telescope  

NASA Astrophysics Data System (ADS)

The 1-m New Vacuum Solar Telescope (NVST), located at Full-shine Lake Solar Observatory, Kunming, Yunnan, is the largest solar telescope in China recently. A 37-elemnt low-order solar adaptive optics (AO) system had been developed and installed on the telescope in 2011, and AO-corrected high resolution solar images were obtained at wavelength 430.5nm, 705.7nm and 1555nm simultaneously. The low-order AO system can yield diffraction limited images only in the near infrared under good seeing and in the visible under excellent seeing, which cannot satisfy the requirement of Solar Physics study. A high-order 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 127-element deformable mirror, a correlating Shack-Hartmann wavefront sensor and a real-time controller, is under development. A multi-conjugate adaptive optics (MCAO) experiments are also carried on the telescope. This paper summarizes the progress of the solar adaptive optics in China and presents the observational results of the low-order AO system. The design of the high-order AO system and MCAO experimental prototype are given.

Rao, Changhui; Zhu, Lei; Gu, Naiting; Rao, Xuejun; Zhang, Lanqiang

2013-12-01

139

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

NASA Technical Reports Server (NTRS)

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 Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near equilibrium temperature of 2072 K was achieved. The aperture shield sustained no visible damage as a result of the exposures. This paper describes the aperture shield thermal-vacuum qualification test program including the test article, test facility, procedures, data collection, test success criteria, results and conclusions.

Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.

1997-01-01

140

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

NASA Astrophysics Data System (ADS)

A 10-cm aperture telescope equipped with coronagraphic capabilities, using occulting masks of various size and material, has 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 and recent findings about the extraordinarily long tails of sodium gas discovered in the lunar and hermean exospheres. Spatial and temporal variability patterns captured in such images can be used to study changes in surface sputtering processes and radiation pressure acceleration effects in the inner solar system.

Baumgardner, Jeffrey; Mendillo, Michael

2009-09-01

141

The soft x ray telescope for Solar-A  

NASA Technical Reports Server (NTRS)

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 will be in September 1991. Earlier resolution and efficiency tests on the grazing incidence mirror have established its performance in soft x rays. The one-piece, two mirror grazing incidence telescope is supported in a strain free mount separated from the focal plane assembly by a carbon-epoxy metering tube whose windings and filler are chosen to minimize thermal and hygroscopic effects. The CCD detector images both the x ray and the concentric visible light aspect telescope. Optical filters provide images at 4308 and 4700 A. The SXT will be capable of producing over 8000 of the smallest partial frame images per day, or fewer but larger images, up to 1024 x 1024 pixel images. Image sequence with two or more of the five x ray analysis filters, with automatic exposure compensation to optimize the charge collection by the CCD detector, will be used to provide plasma diagnostics. Calculations using a differential emission measure code were used to optimize filter selection over the range of emission measure variations and to avoid redundancy, but the filters were chosen primarily to give ratios that are monotonic in plasma temperature.

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

1989-01-01

142

Electric hardware system design for the Space Solar Telescope  

NASA Astrophysics Data System (ADS)

The Space Solar Telescope (SST) is being researched, developed and manufactured by National Astronomical Observatories, Chinese Academy of Sciences (NAOC) in China. It is designed for further solar physics research. There are five payloads with different observation modes on SST, including a Main Optical Telescope (MOT) with 1-meter diameter. Two of five payloads have simple and one-dimension data format, while the others are CCD imaging telescopes. There are 16 CCDs with different resolutions on SST. The total data amount is about 50GB per day. So, onboard electric hardware system is very complex. The whole system is divided into three levels. The top level is for the spacecraft housekeeping, including attitude, thermal, power, and TC/TM etc. control units. The middle level is to manage the five payloads. And the bottom level includes the Scientific Data Processing Unit (SDPU), which will be used to process the original data. 1553B bus and RS-422 bus will take the responsibility for transmitting information between the three levels. The electric hardware system should satisfy the demands of different observation modes and different data formats. In this paper, the hardware system design methods are discussed in detail.

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

2003-02-01

143

Site-seeing measurements for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

Seeing measurements are crucial for the optimum design of (multi-conjugate) adaptive optics systems operating at solar telescopes. For the design study of the 4-meter European Solar Telescope, to be located in the Canary Islands, several instruments have been constructed and operated, at the Observatorio del Roque de los Muchachos (La Palma) and at the Observatorio del Teide (Tenerife), to measure the properties of the ground layer and medium-high altitude turbulence. Several units of short (42.34 cm) and two long (323.06 cm) scintillometer bars are, or are to be, installed at both observatories. In addition to them, two wide-field wavefront sensors will be attached to the optical beams of the Swedish tower, on La Palma, and of the German VTT, on Tenerife, simultaneously used with the normal operation of the telescopes. These wavefront sensors are of Shack-Hartmann type with ~1 arcminute field of view. In this contribution, the instruments setup and their performance are described.

Berkefeld, Th.; Bettonvil, F.; Collados, M.; López, R.; Martín, Y.; Peñate, J.; Pérez, A.; Scharmer, G. B.; Sliepen, G.; Soltau, D.; Waldmann, T. A.; van Werkhoven, T.

2010-07-01

144

An Airborne Infrared Telescope and Spectrograph for Solar Eclipse Observations  

NASA Astrophysics Data System (ADS)

The solar infrared spectrum offers great possibilities for direct spatially resolved measurements of the solar coronal magnetic fields, via imaging of the plasma that is constrained to follow the magnetic field direction and via spectro-polarimetry that permits measurement of the field strength in the corona. Energy stored in coronal magnetic fields is released in flares and coronal mass ejections (CME) and provides the ultimate source of energy for space weather. The large scale structure of the coronal field, and the opening up of the field in a transition zone between the closed and open corona determines the speed and structure of the solar wind, providing the background environment through which CMEs propagate. At present our only direct measurements of the solar magnetic fields are in the photosphere and chromosphere. The ability to determine where and why the corona transitions from closed to open, combined with measurements of the field strength via infrared coronal spectro-polarimetry will give us a powerful new tool in our quest to develop the next generation of forecasting models.We describe a first step in achieving this goal: a proposal for a new IR telescope, image stabilization system, and spectrometer, for the NCAR HIPER GV aircraft. The telescope/spectrograph will operate in the 2-6micron wavelength region, during solar eclipses, starting with the trans-north American eclipse in August 2017. The HIAPER aircraft flying at ~35,000 ft will provide an excellent platform for IR observations. Our imaging and spectroscopy experiment will show the distribution and intensity of IR forbidden lines in the solar corona.

DeLuca, Edward E.; Cheimets, Peter; Golub, Leon

2014-06-01

145

Extra Solar Planetary Imaging Coronagraph and Science Requirements for the James Webb Telescope Observatory  

NASA Technical Reports Server (NTRS)

1) Extra solar planetary imaging coronagraph. Direct detection and characterization of Jovian planets, and other gas giants, in orbit around nearby stars is a necessary precursor to Terrestrial Planet Finder 0 in order to estimate the probability of Terrestrial planets in our stellar neighborhood. Ground based indirect methods are biased towards large close in Jovian planets in solar systems unlikely io harbor Earthlike planets. Thus to estimate the relative abundances of terrestrial planets and to determine optimal observing strategies for TPF a pathfinder mission would be desired. The Extra-Solar Planetary Imaging Coronagraph (EPIC) is such a pathfinder mission. Upto 83 stellar systems are accessible with a 1.5 meter unobscured telescope and coronagraph combination located at the Earth-Sun L2 point. Incorporating radiometric and angular resolution considerations show that Jovians could be directly detected (5 sigma) in the 0.5 - 1.0 micron band outside of an inner working distance of 5/D with integration times of -10 - 100 hours per observation. The primary considerations for a planet imager are optical wavefront quality due to manufacturing, alignment, structural and thermal considerations. pointing stability and control, and manufacturability of coronagraphic masks and stops to increase the planetary-to- stellar contrast and mitigate against straylight. Previously proposed coronagraphic concepts are driven to extreme tolerances. however. we have developed and studied a mission, telescope and coronagraphic detection concept, which is achievable in the time frame of a Discovery class NASA mission. 2) Science requirements for the James Webb Space Telescope observatory. The James Webb Space Observatory (JWST) is an infrared observatory, which will be launched in 201 1 to an orbit at L2. JWST is a segmented, 18 mirror segment telescope with a diameter of 6.5 meters, and a clear aperture of 25 mA2. The telescope is designed to conduct imaging and spectroscopic observations from 0.6-27 microns. The primary mirror find and understand predicted first light objects, observe galaxies back to their earliest precursors so that we can understand their growth and evolution, unravel the birth and early evolution of stars and planetary systems, and study planetary systems and the origins of life. In this paper we discuss the science goals for JWST in the context of the performance requirements they levy on the observatory.

Clampin, Mark

2004-01-01

146

Hubble Space Telescope solar cell module thermal cycle test  

NASA Technical Reports Server (NTRS)

The Hubble Space Telescope (HST) solar array consists of two identical double roll-out wings designed after the Hughes flexible roll-up solar array (FRUSA) and was developed by the European Space Agency (ESA) to meet specified HST power output requirements at the end of 2 years, with a functional lifetime of 5 years. The requirement that the HST solar array remain functional both mechanically and electrically during its 5-year lifetime meant that the array must withstand 30,000 low Earth orbit (LEO) thermal cycles between approximately +100 and -100 C. In order to evaluate the ability of the array to meet this requirement, an accelerated thermal cycle test in vacuum was conducted at NASA's Marshall Space Flight Center (MSFC), using two 128-cell solar array modules which duplicated the flight HST solar array. Several other tests were performed on the modules. The thermal cycle test was interrupted after 2,577 cycles, and a 'cold-roll' test was performed on one of the modules in order to evaluate the ability of the flight array to survive an emergency deployment during the dark (cold) portion of an orbit. A posttest static shadow test was performed on one of the modules in order to analyze temperature gradients across the module. Finally, current in-flight electrical performance data from the actual HST flight solar array will be tested.

Douglas, Alexander; Edge, Ted; Willowby, Douglas; Gerlach, Lothar

1992-01-01

147

Fibered nulling telescope for extra-solar coronagraphy.  

PubMed

A family of fibered nulling telescopes is described, based on the joint use of several recent suggested or demonstrated techniques, namely, pupil densification, multiaxial recombination and single-mode fiber modal filtering, and the use of a fully symmetric beam splitter arrangement. The concept seems appropriate for the realization of a spaceborne nulling telescope, searching for Jupiter-like extra-solar planets and a precursor of future missions, such as Darwin or terrestrial planet finder interferometer (TPF-I). However, it is generally not possible to satisfy at the same time two major requirements, being the depth and size of the central nulling area, and the global throughput for the observed planet. PMID:19340231

Hénault, François

2009-04-01

148

NIRIS: The Second Generation Near-Infrared Imaging Spectro-polarimeter for the 1.6 Meter New Solar Telescope  

NASA Astrophysics Data System (ADS)

The largest aperture solar telescope, the 1.6 m New Solar Telescope (NST) has been installed at the Big Bear Solar Observatory (BBSO). To take full advantage of the NST's greatest potential, we are upgrading the routinely operational InfraRed Imaging Magnetograph (IRIM) to its second generation, the NIRIS (Near-InfraRed Imaging Spectropolarimeter). NIRIS will offer unprecedented high resolution spectroscopic and polarimetric imaging data of the solar atmosphere from the deepest photosphere through the base of the corona. With the aid of the BBSO adaptive optics (AO) system, the spatial resolution will be close to the diffraction limit of the NST. The spectroscopic cadence will reach one second, while polarimetric measurements, including Stokes I, Q, U, V profiles, remain at a better than 10 s cadence. Polarization sensitivity is expected to be reach ˜ 10-4Ic. NIRIS will cover a broad spectral range from 1.0 to 1.7?m, with particular attention to two unique spectral lines: the Fe I 1565 nm doublet has already proven to be the most sensitive to Zeeman effect for probing the magnetic field in the deepest photosphere; the He I 1083 nm multiplet is one of the best currently available diagnostic of upper chromospheric magnetic fields that allows one to map the vector field at the base of the corona. NIRIS will be built on dual Fabry-Pérot Interferometers (FPIs), each of which has an aperture of 100 mm. The larger aperture of FPIs allows the available field-of-view up to one and half minutes with a spectral power of ˜ 105.

Cao, W.; Goode, P. R.; Ahn, K.; Gorceix, N.; Schmidt, W.; Lin, H.

2012-12-01

149

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Technical Reports Server (NTRS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fail apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

1984-01-01

150

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Technical Reports Server (NTRS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluoroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fall apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

1984-01-01

151

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Technical Reports Server (NTRS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the Sun, motion of the concentrator may stop. As the Sun moves relative to the Earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluoroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fall apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

1984-01-01

152

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Astrophysics Data System (ADS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the Sun, motion of the concentrator may stop. As the Sun moves relative to the Earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluoroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fall apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

1984-03-01

153

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Astrophysics Data System (ADS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluoroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fall apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

154

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Astrophysics Data System (ADS)

If a malfunction occurs in a solar thermal point-focus distributed receiver power plant while a concentrator is pointed at the sun, motion of the concentrator may stop. As the sun moves relative to the earth, the spot of concentrated sunlight then slowly walks off the receiver aperture, across the receiver face plate, and perhaps across adjacent portions of the concentrator. Intense local heating by the concentrated sunlight may damage or destroy these parts. The behavior of various materials under conditions simulating walk-off of a parabolic dish solar collector were evaluated. Each test consisted of exposure to concentrated sunlight at a peak flux density of about 7000 kW/square meter for 15 minutes. Types of materials tested included graphite, silicon carbide, silica, various silicates, alumina, zirconia, aluminum, copper, steel, and polytetrafluroethylene. The only material that neither cracked nor melted was grade G-90 graphite. Grade CS graphite, a lower cost commercial grade, cracked half-way across, but did not fail apart. Both of these grades are medium-grain extruded graphites. A graphite cloth (graphitized polyacrylonitrile) showed fair performance when tested as a single thin ply; it might be useful as a multi-ply assembly. High purity slipcast silica showed some promise also.

Jaffe, L. D.

1984-11-01

155

The cern axion solar telescope (CAST): an update  

NASA Astrophysics Data System (ADS)

The CERN Axion Solar Telescope (CAST), a 10 meter long LHC, 9 Tesla, test magnet is mounted on a moving platform that tracks the sun about 1.5 hours during sunrise, again during sunset. It moves ±80 vertically and ±400 horizontally. It has been taking data continuously since July 10, 2003. Data analyzed thus far yield an upper bound on the photon-axion coupling constant, ga?? ? 3 × 10-10 GeV-1 for axion masses less than 5 × 10-2 eV.

Andriamonje, S.; Arsov, V.; Aune, S.; Aune, T.; Avignone, F. T.; Barth, K.; Belov, A.; Beltran, B.; Bräuninger, H.; Carmona, J.; Cebrián, S.; Chesi, E.; Cipolla, G.; Collar, J.; Creswick, R.; Dafni, T.; Davenport, M.; Dedousis, S.; Delattre, M.; Delbart, A.; Deoliveira, R.; Dilella, L.; Eleftheriadis, C.; Engelhauser, J.; Fanourakis, G.; Farach, H.; Ferrer, E.; Fischer, H.; Formenti, F.; Franz, J.; Friedrich, P.; Geralis, T.; Giomataris, I.; Gninenko, S.; Golubev, N.; Hartmann, R.; Hasinoff, M.; Heinsius, F.-H.; Hoffmann, D. H. H.; Irastorza, I.; Jacoby, J.; Joux, J.-N.; Kang, D.; Königsmann, K.; Kotthaus, R.; Krcmar, M.; Kuster, M.; Lakic, B.; Lasseur, C.; Liolios, A.; Lippitsch, A.; Ljubicic, A.; Lutz, G.; Luzon, G.; Morales, A.; Morales, J.; Mutterer, M.; Nikolaidis, A.; de Solorzano, A. Ortiz; Papaevangelou, T.; Placci, A.; Raffelt, G.; Rammos, P.; Robert, J. P.; Ruz, J.; Sarsa, M.; Schill, C.; Serber, W.; Semertzidis, Y.; Vieira, J.; Villar, J.; Vullierme, B.; Walckiers, L.; Zioutas, K.

2005-01-01

156

Vector magnetograph observations by the solar flare telescope at BOAO.  

NASA Astrophysics Data System (ADS)

The authors report that vector magnetograph (VMG) observations of the solar photosphere are being carried out by the Solar Flare Telescope (SOFT) at BOAO. The VMG uses a narrow band Lyot filter (FWHM = 0.125 A) for Stokes parameter (I,Q,U,V) observations to obtain longitudinal and transverse fields. The authors have obtained a filter-convolved line profile of Fe I 6302.5 for VMG by changing the central wavelength of the Lyot filter, which is consistent with the Sacramento Peak spectral atlas data. Using the line profile, the authors have determined calibration coefficients of longitudinal and transverse fields by the line slope method. Then they have compared vector fields of AR 8422 observed at BOAO with those at Mitaka. The comparison shows that longitudinal fields are very similar to each other, but transverse fields are a little different.

Park, Y. D.; Moon, Y.-J.; Yun, H. S.

1999-12-01

157

Observing Solar System Objects with the James Webb Space Telescope  

NASA Technical Reports Server (NTRS)

The James Webb Space Telescope (JWST) will have the capability to observe Solar System objects having apparent rates of motion up to 30 milliarcseconds/sec. The key science drivers are the study of Kuiper Belt Objects, asteroids, comets, and the outer planets and their moons at near and mid-infrared wavelengths. This poster presents the results from a recent study that defined the conceptual design for a capability for JWST to track and observe moving targets. We illustrate about how guide star acquisition and tracking wi11 be handled while retaining the efficient and flexible execution characteristics of JWST event-driven operations. We also show how the JWST pointing control system can readily support moving target observations. The characteristics of Solar System objects that can be observed by JWST are summarized along with descriptions of the major aspects of moving target science observation planning and on-board event-driven execution.

Sonneborn, George; Issacs, J.; Balzano, V.; Nelan, E.P.; Anandakrishnan, S.; Hammel, H.

2008-01-01

158

Goldhelox: a soft X-ray solar telescope.  

NASA Astrophysics Data System (ADS)

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 - 181 Å 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.

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. A.; Savage, M. B.; Eastman, P. F.; Jensen, V.

1995-03-01

159

Characterization of habitable exoplanets with simultaneous coronagraphy and astrometry with a single aperture telescope  

NASA Astrophysics Data System (ADS)

With sub-microarcsecond astrometry, exoplanets can be identified and their masses measured. Coronagraphic imaging of these exoplanets is required to study their atmospheres and surfaces in sufficient detail to identify possible signs of biological activity. We show how both measurements can be simultaneously acquired with a single telescope in which the central field is directed to a coronagraph instrument providing high contrast images, while the surrounding field is imaged with a wide field camera in which numerous faint background stars are used as an astrometric reference. To calibrate astrometric distortions due to optics and focal plane detector array imperfections and variations, we propose to place small dark spots on the telescope primary mirror. The spots, arranged in a regular grid containing no low spatial frequencies, do not affect the coronagraph performance. In the wide field image, they create diffraction spikes originating from the central bright star, which are affected by changes in intrumental distortions in exactly the same way as the background stars used for reference, thus allowing calibration of instrumental errors to micro-arcsecond level. We show that combining simultaneous astrometric and coronagraphic measurements allows reliable detection and characterization of exoplanets. Recent laboratory tests performed at the University of Arizona and NASA Ames validate the concept, demonstrating both the ability to accurately calibrate astrometric distortions, and compatibility with high contrast imaging systems.

Guyon, Olivier; Bendek, Eduardo; Ammons, S. Mark; Shao, Michael; Shaklan, Stuart; Woodruff, Robert A.; Belikov, Ruslan; Milster, Thomas

2012-09-01

160

Engineering Specification for Large-aperture UVO Space Telescopes Derived from Science Requirements  

NASA Technical Reports Server (NTRS)

The Advance Mirror Technology Development (AMTD) project is a three year effort initiated in FY12 to mature by at least a half TRL step six critical technologies required to enable 4 to 8 meter UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND result in a high-performance low-cost low-risk system. To provide the science community with options, we are pursuing multiple technology paths. We have assembled an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes. A key accomplishment is deriving engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicles and their mass and volume constraints.

Stahl, H. Philip; Postman, Marc; Smith, W. Scott

2013-01-01

161

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

162

The Focal Plane Package of the Solar Optical telescope on Solar B  

Microsoft Academic Search

The Solar-B satellite will be launched into a full-sun low-earth orbit in the fall of 2006 from Japan's Uchinoura Space center. It includes the 50-cm diameter Solar Optical Telescope with its Focal Plane Package (FPP), for near-UV and visible observations of the photosphere and chromosphere at very high (diffraction limited) angular resolution. The FPP has a Spectro-Polarimeter (SP) for precision

Theodore D. Tarbell

2006-01-01

163

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

164

The Solar Optical Telescope on Hinode: Performance and Capabilities  

NASA Astrophysics Data System (ADS)

The Hinode (Solar B) satellite includes the Solar Optical Telescope (SOT) with its 50 cm diameter Optical Telescope Assembly (OTA) and Focal Plane Package (FPP), for near UV and visible observations of the photosphere and chromosphere at very high (diffraction limited) angular resolution. The FPP has a Spectropolarimeter (SP) for precision measurements of photospheric vector magnetic fields over a 160 x 320 arcsecond field of view; a Narrowband Filter Imager (NFI) with a tunable birefringent filter for magnetic, Doppler, and intensity maps over the same field of view; and a Broadband Filter Imager (BFI) for highest resolution images in six wavelengths (G band, Ca II H, continua, etc.) over two thirds of that field of view. A polarization modulator in the telescope allows measurement of Stokes parameters at all wavelengths in the SP and NFI. This poster gives examples of SOT observables from the performance verification and initial observing phases of the mission. The SP routinely collects Stokes profiles with spatial resolution 0.16 arc seconds (pixel) and rms noise less than 0.001. Initially the NFI only made magnetograms in Fe I 6302.5 with rms noise less than 0.002; more recently it has begun to observe the other photospheric and chromospheric lines available. The BFI movies have unprecedented uniformity and stability for such high spatial resolution; cadence can be 4 seconds or less. All images are stabilized to 0.01 arc seconds by a tip tilt mirror and correlation tracker. The process for requesting Hinode observations is described, along with guidelines for SOT observing programs. Starting in May, 2007, the Hinode data policy becomes completely open, with all data available to the community immediately after receipt and reformatting at ISAS. Hinode is an international cooperative mission between JAXA/ISAS of Japan, NASA of the United States, PPARC of the United Kingdom, and ESA.

Tarbell, Theodore D.; Tsuneta, S.; SOT Team

2007-05-01

165

The New Solar Telescope in Big Bear: Polarimetry II  

NASA Astrophysics Data System (ADS)

IRIM (Infrared Imaging Magnetograph) is one of the first imaging solar spectro-polarimeters working in the near infrared (NIR). IRIM is being installed and commissioned in the Coudé Lab of the 1.6-meter New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO). This innovative system, which includes a 2.5 nm interference filter, a unique 0.25 nm birefringent Lyot filter, and a Fabry-Pérot etalon, is capable of providing a bandpass as low as 0.01 nm over a field-of-view of 50" in a telecentric configuration. An NIR waveplate rotates ahead of M3 in the NST as the polarimeter modulator, and ahead of it locates a calibration unit to reduce polarization cross-talk induced by subsequent oblique mirrors. Dual-beam differential polarimetry is employed to minimize seeing-induced spurious polarization. Based on the unique advantages in IR window, the very capable NST with adaptive optics, IRIM will provide unprecedented solar spectro-polarimetry with high Zeeman sensitivity (10-3Ic), high spatial resolution (0.2"), and high cadence (15 s). In this paper, we discuss the design, fabrication, and calibration of IRIM, as well as the results of the first light observations.

Cao, W.; Ahn, K.; Goode, P. R.; Shumko, S.; Gorceix, N.; Coulter, R.

2011-04-01

166

Detection of Small-scale Granular Structures in the Quiet Sun with the New Solar Telescope  

NASA Astrophysics Data System (ADS)

Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet-Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope at Big Bear Solar Observatory and with a broadband filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0farcs0375) augmented by the very high image contrast (15.5% ± 0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties, and role of the population of mini-granular structures in the solar magnetoconvection are yet to be explored.

Abramenko, V. I.; Yurchyshyn, V. B.; Goode, P. R.; Kitiashvili, I. N.; Kosovichev, A. G.

