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1

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

2

Eyeglass. 1. Very large aperture diffractive telescopes  

Microsoft Academic Search

The Eyeglass is a very large aperture (25100-m) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope{close_quote}s large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is

Roderick A. Hyde

1999-01-01

3

Infrared observations of the solar system in support of Large Aperture Infrared Telescope (LARITS): Calibration. Appendices  

Microsoft Academic Search

An infrared (IR) optics package designed for a IR detector calibration survey will be used in conjunction with the 90 inch telescope at the University of Wyoming, or as a portable, stand along unit. An important part of this instrument package is a mechanical light beam chopper which rotates with a fixed phase relation with respect to a wobbling secondary

Richard W. Shorthill

1990-01-01

4

Eyeglass: A Very Large Aperture Diffractive Space Telescope  

Microsoft Academic Search

Eyeglass is a very large aperture (25 - 100 meter) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope's large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes;

Roderick A. Hyde; Shamasundar N. Dixit; Andrew H. Weisberg; Michael C. Rushford

2002-01-01

5

The Historical Growth of Telescope Aperture  

NASA Astrophysics Data System (ADS)

This paper analyzes a compilation of aperture diameters D and commissioning dates t for 177 optical telescopes, including those that have been among the largest of their time. We offer the following findings, and draw the following inferences, about aperture growth D(t) over four centuries: 1. From the days of Galileo to the present, telescope diameters have steadily grown, with a doubling time t2× of nearly 50 yr. 2. Beginning in 1730, major refractors' apertures followed a strictly exponential curve of growth, with t2×=45 yr, before stopping with the Yerkes 40 inch (1.02 m) in 1897. 3. Over the last 300 yr, the very largest ``frontier'' reflectors have defined a sharp and distinct upper boundary to the D(t) distribution, with t2×=48 yr and D1900=2.3 m. This exponential growth is taken to have been imposed strictly by the rate at which telescope technology has progressed. 4. Data for second-tier ``large'' reflectors yield D1900=1.0 m and t2×=47 yr until 1950 and suggest an exponential decrease of the doubling time afterwards, e-folding in ~70 yr and leading to t2×=20 yr in 2000. This may be the result of a gradual relief, through increased collaboration, of constraints that prevented the limits of technology from being reached. 5. The curves of growth for large and for frontier reflectors cross in ~2010. Whether the aperture growth in the 21st century is limited by demographics-collaborations-or by technology remains to be seen. 6. During the 20th century, commissioning of large telescopes tended to occur in bursts at ~35 yr intervals. 7. Giant telescopes with serious shortcomings were not uncommon before 1850. These typically had twice the aperture of their more productive contemporaries. 8. The completion of the current burst of ambitiously large 20-100 m telescope projects with the scheduled launch of the James Webb Space Telescope in the 2010s would constitute a dramatic break with 4 centuries of historical evolution.

Racine, René

2004-01-01

6

Large-Aperture Segmented Mirror Telescope Design Concept  

E-print Network

Large-Aperture Segmented Mirror Telescope Design Concept (Image courtesy of John Frassanito (ATLAS) Telescope: A Technology Roadmap for the Next Decade Principal Investigator: Dr. Marc Postman Telescope .......................................2 2 Science Objectives and Expected Impact of an ATLAS

Sirianni, Marco

7

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

8

CALISTO: The Cryogenic Aperture Large Infrared Space Telescope Observatory  

NASA Astrophysics Data System (ADS)

CALISTO, the Cryogenic Aperture Large Infrared Space Telescope Observatory, will enable extraordinarily high sensitivity far-infrared continuum and moderate (R 1000) resolution spectroscopic observations from 20µm into the submillimeter, wavelengths between those accessible by JWST and future ground based facilities,. Such observations will provide vital information about a wide range of important astronomical questions including (1) the formation of the first structure in the universe traced by H2 emission; (2) the evolution of galaxies and the star formation that takes place within them; (3) the formation of planetary systems through observations of protostellar and debris disks; (4) the outermost portions of our solar system through observations of Trans-Neptunian Objects (TNOs) and the Oort cloud. With low emissivity optics cooled to below 5 K, the photon fluctuations from the astronomical background (Zodiacal, Galactic, and extragalactic) exceed those of the telescope. Detectors with a noise equivalent power below that set by the background allow us to achieve astronomical background sensitivity through the submillimeter/far-infrared region. CALISTO builds on studies for the SAFIR (Single Aperture Far Infrared) telescope mission, employing a 4m x 6m off-axis Gregorian telescope which has a simple deployment from an Atlas V launch vehicle. The telescope and cold stop have minimal sidelobes and scattering, enabling astronomical background limited observations over a large fraction of the sky. We discuss CALISTO optics, performance, instrument complement, and mission design, and give an overview of key science goals and required technology development to enable this important future mission.