2012-09-01

167

DETECTION OF SMALL-SCALE GRANULAR STRUCTURES IN THE QUIET SUN WITH THE NEW SOLAR TELESCOPE  

SciTech Connect

Results of a statistical analysis of solar granulation are presented. A data set of 36 images of a quiet-Sun area on the solar disk center was used. The data were obtained with the 1.6 m clear aperture New Solar Telescope at Big Bear Solar Observatory and with a broadband filter centered at the TiO (705.7 nm) spectral line. The very high spatial resolution of the data (diffraction limit of 77 km and pixel scale of 0.''0375) augmented by the very high image contrast (15.5% {+-} 0.6%) allowed us to detect for the first time a distinct subpopulation of mini-granular structures. These structures are dominant on spatial scales below 600 km. Their size is distributed as a power law with an index of -1.8 (which is close to the Kolmogorov's -5/3 law) and no predominant scale. The regular granules display a Gaussian (normal) size distribution with a mean diameter of 1050 km. Mini-granular structures contribute significantly to the total granular area. They are predominantly confined to the wide dark lanes between regular granules and often form chains and clusters, but different from magnetic bright points. A multi-fractality test reveals that the structures smaller than 600 km represent a multi-fractal, whereas on larger scales the granulation pattern shows no multi-fractality and can be considered as a Gaussian random field. The origin, properties, and role of the population of mini-granular structures in the solar magnetoconvection are yet to be explored.

Abramenko, V. I.; Yurchyshyn, V. B.; Goode, P. R. [Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314 (United States); Kitiashvili, I. N.; Kosovichev, A. G. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)

2012-09-10

168

The Multi-Spectral Solar Telescope Array (MSSTA)  

NASA Technical Reports Server (NTRS)

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 complex at ((lambda)lambda) approx. 171 A to 175 A, and He II Lyman (beta) at 256 A. Subsequently, we developed a rocket borne solar observatory, the Multi Spectral Solar Telescope Array (MSSTA) that pioneered multi-thermal imaging of the solar atmosphere, using high resolution narrow band X-ray, EUV and FUV optical systems. Analysis of MSSTA observations has resulted in four significant insights into the structure of the solar atmosphere: (1) the diameter of coronal loops is essentially constant along their length; (2) models of the thermal and density structure of polar plumes based on MSSTA observations have been shown to be consistent with the thesis that they are the source of high speed solar wind streams; (3) the magnetic structure of the footpoints of polar plumes is monopolar, and their thermal structure is consistent with the thesis that the chromosphere at their footpoints is heated by conduction from above; (4) coronal bright points are small loops, typically 3,500 - 20,000 km long (5 sec - 30 sec); their footpoints are located at the poles of bipolar magnetic structures that are are distinguished from other network elements by having a brighter Lyman a signature. Loop models derived for 26 bright points are consistent with the thesis that the chromosphere at their footpoints is heated by conduction from the corona.

Walker, A. B. C., Jr.; Barbee, Troy W., Jr.; Hoover, Richard B.

1997-01-01

169

Solar System Observing with the Space Infrared Telescope Facility (SIRTF)  

NASA Technical Reports Server (NTRS)

SIRTF is NASA's Space Infrared Telescope Facility. Currently planned for launch on 15 Apr 2003, it is the final element in NASA's Great Observatories Program. SIRTF has an 85 cm diameter f/12 lightweight beryllium telescope, cooled to lekss than 5.5K. It is diffraction-limited at 6.5 microns, and has wavelengthcoverage from 3-180 microns. Its estimated lifetime (limited by cryogen) is 2.5 years at minimum, with a goal of 5+ years. SIRTF has three instruments, IRAC, IRS, and MIPS. IRAC (InfraRed Array Camera) provides simultaneous images at wavelengths of 3.6, 4.5, 5.8, and 8.0 microns. IRS (InfraRed Spectrograph) has 4 modules providing low-resolution (R=60-120) spectra from 5.3 to 40 microns, high-resolution (R=600) spectra from 10 to 37 microns, and an autonomous target acquisition system (PeakUp) which includes small-field imaging at 15 microns. MIPS (Multiband Imaging Photometer for SIRTF)} does imaging photometry at 24, 70, and 160 m and low-resolution (R=15-25) spectroscopy (SED) between 55 and 96 microns. The SIRTF Guaranteed Time Observers (GTOs) are planning to observe Outer Solar System satellites and planets, extinct comets and low-albedo asteroids, Centaurs and Kuiper Belt Objects, cometary dust trails, and a few active short-period comets. The GTO programs are listed in detail in the SIRTF Reserved Observations Catalog (ROC). We would like to emphasize that there remain many interesting subjects for the General Observers (GO). Proposal success for the planetary observer community in the first SIRTF GO proposal cycle (GO-1) determines expectations for future GO calls and Solar System use of SIRTF, so we would like promote a strong set of planetary GO-1 proposals. Towards that end, we present this poster, and we will convene a Solar System GO workshop 3.5 months after launch.

Cleve, J. Van; Meadows, V. S.; Stansberry, J.

2003-01-01

170

KAPAO-Alpha: An On-The-Sky Testbed for Adaptive Optics on Small Aperture Telescopes  

NASA Astrophysics Data System (ADS)

We present initial in-lab and on-sky results of a natural guide star adaptive optics instrument, KAPAO-Alpha, being deployed on Pomona College’s 1-meter telescope at Table Mountain Observatory. The instrument is an engineering prototype designed to help us identify and solve design and integration issues before building KAPAO, a low-cost, dual-band, natural guide star AO system currently in active development and scheduled for first light in 2013. The Alpha system operates at visible wavelengths, employs Shack-Hartmann wavefront sensing, and is assembled entirely from commercially available components that include: off-the-shelf optics, a 140-actuator BMC deformable mirror, a high speed SciMeasure Lil’ Joe camera, and an EMCCD for science image acquisition. Wavefront reconstruction operating at 1-kHz speeds is handled with a consumer-grade computer running custom software adopted from the Robo-AO project. The assembly and integration of the Alpha instrument has been undertaken as a Pomona College undergraduate thesis. As part of the larger KAPAO project, it is supported by the National Science Foundation under Grant No. 0960343.

Morrison, Will; Choi, P. I.; Severson, S. A.; Spjut, E.; Contreras, D. S.; Gilbreth, B. N.; McGonigle, L. P.; Rudy, A. R.; Xue, A.; Baranec, C.; Riddle, R.

2012-05-01

171

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

172

First Solar System Results of the Spitzer Space Telescope  

NASA Technical Reports Server (NTRS)

The Spitzer Space Telescope, formerly known as SIRTF, is now operational and delivers unprecedented sensitivity for the observation of Solar System targets. Spitzer's capabilities and first general results were presented at the January 2004 AAS meeting. In this poster, we focus on Spitzer's performance for moving targets, and the first Solar System results. Spitzer has three instruments, IRAC, IRS, and MIPS. IRAC (InfraRed Array Camera) provides simultaneous images at wavelengths of 3.6, 4.5, 5.8, and 8.0 microns. IRS (InfraRed Spectrograph) has 4 modules providing low-resolution (R=60-120) spectra from 5.3 to 40 microns, high-resolution (R=600) spectra from 10 to 37 m, and an autonomous target acquisition system (PeakUp) which includes small-field imaging at 15 m. MIPS (Multiband Imaging Photometer for SIRTF) does imaging photometry at 24, 70, and 160 m and low-resolution (R=15-25) spectroscopy (SED) between 55 and 96 microns. Guaranteed Time Observer (GTO) programs include the moons of the outer Solar System, Pluto, Centaurs, Kuiper Belt Objects, and comets

VanCleve, J.; Cruikshank, D. P.; Stansberry, J. A.; Burgdorf, M. J.; Devost, D.; Emery, J. P.; Fazio, G.; Fernandez, Y. R.; Glaccum, W.; Grillmair, C.

2004-01-01

173

Flight hardware for the Hubble Space Telescope solar array damper  

NASA Astrophysics Data System (ADS)

The Hubble Space Telescope (HST) is currently operating with two flexible solar arrays (or 'wings'), referred to as SA2, that were installed during Servicing Mission 1. These flexible solar arrays are to be replaced with two rigid solar arrays, SA3, during Servicing Mission 3B which is currently scheduled for May, 2001. The key requirements for these arrays are to: (1) increase long term power to support the HST mission, (2) improve the jitter performance while maintaining stability margin requirements, and (3) withstand re-boost loads without astronaut or ground intervention. Analysis of the original SA3 design showed that the Pointing Control System (PCS) stability margin requirements would be violated because of the modal characteristics of the SA3 fundamental bending modes. One of the options to regain the stability margins was to increase the damping of these modes. Damping of 1.5% of critical of the SA3 fundamental bending modes, at the HST system level, is needed to meet stability margin requirements. Therefore, the development of a discrete damping device was undertaken to provide adequate damping of the SA3 fundamental bending modes for all operational conditions.

Maly, Joseph R.; Anandakrishnan, Satya M.; Pendleton, Scott C.; Shade, E.; Sills, J. W.

2000-04-01

174

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

175

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

176

Lupus I Observations from the 2010 Flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry  

NASA Astrophysics Data System (ADS)

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 ?m. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

Matthews, Tristan G.; Ade, Peter A. R.; Angilè, Francesco E.; Benton, Steven J.; Chapin, Edward L.; Chapman, Nicholas L.; Devlin, Mark J.; Fissel, Laura M.; Fukui, Yasuo; Gandilo, Natalie N.; Gundersen, Joshua O.; Hargrave, Peter C.; Klein, Jeffrey; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Netterfield, Calvin B.; Novak, Giles; Nutter, David; Olmi, Luca; Pascale, Enzo; Poidevin, Frédérick; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A.; Soler, Juan Diego; Tachihara, Kengo; Thomas, Nicholas E.; Truch, Matthew D. P.; Tucker, Carole E.; Tucker, Gregory S.; Ward-Thompson, Derek

2014-04-01

177

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

178

Telescopes  

NSDL National Science Digital Library

The first Web site on telescopes comes from Enchanted Learning.com, called Inventions: Telescopes (1). This site gives a brief description of the history of telescopes and their inventors, beginning with Hans Lippershey and his refracting telescope in 1608. The next site, offered by NASA, is the Telescope in Education site (2). This program provides students from around the world the opportunity to use a remotely controlled telescope and charge-coupled device camera in a real-time, hands-on, interactive environment. All of the information needed for educators to set up the program can be found within. The third site, from the online periodical Sky and Telescope, is called Telescopes and Binoculars (3). These how-to links give information on choosing your first telescope, caring for optics, using a map for your telescope, making a backyard observatory, and more. From the Australia Telescope National Facility comes the next site, Australia Telescope Compact Array LIVE! (4). The array is a radio telescope made up of six 22m antennas whose locational and other information is updated every ten seconds on the site. Telescope images and links to other similar sites can also be found here. The next site, from the National Optical Astronomy Observatory, is the Kitt Peak Virtual Tour (5). The Kitt Peak National Observatory is the first national observatory of the United States and has the world's largest collection of optical telescopes. The site gives a complete tour of the grounds and telescopes, along with descriptions, maps, photographs, and more. The Space Telescope Science Institute's Web site, Hubble Space Telescope Public Pictures (6), provides a large database of space photographs and press releases regarding Hubble. The extraordinary pictures are categorized by subject and the press releases by year (which also contain relevant photographs). The next site from the Sloan Digital Sky Survey called Image Gallery: Telescope Photos (7) contains pictures not of what the telescopes are viewing but of the telescopes themselves. The short descriptions and impressive photographs give unfamiliar users an idea of what these machines actually look like. The last site, Telescope Data Center (8), is maintained by the Smithsonian Astrophysical Observatory, which is part of the Harvard-Smithsonian Center for Astrophysics. The Data Center supports scheduling, observation, data reduction, analysis, and data archiving for the optical telescopes, and offers these products on the site for anyone interested.

Brieske, Joel A.

2002-01-01

179

First Results from the CERN Axion Solar Telescope  

NASA Astrophysics Data System (ADS)

Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by the Primakoff process. In a laboratory magnetic field (“axion helioscope”), they would be transformed into x-rays with energies of a few keV. Using a decommissioned Large Hadron Collider test magnet, the CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from the analysis of these data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling ga?<1.16×10-10 GeV-1 at 95% C.L. for ma?0.02 eV. This limit, assumption-free, is comparable to the limit from stellar energy-loss arguments and considerably more restrictive than any previous experiment over a broad range of axion masses.

Zioutas, K.; Andriamonje, S.; Arsov, V.; Aune, S.; Autiero, D.; Avignone, F. T.; Barth, K.; Belov, A.; Beltrán, B.; Bräuninger, H.; Carmona, J. M.; Cebrián, S.; Chesi, E.; Collar, J. I.; Creswick, R.; Dafni, T.; Davenport, M.; di Lella, L.; Eleftheriadis, C.; Englhauser, J.; Fanourakis, G.; Farach, H.; Ferrer, E.; Fischer, H.; Franz, J.; Friedrich, P.; Geralis, T.; Giomataris, I.; Gninenko, S.; Goloubev, N.; Hasinoff, M. D.; Heinsius, F. H.; Hoffmann, D. H.; Irastorza, I. G.; Jacoby, J.; Kang, D.; Königsmann, K.; Kotthaus, R.; Kr?mar, M.; Kousouris, K.; Kuster, M.; Laki?, B.; Lasseur, C.; Liolios, A.; Ljubi?i?, A.; Lutz, G.; Luzón, G.; Miller, D. W.; Morales, A.; Morales, J.; Mutterer, M.; Nikolaidis, A.; Ortiz, A.; Papaevangelou, T.; Placci, A.; Raffelt, G.; Ruz, J.; Riege, H.; Sarsa, M. L.; Savvidis, I.; Serber, W.; Serpico, P.; Semertzidis, Y.; Stewart, L.; Vieira, J. D.; Villar, J.; Walckiers, L.; Zachariadou, K.

2005-04-01

180

First results from the CERN axion solar telescope.  

PubMed

Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by the Primakoff process. In a laboratory magnetic field ("axion helioscope"), they would be transformed into x-rays with energies of a few keV. Using a decommissioned Large Hadron Collider test magnet, the CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from the analysis of these data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling g(agamma)<1.16x10(-10) GeV-1 at 95% C.L. for m(a) less, similar 0.02 eV. This limit, assumption-free, is comparable to the limit from stellar energy-loss arguments and considerably more restrictive than any previous experiment over a broad range of axion masses. PMID:15903903

Zioutas, K; Andriamonje, S; Arsov, V; Aune, S; Autiero, D; Avignone, F T; Barth, K; Belov, A; Beltrán, B; Bräuninger, H; Carmona, J M; Cebrián, S; Chesi, E; Collar, J I; Creswick, R; Dafni, T; Davenport, M; Di Lella, L; Eleftheriadis, C; Englhauser, J; Fanourakis, G; Farach, H; Ferrer, E; Fischer, H; Franz, J; Friedrich, P; Geralis, T; Giomataris, I; Gninenko, S; Goloubev, N; Hasinoff, M D; Heinsius, F H; Hoffmann, D H H; Irastorza, I G; Jacoby, J; Kang, D; Königsmann, K; Kotthaus, R; Krcmar, M; Kousouris, K; Kuster, M; Laki?, B; Lasseur, C; Liolios, A; Ljubici?, A; Lutz, G; Luzón, G; Miller, D W; Morales, A; Morales, J; Mutterer, M; Nikolaidis, A; Ortiz, A; Papaevangelou, T; Placci, A; Raffelt, G; Ruz, J; Riege, H; Sarsa, M L; Savvidis, I; Serber, W; Serpico, P; Semertzidis, Y; Stewart, L; Vieira, J D; Villar, J; Walckiers, L; Zachariadou, K

2005-04-01

181

A high-resolution spectrograph for the solar telescope GREGOR  

NASA Astrophysics Data System (ADS)

This communication shows the design, layout, mounting and start-up of a high-resolution grating spectrograph for VIS-NIR at GREGOR 1.5m Solar Telescope (Observatorio del Teide, Tenerife, Canary Islands). The instrument will be used together with the Tenerife Infrared Polarimeter (TIP-II). As special characteristics of the design, the following can be mentioned: The first folding mirror of the spectrograph can be placed in two positions to take into account the change of the optical axis introduced by the polarizing beamsplitter of TIP-II. This way the instrument is optimally aligned when used in situations with and without polarimeter. The second and third mirrors rotate the image of the entrance slit, making it parallel to the grating grooves. A system of prisms are used to adequately fit onto the detector the two orthogonal polarized beams generated by the polarimeter. Two output beams are possible, to make feasible simultaneous visible and near-infrared observations.

Collados, Manuel; Calcines, A.; Díaz, J. J.; Hernnádez, E.; López, R.; Páez, E.

2008-08-01

182

Hubble Space Telescope Spectrophotometry and Models for Solar Analogs  

NASA Astrophysics Data System (ADS)

Absolute flux distributions for seven solar analog stars are measured from 0.3 to 2.5 ?m by Hubble Space Telescope (HST) spectrophotometry. In order to predict the longer wavelength mid-IR fluxes that are required for James Webb Space Telescope calibration, the HST spectral energy distributions are fit with Castelli & Kurucz model atmospheres; and the results are compared with fits from the MARCS model grid. The rms residuals in 10 broadband bins are all <0.5% for the best fits from both model grids. However, the fits differ systematically: the MARCS fits are 40-100 K hotter in T eff, 0.25-0.80 higher in log g, 0.01-0.10 higher in log z, and 0.008-0.021 higher in the reddening E(B - V), probably because their specifications include different metal abundances. Despite these differences in the parameters of the fits, the predicted mid-IR fluxes differ by only ~1%; and the modeled flux distributions of these G stars have an estimated ensemble accuracy of 2% out to 30 ?m.

Bohlin, R. C.

2010-04-01

183

Solar System Studies with the Space Infrared Telescope Facility (SIRTF)  

NASA Technical Reports Server (NTRS)

SIRTF (Space Infrared Telescope Facility) is the final element in NASA's 'Great Observatories' program. It consists of an 85-cm cryogenically-cooled observatory for infrared astronomy from space. SIRTF is scheduled for launch in late 2001 or early 2002 on a Delta rocket into a heliocentric orbit trailing the Earth. Data from SIRTF will be processed and disseminated to the community through the SIRTF Science Center (SSC) located at the Infrared Processing and Analysis Center (IPAC) at Caltech. Some 80/% of the total observing time (estimated at a minimum of 7500 hours of integration time per year for the mission lifetime of about 4 years) will be available to the scientific community at large through a system of refereed proposals. Three basic instruments are located in the SIRTF focal plane. The Multiband Imaging Photometer (MIPS), the Infrared Array Camera (IRAC), and the Infrared Spectrometer (IRS), taken together, provide imaging and spectroscopy from 3.5 to 160 microns. Among the solar system studies suited to SIRTF are the following: 1) spectroscopy and radiometry of small bodies from the asteroid main belt, through the Trojan clouds, to the Kuiper Disk; 2) dust distribution in the zodiacal cloud and the Earth's heliocentric dust ring; 3) spectroscopy and radiometry of comets; and 4) spectroscopy and radiometry of planets and their satellites. Searches for, and studies of dust disks around other stars, brown dwarfs, and superplanets will also be conducted with SIRTF. The SORTIE web site (http://ssc.ipac.caltech.edu/sirtf) contains important details and documentation on the project, the spacecraft, the telescope, instruments, and observing procedures. A community-wide workshop for solar system studies with SIRTF is in the planning stages by the author and Martha S. Hanner for the summer of 1999.

Cruikshank, Dale P.; DeVincenzi, Donald L. (Technical Monitor)

1998-01-01

184

Overview and Recent Accomplishments of the Advanced Mirror Technology Development (AMTD) for Large Aperture UVOIR Space Telescopes Project  

NASA Technical Reports Server (NTRS)

Per Astro2010, a new, larger UVO telescope is needed to answer fundamental scientific questions, such as: is there life on Earth-like exoplanets; how galaxies assemble stellar populations; how baryonic matter interacts with intergalactic medium; and how solar systems form and evolve. And, present technology is not mature enough to affordably build and launch any potential UVO concept. Advanced Mirror Technology Development (AMTD) is a funded SAT project. Our objective is to mature to TRL-6 the critical technologies needed to produce 4-m or larger flight-qualified UVOIR mirrors by 2018 so that a viable mission can be considered by the 2020 Decadal Review. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND result in a high-performance low-cost low-risk system. To provide the science community with options, we are pursuing multiple technology paths. We have assembled an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes. One of our key accomplishments is that we have derived engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicle and its inherent mass and volume constraints. We defined and initiated a program to mature 6 key technologies required to fabricate monolithic and segmented space mirrors.

Stahl, H. Philip

2013-01-01

185

Transient Small-Scale Magnetic Flux Emergence and Atmospheric Response Observed with New Solar Telescope and SDO  

NASA Astrophysics Data System (ADS)

State-of-the art solar instrumentation is now revealing the activity of the Sun at the highest temporal and spatial resolution. Granular-scale magnetic flux emergence and the response of the solar atmosphere is one of the key topics. Observations with the 1.6m aperture New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO) are making next steps in our understanding of the solar surface structure. On August 7, 2013, NST observed active region NOAA 11810 in different photospheric and chromospheric wavelengths. The region displays a group of solar pores, in the vicinity of which we detected a site of emerging magnetic flux accompanied by intense and very confined abnormal granulation dynamics, observed in the photospheric TiO 7057 A with a resolution of 0.034 “/pix. Following the expansion of exploding granules in this site, we observed a sudden appearance of an extended surge in the HeI 10830A data (bandpass of 0.05 A). The SDO/HMI data used to study the evolution of the magnetic field and Doppler velocities reveal a short-lived emerging loop-like structure with strong upflows. We used the SDO/AIA data to investigate the response of the transition region and corona to the transient emerging flux phenomenon. We compare the results with previous observations, and propose a scenario for the production of plasma surges by the transient magnetic flux emergence events.

Vargas Domínguez, Santiago; Kosovichev, Alexander G.

2014-06-01

186

The IMaX polarimeter for the solar telescope SUNRISE of the NASA long duration balloon program  

NASA Astrophysics Data System (ADS)

On June 8th 2009 the SUNRISE mission was successfully launched. This mission consisted of a 1m aperture solar telescope on board of a stratospheric balloon within the Long Duration Balloon NASA program. The flight followed the foreseen circumpolar trajectory over the Artic and the duration was 5 days and 17 hours. One of the two postfocal instruments onboard was IMaX, the Imaging Magnetograph eXperiment. This instrument is a solar magnetograph which is a diffraction limited imager capable to resolve 100 km on the solar surface, and simultaneously a high sensitivity polarimeter (<10-3) and a high resolution spectrograph (bandwidth <70mÅ). The magnetic vectorial map can be extracted thanks to the well-know Zeeman effect, which takes place in the solar atoms, allowing to relate polarization and spectral measurements to magnetic fields. The technological challenge of the IMaX development has a special relevance due to the utilization of innovative technologies in the Aeroespacial field and it is an important precedent for future space missions such as Solar Orbiter from ESA. Among these novel technologies the utilization of Liquid Crystal Variable Retarders (LCVRs) as polarization modulators and a LiNbO3 etalon as tunable spectral filter are remarkable. Currently the data obtained is being analyzed and the preliminary results show unprecedented information about the solar dynamics.

Alvarez-Herrero, A.; Martínez-Pillet, V.; Del Toro Iniesta, J. C.; Domingo, V.

2010-06-01

187

Vector Magnetograph Observations by the Solar Flare Telescope at Boao  

NASA Astrophysics Data System (ADS)

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 video CCD cameras which are digitized in 8-bit by an image processor, MVC 150/40 manufactured by ITI(Image Technology Incorporate). The digitized images are saved in 16 bit after integration (up to 256 frames) or in 8-bit multiple frames for analysis. Since the transmission wavelength of Lyot filter is very sensitive to environmental temperature (0.35A/deg), it requires a careful temperature control of the filter interior. For this, we have made a continuous effort to maintain the temperature stability within the accuracy of less than 0.05 deg. with NAIRC (Nanjing Astronomical Instrument Research Center) team. We have obtained clean line profiles of FeI 6302.5 from our VMG by scanning the individual profiles by changing the central wavelength of the Lyot filter. We present some of our observed VMG observations, which are compared with those made with similar vector magnetographs at other observatories.

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

188

The dynamic solar chromosphere: recent advances from high resolution telescopes  

NASA Astrophysics Data System (ADS)

This review focuses on the solar chromosphere, a very inhomogeneous and dynamic layer that exhibits phenomena on a large range of spatial and temporal scales. High-resolution observa-tions from existing telescopes (DST, SST, DOT), as well as long-duration observations with Hinode's SOT employing lines such as the Ca II infrared lines, the Ca II HK and above all the H? line reveal an incredibly rich, dynamic and highly structured environment, both in quiet and active regions. The fine-structure chromosphere, is mainly constituted by fibrilar features that connect various parts of active regions or span across network cell interiors. We discuss this highly dynamical solar chromosphere, especially below the magnetic canopy, which is gov-erned by flows reflecting both the complex geometry and dynamics of the magnetic field and the propagation and dissipation of waves in the different atmospheric layers. A comprehensive view of the fine-structure chromosphere requires deep understanding of the physical processes involved, investigation of the intricate link with structures/processes at lower photospheric lev-els and analysis of its impact on the mass and energy transport to higher atmospheric layers through flows resulting from different physical processes such as magnetic reconnection and waves. Furthermore, we assess the challenges facing theory and numerical modelling which require the inclusion of several physical ingredients, such as non-LTE and three-dimensional numerical simulations.

Tziotziou, Konstantinos; Tsiropoula, Georgia

189

Sunspot Umbral Dots Detected with the New Solar Telescope  

NASA Astrophysics Data System (ADS)

We present a study of bright umbral dots detected inside a large sunspot of NOAA AR 11108. This study is based on high resolution data recorded on September 20, 2010 with the New Solar Telescope (NST) at Big Bear Solar Observatory. The data set, spanning 46 min, consists of a total of 184 adaptive optics corrected and speckle reconstructed images obtained with a 0.3 nm passband TiO filter centered on the 705.7 nm spectral line. The image cadence is 15 s and the pixel size of 0.0375 arcsec. Bright umbral dots (UDs) were detected and tracked using an automatic routine. Here we only focus on long living UDs (>150 s in life time) and a total of 513 such features were detected during the observed period. We found that the average lifetime of a UD is 7.4 min and an average size is 0.34 arcsec. There is a tendency for larger UDs to be brighter (and more circular). Many UDs are not of circular shape. We will also present probability distribution of various physical parameters and compare the results to similar earlier studies.

Kilcik, Ali; Yurchyshyn, V.; Abramenko, V.; Goode, P.; Cao, W.

2011-05-01

190

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

191

ATST telescope pier  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world with a 4m aperture primary mirror. The off axis nature of the telescope optical layout, has the proportions of an 8 metre class telescope. Accordingly the instrumentation for solar observations a 16m diameter co-rotating laboratory (Coude Rotator) is also located within the telescope pier. The pier has a lower cylindrical profile with an upper conical section to support both the telescope mount with a 9m bearing diameter and contain the 16m diameter Coudé rotator. The performance of this pier cannot be considered in isolation but must account for ancillary equipment, access and initial installation. The Coude rotator structure and bearing system are of similar size to the telescope base structure and therefore this is the proverbial 'ship in a bottle' problem. This paper documents the competing requirements on the pier design and the balancing of these as the design progresses. Also summarized is the evolution of the design from a conceptual traditional reinforced concrete pier to a composite concrete and steel framed design. The stiffness requirements of the steel frame was a unique challenge for both the theoretical performance and overall design strategy considering constructability. The development of design acceptance criteria for the pier is discussed along with interfacing of the AandE firm responsible for the pier design and the telescope designer responsible for the telescope performance.

Jeffers, Paul; Manuel, Eric; Dreyer, Oliver; Kärcher, Hans

2012-09-01

192

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

193

The 1.6 m Off-Axis New Solar Telescope (NST) in Big Bear  

NASA Astrophysics Data System (ADS)

The New Solar Telescope (NST) in Big Bear is the first facility-class solar telescope built in the US in a generation, and it has an off-axis design as is planned for the Advanced Technology Solar Telescope (ATST). The NST is in regular operation with adaptive optics (AO) correcting the light currently feeding photometric and near-IR polarimetric systems, as well as an imaging spectrograph. Here we show the high resolution capabilities of the NST. As well, we sketch our plans for, and reasoning behind the next generation NST instrumentation.

Goode, P. R.; Cao, W.

2012-12-01

194

Solar System Observations with Spitzer Space Telescope: Preliminary Results  

NASA Technical Reports Server (NTRS)

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 microns, and the detection of emission bands in the spectra of several distant asteroids (Trojans) around 10 and 25 microns. 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 AW(sub l97)] has an albedo of 0.17 plus or minus 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 plus or minus 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.

2005-01-01

195

GoldHelox solar x-ray telescope testing progress report  

Microsoft Academic Search

The GoldHelox Solar X-ray Telescope underwent several tests during the years of 1997 - 1999, and continues through the testing phase of the project. The instrument itself, a solar telescope to ride on board the Space Shuttle, is designed to photograph the sun in soft x-ray wavelengths between 171 angstroms to 181 angstroms. Critical to its success, many tests are

Jonathan P. Barnes; Peter W. Roming; J. W. Moody; R. S. Turley; Paul F. Eastman; T. Lloyd; K. D. Eldredge; Allen L. Raines; J. Cary Reily; Jeffrey R. Kegley; John W. Keidel; Jeff E. McCracken; Kenneth M. Whitley; Ernest R. Wright; Markus A. Baker; James R. Carpenter; D. G. Chavers; Harlan J. Haight; K. Barry Hale; Thomas A. Hill; David R. Javins; Joseph K. Norwood; Richard D. Siler; John M. Tucker; David W. Watson; R. Takahashi

2000-01-01

196

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

197

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

Microsoft Academic Search

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

Joseph B. Houston

2002-01-01

198

TINY PORES OBSERVED BY HINODE/SOLAR OPTICAL TELESCOPE  

SciTech Connect

The study of pores, small penumbraless sunspots, can give us a chance to understand how strong magnetic fields interact with convective motions in the photosphere. For a better understanding of this interaction, we investigate the temporal variation of several tiny pores smaller than 2''. These pores were observed by the Solar Optical Telescope on board Hinode on 2006 December 29. We have analyzed the high-resolution spectropolarimetric (SP) data and the G-band filtergrams taken during the observation. Magnetic flux density and Doppler velocities of the pores are estimated by applying the center-of-gravity method to the SP data. The horizontal motions in and around the pores are tracked by adopting the nonlinear affine velocity estimator method to the G-band filter images. As a result, we found the following. (1) The darkness of the pores is positively correlated with the magnetic flux density. (2) Downflows always exist inside and around the pores. (3) The speed of downflows inside the pores is negatively correlated with their darkness. (4) The pores are surrounded by strong downflows. (5) Brightness changes of the pores are correlated with the divergence of mass flow (correlation coefficient >0.9). (6) The pores in the growing phase are associated with the converging flow pattern and the pores in the decay phase with the diverging flow pattern. Our results support the idea that a pore grows as the magnetic flux density increases due to the convergence of ambient mass flow and it decays with the decrease of the flux density due to the diverging mass flow.

Cho, Kyung-Suk; Bong, Su-Chan; Kim, Yeon-Han; Park, Young-Deuk [Korea Astronomy and Space Science Institute, Daejeon, 305-348 (Korea, Republic of); Chae, Jongchul, E-mail: kscho@kasi.re.k [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

2010-11-01

199

A Large Sparse Aperture Densified Pupil Hypertelescope Concept for Ground Based Detection of Extra-Solar Earth-Like Planets  

NASA Technical Reports Server (NTRS)

A concept is presented for a large (10 - 30 meter) sparse aperture hyper telescope to image extrasolar earth-like planets from the ground in the presence of atmospheric seeing. The telescope achieves high dynamic range very close to bright stellar sources with good image quality using pupil densification techniques. Active correction of the perturbed wavefront is simplified by using 36 small flat mirrors arranged in a parabolic steerable array structure, eliminating the need for large delat lines and operating at near-infrared (1 - 3 Micron) wavelengths with flats comparable in size to the seeing cells.

Gezari, D.; Lyon, R.; Woodruff, R.; Labeyrie, A.; Oegerle, William (Technical Monitor)

2002-01-01

200

Kees Zwaan, open principle, future of high-resolution solar telescopes  

NASA Astrophysics Data System (ADS)

It was around the 1970s that during site-test campaigns masts were erected up till 30 m height with sensors at several heights for the measurement of temperature fluctuations. Kees Zwaan discovered that the fluctuations decrease drastically at heights from about 15 m and upward when there is some wind. The conclusion from this experience was the open telescope principle: a telescope completely free in the air 15 m or more above the ground. The Dutch Open Telescope (DOT) was the pioneering demonstrator of the open-telescope technology. Now that larger high-resolution telescopes come in view, it is time to analyze again the principle: the essentials for proper working of the open principle and the design consequences for the new generation of high-resolution solar telescopes.

Hammerschlag, R. H.; Bettonvil, F. C. M.

2013-01-01

201

Wavefront sensing and wavefront reconstruction for the 4m European Solar Telescope EST  

NASA Astrophysics Data System (ADS)

We give an overview of the Adaptive Optics (AO) and Multi-conjugate Adaptive Optics (MCAO) system of the planned 4m European Solar Telescope (EST). The parameter space and the problems of solar MCAO working in the visible are explained. The wavefront reconstruction schemes presently being considered are explained. First estimates of the expected MCAO performance for varying parameter sets are given.

Berkefeld, Thomas; Soltau, Dirk; Del Moro, Dario; Löfdahl, Mats

2010-07-01

202

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 electromagnetic 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 W.

2011-05-19

203

Turbulent kinetic energy spectra of solar convection from New Solar Telescope observations and realistic magnetohydrodynamic simulations  

NASA Astrophysics Data System (ADS)

Turbulent properties of the quiet Sun represent the basic state of surface conditions and a background for various processes of solar activity. Therefore, understanding the properties and dynamics of this ‘basic’ state is important for the investigation of more complex phenomena, the formation and development of observed phenomena in the photosphere and atmosphere. For the characterization of turbulent properties, we compare the kinetic energy spectra on granular and sub-granular scales obtained from infrared TiO observations with the New Solar Telescope (Big Bear Solar Observatory) and from three-dimensional radiative magnetohydrodynamic (MHD) numerical simulations (‘SolarBox’ code). We find that the numerical simulations require high spatial resolution with a 10-25 km grid step in order to reproduce the inertial (Kolmogorov) turbulence range. The observational data require an averaging procedure to remove noise and potential instrumental artifacts. The resulting kinetic energy spectra reveal good agreement between the simulations and the observations, opening up new perspectives for detailed joint analyses of more complex turbulent phenomena on the Sun and possibly on other stars. In addition, using the simulations and observations, we investigate the effects of a background magnetic field, which is concentrated in self-organized complicated structures in intergranular lanes, and observe an increase of the small-scale turbulence energy and its decrease at larger scales due to magnetic field effects.

Kitiashvili, I. N.; Abramenko, V. I.; Goode, P. R.; Kosovichev, A. G.; Lele, S. K.; Mansour, N. N.; Wray, A. A.; Yurchyshyn, V. B.

2013-07-01

204

WILL THE LARGE SYNOPTIC SURVEY TELESCOPE DETECT EXTRA-SOLAR PLANETESIMALS ENTERING THE SOLAR SYSTEM?  

SciTech Connect

Planetesimal formation is a common by-product of the star formation process. Taking the dynamical history of the solar system as a guideline-in which the planetesimal belts were heavily depleted due to gravitational perturbation with the giant planets-and assuming similar processes have taken place in other planetary systems, one would expect the interstellar space to be filled with extra-solar planetesimals. However, not a single one of these objects has been detected so far entering the solar system, even though it would clearly be distinguishable from a solar system comet due to its highly hyperbolic orbit. The Large Synoptic Survey Telescope (LSST) will provide wide coverage maps of the sky to a very high sensitivity, ideal to detect moving objects like comets, both active and inactive. In anticipation of these observations, we estimate how many inactive 'interstellar comets' might be detected during the duration of the survey. The calculation takes into account estimates (from observations and models) of the number density of stars, the amount of solids available to form planetesimals, the frequency of planet and planetesimal formation, the efficiency of planetesimal ejection, and the possible size distribution of these small bodies.

Moro-Martin, Amaya [Centro de AstrobiologIa (CSIC-INTA), 28850 Torrejon de Ardoz, Madrid (Spain); Turner, Edwin L. [Princeton University Observatory, Princeton, NJ 08544 (United States); Loeb, Abraham [Harvard University, Center for Astrophysics, MS 51, 60 Garden Street, Cambridge, MA 02138 (United States)

2009-10-10

205

ATST telescope mount: telescope of machine tool  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) will be the largest solar telescope in the world, and will be able to provide the sharpest views ever taken of the solar surface. The telescope has a 4m aperture primary mirror, however due to the off axis nature of the optical layout, the telescope mount has proportions similar to an 8 meter class telescope. The technology normally used in this class of telescope is well understood in the telescope community and has been successfully implemented in numerous projects. The world of large machine tools has developed in a separate realm with similar levels of performance requirement but different boundary conditions. In addition the competitive nature of private industry has encouraged development and usage of more cost effective solutions both in initial capital cost and thru-life operating cost. Telescope mounts move relatively slowly with requirements for high stability under external environmental influences such as wind buffeting. Large machine tools operate under high speed requirements coupled with high application of force through the machine but with little or no external environmental influences. The benefits of these parallel development paths and the ATST system requirements are being combined in the ATST Telescope Mount Assembly (TMA). The process of balancing the system requirements with new technologies is based on the experience of the ATST project team, Ingersoll Machine Tools who are the main contractor for the TMA and MT Mechatronics who are their design subcontractors. This paper highlights a number of these proven technologies from the commercially driven machine tool world that are being introduced to the TMA design. Also the challenges of integrating and ensuring that the differences in application requirements are accounted for in the design are discussed.

Jeffers, Paul; Stolz, Günter; Bonomi, Giovanni; Dreyer, Oliver; Kärcher, Hans

2012-09-01

206

Optomechanical and thermal design of the Multi-Application Solar Telescope for USO  

NASA Astrophysics Data System (ADS)

The Multi-Application Solar Telescope (MAST) is a 50 cm diameter class telescope to be installed on the Udaipur Solar Observatory's Island on the Lake Fatehsagar in Udaipur, India. It is dedicated to solar observation. The telescope is designed, manufactured, assembled and installed on-site by the belgian company AMOS SA for the Udaipur Solar Observatory (USO), an academic division of the Physical Research Laboratory (PRL) in India. Despite its limited size, the telescope is expected to be competitive with respect to worldwide large and costly projects thanks to its versatility regarding science goals and also thanks to its demanding optomechanical and thermal specification. This paper describes the optomechanical and thermal design of this telescope and presents solutions adopted by AMOS to meet the specific requirements. The optical configuration of the telescope is based on an afocal off-axis gregorian combination integrated on an Alt.-Az. mechanical mount, with a suite of flat folding mirrors to provide the required stationary collimated beam.

Denis, Stefan; Coucke, Pierre; Gabriel, Eric; Delrez, Christophe; Venkatakrishnan, Parameshwaran

2008-08-01

207

Fast Imaging Solar Spectrograph of the 1.6 Meter New Solar Telescope at Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

For high resolution spectral observations of the Sun - particularly its chromosphere, we have developed a dual-band echelle spectrograph named Fast Imaging Solar Spectrograph (FISS), and installed it in a vertical optical table in the Coudé Lab of the 1.6 meter New Solar Telescope at Big Bear Solar Observatory. This instrument can cover any part of the visible and near-infrared spectrum, but it usually records the H? band and the Ca ii 8542 Å band simultaneously using two CCD cameras, producing data well suited for the study of the structure and dynamics of the chromosphere and filaments/prominences. The instrument does imaging of high quality using a fast scan of the slit across the field of view with the aid of adaptive optics. We describe its design, specifics, and performance as well as data processing

Chae, Jongchul; Park, Hyung-Min; Ahn, Kwangsu; Yang, Heesu; Park, Young-Deuk; Nah, Jakyoung; Jang, Bi Ho; Cho, Kyung-Suk; Cao, Wenda; Goode, Philip R.

2013-11-01

208

Evaluation of the cosmic-ray induced background in coded aperture high energy gamma-ray telescopes  

NASA Technical Reports Server (NTRS)

While the application of coded-aperture techniques to high-energy gamma-ray astronomy offers potential arc-second angular resolution, concerns were raised about the level of secondary radiation produced in a thick high-z mask. A series of Monte-Carlo calculations are conducted to evaluate and quantify the cosmic-ray induced neutral particle background produced in a coded-aperture mask. It is shown that this component may be neglected, being at least a factor of 50 lower in intensity than the cosmic diffuse gamma-rays.

Owens, Alan; Barbier, Loius M.; Frye, Glenn M.; Jenkins, Thomas L.

1991-01-01

209

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

210

Thermal analysis of the baffle structure of the Solar Space Telescope  

Microsoft Academic Search

The SST (Space Solar Telescope) is an astronomical telescope with a primary mirror of 1 m in diameter. It observes the sun\\u000a with a small view field to ensure that its high spatial resolution imaging has 0.1?–0.15? and high SNR (signal to noise ratio).\\u000a Surrounding the small view field is still the sun, which is an intense source of both

Rong Li; Sen Wang

2010-01-01

211

The 1.6 m off-axis New Solar Telescope (NST) in Big Bear  

NASA Astrophysics Data System (ADS)

The 1.6-m New Solar Telescope (NST) has been used to observe the Sun for more than three years with ever increasing capabilities as its commissioning phase winds down. The NST is the first facility-class solar telescope built in the U.S. in a generation, and it has an off-axis design as is planned for the 4 m Advanced Technology Solar Telescope. Lessons learned will be discussed. Current NST post-focus instrumentation includes adaptive optics (AO) feeding photometric and near-IR polarimetric sytems, as well as an imaging spectrograph. On-going instrumentation projects will be sketched, including Multi-Conjugate AO (MCAO), next generation (dual Fabry- Perot) visible light and near-IR polarimeters and a fully cryogenic spectrograph. Finally, recent observational results illustrating the high resolution capabilities of the NST will be shown.

Goode, Philip R.; Cao, Wenda

2012-09-01

212

Solar Tests of Aperture Plate Materials for Solar Thermal Dish Collectors.  

National Technical Information Service (NTIS)

In parabolic dish solar collectors, walk-off of the spot of concentrated sunlight can be a hazard if a malfunction causes the concentration to stop following the sun. Therefore, a test program was carried out to evaluate the behavior of various ceramics, ...

L. D. Jaffe

1983-01-01

213

Active reconstruction and alignment strategies for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) is a 4m off-axis telescope with a Gregorian front end. At the time of its construction it will be the world's largest solar astronomical telescope. During scientific operations the ATST mirrors and structure will be deformed due to thermal and gravitational loading. The ATST team has developed a quasi-static alignment scheme that utilizes the wavefront sensing signals from at least one and as many as three wavefront sensors in the telescope science field of view, and active figure control of the primary mirror and rigid body control of the secondary mirror to achieve least-squares optical control of the telescope. This paper presents the quasi-static alignment model for the ATST, and three different active alignment schemes that are the damped least-squares control, force optimized control that defines a least-squares aligned state of the telescope subject to minimum primary actuator force, and pivot-point control of the secondary mirror. All three strategies achieve the desired minimum RMS wavefront error, but demonstrate different optimized states of the telescope.

Upton, Robert; Rimmele, Thomas

2010-08-01

214

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

215

Solar tests of aperture plate materials for solar thermal dish collectors  

NASA Technical Reports Server (NTRS)

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.

1983-01-01

216

Solar neutrino detection utilizing a variant of a coded aperture on a large scale (HERON)  

NASA Astrophysics Data System (ADS)

A neutrino-electron scattering occuring in liquid 4 He results in an energetic electron that deposits its energy into the liquid through various mechanics. Some of this energy deposition is released in the form of detectable signals, among which is the scintillation signals: photons in the extreme ultraviolet range. The isotropic scintillation signal can be detected and analysed to reconstruct the energy and position of the original electron in the neutrino scattering, which provides information regarding the energy spectrum of the neutrino flux itself. In one proposed version of a neutrino detector, the scintillation signals are observed using ~2000 sensors capable of detecting individual 16 eV photons. Each of these sensor is a calorimeter in the shape of a thin metallic film deposited on a large wafer. The wafers are arranged in two parallel planes above the liquid body, forming a coded-aperture imaging array. Large numbers of Monte Carlo events are generated with various sets of design parameters of the system, and the systematic and statistical behavior is studied to decide the optimal design and its accuracy in determining solar neutrino fluxes. This method of detecting scintillation signals is intended to be used in HERON, a proposed detector for low energy solar neutrinos-- pp and 7 Be neutrinos from the Sun. The study shows that, at temperatures below 40 mK, with ~40 ton-year worth of fiducial events from the 4 He body, the pp and 7 Be solar neutrino fluxes can be determined with a combined systematic and statistical error of < 1.5% for total flux, and separately < 1.7% for pp and < 3.5% for 7 Be.

Huang, Yun-Hu

2007-08-01

217

Thermal Implications from the Hubble Space Telescope Solar Array Bi-Stem Boom in-Orbit Disturbance.  

National Technical Information Service (NTIS)

The Hubble Space Telescope, launched on Apr. 24 1990, has two solar array wings. After the deployment of the arrays in orbit, attitude control disturbances were apparent, affecting the telescope, and which are believed to be due to the solar arrays. The m...

P. Poinas G. I. M. Beere

1991-01-01

218

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

219

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

220

OSCILLATORY BEHAVIOR IN THE QUIET SUN OBSERVED WITH THE NEW SOLAR TELESCOPE  

SciTech Connect

Surface photometry of the quiet Sun has achieved an angular resolution of 0.''1 with the New Solar Telescope at Big Bear Solar Observatory, revealing that a disproportionate fraction of the oscillatory events appear above observed bright point-like structures. During the tracking of these structures, we noted that the more powerful oscillatory events are cospatial with them, indicating that observed flux tubes may be the source of many observed oscillatory events.

Andic, A.; Goode, P. R.; Cao, W.; Yurchyshyn, V.; Abramenko, V. [Big Bear Solar Observatory, 40386 North Shore Lane, Big Bear City, CA 92314 (United States); Chae, J.; Ahn, K. [Also at Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-741 (Korea, Republic of)

2010-07-10

221

Radiation concerns for the Solar-A soft x-ray telescope  

Microsoft Academic Search

The charge-coupled device (CCD) camera of the Soft X-ray Telescope (SXT) for the Japanese Solar-A Mission utilizes a 1024 X 1024 virtual phase CCD manufactured by Texas Instruments in Japan. This sensor will be subject to radiation in the form of trapped protons from the earth's radiation belts and soft x-rays (0.2-4 keV) in the solar image. Proton damage produces

Loren W. Acton; Mons D. Morrison; James R. Janesick; Tom S. Elliott

1991-01-01

222

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

223

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

Microsoft Academic Search

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

S. V. Lesovoy

2002-01-01

224

Summary of studies for a solar optical telescope in space: 1968-1976  

NASA Technical Reports Server (NTRS)

The primary objective of this review is to tabulate the basic recommendations of several solar telescope studies. A primary matrix, listing some of the basic optical parameters, was compiled and forms the basis for a table. From this table it is apparent that a strong consensus exists on the configuration of the telescope and on its fundamental dimensionless parameters. Other tables presented in this document address the basic approach of each study to the telescope design as well as to the design of critical subsystems. These subsystem problems include the material, coating, configuration, mounting, launch locks, and thermal control of the primary mirror, the structure of the main telescope and the instrument bay, the mechanisms for radiation rejection, thermal control, and meteoroid shielding, and methods of maintaining image quality by proper alignment and by image motion compensation.

Bremer, J.; Kaul, R.

1976-01-01

225

Quasi-static wavefront control for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) requires active control of quasi-static telescope aberrations in order to meet image quality standards set by its science requirements. Wavefront control is managed by the Telescope Control System, with many telescope subsystems playing key roles. We present the design of the ATST quasi-static wavefront and alignment control architecture and the algorithms used to control its four active mirrors. Two control algorithms are presented, one that minimizes force on M1 actuators and another that employs a neutral-pointing constraint on M2 to reduce pointing error. We also present simulations that generate typical daily active mirror trajectories which correct optical misalignments due to changing gravitational and thermal loads.

Johnson, Luke C.; Upton, R.; Rimmele, T.; Barden, S.

2012-09-01

226

Seeing the Deep Sky: Telescopic Astronomy Projects Beyond the Solar System  

Microsoft Academic Search

Packed with a vast array of telescopic projects involving different kind of stars, star clusters, nebulae and galaxies which lie beyond our solar system. Takes a look at stars of diverse chemical or atomic ``brew'', old and new, tiny or vast, dense or tenuous; the ways in which they behave and much more.

Fred Schaaf

1992-01-01

227

Exploring the Solar System, the Galaxies, and the Universe with the Hubble Space Telescope  

NSDL National Science Digital Library

The Hubble Telescope site (http://hubblesite.org) contains numerous teaching tools including videos, news articles about the solar system and the Universe, and games that introduce and reinforce astronomy and space science content and concepts. Teachers can design activities for multiple grade levels using the site as a foundation.