Goldsmith, Paul

9

TECHNOLOGY DEVELOPMENT PROJECT PLAN Advanced Technology Large Aperture Space Telescope  

E-print Network

TECHNOLOGY DEVELOPMENT PROJECT PLAN for the Advanced Technology Large Aperture Space Telescope, and Ronald Polidan. #12;Advanced Technology Large-Aperture Space Telescope (ATLAST) 22 TABLE OF CONTENTS 1 (ATLAST) A Roadmap for UVIOR Technology, 2010-2020 24 April, 2009 T. Tupper Hyde, ATLAST Technologist

Sirianni, Marco

10

Progress on the 1.6-meter New Solar Telescope at Big Bear Solar Observatory  

E-print Network

of the drivers for building solar telescopes with large apertures. Recent advances in adaptive optics (AO) make it possible to build solar telescopes in an open configuration and thus go beyond the conventional meterProgress on the 1.6-meter New Solar Telescope at Big Bear Solar Observatory C. Denkera, P. R

11

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

12

CALISTO: the Cryogenic Aperture Large Infrared Space Telescope Observatory  

NASA Astrophysics Data System (ADS)

CALISTO, the Cryogenic Aperture Large Infrared Space Telescope Observatory, will enable extraordinarily high sensitivity far-infrared continuum and moderate (R ~ 1000) resolution spectroscopic observations at wavelengths from ~30µm to ~300 ?m - the wavelengths between those accessible by JWST and future ground based facilities. CALISTO's observations will provide vital information about a wide range of important astronomical questions including (1) the first stars and initial heavy element production in the universe; (2) structures in the universe traced by H2 emission; (3) the evolution of galaxies and the star formation within them (4) the formation of planetary systems through observations of protostellar and debris disks; (5) the outermost portions of our solar system through observations of Trans-Neptunian Objects (TNOs) and the Oort cloud. With optics cooled to below 5 K, the photon fluctuations from the astronomical background (Zodiacal, Galactic, and extragalactic) exceed those from the telescope. Detectors with a noise equivalent power below that set by the background will make possible astronomical-background-limited sensitivity through the submillimeter/far-infrared region. CALISTO builds on studies for the SAFIR (Single Aperture Far Infrared) telescope mission, employing a 4m x 6m off-axis Gregorian telescope which has a simple deployment using an Atlas V launch vehicle. The unblocked telescope with a cold stop has minimal sidelobes and scattering. The clean beam will allow astronomical background limited observations over a large fraction of the sky, which is what is required to achieve CALISTO's exciting science goals. The maximum angular resolution varies from 1.2" at 30 µm to 12" at 300 ?m. The 5? 1 hr detectable fluxes are ?S(d?/? = 1.0) = 2.2x10-20 Wm-2, and ?S(d?/? = 0.001) = 6.2x10-22 Wm-2. The 8 beams per source confusion limit at 70 ?m is estimated to be 5 ?Jy. We discuss CALISTO optics, performance, instrument complement, and mission design, and give an overview of key science goals and required technology development to enable this promising far IR/submm mission.

Goldsmith, Paul F.; Bradford, Matt; Dragovan, Mark; Paine, Chris; Satter, Celeste; Langer, Bill; Yorke, Harold; Huffenberger, Kevin; Benford, Dominic; Lester, Dan

2008-07-01

13

Solar Central Receiver with an Irising Aperture  

E-print Network

. If the aperture is small, it will be inefficient for periods when the solar isolation is inclined due to spillage. However, if the aperture is large, it will be inefficient for periods when the solar isolation is normal, due to excess heat radiation and convection...

Galal, T.; Kulaib, A. M.; Abuzaid, M.