Dodge, Rebecca

228

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

229

OpTIIX: An ISS-Based Testbed Paving the Roadmap Toward a Next Generation Large Aperture UV/Optical Space Telescope  

NASA Technical Reports Server (NTRS)

The next generation large aperture UV/Optical space telescope will need a diameter substantially larger than even that of JWST in order to address some of the most compelling unanswered scientific quests. These quests include understanding the earliest phases of the Universe and detecting life on exo-planets by studying spectra of their atmospheres. Such 8-16 meter telescopes face severe challenges in terms of cost and complexity and are unlikely to be affordable unless a new paradigm is adopted for their design and construction. The conventional approach is to use monolithic or preassembled segmented mirrors requiring complicated and risky deployments and relying on future heavy-lift vehicles, large fairings and complex geometry. The new paradigm is to launch component modules on relatively small vehicles and then perform in-orbit robotic assembly of those modules. The Optical Testbed and Integration on ISS eXperiment (OpTIIX) is designed to demonstrate, at low cost by leveraging the infrastructure provided by ISS, telescope assembly technologies and end-to-end optical system technologies. The use of ISS as a testbed permits the concentration of resources on reducing the technical risks associated with robotically integrating the components. These include laser metrology and wavefront sensing and control (WFS&C) systems, an imaging instrument, lightweight, low-cost deformable primary mirror segments and the secondary mirror. These elements are then aligned to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems like the Special Purpose Dexterous Manipulator (SPDM), or by the ISS flight crew, allows for future experimentation, as well as repair.

Carpenter, Kenneth G.; Etemad, Shar; Seery, Bernard D.; Thronson, Harley; Burdick, Gary M.; Coulter, Dan; Goullioud, Renaud; Green, Joseph J.; Liu, Fengchuan; Ess, Kim; Postman, Marc; Sparks, Williams

2012-01-01

230

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

231

Pilot installation of the gallium-germanium solar neutrino telescope  

Microsoft Academic Search

The advantages and disadvantages of using a metal gallium target in a gallium solar neutrino experiment are briefly reviewed, and a pilot gallium-germanium installation using 7 tons of gallium metal is described. In particular, attention is given to the chemical procedure, the counting system, and preliminary results of Ge-71 and Ge-69 yields from cosmic rays. Finally, the possibility of conducting

I. R. Barabanov; E. P. Veretenkin; V. N. Gavrin; S. N. Danshin; L. A. Eroshkina; G. T. Zatsepin; Y. I. Zakharov; S. A. Klimova; Y. B. Klimov; T. V. Knodel

1985-01-01

232

The x-ray/EUV telescope for the Solar-C mission: science and development activities  

NASA Astrophysics Data System (ADS)

We report science and development activities of the X-ray/EUV telescope for the Japanese Solar-C mission whose projected launch around 2019. The telescope consists of a package of (a) a normal-incidence (NI) EUV telescope and (b) a grazing-incidence (GI) soft X-ray telescope. The NI telescope chiefly provides images of low corona (whose temperature 1 MK or even lower) with ultra-high angular resolution (0.2-0.3"/pixel) in 3 wavelength bands (304, 171, and 94 angstroms). On the other hand, the GI telescope provides images of the corona with a wide temperature coverage (1 MK to beyond 10 MK) with the highest-ever angular resolution (~0.5"/pixel) as a soft X-ray coronal imager. The set of NI and GI telescopes should provide crucial information for establishing magnetic and gas-dynamic connection between the corona and the lower atmosphere of the Sun which is essential for understanding heating of, and plasma activities in, the corona. Moreover, we attempt to implement photon-counting capability for the GI telescope with which imaging-spectroscopy of the X-ray corona will be performed for the first time, in the energy range from ~0.5 keV up to 10 keV. The imaging-spectroscopic observations will provide totally-new information on mechanism(s) for the generation of hot coronal plasmas (heated beyond a few MK), those for magnetic reconnection, and even generation of supra-thermal electrons associated with flares. An overview of instrument outline and science for the X-ray photoncounting telescope are presented, together with ongoing development activities in Japan towards soft X-ray photoncounting observations, focusing on high-speed X-ray CMOS detector and sub-arcsecond-resolution GI mirror.

Sakao, Taro; Narukage, Noriyuki; Imada, Shinsuke; Suematsu, Yoshinori; Shimojo, Masumi; Tsuneta, Saku; DeLuca, Edward E.; Watanabe, Kyoko; Ishikawa, Shin-nosuke

2012-09-01

233

Mapping the kinematics and chemistry of the Solar neighborhood with a 61cm telescope  

NASA Astrophysics Data System (ADS)

The 61cm Varese telescope and its Multi Mode Spectrograph operated in the Echelle mode is used to observe nearby Red Clump stars in the Solar neighborhood, with more distant ones being targeted by Asiago 1.22m and 1.82m telescopes. So far high resolution, high S/N spectra of 260 program RC stars have been obtained (85 on a 2nd epoch) providing radial velocities accurate to 0.7 km/s, Teff to 56 K, logg to 0.21 dex, and [M/H] to 0.11 dex.

Milani, A.; Valisa, P.; Munari, U.

2014-03-01

234

The Soft X-ray Telescope for Solar-A - Design evolution and lessons learned  

NASA Astrophysics Data System (ADS)

The Japanese Solar-A satellite mission's Soft X-ray Telescope uses grazing-incidence optics, a CCD detector, and a pair of filter wheels for wavelength selection. A coaxially-mounted visible-light lens furnished sunspot and magnetic plage images, together with aspect information which aids in aligning the soft X-ray images with those from the satellite's Hard X-ray Telescope. Instrument electronics are microprocessor-based, and imbedded in a tightly integrated distributed system. Control software is divided between the instrument microprocessor and the spacecraft control computer.

Bruner, Marilyn E.

1992-01-01

235

Results of the multi-conjugate adaptive optics system at the German solar telescope, Tenerife  

NASA Astrophysics Data System (ADS)

We present the optical setup, reconstruction scheme and observational results of the Multi-conjugate Adaptive Optics (MCAO) system at the German 70cm Vacuum Tower Telescope, Observatorio del Teide, Tenerife. The system serves as a testbed for the future MCAO of the new 1.5m GREGOR solar telescope and is an extension of the conventional Adaptive Optics (CAO) system. We demonstrate that the use of one additional MCAO wavefront sensor and one additional deformable mirror increases the corrected field of view from 10 to 35 arcseconds.

Berkefeld, Thomas; Soltau, Dirk; von der Luehe, Oskar

2005-08-01

236

Astrometry of Outer Solar System Bodies - Experience with a Small Telescope and Future Plans  

NASA Astrophysics Data System (ADS)

Astrometry of faint and slowly moving objects in the outer solar system is considered to be the target for large telescopes, but in special cases observations using small telescopes were obtained. We have measured precise positions of several Centaur-type asteroids (including recovery of 1997 CU26) and also of the Transneptunian Object 1996 TL66 using a 0.57-m reflector equipped with a CCD at the Klet' Observatory. This work will be extended to fainter objects with new 1.02-m reflector at Klet', whose start of operation is planned at the turn of 1998/1999.

Tichá, Jana; Tichý, Miloš; Moravec, Zden?k

237

Grazing-incidence telescope-spectrograph for space solar-imaging spectroscopy.  

PubMed

The design of a stigmatic grazing-incidence instrument for space applications to solar-imaging spectroscopy is presented. It consists of a double telescope and a spectrograph: Telescope I consists of a single cylindrical mirror with parabolic section, focusing the radiation on the entrance slit of the spectrograph in the spectral dispersion plane; telescope II consists of two cylindrical mirrors with aspherical section in a Wolter configuration, focusing the radiation on the spectrograph focal plane in the direction perpendicular to the spectral dispersion plane. The spectrograph consists of a grazing-incidence spherical variable-line-spaced grating with flat-field properties. Telescope II is crossed with respect to the grating and telescope I; i.e., it is mounted with its tangential planes coincident with the grating equatorial plane. The spectrum is acquired by a detector mounted at near-normal incidence with respect to the direction of the exit beam. The spectral resolution is also preserved for off-axis angles. The effective collecting area of the instrument can be preserved by adoption of a nested configuration for telescope II without degradation of the spectral resolution. PMID:18357295

Poletto, L; Tondello, G

2001-06-01

238

Gregor@night: The future high-resolution stellar spectrograph for the GREGOR solar telescope  

NASA Astrophysics Data System (ADS)

We describe the future night-time spectrograph for the GREGOR solar telescope and present its science core projects. The spectrograph provides a 3-pixel resolution of up to R=87 000 in 45 échelle orders covering the wavelength range 390-900 nm with three grating settings. An iodine cell can be used for high-precision radial velocity work in the 500-630 nm range. The operation of the spectrograph and the telescope will be fully automated without the presence of humans during night-time and will be based on the successful STELLA control system. Future upgrades include a second optical camera for even higher spectral resolution, a Stokes-V polarimeter and a link to the laser-frequency comb at the Vacuum Tower Telescope. The night-time core projects are a study of the angular-momentum evolution of ``The Sun in Time'' and a continuation of our long-term Doppler imaging of active stars.

Strassmeier, K. G.; Ilyin, I. V.; Woche, M.; Granzer, T.; Weber, M.; Weingrill, J.; Bauer, S.-M.; Popow, E.; Denker, C.; Schmidt, W.; von der Lühe, O.; Berdyugina, S.; Collados, M.; Koubsky, P.; Hackman, T.; Mantere, M. J.

2012-11-01

239

Study of a Solar X-Ray Telescope  

NASA Technical Reports Server (NTRS)

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 10(exp 4) K to greater than 10(exp 6) 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 10(exp 6) K, a particle density of 10(exp 9)/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 observ

Golub, Leon

1997-01-01

240

Scientific Programmes with India's National Large Solar Telescope and their contribution to Prominence Research  

NASA Astrophysics Data System (ADS)

The primary objective of the 2-m National Large Solar Telescope (NLST) is to study the solar atmosphere with high spatial and spectral resolution. With an innovative optical design, NLST is an on-axis Gregorian telescope with a low number of optical elements and a high throughput. In addition, it is equipped with a high order adaptive optics system to produce close to diffraction limited performance. NLST will address a large number of scientific questions with a focus on high resolution observations. With NLST, high spatial resolution observations of prominences will be possible in multiple spectral lines. Studies of magnetic fields, filament eruptions as a whole, and the dynamics of filaments on fine scales using high resolution observations will be some of the major areas of focus.

Hasan, S. S.

2014-01-01

241

Solar-Array-Induced Disturbance of the Hubble Space Telescope Pointing System  

NASA Technical Reports Server (NTRS)

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.

1995-01-01

242

The solar array-induced disturbance of the Hubble Space Telescope pointing system  

NASA Technical Reports Server (NTRS)

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 magnitudes of the disturbances were considerably larger than the design jitter requirements. 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, C. L.; Tinker, M. L.; Nurre, G. S.; Till, W. A.

1995-01-01

243

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

244

The 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 magnitudes of the disturbances were considerably larger than the design jitter requirements. 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, C. L.; Tinker, M. L.; Nurre, G. S.; Till, W. A.

1995-05-01

245

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

246

Multi-Spectral Solar Telescope Array. II - Soft X-ray/EUV reflectivity of the multilayer mirrors  

NASA Technical Reports Server (NTRS)

The Multispectral Solar Telescope Array is a rocket-borne observatory which encompasses seven compact soft X-ray/EUV, multilayer-coated, and two compact far-UV, interference film-coated, Cassegrain and Ritchey-Chretien telescopes. Extensive measurements are presented on the efficiency and spectral bandpass of the X-ray/EUV telescopes. Attention is given to systematic errors and measurement errors.

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

1991-01-01

247

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

248

Multi-Spectral Solar Telescope Array. IV - The soft X-ray and extreme ultraviolet filters  

NASA Technical Reports Server (NTRS)

NASA's Multi-Spectral Solar Telescope Array uses various combinations of thin foil filters composed of Al, C, Te, Be, Mo, Rh, and phthalocyanine to achieve the requisite radiation-rejection characteristics. Such rejection is demanded by the presence of strong EUV radiation at longer wavelengths where the specular reflectivity of multilayer mirrors can cause 'contamination' of the image in the narrow band defined by the Bragg condition.

Lindblom, Joakim F.; O'Neal, Ray H.; Walker, Arthur B. C., Jr.; Powell, Forbes R.; Barbee, Troy W., Jr.; Hoover, Richard B.

1991-01-01

249

The chemistry of micrometeoroid and space debris remnants captured on hubble space telescope solar cells  

Microsoft Academic Search

Prior to the retrieval in 1993 from low Earth orbit (LEO), the “—V2” Solar Array wing of the Hubble Space Telescope was exposed to hypervelocity impacts (micrometre to millimetre scale) from both micrometeoroids and space debris. The initial survey of the damage (100–3500?m diameter sized craters) identified that micrometeoroid remnants dominated the flux in the 100–1000?m size regime, with debris

G. A. Graham; N. McBride; A. T. Kearsley; G. Drolshagen; S. F. Green; J. A. M. McDonnell; M. M. Grady; I. P. Wright

2001-01-01

250

Focal plane CCD camera for the X-Ray Telescope (XRT) aboard SOLAR-B  

Microsoft Academic Search

We present scientific as well as engineering overview of the X-Ray Telescope (XRT) aboard the Japanese Solar-B mission to be launched in 2006, with emphasis on the focal plane CCD camera that employs a 2k x 2k back-thinned CCD. Characterization activities for the flight CCD camera made at the National Astronomical Observatory of Japan (NAOJ) are discussed in detail with

Taro Sakao; Ryouhei Kano; Hirohisa Hara; Keiichi Matsuzaki; Masumi Shimojo; Saku Tsuneta; Takeo Kosugi; Kiyoto Shibasaki; Kazuyoshi Kumagai; Masaki Sawa; Tomonori Tamura; Satoru Iwamura; Mitsuhiko Nakano; Zhangong Du; Kenji Hiyoshi; Michihiro Horii; Leon Golub; Jay A. Bookbinder; Peter C. Cheimets; Lawrence D. Hill; Jerry K. Owens

2004-01-01

251

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

252

Measurements of local astroclimate characteristics near the Large Solar Vacuum Telescope  

NASA Astrophysics Data System (ADS)

The work presents the results of measuring the characteristics of local astroclimate near the Large Solar Vacuum Telescope (LSVT, located in the Listvyanka village of Irkutsk region). For measurements we used a mobile ultrasonic meteorological system "Meteo2M" designed at the Institute of Atmospheric Optics. The measurements were performed near the telescope and on the telescope siderostat platform near the dome and the mirror. Then we are measuring the high-altitude profiles of the fluctuations of the refractive index (structure constant) C n2 along the telescope tower. It has been established that the profiles of the C n2, the averaged temperature and other parameters do not coincide with the results of the similarity theory for a flat underlying surface. In our measurements the oscillating behaviour of high-altitude profiles is observed. On the basis of the results obtained we can explain the oscillating character by the presence of periodic inhomogeneities of the underlying surface near the telescope, as the surface has various degrees of heating.

Nosov, V. V.; Grigoryev, V. M.; Kovadlo, P. G.; Lukin, V. P.; Torgaev, A. V.

2006-11-01

253

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

254

Solar Polar ORbit Telescope (SPORT): A Potential Space Weather Mission of China  

NASA Astrophysics Data System (ADS)

We describe a spacecraft mission, named Solar Polar ORbit Telescope (SPORT), which is currently under a scientific and engineering background study in China. SPORT was originally proposed in 2004 by the National Space Science Center, Chinese Academy of Sciences. It will carry a suite of remote-sensing and in-situ instruments to observe coronal mass ejections (CMEs), solar high-latitude magnetism, and the fast solar wind from a polar orbit around the Sun. It is intended to be the first mission that carries remote-sensing instruments from a high-latitude orbit around the Sun, the first mission that could image interplanetary CMEs at radio wavelengths from space, and the first mission that could measure solar high-latitude magnetism leading to eruptions and the fast solar wind. The first extended view of the polar region of the Sun and the ecliptic plane enabled by SPORT will provide a unique opportunity to study CME propagation through the inner heliosphere and solar high-latitude magnetism giving rise to eruptions and the fast solar wind.

Liu, Y. D.; Xiong, M.; Wu, J.; Liu, H.; Zheng, J.; Li, B.; Zhang, C.; Sun, W.

2013-12-01

255

Solar Daily Variation Recorded at a Low Latitude Station by East and West Pointing Telescopes During Periods of Maximum and Minimum Solar Activity.  

National Technical Information Service (NTIS)

An examination was made of the characteristics of the solar daily variations recorded by east and west pointing directional telescopes at Mt. Chacaltaya (altitude = 5200 m, geomagnetic latitude = -4.8 degrees) during the years of maximum (1958) and minimu...

H. S. Ahluwalia V. I. Escobar M. Zubieta R. Anda M. Schreier

1965-01-01

256

Experimental study of natural convection heat transfer through an aperture in passive solar heated buildings  

SciTech Connect

The objective of this study is to obtain correlations between natural convection heat transfer through an aperture and temperature difference between the two rooms. A one-fifth similitude model of a two-room building is used. The model is filled with Freon gas to satisfy similarity of the experiment to full-scale conditions in air. The experimental apparatus and experimental techniques are explained. Experimental results are presented in terms of Grashof, Nusselt, and Prandtl numbers. The effects of the height, the width, and the vertical position of the apertures are investigated, as is the effect of the room volume.

Yamaguchi, Kenjiro

1984-01-01

257

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

NASA Technical Reports Server (NTRS)

A new solar gamma-ray telescope is described which is intended to take advantage of current long-duration ballon facilities such as the RACOON system. The primary scientific objective is to detect and measure gamma-ray lines from solar flares, along with the associated low-energy continuum. The proposed instrument is centered on a multiheaded Ge system and is designed to operate over the energy range 50 keV to 200 200 MeV. In the nuclear transition energy region, the average energy resolution of the primary detectors is over 20 times better than that achieved with the gamma-ray spectrometer on the Solar Maximum Mission satellite.

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

1989-01-01

258

Reflectivity, polarization properties, and durability of metallic mirror coatings for the European Solar Telescope  

NASA Astrophysics Data System (ADS)

In the context of the conceptual design study for the European Solar Telescope (EST) we have investigated different metallic mirror coatings in terms of reflectivity, polarization properties and durability. Samples of the following coating types have been studied: bare aluminum, silver with different dielectric layers for protection and UV enhancement, and an aluminum-silver combination. From 2009 to 2011 we have carried out a long-term durability test under realistic observing conditions at the VTT solar telescope of the Observatorio del Teide (Tenerife, Spain), accompanied by repeated reflectivity measurements in the EST spectral working range (0.3 - 20 ?m), and by polarization measurements in the visible range. The test results allow us to find the optimum coatings for the different mirrors in the EST beampath and to eventually assess aging effects and re-coating cycles. The results of the polarization measurements are a valuable input for an EST telescope polarization model, helping to meet the stringent requirements on polarimetric accuracy.

Feller, A.; Krishnappa, N.; Pleier, O.; Hirzberger, J.; Jobst, P. J.; Schürmann, M.

2012-09-01

259

Astroclimate inside the dome of AZT-14 telescope of Sayan Solar Observatory  

NASA Astrophysics Data System (ADS)

This work presents the results of measurements of intradome astroclimate parameters of the AZT-14 telescope of Sayan solar observatory of the ISTP SB. The picture of airflows concerned with the warm air run-out though leaky connections and air mixing inside the telescope after dome opening is obtained. It is shown that the value of the structure characteristic of the refractive index Cn2 in closed and open dome can 1.5-2 times differ. Essential turbulence intensification in front of the entrance telescope mirror when dome opening is ascertained. Strongly unstable stratification near the receiver is observable, caused by the stair opening in the concrete floor of the dome, which can result in intensification of the refractive index fluctuations in the presence of even small heat sources. Conclusions are drawn from the measurements, which can be related to all telescope of the considered class. It is necessary to prevent foreign heat sources in the dome and block warmer airflows from the stair opening; astronomical observations are to be carried out after completion of transient processes related to the dome opening.

Nosov, V. V.; Grigoriev, V. M.; Kovaldo, P. G.; Lukin, V. P.; Papushev, P. G.; Torgaev, A. V.

2008-05-01

260

Solar System Research with the Spacewatch 1.8-m Telescope  

NASA Technical Reports Server (NTRS)

During this grant period, the 1.8-m Spacewatch telescope was put into routine operation to search for asteroids and comets ranging in location from near-Earth space to regions beyond the orbit of Neptune. All of these classes of objects can be detected simultaneously with our uniform scanning procedures. We are studying near Earth objects (NEOs), main belt asteroids, comets, Centaurs, and trans-Neptunian objects (TNOs), as well as the interrelationships of these classes and their bearing on the origin and evolution of the solar system. The Spacewatch 1.8-meter telescope is sensitive to V(mag) < 22.6 in sidereal scanning mode and is able to reach even fainter in longer 'staring' exposures, with a field of view 0.5 degrees square. These faint limits make the operation of the Spacewatch 1.8-m telescope complementary to asteroid surveys being done by other groups. Specifically, EAs smaller than 100 m in diameter and small main belt asteroids can be found, as well as more distant objects such as Centaurs/Scattered Disk Objects (SDOs) and TNOs. The 1.8-m telescope is also being used to do recoveries and astrometry of recently-discovered asteroids that subsequently become too faint for the other groups before good orbits are established.

McMillan, Robert S.

2001-01-01

261

Demonstration of synthetic aperture imaging ladar  

Microsoft Academic Search

The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. This paper details our

W. Buell; N. Marechal; J. Buck; R. Dickinson; D. Kozlowski; T. Wright; S. Beck

2005-01-01

262

Photogrammetric Assessment of the Hubble Space Telescope Solar Arrays During the Second Servicing Mission  

NASA Technical Reports Server (NTRS)

This report documents the photogrammetric assessment of the Hubble Space Telescope (HST) solar arrays conducted by the NASA c Center Image Science and Analysis Group during Second Servicing Mission 2 (SM-2) on STS-82 in February 1997. Two type solar array analyses were conducted during the mission using Space Shuttle payload bay video: (1) measurement of solar array motion due to induced loads, and (2) measurement of the solar array static or geometric twist caused by the cumulative array loading. The report describes pre-mission planning and analysis technique development activities conducted to acquire and analyze solar array imagery data during SM-2. This includes analysis of array motion obtained during SM-1 as a proof-of-concept of the SM-2 measurement techniques. The report documents the results of real-time analysis conducted during the mission and subsequent analysis conducted post-flight. This report also provides a summary of lessons learned on solar array imagery analysis from SM-2 and recommendations for future on-orbit measurements applicable to HST SM-3 and to the International Space Station. This work was performed under the direction of the Goddard Space Flight Center HST Flight Systems and Servicing Project.

Sapp, C. A.; Dragg, J. L.; Snyder, M. W.; Gaunce, M. T.; Decker, J. E.

1998-01-01

263

Rocket studies of solar corona and transition region. [X-Ray spectrometer/spectrograph telescope  

NASA Technical Reports Server (NTRS)

The XSST (X-Ray Spectrometer/Spectrograph Telescope) rocket payload launched by a Nike Boosted Black Brant was designed to provide high spectral resolution coronal soft X-ray line information on a spectrographic plate, as well as time resolved photo-electric records of pre-selected lines and spectral regions. This spectral data is obtained from a 1 x 10 arc second solar region defined by the paraboloidal telescope of the XSST. The transition region camera provided full disc images in selected spectral intervals originating in lower temperature zones than the emitting regions accessible to the XSST. A H-alpha camera system allowed referencing the measurements to the chromospheric temperatures and altitudes. Payload flight and recovery information is provided along with X-ray photoelectric and UV flight data, transition camera results and a summary of the anomalies encountered. Instrument mechanical stability and spectrometer pointing direction are also examined.

Acton, L. W.; Bruner, E. C., Jr.; Brown, W. A.; Nobles, R. A.

1979-01-01

264

Sub-arcsecond Structure and Dynamics of Flare Ribbons Observed with New Solar Telescope  

NASA Astrophysics Data System (ADS)

Emission of solar flares across the electromagnetic spectrum is often observed in the form of two expanding ribbons. The standard flare model explains the flare ribbons as footpoints of magnetic arcades, emitting due to the interaction of energetic particles with the chromospheric plasma. However, the physics of this interaction and properties of the accelerated particles are still unknown. We present results of multiwavelength observations of C2.1 flare of August 15, 2011, observed with the 1.6-meter New Solar Telescope of Big Bear Solar Observatory. These unique data are characterized by the great spatial resolution reaching the telescope diffraction limit with good spectral scanning of H-alpha line, and photospheric imaging. The observations reveal previously unresolved sub-arcsecond structure of the flare ribbons in regions of strong magnetic field. We discuss the fine structure of the flare ribbons, their dynamics, and possible mechanisms of the energy release and transport, using also data from SDO, GOES and FERMI spacecraft.

Sharykin, Ivan; Kosovichev, Alexander G.

2014-06-01

265

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

266

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

267

Stokes imaging polarimetry using image restoration at the Swedish 1-m solar telescope  

NASA Astrophysics Data System (ADS)

Aims: We aim to achieve both high spatial resolution and high polarimetric sensitivity, using an earth-based 1m-class solar telescope, for the study of magnetic fine structure on the surface of the Sun. Methods: We use a setup with 3 high-speed, low-noise cameras to construct datasets with interleaved polarimetric states, particularly suitable for Multi-Object Multi-Frame Blind Deconvolution image restorations. We discuss the polarimetric calibration routine and various potential sources of error in the results. Results: We obtained near diffraction limited images, which have a noise level of ? 10-3 I_cont. We confirm that dark cores have a weaker magnetic field and a lower inclination angle with respect to the solar surface than the edges of the penumbral filament. We demonstrate that the magnetic field strength in faculae-striations is significantly lower than in other nearby parts of the faculae.

van Noort, M. J.; Rouppe van der Voort, L. H. M.

2008-10-01

268

Solar-B X-ray Telescope (XRT) Concept Study Report  

NASA Technical Reports Server (NTRS)

The X-ray observations from the Yohkoh SXT provided the greatest step forward in our understanding of the solar corona in nearly two decades. Expanding on the accomplishments of Yohkoh, we believe that the scientific objectives of the Solar-B mission are achieved with a significantly improved X-ray telescope (XRT) similar to the SXT. The Solar-B XRT will have twice the spatial resolution and a broader temperature response, while building on the knowledge gained from the successful Yohkoh mission. We present the scientific justification for this view, discuss the instrumental requirements that flow from the scientific objectives, and describe the instrumentation to meet these requirements. We then provide a detailed discussion of the design activities carried out during Phase A, noting the conclusions that were reached in terms of their implications for the detailed design activities which are now commencing. Details of the instrument that have changed as a result of the Phase A studied are specifically noted, and areas of concern going into Phase B are highlighted. XRT is a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35cm inner diameter and 2.7m focal length. The 2048x2048 back-illuminated CCD (now an ISAS responsibility) has 13.5 micron pixels, corresponding to 1.0 arcsec and giving full Sun field of view. This will be the highest resolution GI X-ray telescope ever flown for Solar coronal studies, and it has been designed specifically to observe both the high and low temperature coronal plasma. A small optical telescope provides visible light images for co-alignment with the Solar-B optical and EUV instruments. The XRT science team is working in close cooperation with our Japanese colleagues in the design and construction of this instrument. All of the expertise and resources of the High Energy and Solar/Stellar Divisions of the Center for Astrophysics are being made available to this program, and our team will carry its full share of responsibility for mission operations, data reduction and education and public outreach. All aspects of the XRT design were reviewed during Phase A. The study focussed particularly on those aspects that have the greatest affect on instrument performance and extended lifetime, on the image quality error budget, and on the camera (mechanical and electrical) interface and the instrument mounting interfaces. The present instrument design differs in some details from that originally proposed. Selection of the XRT for Phase A study was contingent upon the removal of the camera and its associated electronics, and the acceptance of a stringent cost cap. The removal of the electronics left the XRT without control electronics for the instrument mechanisms. A mechanism controller was therefore added. The removal of the camera resulted in major complications to the integration and test plan. After many discussions, it was decided that the system would be less expensive, and the risk of unacceptable performance lower, if we include a focus mechanism. The remainder of the XRT design baseline matches the proposed configuration. Data requirements for the XRT are driven by the science plans, which are based on the physical processes in the solar outer atmosphere. Discussions to date of the XRT observing plan, both alone and in conjunction with the other Solar-B instruments, shows that the XRT needs 2 Gbits of on-board storage, at least one circulating buffer of 640 Mbits, and twelve 10- minute downlinks per day in order to carry out its required programs.

Golub, Leon

1999-01-01

269

Life Cycle Testing of Viscoelastic Material for Hubble Space Telescope Solar Array 3 Damper  

NASA Technical Reports Server (NTRS)

During the March 2002 Servicing Mission by Space Shuttle (STS 109), the Hubble Space Telescope (HST) was refurbished with two new solar arrays that now provide all of its power. These arrays were built with viscoelastic/titanium dampers, integral to the supporting masts, which reduce the interaction of the wing bending modes with the Telescope. Damping of over 3% of critical was achieved. To assess the damper s ability to maintain nominal performance over the 10-year on-orbit design goal, material specimens were subjected to an accelerated life test. The test matrix consisted of scheduled events to expose the specimens to pre-determined combinations of temperatures, frequencies, displacement levels, and numbers of cycles. These exposure events were designed to replicate the life environment of the damper from fabrication through testing to launch and life on-orbit. To determine whether material degradation occurred during the exposure sequence, material performance was evaluated before and after the accelerated aging with complex stiffness measurements. Based on comparison of pre- and post-life-cycle measurements, the material is expected to maintain nominal performance through end of life on-orbit. Recent telemetry from the Telescope indicates that the dampers are performing nominally.

Maly, Joseph R.; Reed, Benjamin B.; Viens, Michael J.; Parker, Bradford H.; Pendleton, Scott C.

2003-01-01

270

Astroclimate of specialized stations of the Large Solar Vacuum Telescope: Part I  

NASA Astrophysics Data System (ADS)

The paper presents the results of measurements of characteristics of local astroclimate in special production areas of the Large solar vacuum telescope (the Baikal astrophysical observatory of the Institute of Solar-Terrestrial Physics SB RAS). It is demonstrated that the temperature gradients in the telescope rooms are the cause of the initiation of the Benard cell and originating (incipient) turbulence in the pavilion of the astronomical spectrograph. The characteristics of the originating turbulence were studied in detail. It has been found that the measurements date have supported the basic scenarios of stochastization (Landau-Hopf, Ruelle-Takens, Feigenbaum, Pomeau-Menneville scenarios). The Feigenbaum bifurcation diagram has experimentally been supported. It is shown that the basic vortex in Benard cell breaks down into smaller vortices as the result of ten bifurcations of the period duplication. It has been found that the originating turbulence introduced large errors in the data of spectral measurements, even at the path of small length. The horizontal random displacements of spectral lines, appearing due to the pavilion effects, in the horizontal Ebert scheme can reach 1 second of arc. In this case the line displacements occur slowly, at the frequency about 0.01 Hz. Because of low frequencies of line displacements the originating turbulence by its optical characteristics approximated the regular refraction.

Nosov, V. V.; Grigoriev, V. M.; Kovadlo, P. G.; Lukin, V. P.; Nosov, E. V.; Torgaev, A. V.

2008-05-01

271

Astroclimate of specialized stations of the Large Solar Vacuum Telescope: Part II  

NASA Astrophysics Data System (ADS)

The paper presents the results of measurements of characteristics of local astroclimate in special production areas of the Large solar vacuum telescope (the Baikal astrophysical observatory of the Institute of Solar-Terrestrial Physics SB RAS). It is demonstrated that the temperature gradients in the telescope rooms are the cause of the initiation of the Benard cell and originating (incipient) turbulence in the pavilion of the astronomical spectrograph. The characteristics of the originating turbulence were studied in detail. It has been found that the measurements date have supported the basic scenarios of stochastization (Landau-Hopf, Ruelle-Takens, Feigenbaum, Pomeau-Menneville scenarios). The Feigenbaum bifurcation diagram has experimentally been supported. It is shown that the basic vortex in Benard cell breaks down into smaller vortices as the result of ten bifurcations of the period duplication. It has been found that the originating turbulence introduced large errors in the data of spectral measurements, even at the path of small length. The horizontal random displacements of spectral lines, appearing due to the pavilion effects, in the horizontal Ebert scheme can reach 1 second of arc. In this case the line displacements occur slowly, at the frequency about 0.01 Hz. Because of low frequencies of line displacements the originating turbulence by its optical characteristics approximated the regular refraction.

Nosov, V. V.; Grigoriev, V. M.; Kovadlo, P. G.; Lukin, V. P.; Nosov, E. V.; Torgaev, A. V.

2008-05-01

272

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

273

Design and Analysis of the Aperture Shield Assembly for a Space Solar Receiver.  

National Technical Information Service (NTIS)

A joint U.S./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 dynami...

H. J. Strumpf T. Trinh W. Westelaken C. Krystkowiak V. Avanessian T. W. Kerslake

1997-01-01

274

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

275

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

276

Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas.  

PubMed

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (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 (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?m(a)?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(a?)?2.3×10(-10) GeV(-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(a)?1.15 eV, comfortably overlapping with cosmological hot dark matter bounds. PMID:22243149

Arik, M; Aune, S; Barth, K; Belov, A; Borghi, S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Dafni, T; Davenport, M; Eleftheriadis, C; Elias, N; Ezer, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Gazis, E N; Geralis, T; Giomataris, I; Gninenko, S; Gómez, H; Gruber, E; Guthörl, T; Hartmann, R; Haug, F; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakov?i?, K; Karuza, M; Königsmann, K; Kotthaus, R; Kr?mar, M; Kuster, M; Laki?, B; Laurent, J M; Liolios, A; Ljubi?i?, A; Lozza, V; Lutz, G; Luzón, G; Morales, J; Niinikoski, T; Nordt, A; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Rashba, T; Riege, H; Rodríguez, A; Rosu, M; Ruz, J; Savvidis, I; Silva, P S; Solanki, S K; Stewart, L; Tomás, A; Tsagri, M; van Bibber, K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K

2011-12-23

277

The Tandem Etalon Magnetograph of the Solar Magnetic Activity Research Telescope (SMART) at Hida Observatory  

NASA Astrophysics Data System (ADS)

The imaging photospheric magnetograph using tandem Fabry-Perot filters is newly installed in the Solar Magnetic Activity Research Telescope (SMART) of Hida Observatory, Kyoto University. The instrument, Tandem Etalon Magnetograph (TEM), consists of a rotating wave plate, tandem Fabry-Perot filters which scan the Fe I 6302.5 Å line with ˜ 130 mÅ bandwidth, a polarizing beam splitter, and two CCD cameras simultaneously taking orthogonally polarized light with a frame rate of 30 frames per second. We have confirmed that the Stokes vector map deduced from 20 s integration achieves a polarimetric sensitivity of ˜ 5 × 10-4 for all polarization states at one wavelength, which is higher than is achieved with a space instrument such as the Spectro-Polarimeter aboard Hinode or the Helioseismic and Magnetic Imager aboard the Solar Dynamic Observatory (SDO). We expect the complementary observations by SMART/TEM, Hinode, and SDO can shed new light on the trigger and energy storage mechanism of solar flares.

Nagata, Shin'ichi; Morita, Satoshi; Ichimoto, Kiyoshi; Nishida, Keisuke; Nakatani, Yoshikazu; Kimura, Goichi; Kaneda, Naoki; Kitai, Reizaburou; UeNo, Satoru; Ishii, Takako T.

2014-04-01

278

Progress making the top end optical assembly (TEOA) for the 4-meter Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

L-3 Integrated Optical Systems (IOS) Division has been selected by the National Solar Observatory (NSO) to design and produce the Top End Optical Assembly (TEOA) for the 4-meter Advanced Technology Solar Telescope (ATST) to operate at Haleakal', Maui. ATST will perform to a very high optical performance level in a difficult thermal environment. The TEOA, containing the 0.65-meter silicon carbide secondary mirror and support, mirror thermal management system, mirror positioning and fast tip-tilt system, field stop with thermally managed heat dump, thermally managed Lyot stop, safety interlock and control system, and support frame, operates in the "hot spot" at the prime focus of the ATST and so presents special challenges. In this paper, we describe progress in the L-3 technical approach to meeting these challenges, including silicon carbide off-axis mirror design, fabrication, and high accuracy figuring and polishing all within L-3; mirror support design; the design for stray light control; subsystems for opto-mechanical positioning and high accuracy absolute mirror orientation sensing; Lyot stop design; and thermal management of all design elements to remain close to ambient temperature despite the imposed solar irradiance load.

Canzian, Blaise; Barentine, J.; Arendt, J.; Bader, S.; Danyo, G.; Heller, C.

2012-09-01

279

[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

280

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

281

Calibration of data from InfraRed Imaging Magnetograph for the New Solar Telescope  

NASA Astrophysics Data System (ADS)

The InfraRed Imaging Magnetograph (IRIM) takes advantage of the high spatial resolution of New Solar Telescope (NST). It adopts a rotating birefringent polymer to modulate polarization signals and two Wollaston prisms as analyzer. Dual beam setup is used to minimize the effect of image motion caused by seeing. Its field of view is 50" x 25" and the wavelengths of operation are Fe I 15648 A and He I 10830 A. Due to the off-axis shape of the NST primary and secondary mirrors, multiple calibration techniques should be combined to reconstruct the original Stokes parameters. Here, we would like to introduce current status of our calibration efforts and discuss how IRIM data can be used for scientific purposes.

Ahn, Kwangsu; Cao, W.; Gorceix, N.; Goode, P. R.

2012-05-01

282

Wolter-Schwarzschild solar telescope coronal diagnostic spectrometer (CDS) flight model: manufacturing and assembly  

NASA Astrophysics Data System (ADS)

The Coronal Diagnostic Spectrometer (CDS) is one of the key instruments of the ESA cornerstone mission SOHO, scheduled for launch in 1995. It is designed to study the solar corona in the EUV. After successful completion of an engineering model in 1991 the flight model fabrication was started end of 1992. In August 1993 the optical alignment of the CDS flight mirror (FM) module was completed. The paper reports about the fabrication and achieved quality of the primary and secondary mirrors as well as the alignment of the mirror system. The predicted optical quality (half energy width) of the whole telescope is HEW = 10 mm and = 3 mm (2).

Schmidt, Michael; Dinger, Udo; Petasch, T.; Trebstein, Friedrich

1994-09-01

283

Optical design of a near-infrared imaging spectropolarimeter for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

In designing the optics of an imaging multi-etalon spectropolarimeter as a post-focus instrument for the Advanced Technology Solar Telescope (ATST), many constraints must be considered. Among these are the large entrance pupil diameter of the telescope (4 m), the demanded large field of view (?90 arc sec), high spectral resolving power (?200,000), and limited field-dependent blue-shift of the instrumental profile [?3 full width at half maximum (FWHM)], which require Fabry-Perot 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 with a relatively small diameter (?70 mm) and placed between the interferometers to reduce the inter-reflections in axial-mount, a "pupil adapter" must be included with a further increase of the optical path length. Although a multi-etalon spectropolarimeter works in quasi-monochromatic light, the Fraunhofer lines of interest cover a wide range of wavelengths (850 to 1650 nm), which demands a good chromatic aberration control. A low instrumental polarization (?0.5%) is also required to allow a high polarimetric precision. Finally, some secondary optical paths are required to perform the initial instrumental setup and to secure the best instrumental performances. A diffraction-limited optical solution for ATST is described that fulfills all the above requirements in a relative small volume.

Greco, Vincenzo; Cavallini, Fabio

2013-06-01

284

Image quality assessment of sparse-aperture designs with decreasing fill factors  

Microsoft Academic Search

Sparse aperture designs can increase the effective aperture size of a remote sensing system, thus allowing the satellite to be placed in a higher orbit without compromising the resolution. The fill factor of a sparse aperture is the total area of the telescope apertures divided by the effective aperture size of the combined telescopes. Reducing the fill factor, F, reduces

Robert D. Fiete; James A. Mooney; Theodore A. Tantalo; Jason R. Calus

2000-01-01

285

Co-Alignment System (CAS) study. Report on task 1-3. [Solar Extreme Ultraviolet Telescope and Spectrometer pointing system  

NASA Technical Reports Server (NTRS)

The design of a suitable coalignment system (CAS) for the Solar Extreme Ultraviolet Telescope and Spectrometer (SEUTS) is presented. The CAS provides offset adjustment capabilities to SEUTS which will be mounted on a single large pointing system with other devices. The suitability of existing designs is determined and modifications are suggested.

Anderson, N. T.

1980-01-01

286

Solar dynamic modules for Space Station Freedom: The relationship between fine-pointing control and thermal loading of the aperture plate  

NASA Technical Reports Server (NTRS)

Dynamic simulations of Space Station Freedom (SSF) configured with solar dynamic (SD) power modules were performed. The structure was subjected to Space Shuttle docking disturbances, while being controlled with a 'natural' vibration and tracking control approach. Three control cases were investigated for the purpose of investigating the relationship between actuator effort, SD pointing, and thermal loading on the receiver aperture plate. Transient, one-dimensional heat transfer analyses were performed to conservatively predict temperatures of the multi-layered receiver aperture plate assembly and thermal stresses in its shield layer. Results indicate that the proposed aperture plate is tolerant of concentrated flux impingement during short-lived structural disturbances. Pointing requirements may be loosened and the requirement control torques lessened from that previously specified. Downsizing and simplifying the joint drive system should result in a considerable savings mass.

Quinn, Roger D.; Kerslake, Thomas W.

1992-01-01

287

Impact of solar radiation on sea surface salinity remote sensing by spaceborne synthetic aperture imaging radiometers  

Microsoft Academic Search

Since the Sun is a very bright radiation source at L-band, reception of direct and Earth-reflected solar radiations by downward-looking radiometers raises a significant challenge for the remote sensing of ocean surface salinity. For a given spaceborne mission concept, the impact of the Sun radiations depends on the sensor antenna properties, the location of the Sun relative to both the

Bruno Picard; Nicolas Reul; Philippe Waldteufel; Eric Anterrieu

2004-01-01

288

Hubble Space telescope thermal cycle test report for large solar array samples with BSFR cells (Sample numbers 703 and 704)  

NASA Technical Reports Server (NTRS)

The Hubble space telescope (HST) solar array was designed to meet specific output power requirements after 2 years in low-Earth orbit, and to remain operational for 5 years. The array, therefore, had to withstand 30,000 thermal cycles between approximately +100 and -100 C. The ability of the array to meet this requirement was evaluated by thermal cycle testing, in vacuum, two 128-cell solar cell modules that exactly duplicated the flight HST solar array design. Also, the ability of the flight array to survive an emergency deployment during the dark (cold) portion of an orbit was evaluated by performing a cold-roll test using one module.

Alexander, D. W.

1992-01-01

289

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

290

Properties of Umbral Dots as Measured from the New Solar Telescope Data and MHD Simulations  

NASA Astrophysics Data System (ADS)

We studied bright umbral dots (UDs) detected in a moderate size sunspot and compared their statistical properties to recent MHD models. The study is based on high-resolution data recorded by the New Solar Telescope at the Big Bear Solar Observatory and three-dimensional (3D) MHD simulations of sunspots. Observed UDs, living longer than 150 s, were detected and tracked in a 46 minute long data set, using an automatic detection code. A total of 1553 (620) UDs were detected in the photospheric (low chromospheric) data. Our main findings are (1) none of the analyzed UDs is precisely circular, (2) the diameter-intensity relationship only holds in bright umbral areas, and (3) UD velocities are inversely related to their lifetime. While nearly all photospheric UDs can be identified in the low chromospheric images, some small closely spaced UDs appear in the low chromosphere as a single cluster. Slow-moving and long-living UDs seem to exist in both the low chromosphere and photosphere, while fast-moving and short-living UDs are mainly detected in the photospheric images. Comparison to the 3D MHD simulations showed that both types of UDs display, on average, very similar statistical characteristics. However, (1) the average number of observed UDs per unit area is smaller than that of the model UDs, and (2) on average, the diameter of model UDs is slightly larger than that of observed ones.

Kilcik, A.; Yurchyshyn, V. B.; Rempel, M.; Abramenko, V.; Kitai, R.; Goode, P. R.; Cao, W.; Watanabe, H.

2012-02-01

291

PROPERTIES OF UMBRAL DOTS AS MEASURED FROM THE NEW SOLAR TELESCOPE DATA AND MHD SIMULATIONS  

SciTech Connect

We studied bright umbral dots (UDs) detected in a moderate size sunspot and compared their statistical properties to recent MHD models. The study is based on high-resolution data recorded by the New Solar Telescope at the Big Bear Solar Observatory and three-dimensional (3D) MHD simulations of sunspots. Observed UDs, living longer than 150 s, were detected and tracked in a 46 minute long data set, using an automatic detection code. A total of 1553 (620) UDs were detected in the photospheric (low chromospheric) data. Our main findings are (1) none of the analyzed UDs is precisely circular, (2) the diameter-intensity relationship only holds in bright umbral areas, and (3) UD velocities are inversely related to their lifetime. While nearly all photospheric UDs can be identified in the low chromospheric images, some small closely spaced UDs appear in the low chromosphere as a single cluster. Slow-moving and long-living UDs seem to exist in both the low chromosphere and photosphere, while fast-moving and short-living UDs are mainly detected in the photospheric images. Comparison to the 3D MHD simulations showed that both types of UDs display, on average, very similar statistical characteristics. However, (1) the average number of observed UDs per unit area is smaller than that of the model UDs, and (2) on average, the diameter of model UDs is slightly larger than that of observed ones.

Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.; Cao, W. [Big Bear Solar Observatory, Big Bear City, CA 92314 (United States); Rempel, M. [High Altitude Observatory, NCAR, Boulder, CO 80307-3000 (United States); Kitai, R.; Watanabe, H. [Kwasan and Hida Observatories, Kyoto University, Kyoto 607-8417 (Japan)

2012-02-01

292

Photospheric and Chromospheric Dynamics of Sunspots Observed with New Solar Telescope  

NASA Astrophysics Data System (ADS)

The 1.6m New Solar Telescope (NST) of Big Bear Solar Observatory allows us to investigate the structure and dynamics of sunspots with unprecedented spatial and temporal resolutions. We present results of simultaneous observations of a sunspot in the photosphere with a broad-band TiO-line filter and in the chromospheric H-alpha line with Visible Imaging Spectrometer, and compare the observational results with MHD models of sunspots. The observations reveal previously unresolved features of the sunspot umbra and penumbra. In particular, the TiO data clearly demonstrate highly twisted dynamics of penumbral filaments and umbral dots and reveal strong shearing plasma flows in sunspot bridges, not explained by the MHD simulations. The high-resolution H-alpha spectroscopic data provide new views of the sunspot chromospheric dynamics, including the fine structure of oscillations and waves, penumbral jets, ubiquitous small-scale eruptions, and accretion flows in a form of dense plasma sheets. The diffraction-limited NST observations show that the sunspot dynamics is more complicated and much richer than it is described by the current sunspot models.

Kosovichev, Alexander G.; Yurchyshyn, Vasyl B.

2014-06-01

293

PET - A proton/electron telescope for studies of magnetospheric, solar, and galactic particles  

NASA Technical Reports Server (NTRS)

The Proton/Electron Telescope (PET) on SAMPEX 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 about 1 to about 30 MeV and H and He nuclei from about 20 to about 300 MeV/nuc, with isotope resolution of H and He extending from about 20 to about 80 MeV/nuc. As SAMPEX scans all local times and geomagnetic cutoffs over the course of its near-polar orbit, PET will characterize precipitating relativistic electron events during periods of declining solar activity, and it will examine whether the production rate of odd nitrogen and hydrogen molecules in the middle atmosphere by precipitating electrons is sufficient to affect O3 depletion. In addition, PET will complement studies of the elemental and isotopic composition of energetic heavy (Z greater than 2) nuclei on SAMPEX by providing measurements of H, He, and electrons. Finally, PET has limited capability to identify energetic positrons from potential natural and man-made sources.

Cook, Walter R.; Cummings, Alan C.; Cummings, Jay R.; Garrard, Thomas L.; Kecman, Branislav; Mewaldt, Richard A.; Selesnick, Richard S.; Stone, Edward C.; Baker, Daniel N.; Von Rosenvinge, Tycho T.

1993-01-01

294

The longitudinal magnetic field observation calibration of several solar photospheric Fe I lines for multichannel birefringence filter solar magnetic field telescope. II  

Microsoft Academic Search

The changes of the formation depth of 6 Fe I lines, used by the multichannel birefringence filter solar magnetic field telescope, are studied. The mean square root errors at certain points from the line-center, corresponding to the narrowest and the widest bandwidth of the filter, are computed. Hence general properties of the formation depth of the normal and anomalous Zeeman

Weihong Song; Guoxiang Ai; Hongqi Zhang; Li Xiaochang

1992-01-01

295

Observations of Cosmic Rays and Solar Energetic Particles from the Ulysses COSPIN High Energy Telescope Following Completion of the Solar Maximum Solar Polar Passes.*  

NASA Astrophysics Data System (ADS)

At the end of 2002, following its second pass over the Sun's north polar region, Ulysses had reached a radial distance of about 4.5 AU at a heliographic latitude of 24°N. While solar activity remained high, the modulated intensity of cosmic rays observed by Ulysses’ COSPIN High Energy Telescope had increased significantly from the levels observed early in 2001, which most likely represented the maximum modulation for this solar cycle. Despite continuing solar activity, the new qA<0 magnetic polarity of the Sun's dipole field was fully established for both poles since the change in the North Pole polarity in 2000. Although the current sheet tilt was still large (>40° as reported by the Wilcox Solar Observatory) and the solar wind was still frequently disturbed by solar activity, it is worthwhile to examine the recent increase in the quiet-time cosmic ray fluxes for evidence of the change in latitudinal gradients expected upon change of magnetic polarity. A difficulty is the lack of a well-matched 1 AU base-line to help distinguish spatial from temporal variations following the termination of IMP-8 operations in late 2001. We will summarize Ulysses observations of energetic (>~30 MeV/n) protons and helium through the most recent available data, and will discuss available options for determining baseline fluxes at 1 AU for studies of the radial and latitudinal gradients. **This work was supported in part by NASA/JPL Contract 955432, by NASA Grant NASA 5-28516 and by NSF grant ATM 99-12341.