2010-01-01

14

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

15

Optical Performance of Designs for a Large Aperture Far-Infrared Telescope  

NASA Astrophysics Data System (ADS)

We have developed two designs for a large single aperture far-infrared space telescope. Achieving the ultimate sensitivity in the far infrared (30 to 300 microns wavelength) requires a telescope cooled to 4 K with a large collecting area. The performance of the system can be degraded by radiation from dust in the solar system (“zodi”), from the Milky Way, and from the spacecraft. It is thus critical to understand the response of any telescope design at angles far from the direction of peak response. We have carried out detailed calculations of the radiation pattern from two different telescope designs for a 10m diameter aperture. This is the nominal diameter of the Single Aperture Far InfraRed (SAFIR) telescope, but can easily be extended to the 6m by 4m aperture proposed for the Cryogenic Aperture Large Infrared Space Telescope Observatory (CALISTO). The first design is the on-axis (symmetric) telescope as described in the SAFIR Vision Mission (VM) Report, while the second is off-axis (unobscured). The calculations, which have been carried out at a wavelength of 1mm, utilize a combination of physical optics/physical theory of diffraction (PO/PTD) and geometrical optics/geometrical theory of diffraction (GO/GTD). The on-axis SAFIR VM design has a relatively large subreflector (0.09 fractional area obscuration) and its feed legs obscure 0.027 of the collecting area. Relative to this inefficient geometry, the unobscured design has higher gain by a factor of 1.45 (1.6 dB) with a 12 dB edge taper Gaussian illumination. It is also characterized by a far lower sidelobe level. The off-axis design is preferable in terms of aperture efficiency and its lower scattered radiation at large angles from the main beam, thus minimizing coupling to the sunshield and allowing observation of a large portion of the sky without compromising sensitivity as a result of extraneous pickup.

Goldsmith, Paul; Khayatian, B.; Bradford, C. M.; Dragovan, M.; Imbriale, W.; Lee, R.; Paine, C.; Yorke, H.; Zmuidzinas, J.

2006-12-01

16

The balloon-borne large aperture sub-millimeter telescope  

Microsoft Academic Search

The balloon-borne large aperture sub-millimeter telescope (BLAST) is a new instrument to study galaxies at high redshift and to help answer questions about our galaxy and star formation. BLAST will fly from a long duration balloon. The telescope design incorporates a 2-m primary mirror with large-format bolometer arrays operating at 250, 350 and 500 ?m with 149, 88 and 43

G. S. Tucker; P. A. R. Ade; J. J. Bock; M. Devlin; M. Griffin; J. Gundersen; M. Halpern; P. Hargrave; D. Hughes; J. Klein; P. Mauskopf; C. B. Netterfield; L. Olmi; D. Scott

2004-01-01

17

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

18

The balloon-borne large aperture submillimeter telescope (BLAST)  

Microsoft Academic Search

This thesis presents a description of the instrumentation and Galactic science from the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). BLAST was designed to conduct large area submillimeter surveys to constrain the star formation history of the high-redshift universe and to probe the earliest stages of star formation within our own galaxy. It operates on a balloon platform at an altitude

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

2007-01-01

19

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

20

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

NASA Astrophysics Data System (ADS)

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 previous 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; our expectation is that space-based structures will ultimately gain economic advantage over ground-based ones.

van Belle, Gerard T.; Meinel, Aden B.; Meinel, Marjorie P.

2004-10-01

21

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

22

ULTIMA free-flying large-aperture space telescope  

Microsoft Academic Search

Project ULTIMA is an investigation into the feasibility of building ultralarge aperture visible\\/mid-LR space telescopes. A promising concept found by the study is a freely flying spherical primary mirror, 20 m or more in diameter, located at the L1 or L2 Earth-sun libration point. The primary would be passively cooled to 45 K. There would be no metering structure. Instead,

Jonathan W. Campbell; Charles R. Taylor

1997-01-01

23

Advanced Technology Solar Telescope: a progress report  

Microsoft Academic Search

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

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

2005-01-01

24

Polarimetric Calibration of Large-Aperture Telescopes II: The sub-aperture method  

E-print Network

A new method for absolute polarimetric calibration of large telescopes is presented. The proposed method is highly accurate and is based on the calibration of a small sub-aperture, which is then extended to the full system by means of actual observations of an astronomical source. The calibration procedure is described in detail along with numerical simulations that explore its robustness and accuracy. The advantages and disadvantages of this technique with respect to other possible alternatives are discussed.