McKibben, R. B.; Lopate, C.; Connell, J. J.; Posner, A.

2003-04-01

296

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

297

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

298

Site evaluation study for the Indian National Large Solar Telescope using microthermal measurements  

NASA Astrophysics Data System (ADS)

A microthermal seeing measurement device has been developed in-house to measure the temperature structure function DT(r, h) and the air temperature Tair(h). A pressure sensor, located adjacent to it, measures the average barometric pressure P(h). From the data measured, the temperature structure coefficient C_T^2(r, h) and the refractive index structure constant C_N^2(h) are computed for the five equidistant microthermal seeing layers in the 3-15 m range in the surface layers. A statistical analysis is performed on the local coherence length ro(loc)(h1, h2). Corresponding values of the atmospheric seeing ?(loc)(h1, h2) for all 10 microthermal seeing slabs is also computed and plotted, and the data are logged in real time. Because the characterization of the three sites is under way and the best site for the National Large Solar Telescope facility is yet to be determined, in this paper I discuss the preliminary results obtained from the Hanle site. A summary of the first results is as follows: ?(loc) (3 m, 6 m) = 0.663 arcsec, ?(loc) (6 m, 9 m) = 0.465 arcsec, ?(loc) (9 m, 12 m) = 0.363 arcsec and ?(loc) (12 m, 15 m) = 0.315 arcsec.

Dhananjay, K.

2014-01-01

299

On the Ability of an Extreme-Ultraviolet Multilayer Normal-Incidence Telescope to Provide Temperature Information for Solar Plasmas  

Microsoft Academic Search

In recent years, multilayer-coated optics have been used in solar-soft X-ray and extreme-ultraviolet telescopes to record high-resolution, full Sun images. The multilayer coatings reflect efficiently over rather narrow wavelength bands that are selected to contain spectral emission lines considered to have plasma diagnostic importance for determining approximate electron temperatures. The purpose of this Letter is to discuss the effect of

U. Feldman; J. M. Laming; G. A. Doschek; H. P. Warren; L. Golub

1999-01-01

300

The Sardinia Radio Telescope  

Microsoft Academic Search

We describe the Sardinia Radio Telescope (SRT), a new general purpose, fully steerable antenna of the National Institute for Astrophysics. The radio telescope is under construction near Cagliari (Sardinia). With its large aperture (64m diameter) and its active surface, SRT is capable of operations up to ˜100GHz, it will contribute significantly to VLBI networks and will represent a powerful single-dish

G. Grueff; G. Alvito; R. Ambrosini; P. Bolli; N. D'Amico; A. Maccaferri; G. Maccaferri; M. Morsiani; L. Mureddu; V. Natale; L. Olmi; A. Orfei; C. Pernechele; A. Poma; I. Porceddu; L. Rossi; G. Zacchiroli

2004-01-01

301

High resolution telescope  

DOEpatents

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 activites. The cost of the telescope scales with the first power of the aperture rather than its third power as in conventional telescopes.

Massie, Norbert A. (San Ramon, CA); Oster, Yale (Danville, CA)

1992-01-01

302

A search for solar-like oscillations in the stars of M67 with CCD ensemble photometry on a network of 4 M telescopes  

Microsoft Academic Search

Results are presented from a large observational project directed toward the detection of solar-like oscillations in an ensemble of open cluster stars. Seven groups collaborated in 1992 January to observe twelve stars in M67 with 4 m class telescopes for a one week period. High quality time series were collected on 22 telescope nights for a total of 156 h.

R. L. Gilliland; T. M. Brown; H. Kjeldsen; J. K. McCarthy; M. L. Peri; J. A. Belmonte; I. Vidal; L. E. Cram; J. Palmer; S. Frandsen; M. Parthasarathy; L. Petro; H. Schneider; P. B. Stetson; W. W. Weiss

1993-01-01

303

LSST Telescope Design Developments  

Microsoft Academic Search

The proposed Large Synoptic Survey Telescope (LSST) has an 8.4 meter aperture with a 3.5 degree diameter field of view and must meet the challenging cadence requirements necessary to perform the LSST survey mission. Several advances have been made in the concept design of the telescope. The telescope optical system is based on a Paul-Baker three element design with a

V. L. Krabbendam; J. H. Burge; C. F. Claver; B. Cuerden; W. Davison; W. J. Gressler; J. Kingsley; H. M. Martin; D. R. Neill; S. Olivier; D. Phillion; J. Sebag; D. Sweeney

2005-01-01

304

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

305

A normal incidence, high resolution X-ray telescope for solar coronal observations  

NASA Technical Reports Server (NTRS)

A Normal Incidence high resolution X-ray Telescope is reported. The design of a telescope assembly which, after fabrication, will be integrated with the mirror fabrication process is described. The assembly is engineered to fit into the Black Brant rocket skin to survive sounding rocket launch conditions. A flight ready camera is modified and tested.

Golub, L.

1984-01-01

306

Simulated Solar Flare X-Ray and Thermal Cycling Durability Evaluation of Hubble Space Telescope Thermal Control Candidate Replacement Materials  

NASA Technical Reports Server (NTRS)

During the Hubble Space Telescope (HST) second servicing mission (SM2), astronauts noticed that the multilayer insulation (MLI) covering the telescope was damaged. Large pieces of the outer layer of MLI (aluminized Teflon fluorinated ethylene propylene (Al-FEP)) were torn in several locations around the telescope. A piece of curled up Al-FEP was retrieved by the astronauts and was found to be severely embrittled, as witnessed by ground testing. Goddard Space Flight Center (GSFC) organized a HST MLI Failure Review Board (FRB) to determine the damage mechanism of FEP in the HST environment, and to recommend replacement insulation material to be installed on HST during the third servicing mission (SM3) in 1999. Candidate thermal control replacement materials were chosen by the FRB and tested for environmental durability under various exposures and durations. This paper describes durability testing of candidate materials which were exposed to charged particle radiation, simulated solar flare x-ray radiation and thermal cycling under load. Samples were evaluated for changes in solar absorptance and tear resistance. Descriptions of environmental exposures and durability evaluations of these materials are presented.

deGroh, Kim K.; Banks, Bruce A.; Sechkar, Edward A.; Scheiman, David A.

1998-01-01

307

A Scanning Hartmann Focus Test for the EUVI Telescopes aboard STEREO  

NASA Technical Reports Server (NTRS)

The Solar TErrestrial RElations Observatory (STEREO), the third mission in NASA s Solar Terrestrial Probes program, was launched in 2006 on a two year mission to study solar phenomena like coronal mass ejections. STEREO consists of two nearly identical satellites, each carrying a suite of instruments that provide, among other data, simultaneous images of the Sun. One of these telescopes is the Extreme Ultraviolet Instrument (EUVI). There are two EUVI telescopes, one on each STEREO satellite (EUVI-A and EUVI-B). EUVI is a normal incidence, 98mm diameter, Ritchey-Chretien telescope designed to obtain wide field of view (approx.1deg) images of the Sun at short wavelengths (approx.20nm) using a CCD detector. The telescope entrance aperture is divided into four quadrants by a mask near the secondary mirror spider veins. A mechanism that rotates another mask allows only one of these sub-apertures to accept light from the Sun during an observation. The EUVI is thus four co-aligned, off-axis telescopes. Each off-axis segment on the primary and secondary mirrors has a different extreme ultraviolet coating stack. Furthermore, the aperture select mechanism is synchronized with a filter wheel mechanism near the CCD detector. The EUVI contains no focus mechanism. Models predict that the difference in on-orbit operating temperature and ambient clean room conditions yield a "best focus" difference between integration and operation of approx. 0.2mm.

Ohl, R.; Antonille, S.; Aronstein, D.; Dean, B.; Delmont, M.; Eichord, W.; Frey, B.; Kubalak, D.; Wilson, M.; Redman, K.; Hynes, S.; Shiri, R.; Smith, J. S.; Thompson, P.

2007-01-01

308

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

SciTech Connect

The High-resolution Lightweight Telescope for the EUV (HiLiTE) is a Cassegrain telescope that will be made entirely of Silicon Carbide (SiC), optical substrates and metering structure alike. Using multilayer coatings, this instrument will be tuned to operate at the 465 {angstrom} Ne VII emission line, formed in solar transition region plasma at {approx}500,000 K. HiLiTE will have an aperture of 30 cm, angular resolution of {approx}0.2 arc seconds and operate at a cadence of {approx}5 seconds or less, having a mass that is about 1/4 that of one of the 20 cm aperture telescopes on the Atmospheric Imaging Assembly (AIA) instrument aboard NASA's Solar Dynamics Observatory (SDO). This new instrument technology thus serves as a path finder to a post-AIA, Explorer-class missions.

Martinez-Galarce, D S; Boerner, P; Soufli, R; De Pontieu, B; Katz, N; Title, A; Gullikson, E M; Robinson, J C; Baker, S L

2008-06-02

309

Search for solar axions by the CERN axion solar telescope with 3He buffer gas: closing the hot dark matter gap.  

PubMed

The CERN Axion Solar Telescope has finished its search for solar axions with (3)He buffer gas, covering the search range 0.64 eV ? ma ? 1.17 eV. This closes the gap to the cosmological hot dark matter limit and actually overlaps with it. 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 ga? ? 3.3 × 10(-10)? GeV(-1) at 95% C.L., with the exact value depending on the pressure setting. Future direct solar axion searches will focus on increasing the sensitivity to smaller values of ga?, for example by the currently discussed next generation helioscope International AXion Observatory. PMID:24655238

Arik, M; Aune, S; Barth, K; Belov, A; Borghi, S; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Collar, J I; Da Riva, E; Dafni, T; Davenport, M; Eleftheriadis, C; Elias, N; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Garza, J G; Gazis, E N; Geralis, T; Georgiopoulou, E; Giomataris, I; Gninenko, S; Gómez, H; Gómez Marzoa, M; Gruber, E; Guthörl, T; Hartmann, R; Hauf, S; Haug, F; Hasinoff, M D; Hoffmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakov?i?, K; Karuza, M; Königsmann, K; Kotthaus, R; Kr?mar, M; Kuster, M; Laki?, B; Lang, P M; Laurent, J M; Liolios, A; Ljubi?i?, A; Luzón, G; Neff, S; Niinikoski, T; Nordt, A; Papaevangelou, T; Pivovaroff, M J; Raffelt, G; Riege, H; Rodríguez, A; Rosu, M; Ruz, J; Savvidis, I; Shilon, I; Silva, P S; Solanki, S K; Stewart, L; Tomás, A; Tsagri, M; van Bibber, K; Vafeiadis, T; Villar, J; Vogel, J K; Yildiz, S C; Zioutas, K

2014-03-01

310

A normal incidence, high resolution X-ray telescope for solar coronal observations  

NASA Technical Reports Server (NTRS)

Efforts directed toward the completion of an X-ray telescope assembly design, the procurement of major components, and the coordination of optical fabrication and X-ray multilayer testing are reported.

Golub, L.

1984-01-01

311

Thermally Induced Vibrations of the Hubble Space Telescope's Solar Array 3 in a Test Simulated Space Environment  

NASA Technical Reports Server (NTRS)

NASA Goddard Space Flight Center and the European Space Agency (ESA) conducted a disturbance verification test on a flight Solar Array 3 (SA3) for the Hubble Space Telescope using the ESA Large Space Simulator (LSS) in Noordwijk, the Netherlands. The LSS cyclically illuminated the SA3 to simulate orbital temperature changes in a vacuum environment. Data acquisition systems measured signals from force transducers and accelerometers resulting from thermally induced vibrations of the SAI The LSS with its seismic mass boundary provided an excellent background environment for this test. This paper discusses the analysis performed on the measured transient SA3 responses and provides a summary of the results.

Early, Derrick A.; Haile, William B.; Turczyn, Mark T.; Griffin, Thomas J. (Technical Monitor)

2001-01-01

312

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.

313

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

314

Holographically corrected telescopes  

NASA Astrophysics Data System (ADS)

Holographic correction of low-quality telescopes is an inexpensive method of obtaining large aperture devices suitable for lidar, imaging, and directed energy weaponry. We present an analysis of two different methods for producing diffraction-limited telescopes from the holographic correction of spherical mirrors. These evaluations are essential for choosing the optimal design for a given telescope application. Included in our discussion are the results from preliminary experiments into the various designs. The aim of the project is construct the first ever holographically corrected astronomical telescope for both ground and space-based operations.

Andersen, Geoff; Knize, Randall J.

1998-08-01

315

LUTE Telescope Structural Design, (Revised).  

National Technical Information Service (NTIS)

The major objective of the Lunar Ultraviolet Transit Experiment (LUTE) Telescope Structural Design Study was to investigate the feasibility of designing an ultralightweight 1-m aperture system within optical performance requirements and mass budget constr...

G. Ruthven

1993-01-01

316

Temperature of Solar Prominences Obtained with the Fast Imaging Solar Spectrograph on the 1.6 m New Solar Telescope at the Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

We observed solar prominences with the Fast Imaging Solar Spectrograph (FISS) at the Big Bear Solar Observatory on 30 June 2010 and 15 August 2011. To determine the temperature of the prominence material, we applied a nonlinear least-squares fitting of the radiative transfer model. From the Doppler broadening of the H? and Ca ii lines, we determined the temperature and nonthermal velocity separately. The ranges of temperature and nonthermal velocity were 4000 - 20 000 K and 4 - 11 km s-1. We also found that the temperature varied much from point to point within one prominence.

Park, Hyungmin; Chae, Jongchul; Song, Donguk; Maurya, Ram Ajor; Yang, Heesu; Park, Young-Deuk; Jang, Bi-Ho; Nah, Jakyoung; Cho, Kyung-Suk; Kim, Yeon-Han; Ahn, Kwangsu; Cao, Wenda; Goode, Philip R.

2013-11-01

317

A normal incidence, high resolution X-ray telescope for solar coronal observations  

NASA Technical Reports Server (NTRS)

The following major activities were advanced or completed: complete design of the entire telescope assembly and fabrication of all front-end components; specification of all rocket skin sections including bulkheads, feedthroughs and access door; fabrication, curing, and delivery of the large graphite-epoxy telescope tube; engineering analysis of the primary mirror vibration test was completed and a decision made to redesign the mirror attachment to a kinematic three-point mount; detail design of the camera control, payload and housekeeping electronics; and multilayer mirror flats with 2d spacings of 50 A and 60 A.

Golub, L.

1985-01-01

318

Thermal Properties of A Solar Coronal Cavity Observed with the X-Ray Telescope on Hinode.  

National Technical Information Service (NTIS)

Coronal cavities are voids in coronal emission often observed above high latitude filament channels. Sometimes, these cavities have areas of bright X-ray emission in their centers. In this study, we use data from the X-ray Telescope (XRT) on the Hinode sa...

H. S. Hudson K. K. Reeves R. Kano S. E. Gibson T. A. Kucera

2011-01-01

319

Use of the Video-Technique for Observations with a Double Solar Telescope  

NASA Astrophysics Data System (ADS)

Since several years, the staff of the solar department at the Ondrejov Observatory monitors the solar activity with the aid of a video-system developed for the registration and digitization of the solar image. The system fulfils our requirements for the registration and evaluation of solar images of a medium resolution and is not very expensive. It is also suitable for the digitization of the earlier obtained motion-picture materials. We describe the system, discuss its specific behaviour and our accumulated experience.

Klvana, M.; Bumba, V.

320

The Green Bank Telescope  

NASA Astrophysics Data System (ADS)

The Green Bank Telescope (GBT), a new 100 m diameter radio telescope, is under commissioning and early scientific operation. The GBT has a number of novel design features including an unblocked aperture, an active surface, and a precision telescope control system that is designed to allow operation into the 3 mm wavelength range. The unblocked aperture has already paid dividends in high dynamic range images. The active surface has worked very well in its initial operation and has made a substantial improvement in gain and beam quality over a large range of elevation angles. This paper describes the features of the GBT, its status, and some of the early scientific results from the telescope.

Jewell, Phil R.

2002-08-01

321

A solar station in Ica - Mutsumi Ishitsuka: a research center to improve education at the university and schools  

NASA Astrophysics Data System (ADS)

The San Luis Gonzaga National University of Ica has built a solar station, in collaboration with the Geophysical Institute of Peru, the National Astronomical Observatory of Japan and the Hida Observatory. The Solar Station has the following equipment: a digital Spectrograph Solar Refractor Telescope Takahashi 15 cm aperture, 60 cm reflector telescope aperture, a magnetometer-MAGDAS/CPNM and a Burst Monitor Telescope Solar-FMT (Project CHAIN). These teams support the development of astronomical science and Ica in Peru, likewise contributing to science worldwide. The development of basic science will be guaranteed when university students, professors and researchers work together. The Solar Station will be useful for studying the different levels of university education and also for the general public. The Solar Station will be a good way to spread science in the region through public disclosure.

Terrazas-Ramos, Raúl

2012-07-01

322

Radio Telescope Design  

Microsoft Academic Search

\\u000a This is an important chapter concerning radio telescope design. In the first part of this chapter, all the major design issues\\u000a of radio telescopes are discussed, which include the reflector surface transmission loss, the antenna tolerance theory, the\\u000a antenna homology design, the antenna surface best fitting, the antenna component positional tolerance, the antenna aperture\\u000a blockage, the ground radiation pick-up, and

Jingquan Cheng

323

LSST Telescope Design  

Microsoft Academic Search

The proposed Large Synoptic Survey Telescope (LSST) has an 8.4 meter aperture with a 3.5 degree diameter field of view and must meet the challenging cadence requirements necessary to perform the LSST survey mission. The telescope optical system is based on a Paul-Baker three element design with a single captured focus for the dedicated instrument. The large mirrors, 8.4 m

V. Krabbendam; C. F. Claver; L. Daggert; J. Sebag; D. R. Neill; R. Gomez; J. H. Burge; R. Tessieries; W. Davison; B. Cuerden

2004-01-01

324

The Sardinia Radio Telescope  

NASA Astrophysics Data System (ADS)

We describe the Sardinia Radio Telescope (SRT), a new general purpose, fully steerable antenna of the National Institute for Astrophysics. The radio telescope is under construction near Cagliari (Sardinia). With its large aperture (64m diameter) and its active surface, SRT is capable of operations up to ˜100GHz, it will contribute significantly to VLBI networks and will represent a powerful single-dish radio telescope for many science fields. The radio telescope has a Gregorian optical configuration with a supplementary beam-waveguide (BWG), which provides additional focal points. The Gregorian surfaces are shaped to minimize the spill-over and standing wave. After the start of the contract for the radio telescope structural and mechanical fabrication in 2003, in the present year the foundation construction will be completed. The schedule foresees the radio telescope inauguration in late 2006.

Grueff, G.; Alvito, G.; Ambrosini, R.; Bolli, P.; D'Amico, N.; Maccaferri, A.; Maccaferri, G.; Morsiani, M.; Mureddu, L.; Natale, V.; Olmi, L.; Orfei, A.; Pernechele, C.; Poma, A.; Porceddu, I.; Rossi, L.; Zacchiroli, G.

325

Telescope mounting  

NASA Astrophysics Data System (ADS)

A mounting consisting of two revolving sections of a spherical shell is considered for the large European solar telescope. The lower section rotates about a vertical axis, and the upper section revolves on a circular bearing on the lower part. This concept allows for a well balanced and compact design. It may permit a domeless design, leading to substantial weight reduction pointing and tracking are easy, computerized, and robust. However, the telescope tube and its optical system rotate with respect to the plane of the direction of gravity. Tracking very close to the horizon and near zenith is precluded by acceleration strains on drives and bearings, although for solar observations this is not a serious drawback. The design is susceptible to wind induced vibrations. It is therefore of interest mainly in combination with an adequate active optical image stabilization scheme.

1982-04-01

326

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

327

The Hadean, Through a Glass Telescopically: Observations of Young Solar Analogs  

NASA Astrophysics Data System (ADS)

Investigations into the Earth's surface environment during the Hadean eon (prior to 3.8 Ga) are hampered by the paucity of the geological and geochemical record and the relative inaccessibility of better-preserved surfaces with possibly similar early histories (i.e., Mars). One approach is to observe nearby, young solar-mass stars as analogs to the Hadean Sun and its environment. A catalog of 38 G and early K stars within 25 pc was constructed based on main-sequence status, bolometric luminosity, lack of known stellar companions within 800 AU, and coronal X-ray luminosities commensurate with the higher activity of solar-mass stars <0.8 b.y. old. Spectroscopic data support the assignment of ages of 0.2 - 0.8 Ga for most of these stars. Observations of these objects will provide insight into external forces that influenced Hadean atmosphere, ocean, and surface evolution (and potential ecosystems), including solar luminosity evolution, the flux and spectrum of solar ultraviolet radiation, the intensity of the solar wind, and the intensity and duration of a late period of heavy bombardment. The standard model of solar evolution predicts a luminosity of 0.75 solar luminosity at the end of the Hadean, implying a terrestrial surface temperature inconsistent with the presence of liquid water and motivating atmospheric greenhouse models. An alternative model fo solar evolution that invokes mass loss, constructed to explain solar Li depletion, attenuates or reverses this luminosity evolution of the atmospheres of Earth and the other terrestrial planets. This model can be tested by Li abundance measurements. The continuum emission from stellar wind plasma during significant mass loss may be detectable at millimeter and radio wavelengths. The Earth (and Moon) experienced a period of intense bombardment prior to 3.8 Ga, long after accretion was completed in the inner solar system and possibly associated with the clearing of residual planetesimals in the outer solar system. Such a bombardment may have contributed volatiles and organics to the surface, but also have limited the appearacne of a biosphere. While planetary systems around solar systems cannot be detected directly with present technology, the thermal emission from the interplanetary dust generated during a similar heavy bombardment period can be. Midinfrared observations of a large uniform sample of solar analogs are used to constrain the frequency and duration of such events.

Gaidos, E. J.

1998-01-01

328

Challenges and Approach for Making the Top End Optical Assembly for the 4-meter Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

L-3 Integrated Optical Systems (IOS) Division has been selected by the National Solar Observatory (NSO) to make the Top End Optical Assembly (TEOA) for the 4-meter Advanced Technology Solar Telescope (ATST) to operate at Haleakala, Maui. ATST will perform to a very high optical performance level in a difficult thermal environment. The TEOA, containing the 0.65-meter silicon carbide secondary mirror and support, mirror thermal management system, mirror positioning and fast tip-tilt system, field stop with thermally managed heat dump, thermally managed Lyot stop, safety interlock and control system, and support frame, operates in the "hot spot” at the prime focus of the ATST and so presents special challenges. In this paper, we will describe the L-3 IOS technical approach to meet these challenges, including subsystems for opto-mechanical positioning, rejected and stray light control, wavefront tip-tilt compensation, and thermal management. Key words: ATST, TEOA, L-3 IOS, thermal management, silicon carbide (SiC) mirrors, hexapods, solar astronomy

Canzian, Blaise; Barentine, J.; Hull, T.

2012-01-01

329

A deployment mechanism for the double roll-out flexible solar array on the space telescope  

NASA Technical Reports Server (NTRS)

A roll-out flexible array which provides more than 4 kW of power for the space telescope was developed. The Array is configured as two wings. The deployment mechanism for each wing is based on flight-proven FRUSA design. Modifications have been incorporated to accommodate an increase in size and mission requirements. The assembly and operation of the deployment mechanism are described together with environmental and functional tests results.

Cawsey, T. R.

1982-01-01

330

Limitations Placed on the Time Coverage, Isoplanatic Patch Size and Exposure Time for Solar Observations Using Image Selection Procedures in the Presence of Telescope Aberrations  

NASA Astrophysics Data System (ADS)

Image selection, adaptive optics and post-facto image restoration methods are all techniques being used for diffraction limited imaging with ground-based solar and stellar telescopes. Often these techniques are used in a hybrid form like e.g. the application of adaptive optics and/or post-facto image restoration in combination with already good images obtained by image selection in periods of good seeing. Fried (JOSA 56, 1372, 1966), Hecquet and Coupinot (J. Optics/Paris 16, 21, 1985) and Beckers ("Solar and Stellar Granulation", Kluwer, Rutten & Severino Eds, 55, 1988) already discussed the usefulness of image selection, or the "Lucky Observer" mode, for high resolution imaging. All assumed perfect telescope optics. In case of moderate telescope aberrations image selection can still lead to diffraction limited imaging but only when the atmospheric wavefront aberration happens to compensate that of the telescope. In this "Very Lucky Observer" mode the probability of obtaining a good image is reduced over the un-aberrated case, as are the size of the isoplanatic patch and the exposure time. We describe an analysis of these effects for varying telescope aberrations. These result in a strong case for the removal of telescope aberrations either by initial implementation or by the use of slow active optics.