H. Socas-Navarro

2004-10-23

25

MOIRE: ground demonstration of a large aperture diffractive transmissive telescope  

NASA Astrophysics Data System (ADS)

The desire to field space-based telescopes with apertures in excess of 10 meter diameter is forcing the development of extreme lightweighted large optomechanical structures. Sparse apertures, shell optics, and membrane optics are a few of the approaches that have been investigated and demonstrated. Membrane optics in particular have been investigated for many years. The MOIRE approach in which the membrane is used as a transmissive diffractive optical element (DOE) offers a significant relaxation in the control requirements on the membrane surface figure, supports extreme lightweighting of the primary collecting optic, and provides a path for rapid low cost production of the primary optical elements. Successful development of a powered meter-scale transmissive membrane DOE was reported in 2012. This paper presents initial imaging results from integrating meter-scale transmissive DOEs into the primary element of a 5- meter diameter telescope architecture. The brassboard telescope successfully demonstrates the ability to collect polychromatic high resolution imagery over a representative object using the transmissive DOE technology. The telescope includes multiple segments of a 5-meter diameter telescope primary with an overall length of 27 meters. The object scene used for the demonstration represents a 1.5 km square complex ground scene. Imaging is accomplished in a standard laboratory environment using a 40 nm spectral bandwidth centered on 650 nm. Theoretical imaging quality for the tested configuration is NIIRS 2.8, with the demonstration achieving NIIRS 2.3 under laboratory seeing conditions. Design characteristics, hardware implementation, laboratory environmental impacts on imagery, image quality metrics, and ongoing developments will be presented.

Atcheson, Paul; Domber, Jeanette; Whiteaker, Kevin; Britten, Jerald A.; Dixit, Shamasundar N.; Farmer, Brandon

2014-08-01

26

National Large Solar Telescope of Russia  

NASA Astrophysics Data System (ADS)

One of the most important task of the modern solar physics is multi-wavelength observations of the small-scale structure of solar atmosphere on different heights, including chromosphere and corona. To do this the large-aperture telescopes are necessary. At present time there several challenging projects of the large (and even giant) solar telescopes in the world are in the process of construction or designing , the most known ones among them are 4-meter class telescopes ATST in USA and EST in Europe. Since 2013 the development of the new Large Solar Telescope (LST) with 3 meter diameter of the main mirror is started in Russia as a part (sub-project) of National Heliogeophysical Complex (NHGC) of the Russian Academy of Sciences. It should be located at the Sayan solar observatory on the altitude more then 2000 m. To avoid numerous problems of the off-axis optical telescopes (despite of the obvious some advantages of the off-axis configuration) and to meet to available financial budget, the classical on-axis Gregorian scheme on the alt-azimuth mount has been chosen. The scientific equipment of the LST-3 will include several narrow-band tunable filter devices and spectrographs for different wavelength bands, including infrared. The units are installed either at the Nasmyth focus or/and on the rotating coude platform. To minimize the instrumental polarization the polarization analyzer is located near diagonal mirror after M2 mirror. High order adaptive optics is used to achieve the diffraction limited performances. It is expected that after some modification of the optical configuration the LST-3 will operate as an approximately 1-m mirror coronograph in the near infrared spectral lines. Possibilities for stellar observations during night time are provided as well.

Demidov, Mikhail

27

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

28

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

Microsoft Academic Search

An infrared (I.R.) optics package designed for a I.R. detector calibration survey will be used in conjunction with the 90 inch telescope at the University of Wyoming, or as a portable, stand along unit. An important part of this instrument package is a mechanical light beam chopper which rotates with a fixed phase relation with respect to a wobbling secondary

Shorthill

1990-01-01

29

The Telescope Control System of the New Solar Telescope at Big Bear Solar Observatory  

E-print Network

The Telescope Control System of the New Solar Telescope at Big Bear Solar Observatory G. Yang*a, J Telescope (NST) is an advanced solar telescope at Big Bear Solar Observatory (BBSO). It features a 1.6-m the local seeing. The NST Telescope Control System (TCS) is a complex system, which provides powerful

30

Hubble Space Telescope Solar Array  

NASA Technical Reports Server (NTRS)

This is a view of a solar cell blanket deployed on a water table during the Solar Array deployment test. The Hubble Space Telescope (HST) Solar Arrays provide power to the spacecraft. The arrays are mounted on opposite sides of the HST, on the forward shell of the Support Systems Module. Each array stands on a 4-foot mast that supports a retractable wing of solar panels 40-feet (12.1-meters) long and 8.2-feet (2.5-meters) wide, in full extension. The arrays rotate so that the solar cells face the Sun as much as possible to harness the Sun's energy. The Space Telescope Operations Control Center at the Goddard Space Center operates the array, extending the panels and maneuvering the spacecraft to focus maximum sunlight on the arrays. The purpose of the HST, the most complex and sensitive optical telescope ever made, is to study the cosmos from a low-Earth orbit. By placing the telescope in space, astronomers are able to collect data that is free of the Earth's atmosphere. The HST Solar Array was designed by the European Space Agency and built by British Aerospace. The Marshall Space Flight Center had overall responsibility for design, development, and construction of the HST.