Beckers, J. M.; Rimmele, T. R.

1996-12-01

331

A Scanning Hartmann Focus Test for the EUVI Telescopes aboard STEREO  

NASA Technical Reports Server (NTRS)

The Solar TErrestrial RElations Observatory (STEREO), the third mission in NASA's Solar Terrestrial Probes program, was launched in 2006 on a two year mission to study solar phenomena. STEREO consists of two nearly identical satellites, each carrying an Extreme Ultraviolet Imager (EUVI) telescope as part of the Sun Earth Connection Coronal and Heliospheric Investigation instrument suite. EUVI is a normal incidence, 98mm diameter, Ritchey-Chretien telescope designed to obtain wide field of view images of the Sun at short wavelengths (17.1-30.4nm) using a CCD detector. The telescope entrance aperture is divided into four quadrants by a mask near the secondary mirror spider veins. A mechanism that rotates another mask allows only one of these sub-apertures to accept light over an exposure. The EUVI contains no focus mechanism. Mechanical models predict a difference in telescope focus between ambient integration conditions and on-orbit operation. We describe an independent check of the ambient, ultraviolet, absolute focus setting of the EUVI telescopes after they were integrated with their respective spacecraft. A scanning Hartmann-like test design resulted from constraints implied by the EUVI aperture select mechanism. This inexpensive test was simultaneously coordinated with other NASA integration and test activities in a high-vibration, clean room environment. The total focus test error was required to be better than +/-0.05 mm. We describe the alignment and test procedure, sources of statistical and systematic error, and then the focus determination results using various algorithms. The results are consistent with other tests of focus alignment and indicate that the EUVI telescopes meet the ambient focus offset requirements. STEREO is functioning well on-orbit and the EUVI telescopes meet their on-orbit image quality requirements.

Ohl, Ray; Antonille, Scott; Aronstein, Dave; Dean, Bruce; Eichhorn, Bil; Frey, Brad; Kubalak, Dave; Shiri, Ron; Smith, Scott; Wilson, Mark; Redman, Kevin; Janssen, Douglas; d'Entremont, Joseph

2007-01-01

332

A scanning Hartmann focus test for the EUVI telescopes aboard STEREO  

NASA Astrophysics Data System (ADS)

The Solar TErrestrial RElations Observatory (STEREO), the third mission in NASA's Solar Terrestrial Probes program, was launched in 2006 on a two year mission to study solar phenomena. STEREO consists of two nearly identical satellites, each carrying an Extreme Ultraviolet Imager (EUVI) telescope as part of the Sun Earth Connection Coronal and Heliospheric Investigation instrument suite. EUVI is a normal incidence, 98mm diameter, Ritchey-Chrétien telescope designed to obtain wide field of view images of the Sun at short wavelengths (17.1-30.4nm) using a CCD detector. The telescope entrance aperture is divided into four quadrants by a mask near the secondary mirror spider veins. A mechanism that rotates another mask allows only one of these sub-apertures to accept light over an exposure. The EUVI contains no focus mechanism. Mechanical models predict a difference in telescope focus between ambient integration conditions and on-orbit operation. We describe an independent check of the ambient, ultraviolet, absolute focus setting of the EUVI telescopes after they were integrated with their respective spacecraft. A scanning Hartmann-like test design resulted from constraints imposed by the EUVI aperture select mechanism. This inexpensive test was simultaneously coordinated with other integration and test activities in a high-vibration, clean room environment. The total focus test error was required to be better than +/-0.05mm. We cover the alignment and test procedure, sources of statistical and systematic error, data reduction and analysis, and results using various algorithms for determining focus. The results are consistent with other tests of instrument focus alignment and indicate that the EUVI telescopes meet the ambient focus offset requirements. STEREO and the EUVI telescopes are functioning well on-orbit.

Ohl, R., IV; Antonille, S.; Aronstein, D.; Dean, B.; Delmont, M.; d'Entremont, J.; Eichhorn, W.; Frey, B.; Hynes, S.; Janssen, D.; Kubalak, D.; Redman, K.; Shiri, R.; Smith, J. S.; Thompson, P.; Wilson, M.

2007-09-01

333

Hard X-ray imaging from the solar probe. [X ray telescope and mission planning  

NASA Technical Reports Server (NTRS)

The solar probe offers a platform with particular advantages for studying solar nonthermal plasma processes via the observations of hard X-radiation from energetic electrons in the chromosphere and corona, these include (1) high sensitivity, (2) a second line of sign (in addition to the earth's) that can aid in three dimensional reconstruction of the source distribution, and, (3) the possibility of correlation with direct measurements of the nonthermal particles from the probe itself.

Hudson, H. S.

1978-01-01

334

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

PubMed

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. PMID:17514269

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

2007-06-01

335

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

336

Effect of Solar Exposure on the Atomic Oxygen Erosion of Hubble Space Telescope Aluminized-Teflon Thermal Shields  

NASA Technical Reports Server (NTRS)

When exposed to low Earth orbital (LEO) environment, external spacecraft materials degrade due to radiation, thermal cycling, micrometeoroid and debris impacts, and atomic oxygen (AO) interaction. Collisions between AO and spacecraft can result in oxidation of external spacecraft surface materials, which can lead to erosion and severe structural and/or optical property deterioration. It is therefore essential to understand the AO erosion yield (Ey), the volume loss per incident oxygen atom (cu cm/atom), of polymers to assure durability of spacecraft materials. The objective of this study was to determine whether solar radiation exposure can increase the rate of AO erosion of polymers in LEO. The material studied was a section of aluminized-Teflon (DuPont) fluorinated ethylene propylene (Al-FEP) thermal shield exposed to space on the Hubble Space Telescope (HST) for 8.25 years. Retrieved samples were sectioned from the circular thermal shield and exposed to ground laboratory thermal energy AO. The results indicate that the average Ey of the solar facing HST Al-FEP was 1.9 10(exp -24)cu cm/atom, while the average Ey of the anti-solar HST Al-FEP was 1.5 10(exp -24)cu cm/atom. The Ey of the pristine samples was 1.6- 1.7 10(exp -24)cu cm/atom. These results indicate that solar exposure affects the post-flight erosion rate of FEP in a plasma asher. Therefore, it likely affects the erosion rate while in LEO.

Guo, Aobo; Ashmead, Claire C.; deGroh, Kim K.

2012-01-01

337

Telescopic vision contact lens  

NASA Astrophysics Data System (ADS)

We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

2011-02-01

338

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.

339

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

340

The large binocular telescope.  

PubMed

The Large Binocular Telescope (LBT) Observatory is a collaboration among institutions in Arizona, Germany, Italy, Indiana, Minnesota, Ohio, and Virginia. The telescope on Mount Graham in Southeastern Arizona uses two 8.4 m diameter primary mirrors mounted side by side. A unique feature of the LBT is that the light from the two Gregorian telescope sides can be combined to produce phased-array imaging of an extended field. This cophased imaging along with adaptive optics gives the telescope the diffraction-limited resolution of a 22.65 m aperture and a collecting area equivalent to an 11.8 m circular aperture. This paper describes the design, construction, and commissioning of this unique telescope. We report some sample astronomical results with the prime focus cameras. We comment on some of the technical challenges and solutions. The telescope uses two F/15 adaptive secondaries to correct atmospheric turbulence. The first of these adaptive mirrors has completed final system testing in Firenze, Italy, and is planned to be at the telescope by Spring 2010. PMID:20517352

Hill, John M

2010-06-01

341

Cost Modeling for Space Telescope  

NASA Technical Reports Server (NTRS)

Parametric cost models are an important tool for planning missions, compare concepts and justify technology investments. This paper presents on-going efforts to develop single variable and multi-variable cost models for space telescope optical telescope assembly (OTA). These models are based on data collected from historical space telescope missions. Standard statistical methods are used to derive CERs for OTA cost versus aperture diameter and mass. The results are compared with previously published models.

Stahl, H. Philip

2011-01-01

342

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

343

Emission lines of FeXV in spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph  

NASA Astrophysics Data System (ADS)

Recent R-matrix calculations of electron impact excitation rates in Mg-like FeXV are used to derive theoretical emission-line ratios involving transitions in the 243-418 Åwavelength range. A comparison of these with a data set of solar active region, subflare and off-limb spectra, obtained during rocket flights by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and observation, indicating that most of the FeXV emission lines may be employed with confidence as electron density diagnostics. In particular, the 312.55-Åline of FeXV is not significantly blended with a CoXVII transition in active region spectra, as suggested previously, although the latter does make a major contribution in the subflare observations. Most of the FeXV transitions which are blended have had the species responsible clearly identified, although there remain a few instances where this has not been possible. We briefly address the long-standing discrepancy between theory and experiment for the intensity ratio of the 3s21S-3s3p 3P1 intercombination line at 417.25 Åto the 3s21S-3s3p 1P resonance transition at 284.16 Å.

Keenan, F. P.; Aggarwal, K. M.; Milligan, R. O.; Ryans, R. S. I.; Bloomfield, D. S.; Srigengan, V.; O'Mullane, M. G.; Lawson, K. D.; Msezane, A. Z.; Brosius, J. W.; Davila, J. M.; Thomas, R. J.

2005-02-01

344

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

345

Spectral researches of solar system giant planets using 2-m telescope at the Peak Terskol  

NASA Astrophysics Data System (ADS)

Results of observations, processing and an analysis of Uranus and Neptune spectra obtained from 2001-2012 are presented. Observations were carried out at the peak Terskol observatory (Northern Caucasus, Russia) using the coude échelle high-resolution spectrograph and the 2-meter mirror telescope Zeiss-2000. Data were obtained with spectral resolution R=45000 within 3700 - 9000 Ångstroms range. Combination of the specified equipment and spectral resolution allowed to solve the following problems: detecting of contribution of Raman scattering in planet spectra; calculating of spectral geometric albedo Ag taking into account of Raman scattering; research of long- and short-periodic variations for Ag and intensities of some chosen spectral lines; calculations of vertical structure parameters of giant planet atmospheres; search of ammonia NH3 lines in planet spectra. A comparative analysis of Uranus and Neptune spectra for different years was done.

Kuznyetsova, Yu.; Matsiaka, O.; Shliakhetskaya, Ya.; Krushevska, V.; Vidmachenko, A.; Andreev, M.; Sergeev, A.

2014-03-01

346

Preliminary design analysis for the solar optical telescope main mirror actuator  

NASA Technical Reports Server (NTRS)

The resolution of the SOT Gregorian telescope was maintained if the conic foci of the elliptical secondary and parabolic primary were made to coincide within plus or minus 38 microns across the prime focus plane and to within 5 microns in focus. An error in coincidence across the focal plane caused all point images to show additional coma with all the comatic tails pointing in the same direction. An error in focus became magnified by the square of the magnification of the secondary and simply increased the diameter of the point source. Offsetting or rastering the sun may be accomplished by swinging the primary in an arc about the point of coincidence of the conic foci so long as the coincidence is kept to within the tolerance stated.

Dunn, R. B.

1977-01-01

347

The 8m South Pole Telescope  

Microsoft Academic Search

A new 8 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large area surveys with unprecedented sensitivity to low surface brightness emission such as primary and secondary CMB anisotropy. To achieve the highest sensitivity the telescope design employs an off-axis primary with a 10m clear aperture. The

John E. Carlstrom

2003-01-01

348

CHROMOSPHERIC SIGNATURES OF SMALL-SCALE FLUX EMERGENCE AS OBSERVED WITH NEW SOLAR TELESCOPE AND HINODE INSTRUMENTS  

SciTech Connect

With the ever-increasing influx of high-resolution images of the solar surface obtained at a multitude of wavelengths, various processes occurring at small spatial scales have become a greater focus of our attention. Complex small-scale magnetic fields have been reported that appear to have enough stored energy to heat the chromosphere. While significant progress has been made in understanding small-scale phenomena, many specifics remain elusive. We present here a detailed study of a single event of disappearance of a magnetic dipole and associated chromospheric activity. Based on New Solar Telescope H{alpha} data and Hinode photospheric line-of-sight magnetograms and Ca II H images, we report the following. (1) Our analysis indicates that even very small dipoles (elements separated by about 0.''5 or less) may reach the chromosphere and trigger non-negligible chromospheric activity. (2) Careful consideration of the magnetic environment where the new flux is deposited may shed light on the details of magnetic flux removal from the solar surface. We argue that the apparent collision and disappearance of two opposite polarity elements may not necessarily indicate their cancellation (i.e., reconnection, emergence of a 'U' tube, or submergence of {Omega} loops). In our case, the magnetic dipole disappeared by reconnecting with overlying large-scale inclined plage fields. (3) Bright points (BPs) seen in off-band H{alpha} images are very well correlated with the Ca II H BPs, which in turn are cospatial with G-band BPs. We further speculate that, in general, H{alpha} BPs are expected to be cospatial with photospheric BPs; however, a direct comparison is needed to refine their relationship.

Yurchyshyn, V. B.; Goode, P. R.; Abramenko, V. I.; Chae, J.; Cao, W.; Andic, A.; Ahn, K. [Big Bear Solar Observatory, New Jersey Institute of Technology, Big Bear City, CA 92314 (United States)

2010-10-20

349

Manufacturing of the ZERODUR 1.5-m primary mirror for the solar telescope GREGOR as preparation of light weighting of blanks up to 4-m diameter  

NASA Astrophysics Data System (ADS)

The 1.5 m primary ZERODUR® mirror of the solar telescope GREGOR incorporates 420 pockets at the backside for active cooling to avoid the thermal load impact of the sun deteriorating the observation. This design is also under consideration for the 2 m Indian Solar Telescope and for the 4.2 m European Solar Telescope (EST). The tip and tilt M5 mirror of the European Extremely Large Telescope (E-ELT) requires an even more demanding approach in light weighting. The approximately 3 m × 2.4 m elliptical flat mirror is specified to a weight of less than 500 kg. During the successful manufacturing of the GREGOR light weighted mirror, SCHOTT developed a systematic approach for processing such complex and long lead items which are capable for being up-scaled to a dimension of 4 m. In parallel SCHOTT has tested the machining of challenging aspect ratios of rib thickness and pocket height to prove the machinability of the E-ELT M5 design suggestions. The improved data on the bending strengths of ZERODUR® enable aggressive designs for light weighted 4 m class mirrors.

Westerhoff, Thomas; Schäfer, Martin; Thomas, Armin; Weissenburger, Marco; Werner, Thomas; Werz, Alexander

2010-07-01

350

ATM photoheliograph. [at a solar observatory  

NASA Technical Reports Server (NTRS)

The design and fabrication are presented of a 65 cm photoheliograph functional verification unit (FVU) installed in a major solar observatory. The telescope is used in a daily program of solar observation while serving as a test bed for the development of instrumentation to be included in early space shuttle launched solar telescopes. The 65 cm FVU was designed to be mechanically compatible with the ATM spar/canister and would be adaptable to a second ATM flight utilizing the existing spar/canister configuration. An image motion compensation breadboard and a space-hardened, remotely tuned H alpha filter, as well as solar telescopes of different optical configurations or increased aperture are discussed.

Prout, R. A.

1975-01-01

351

Monitoring Solar Radio Bursts at 20.1 MHz with the Furman University Radio Jove Telescope  

Microsoft Academic Search

For an interval of two months, from June 1, 2003 to July 28, 2003, we monitored solar radio bursts at 20.1 MHz using a Radio Jove dual-dipole transit antenna and receiver. We correlated these bursts with those recorded by similar receivers across the US and Europe (available at NASA's Radio Jove Archive center), and with radio and X-ray events logged

J. R. Holtzclaw; D. A. Moffett

2003-01-01

352

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

353

Filled aperture concepts for the Terrestrial Planet Finder  

NASA Astrophysics Data System (ADS)

Filled aperture telescopes can deliver a real, high Strehl image which is well suited for discrimination of faint planets in the vicinity of bright stars and against an extended exo-zodiacal light. A filled aperture offers a rich variety of PSF control and diffraction suppression techniques. Filled apertures are under consideration for a wide spectral range, including visible and thermal-IR, each of which offers a significant selection of biomarker molecular bands. A filled aperture visible TPF may be simpler in several respects than a thermal-IR nuller. The required aperture size (or baseline) is much smaller, and no cryogenic systems are required. A filled aperture TPF would look and act like a normal telescope - vendors and users alike would be comfortable with its design and operation. Filled aperture telescopes pose significant challenges in production of large primary mirrors, and in very stringent wavefront requirements. Stability of the wavefront control, and hence of the PSF, is a major issue for filled aperture systems. Several groups have concluded that these and other issues can be resolved, and that filled aperture options are competitive for a TPF precursor and/or for the full TPF mission. Ball, Boeing-SVS and TRW have recently returned architecture reviews on filled aperture TPF concepts. In this paper, I will review some of the major considerations underlying these filled aperture concepts, and suggest key issues in a TPF Buyers Guide.

Ridgway, Stephen T.

2003-02-01

354

Roof aperture system for selective collection and control of solar energy for building heating, cooling and daylighting  

DOEpatents

The amount of building heating, cooling and daylighting is controlled by at least one pair of solar energy passing panels, with each panel of the pair of panels being exposed to a separate direction of sun incidence. A shutter-shade combination is associated with each pair of panels and the shutter is connected to the shade so that rectilinear movement of the shutter causes pivotal movement of the shade.

Sanders, William J. (Kansas City, KS); Snyder, Marvin K. (Overland Park, KS); Harter, James W. (Independence, MO)

1983-01-01

355

Imaging of the Solar Atmosphere by the Siberian Solar Radio Telescope at 5.7 GHz with an Enhanced Dynamic Range  

NASA Astrophysics Data System (ADS)

The Siberian Solar Radio Telescope (SSRT) is a solar-dedicated directly-imaging interferometer observing the Sun at 5.7 GHz. SSRT has operated in the two-dimensional mode since 1996. The imaging principle of SSRT restricts its opportunities in observations of very bright flare sources, while it is possible to use `dirty' images in studies of low-brightness features, which do not overlap with side lobes from bright sources. The interactive CLEAN technique routinely used for SSRT data provides imaging of active regions, but consumes much time and efforts and does not reveal low-brightness features below the CLEAN threshold. The newly developed technique combines the CLEAN routine with the directly-imaging capability of SSRT, and provides clean images with an enhanced dynamic range automatically. These elaborations considerably extend the range of tasks that can be solved with SSRT. We show here some examples of the present opportunities of SSRT, and compare its data with the images produced by the Nobeyama Radioheliograph at 17 GHz as well as observations in different spectral ranges.

Kochanov, Alexey A.; Anfinogentov, Sergey A.; Prosovetsky, Dmitry V.; Rudenko, George V.; Grechnev, Victor V.

2013-12-01

356

Toward Active X-ray Telescopes II  

NASA Technical Reports Server (NTRS)

In the half century since the initial discovery of an astronomical (non-solar) x-ray source, the sensitivity for detection of cosmic x-ray sources has improved by ten orders of magnitude. Largely responsible for this dramatic progress has been the refinement of the (grazing-incidence) focusing x-ray telescope. The future of x-ray astronomy relies upon the development of x-ray telescopes with larger aperture areas (greater than 1 m2) and finer angular resolution (less than 1.). Combined with the special requirements of grazing-incidence optics, the mass and envelope constraints of space-borne telescopes render such advances technologically challenging.requiring precision fabrication, alignment, and assembly of large areas (greater than 100 m2) of lightweight (approximately 1 kg m2 areal density) mirrors. Achieving precise and stable alignment and figure control may entail active (in-space adjustable) x-ray optics. This paper discusses relevant programmatic and technological issues and summarizes progress toward active x-ray telescopes.

O'Dell, Stephen L.; Aldroft, Thomas L.; Atkins, Carolyn; Button, Timothy W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peter; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Johnson-Wilke, Raegan L.; Kolodziejczak, Jeffery J.; Lillie, Charles F.; Michette, Alan G.; Ramsey, Brian D.; Reid, Paul B.; Sanmartin, Daniel Rodriguez; Saha, Timo T.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Wilke, Rudeger H. T.; Willingale, Richard; Zhang, William W.

2012-01-01

357

Thermal Properties of A Solar Coronal Cavity Observed with the X-Ray Telescope on Hinode  

NASA Technical Reports Server (NTRS)

Coronal cavities are voids in coronal emission often observed above high latitude filament channels. Sometimes, these cavities have areas of bright X-ray emission in their centers. In this study, we use data from the X-ray Telescope (XRT) on the Hinode satellite to examine the thermal emission properties of a cavity observed during July 2008 that contains bright X-ray emission in its center. Using ratios of XRT filters, we find evidence for elevated temperatures in the cavity center. The area of elevated temperature evolves from a ring-shaped structure at the beginning of the observation, to an elongated structure two days later, finally appearing as a compact round source four days after the initial observation. We use a morphological model to fit the cavity emission, and find that a uniform structure running through the cavity does not fit the observations well. Instead, the observations are reproduced by modeling several short cylindrical cavity "cores" with different parameters on different days. These changing core parameters may be due to some observed activity heating different parts of the cavity core at different times. We find that core temperatures of 1.75 MK, 1.7 MK and 2.0 MK (for July 19, July 21 and July 23, respectively) in the model lead to structures that are consistent with the data, and that line-of-sight effects serve to lower the effective temperature derived from the filter ratio.

Reeves, Katherine K.; Gibson, Sarah E.; Kucera, Theresa A.; Hudson, Hugh S.; Kano, Ryouhei

2011-01-01

358

THERMAL PROPERTIES OF A SOLAR CORONAL CAVITY OBSERVED WITH THE X-RAY TELESCOPE ON HINODE  

SciTech Connect

Coronal cavities are voids in coronal emission often observed above high latitude filament channels. Sometimes, these cavities have areas of bright X-ray emission in their centers. In this study, we use data from the X-ray Telescope (XRT) on the Hinode satellite to examine the thermal emission properties of a cavity observed during 2008 July that contains bright X-ray emission in its center. Using ratios of XRT filters, we find evidence for elevated temperatures in the cavity center. The area of elevated temperature evolves from a ring-shaped structure at the beginning of the observation, to an elongated structure two days later, finally appearing as a compact round source four days after the initial observation. We use a morphological model to fit the cavity emission, and find that a uniform structure running through the cavity does not fit the observations well. Instead, the observations are reproduced by modeling several short cylindrical cavity 'cores' with different parameters on different days. These changing core parameters may be due to some observed activity heating different parts of the cavity core at different times. We find that core temperatures of 1.75 MK, 1.7 MK, and 2.0 MK (for July 19, July 21, and July 23, respectively) in the model lead to structures that are consistent with the data, and that line-of-sight effects serve to lower the effective temperature derived from the filter ratio.

Reeves, Katharine K. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS 58, Cambridge, MA 02138 (United States); Gibson, Sarah E. [HAO/NCAR, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Kucera, Therese A. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Hudson, Hugh S. [Space Sciences Laboratories, University of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States); Kano, Ryouhei, E-mail: kreeves@cfa.harvard.edu [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2012-02-20

359

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

360

CRTF Real-Time Aperture Flux System.  

National Technical Information Service (NTIS)

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 ...

D. B. Davis

1980-01-01

361

Switched fragmented aperture antennas  

Microsoft Academic Search

This paper introduces a reconfigurable aperture concept derived from fragmented aperture design where the configuration of the fragmented aperture may be switched by the user to obtain different functionalities. A fragmented aperture antenna is a patchwork of discrete conducting and dielectric units distributed over the specified aperture. The arrangement of the units is determined using an efficient, multistage procedure that

James C. Maloney; Morris P. Kesler; Lisa M. Lust; Lon N. Pringle; T. Lynn Fountain; Paul H. Harms; Glenn S. Smith

2000-01-01

362

Optical Set-Up and Design for Solar Multi-conjugate Adaptive Optics at the 1.6m New Solar Telescope, Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

The Sun is an ideal target for the development and application of Multi-Conjugate Adaptive Optics (MCAO). A solar MCAO system is being developed by the Big Bear Solar Observatory, for the 1.6m New Solar Observatory, with the purpose of extending the corrected science field of view to 1.00Arcmin. A preliminary optical set-up, design and optical performance for such a system is presented and discussed here.

Moretto, Gil; Langlois, Maud; Goode, Philip; Gorceix, Nicolas; Shumko, Sergey

2013-12-01

363

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

364

The Substructure of the Solar Corona Observed in the Hi-C Telescope  

NASA Astrophysics Data System (ADS)

In the summer of 2012, the High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore calculate how the intensity scales from a low-resolution (AIA) pixels to high-resolution (Hi-C) pixels for both the dynamic events and “background” emission (meaning, the steady emission over the 5 minutes of data acquisition time). We find there is no evidence of substructure in the background corona; the intensity scales smoothly from low-resolution to high-resolution Hi-C pixels. In transient events, however, the intensity observed with Hi-C is, on average, 2.6 times larger than observed with AIA. This increase in intensity suggests that AIA is not resolving these events. This result suggests a finely structured dynamic corona embedded in a smoothly varying background.

Winebarger, Amy R.; Cirtain, Jonathan W.; Golub, Leon; DeLuca, Ed; Savage, Sabrina; Alexander, Caroline; Schuler, Timothy

2014-06-01

365

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

NASA Technical Reports Server (NTRS)

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.

1993-01-01

366

Discovery of Finely Structured Dynamic Solar Corona Observed in the Hi-C Telescope  

NASA Astrophysics Data System (ADS)

In the Summer of 2012, the High-resolution Coronal Imager (Hi-C) flew on board a NASA sounding rocket and collected the highest spatial resolution images ever obtained of the solar corona. One of the goals of the Hi-C flight was to characterize the substructure of the solar corona. We therefore examine how the intensity scales from AIA resolution to Hi-C resolution. For each low-resolution pixel, we calculate the standard deviation in the contributing high-resolution pixel intensities and compare that to the expected standard deviation calculated from the noise. If these numbers are approximately equal, the corona can be assumed to be smoothly varying, i.e., have no evidence of substructure in the Hi-C image to within Hi-C's ability to measure it given its throughput and readout noise. A standard deviation much larger than the noise value indicates the presence of substructure. We calculate these values for each low-resolution pixel for each frame of the Hi-C data. On average, 70% of the pixels in each Hi-C image show no evidence of substructure. The locations where substructure is prevalent is in the moss regions and in regions of sheared magnetic field. We also find that the level of substructure varies significantly over the roughly 160 s of the Hi-C data analyzed here. This result indicates that the finely structured corona is concentrated in regions of heating and is highly time dependent.

Winebarger, Amy R.; Cirtain, Jonathan; Golub, Leon; DeLuca, Edward; Savage, Sabrina; Alexander, Caroline; Schuler, Timothy

2014-05-01

367

Development of the remote diagnosis system of the solar radio telescope  

NASA Astrophysics Data System (ADS)

"The remote diagnosis system" which we have developed is the one to monitor the operation conditions of two systems of solar radio observation (Nobeyama Radioheliograph and Nobeyama Radio Polarimeters) from the remote place. Under the condition of very limited human power, it is necessary to minimize the load of observers without degrading data quality. Thereupon, we have mulled measures to alleviate the load of observers, and worked out "the remote diagnosis system" which enables us to monitor the operation conditions and detect troubles, if any, in early stages, even if we are away from the observatory building where control system are concentrated. The plan was materialized by adopting an access through the INTERNET to the section where needed information for diagnosis is gathered.

Kawashima, Susumu; Shinohara, Noriyuki; Sekiguchi, Hideaki

2005-04-01

368

Solar Si II line ratios from the high-resolution telescope and spectrograph  

NASA Technical Reports Server (NTRS)

Theoretical emission-line ratios involving multiplets near 1262, 1306, and 1530 A are derived on the basis of new calculations of electron-impact excitation rates for allowed transition in Si II. A comparison of these line ratios with observational data from a quiet solar region, a sunspot, and an active region, obtained with the HIRTS on board a sounding rocket flight reveals that the 1530-A multiplet is optically thick, which is consistent with a calculation of the optical depth of these lines through a model atmosphere. The 1262- and 1306-A multiplets appear to be effectively optically thin. The average discrepancy between the theoretical and observed ratios is about 40 percent, which may not be significant, since the estimated uncertainties in both the calculated and experimental data are approximately 30 percent.

Keenan, F. P.; Cook, J. W.; Dufton, P. L.; Kingston, A. E.

1992-01-01

369

Cooling Technology for Large Space Telescopes  

NASA Technical Reports Server (NTRS)

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 missions. The new paradigm for cooling to low temperatures will involve passive cooling using lightweight deployable membranes that serve both as sunshields and V-groove radiators, in combination with active cooling using mechanical coolers operating down to 4 K. The Cooling Technology for Large Space Telescopes (LST) mission planned to develop and demonstrate a multi-layered sunshield, which is actively cooled by a multi-stage mechanical cryocooler, and further the models and analyses critical to scaling to future missions. The outer four layers of the sunshield cool passively by radiation, while the innermost layer is actively cooled to enable the sunshield to decrease the incident solar irradiance by a factor of more than one million. The cryocooler cools the inner layer of the sunshield to 20 K, and provides cooling to 6 K at a telescope mounting plate. The technology readiness level (TRL) of 7 will be achieved by the active cooling technology following the technology validation flight in Low Earth Orbit. In accordance with the New Millennium charter, tests and modeling are tightly integrated to advance the technology and the flight design for "ST-class" missions. Commercial off-the-shelf engineering analysis products are used to develop validated modeling capabilities to allow the techniques and results from LST to apply to a wide variety of future missions. The LST mission plans to "rewrite the book" on cryo-thermal testing and modeling techniques, and validate modeling techniques to scale to future space telescopes such as SAFIR.

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

2007-01-01

370

Hubble, a view to the edge of space : telescope tour  

NSDL National Science Digital Library

Eight thumbnail images of key features of the Hubble Space Telescope surround this drawing of Hubble. Users can move their mouse over the image of a feature to reveal both the location(s) of the feature and a description of its function. The solar arrays, communications antennae, aperture door, and fine gauge sensors are among the featured parts. Three of the eight feature descriptions offer users the option to link to additional information about these parts of Hubble. Links to more information and to activities about Hubble are provided at the bottom of the page. Copyright 2005 Eisenhower National Clearinghouse

Exploratorium

2001-01-01

371

Determination of the structure and heating mechanisms of coronal loops from soft X-ray observations with the solar probe. [grazing incidence telescope  

NASA Technical Reports Server (NTRS)

High resolution soft X-ray imaging from the solar probe is justified in terms of the expected scientific returns which include the determination of the temperature and density structure of a coronal loop. The advantages of the grazing incidence telescope over the multiple pinhole camera are discussed. An instrument package is described which includes a grazing incidence mirror, a thermal prefilter, a three position filter wheel and a focal plane detector baselined as an 800 by 800 back-illuminated charge coupled device. The structural assembly together with the data processing equipment would draw heavily on the designs being developed for the Solar Polar Mission.

Davis, J. M.; Krieger, A. S.

1978-01-01

372

Shuttle Infrared Telescope Facility  

NASA Technical Reports Server (NTRS)

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 and stabilized at two levels: the European-developed Instrument Pointing System provides primary pointing and stabilization; and an internal star tracker senses residual errors and drives a folding mirror inside the telescope to null the errors. The folding mirror can also be driven by square or triangular waves to provide space chopping or small-area scanning.

Mccarthy, S. G.

1976-01-01

373

Sub-arcsec X-Ray Telescope for Imaging The Solar Corona In the 0.25 - 1.2 keV Band  

NASA Technical Reports Server (NTRS)

We have developed an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype X-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degee graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 sq cm at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the X-ray telescope's response to the Sun show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight.

Gallagher, Dennis; Cash, Webster; Jelsma, Schuyler; Farmer, Jason

1996-01-01

374

The telescopes of the swift mission  

Microsoft Academic Search

The Swift Gamma-Ray Burst (GRB) Mission is a multi-wavelength observatory designed to capture the early light from GRBs. The observatory consists of three telescopes: the Burst Alert Telescope (BAT), the X-Ray Telescope (XRT), and the Ultra-Violet\\/Optical Telescope (UVOT). The BAT uses coded-aperture mask technology in connection with a CdZnTe detector plane which provides a 1.4 steradian (half-coded) field-of-view (FOV). The

P. Roming; D. N. Burrows; S. D. Barthelmy; N. Gehrels

2004-01-01

375

Advances in Radio Telescopes  

NASA Astrophysics Data System (ADS)

The editors of the third Special Issue on Radio Telescopes, which appeared in the Proceedings of the IEEE in May 1994, surmised in their introduction that "perhaps yet a future issue is merited, one devoted to those new telescopes that are still on the drawing boards." Now, 15 years later, such an issue lies in front of you, featuring 16 papers describing both the realization of new instruments and the status of several giant radio telescopes, most of which are moving from the drawing board to different stages of construction. The development of astronomy over this period has led radio astronomers to concentrate on both the highest and the lowest ranges of the radio spectrum. The technological advance in the millimeter wavelength domain has enabled an enormous improvement in observing capabilities. In the low frequency range, roughly 10 - 2000 MHz, new telescopes are being planned that combine a large instantaneous field of view with a large number of high- resolution antenna beams. In addition to these developments, this issue features papers on several new single aperture telescopes. We also have three papers covering advances in technologies that are applicable to multiple projects, namely, antenna metrology, imaging techniques, and the use of phased array techniques. The issue begins with a short paper by the guest editors on "Radio Astronomy in the Early Twenty-First Century." There we attempt to put the topics of the following papers in historical perspective and to provide background information for readers whose expertise lies outside astronomy. The remaining papers are organized into three broad categories: single antenna telescopes, synthesis array telescopes, and the Square Kilometre Array (SKA). Although the last is also a synthesis array, the intensity of SKA-related work now under way around the world justifies a separate set of papers devoted to it. This issue features new single-aperture and synthesis array radio telescopes and covers advances in antenna metrology, imaging techniques, and the use of phased array technology.

Baars, Jacob W. M.; D'Addario, Larry R.; Thompson, A. Richard

2009-08-01

376

Total coronagraphic extinction of rectangular apertures using linear prolate apodizations  

Microsoft Academic Search

This paper presents a theoretical study of stellar coronagraphy with apodized entrance apertures. The study is restricted to a perfect telescope operating in space, and a monochromatic on-axis unresolved star. It is shown that linear prolate functions are the optimal apodizers for rectangular apertures in stellar coronagraphy. With the phase mask technique (Roddier & Roddier 1997), prolate functions can produce

Claude Aime; Remi Soummer; Andre Ferrari

2002-01-01

377

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

378

The Multiple Telescope Telescope  

NASA Astrophysics Data System (ADS)

Designed and constructed by the Georgia State University Department of Physics and Astronomy, the Multiple Telescope Telescope (MTT) is an efficient, inexpensive 1 meter instrument dedicated to spectroscopic observations. The MTT is composed of nine mirrors, each focused on a separate fiber bundle which is fed directly into a Newtonian-Ebert spectrograph designed for medium to high resolution spectroscopy. The light weight of the optics and small size of the telescope allow for an inexpensive design that any university could conceivably construct. The MTT has been used primarily for observation and reconstruction of separated binary spectra, though work with giant stars, stellar oscillations, and Comet Hale-Bopp are among the other projects that have utilized the MTT.

Riddle, R. L.; Bagnuolo, W. G.; Barry, D. J.

1999-12-01

379

The scientific potential of automatic CCD imaging telescopes  

NASA Astrophysics Data System (ADS)

I discuss the scientific potential of moderate-aperture (about 0.8 m) automatic imaging telescopes (AITs) equipped with CCDs. Such instruments are relatively inexpensive to construct, yet they have a wide range of uses for projects that cannot otherwise be conducted at most private or national observatories. They also have many important advantages over conventional automatic photoelectric telescopes. For illustrative purposes, I concentrate on three scientific areas being pursued by the Berkeley AIT: light curves of supernovae and novae, active galactic nuclei, and solar system objects. AITs are also useful for essentially all types of variable stars. There are enormous gains to be made by using AITs in coordinated ground-based and space-based observations. Finally, AITs have great potential in undergraduate laboratory astrophysics classes.

Filippenko, Alexei V.

380

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

381

A synthetic aperture imaging ladar demonstrator with Ø300mm antenna and changeable footprint  

Microsoft Academic Search

A demonstrator of synthetic aperture imaging ladar (SAIL) is constructed with the maximum aperture Ø300mm of antenna telescope. This demonstrator can be set with a rectangular aperture to produce a rectangular footprint suitable for scanning format with a high resolution and a wide strip. Particularly, the demonstrator is designed not only for the farfield application but also for the verifying

Yu Zhou; Yanan Zhi; Aimin Yan; Nan Xu; Lijuan Wang; Yapeng Wu; Zhu Luan; Jianfeng Sun; Liren Liu

2010-01-01

382

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

383

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

384

Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

An overview of the mission of the Hubble Space Telescope, a joint project between NASA and the European Space Agency which will be used to study deep space, as well as our solar system is presented. The video contains animations depicting the Hubble Space Telescope in orbit, as well as footage of scientists at the Space Telescope Science Institute making real time observations. The images Hubble acquires will be downloaded into a database that contains images of over 19,000,000 celestial objects called the Star Catalog.

1990-01-01

385

Golay3 sparse aperture systems designed on a spherical surface  

NASA Astrophysics Data System (ADS)

High resolution imaging from space telescope for surveillance and astrometry is currently limited by launch vehicles and systems cost. The weight of the telescope is one of major factors which limits the vehicles to be placed in orbit. Sparse aperture optical system uses a reduced aperture area to synthesize the optical performance of a filled aperture. It is more promising in virtue of its light weight, low cost and larger synthetic aperture. The sparse aperture optical system has two types, i.e. the multiple-mirror telescope (MMT) and the multiple-telescope telescope (MTT). A MMT of Golay3 sparse aperture optical system is investigated that three sub-mirrors are located on a spherical primary mirror. Three sub apertures of Golay3 are elliptic that in fact the circular sub-mirrors of spherical primary mirror are projected on the entrance pupil. The relationships between fill factor, radius of sub-mirrors and F number of the primary mirror are presented. The analytical formula is also completed, which shows that the maximum fill factor is limited by F number of the primary mirror. When the aperture radius is equal to curvature radius of the primary mirror approximately, the shape of sub-apertures exhibits to be elliptic obviously. The maximum fill factor reaches the largest one at that time. Modulation Transfer Function (MTF) of Golay3 system is studied. MTF is the correlation of three elliptic sub-apertures. The sub-MTFs are different from those of sub-mirrors located on a plane. The formula is verified by designing two Cassegrain telescopes which primary mirror is made up of three sub-mirrors of Golay3 configuration with Zemax optical program. Three sub-mirrors of primary mirror share a common asphercial secondary mirror. The errors caused by tilt and piston of three sub-apertures are also given out. Because of the loss of MTF for the sparse aperture optical system, the image quality is decreased. Wiener filter technique is utilized to improve the image quality for the sparse aperture system.

Wu, Feng; Wu, Quanying; Qian, Lin

2008-03-01

386

The Largest Feasible Steerable Telescope  

NASA Astrophysics Data System (ADS)

Ever since Grote Reber built a 32-ft steerable dish in 1937, successive generations of radio astronomers world-wide have designed larger and larger fully steerable filled aperture radio telescopes to address a variety of astronomical questions. Paced by the giant 250-ft radio telescope that was built at Jodrell Bank, starting in the 1950’s NRAO, Caltech, and Smithsonian radio astronomers have discused the construction of a series of large steerable dishes ranging in size up to 600-ft in diameter. Although the need for a large steerable radio telescope was repeatedly recognized by the series of NRC decade reviews of astronomy, they were never given the highest priority and were never funded. Meanwhile, in the 1960s and 1970s the Parkes 64-m and the German 100-m telescopes became operational. A freak 1989 accident that caused the collapse of the 300-ft Green Bank transit telescope, led directly to the construction of the 100-m Green Bank Telescope with its novel unblocked aperture and adaptive surface, although by 1989, the 300-ft telescope had long outlived its designed lifetime, and had already been recommended for closure.

Kellermann, Kenneth I.; Bouton, E. N.

2014-01-01

387

Cost Modeling for Space Optical Telescope Assemblies  

NASA Technical Reports Server (NTRS)

Parametric cost models are used to plan missions, compare concepts and justify technology investments. This paper reviews an on-going effort to develop cost modes for space telescopes. This paper summarizes the methodology used to develop cost models and documents how changes to the database have changed previously published preliminary cost models. While the cost models are evolving, the previously published findings remain valid: it costs less per square meter of collecting aperture to build a large telescope than a small telescope; technology development as a function of time reduces cost; and lower areal density telescopes cost more than more massive telescopes.

Stahl, H. Philip; Henrichs, Todd; Luedtke, Alexander; West, Miranda

2011-01-01

388

An overview of the Green Bank Telescope  

Microsoft Academic Search

The Green Bank Telescope (GBT) at the National Radio Astronomy Observatory (NRAO) site in Green Bank, is to be the largest, fully-steerable telescope in the world. The GBT has a main reflector 100 m×100 m with unblocked aperture. The telescope will operate at prime focus in the 230 MHz-1200 MHz frequency range and at Gregorian focus in the 1.15 GHz

S. Srikanth; R. Norrod; L. King; D. Parker

1999-01-01

389

LSST Telescope mount and pier design overview  

Microsoft Academic Search

The Large Synoptic Survey Telescope (LSST) is a large (8.4 meter) wide-field (3.5 degree) survey telescope, which will be located on the summit of Cerro Pachón in Chile. The survey mission requires a short slew and settling time of 5 seconds for a 3.5 degree slew. This is significantly faster than similar aperture telescopes. Since the optical system does not

Douglas R. Neill; Victor L. Krabbendam

2010-01-01

390

Effects of stitching pattern on diffractive telescope image quality  

NASA Astrophysics Data System (ADS)

Diffraction image technology is an updated technology. It has more potential for developing the larger aperture and lightweight telescope than the conventional refractive and reflective optics. In order to develop a large aperture diffractive telescope, the key is to solve the problem of large aperture lens stitching. Different stitching patterns have different effects on the image quality. However, the stitching pattern for diffractive telescope is different from the conventional refractive and reflective telescope. This paper, for the first time, studies the theory of stitching pattern for diffractive telescope. On the basis of theoretical analysis, a long-wavelength infrared diffractive telescope of segmented-lens is designed and for the first time, good results through stitching experiments have been achieved. According to theoretical analysis and experiment verification, the paper gives the best stitching pattern on diffractive telescope.

Zhang, ZhouFeng; Xie, YongJun; Kang, FuZeng; Wang, YanJun

2014-02-01

391

Solar astronomy  

NASA Technical Reports Server (NTRS)

An overview is given of modern solar physics. Topics covered include the solar interior, the solar surface, the solar atmosphere, the Large Earth-based Solar Telescope (LEST), the Orbiting Solar Laboratory, the High Energy Solar Physics mission, the Space Exploration Initiative, solar-terrestrial physics, and adaptive optics. Policy and related programmatic recommendations are given for university research and education, facilitating solar research, and integrated support for solar research.

Rosner, Robert; Noyes, Robert; Antiochos, Spiro K.; Canfield, Richard C.; Chupp, Edward L.; Deming, Drake; Doschek, George A.; Dulk, George A.; Foukal, Peter V.; Gilliland, Ronald L.

1991-01-01

392

Spectral filtration of XUV radiation with the help of thin film filters in the TEREK-C solar telescope and RES-C spectroheliograph  

NASA Astrophysics Data System (ADS)

The characteristics of different types of thin film XUV filters for the TEREK-C solar telescope and the REC-C spectroheliograph developed in the framework of the CORONAS-I program are presented. We describe the design and properties of Al-Formvar composite filters on rigid mesh supports with a spacing of 0.7 mm and 2 mm, which have been mounted in front of the XUV spectral channels of both instruments. It was proposed to use thin films of SiC as bandpass filters with high transparency in the 13 - 30 nm spectral region and effective cutoff blocking of strong solar L(subscript (alpha) ) (121.7 nm) line radiation. The Al and SiC thin films on fine porous polymer membranes with through pores were placed in close proximity of the entrance plane of the image detectors, designed as a combination of open type microchannel plate and CCD-matrix. The problem of elimination of the influence of diffraction effects on X-ray images in the telescope focal plane is considered. All filters have sustained without damage the launching overloads (the launch took place on March 12, 1994) and successfully worked in the TEREK-C and the RES-C instruments.

Mitrofanov, Alexander V.; Pudonin, Fedor A.; Starodubzev, N.; Zhitnik, Igor A.

1998-06-01

393

Geometrical theory of diffraction and telescope stray-light analysis  

Microsoft Academic Search

The paper reviews the geometrical theory of diffraction and telescope stray-light analysis. The control of diffraction effects in telescopes affects the optical design for which the geometrical theory of diffraction provides a computational tool. The nature of the geometrical theory of diffraction is reviewed, and its application to telescope diffraction problems, circular aperture diffraction, the barrel baffle diffraction are discussed.

R. J. Noll

1979-01-01

394

MEMS microshutter arrays for James Webb Space Telescope  

Microsoft Academic Search

MEMS microshutter arrays (MSAs) are being developed at NASA Goddard Space Flight Center for use as an aperture array for the Near-Infrared Spectrometer (NirSpec). The instruments will be carried on the James Webb Space Telescope (JWST), the next generation of space telescope after Hubble Space Telescope retires. The microshutter arrays are designed for the selective transmission of light with high

Mary J. Li; Tomoko Adachi; Christine Allen; Sachi Babu; Sateesh Bajikar; Michael Beamesderfer; Ruth Bradley; Kevin Denis; Nick Costen; Audrey Ewin; David Franz; Larry Hess; Ron Hu; Kamili M. Jackson; Murzy Jhabvala; Dan Kelly; Todd King; Gunther Kletetschka; Alexander Kutyrev; Barney Lynch; Timothy Miller; Harvey Moseley Jr.; Vilem Mikula; Brent Mott; Lance Oh; James T. Pontius; David Rapchun; Chris Ray; Eric Schulte; Scott Schwinger; Peter Shu; Robert Silverberg; Wayne Smith; Steve Snodgrass; David Sohl; Leroy Sparr; Rosalind Steptoe-Jackson; Valeriano Veronica; Liqin Wang; Yun Zheng; Chris Zincke

2007-01-01

395

Status of the Giant Magellan Telescope (GMT) project  

Microsoft Academic Search

The Giant Magellan Telescope (GMT) is a joint project of a consortium of universities and research institutions to build and operate a 21.5-m equivalent aperture astronomical telescope for use at visible and IR wavelengths. This paper briefly summarizes the science goals for the project and provides an overview of the preliminary telescope and enclosure concepts and site test program. The

Matt Johns; J. Roger P. Angel; Stephen Shectman; Rebecca Bernstein; Daniel G. Fabricant; Patrick McCarthy; Mark Phillips

2004-01-01

396

Space Telescopes  

NASA Technical Reports Server (NTRS)

Space telescopes have been a dominant force in astrophysics and astronomy over the last two decades. As Lyman Spitzer predicted in 1946, space telescopes have opened up much of the electromagnetic spectrum to astronomers, and provided the opportunity to exploit the optical performance of telescopes uncompromised by the turbulent atmosphere. This special section of Optical Engineering is devoted to space telescopes. It focuses on the design and implementation of major space observatories from the gamma-ray to far-infrared, and highlights the scientific and technical breakthroughs enabled by these telescopes. The papers accepted for publication include reviews of major space telescopes spanning the last two decades, in-depth discussions of the design considerations for visible and x-ray telescopes, and papers discussing concepts and technical challenges for future space telescopes.

Clampin, Mark; Flanagan, Kathryn A.

2012-01-01

397

High-precision wavefront sensor for the SUNRISE Telescope  

NASA Astrophysics Data System (ADS)

SUNRISE is a 1m solar telescope for the visible and near UV wavelength range. It will be flown in long duration stratospheric balloon flights in Antarctica, with a first scientific flight in 2007. In this paper, we describe the development of a wave-front sensing system that will be used for the automatic in-flight alignment of the SUNRISE telescope and for high-precision tracking. The system is based on the principles of an adaptive optics system. A 19-element wavefront sensor is used to determine low order aberrations of the telescope, including defocus and spherical aberrations. The correction is achieved by controlling the position of the telescope secondary and a focusing mirror in closed-loop. In addition to these quasi-static aberrations, the system will also measure image motion with a dynamical range of at least 30 Hz and with a precision of about 0.005 arcs. To this end, the image displacement measured in all sub-apertures is averaged and used as tip-tilt correction signal. This signal will feed a second closed-loop system that drives the tip-tilt mirror assembly. The tip-tilt mirror unit is designed as a dual-stage system that consists of a slow component with a large range of 60 arcs and a fast component with high bandwidth.

Schmidt, Wolfgang; Berkefeld, Thomas; Friedlein, Ruediger; Heidecke, Frank; Kentischer, Thomas; von der Lühe, Oskar F.; Sigwarth, Michael; Soltau, Dirk; Walde, E.

2004-10-01

398

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

399

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

400

World Wide Telescope  

NSDL National Science Digital Library

WorldWide Telescope is a Web application that brings together imagery from the best ground- and space-based observatories across the world to allow people to easily explore the night sky through their computers. The application may be downloaded free and allows users to browse through the solar system, galaxy and beyond, or take advantage of a growing number of guided tours of the sky hosted by astronomers and educators at major universities and planetariums. Features include: a choice of which telescope to look through, including the Hubble Space Telescope, the Chandra X-Ray Observatory Center, and the Spitzer Space Telescope; a view of planetary locations in the night sky - in the past, present or future; and a view of the universe through different wavelengths of light to reveal hidden structures in other parts of the galaxy.