1985-01-01

31

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

32

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

NASA Astrophysics Data System (ADS)

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

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

33

Advanced Technology Solar Telescope: a progress report  

Microsoft Academic Search

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

J. Wagner; T. R. Rimmele; S. Keil; R. Hubbard; E. Hansen; L. Phelps; M. Warner; B. Goodrich; K. Richards; S. Hegwer; R. Kneale; J. Ditsler

2008-01-01

34

Advanced Technology Solar Telescope: a progress report  

Microsoft Academic Search

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

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

2006-01-01

35

The Balloon-borne Large Aperture Submillimeter Telescope: BLAST  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between 3 arrays, observes simultaneously in broad-band (30%) spectral-windows at 250, 350, and 500 microns. The optical design is based on a 2m diameter telescope, providing a diffraction-limited resolution of 30" at 250 microns. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of ~30"; post-flight pointing reconstruction to ~5" rms is achieved. The on-board telescope control software permits autonomous execution of a pre-selected set of maps, with the option of manual override. In this paper we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test-flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100-hour flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in June 2005; and a 250-hour, circumpolar-flight from McMurdo Station, Antarctica, in December 2006.

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

2007-11-21

36

The Balloon-borne Large Aperture Sub-millimetre Telescope  

E-print Network

The Balloon-borne Large-Aperture Sub-millimetre Telescope (BLAST) will operate on a Long Duration Balloon platform with large format bolometer arrays at 250, 350 and 500 microns, initially using a 2m mirror, with plans to increase to 2.5m. BLAST is a collaboration between scientists in the USA, Canada, UK, Italy and Mexico. Funding has been approved and it is now in its building phase. The test flight is scheduled for 2002, with the first long duration flight the following year. The scientific goals are to learn about the nature of distant extragalactic star forming galaxies and cold pre-stellar sources by making deep maps both at high and low galactic latitudes. BLAST will be useful for planning Herschel key projects which use SPIRE.

Douglas Scott; the BLAST Team

2001-04-03

37

Active control of the Chinese Giant Solar Telescope  

NASA Astrophysics Data System (ADS)

The Chinese Giant Solar Telescope (CGST) is the next generation solar telescope of China with diameter of 8 meter. The unique feature of CGST is that its primary is a ring, which facilitates the polarization detection and thermal control. In its present design and development phase, two primary mirror patterns are considered. For one thing, the primary mirror is expected to construct with mosaic mirror with 24 trapezoidal (or petal) segments, for another thing, a monolithic mirror is also a candidate for its primary mirror. Both of them depend on active control technique to maintain the optical quality of the ring mirror. As a solar telescope, the working conditions of the CGST are quite different from those of the stellar telescopes. To avoid the image deterioration due to the mirror seeing and dome seeing, especially in the case of the concentration of flux in a solar telescope, large aperture solar projects prefer to adopt open telescopes and open domes. In this circumstance, higher wind loads act on the primary mirror directly, which will cause position errors and figure errors of the primary with matters worse than those of the current 10-meter stellar telescopes with dome protect. Therefore, it gives new challenges to the active control capability, telescope structure design, and wind shielding design. In this paper, the study progress of active control of CGST for its mosaic and monolithic mirror are presented, and the wind effects on such two primary mirrors are also investigated.

Dai, Yichun; Yang, Dehua; Jin, Zhenyu; Liu, Zhong; Qin, Wei

2014-07-01

38

Science drivers and requirements for an Advanced Technology Large Aperture Space Telescope (ATLAST): Implications for technology  

E-print Network

Science drivers and requirements for an Advanced Technology Large Aperture Space Telescope (ATLAST, MS SD70 SOMTC, Huntsville, AL USA 35812-0262 ABSTRACT The Advanced Technology Large-Aperture Space to current generation observatory-class space missions. Keywords: Advanced Technology Large-Aperture Space

Sirianni, Marco

39

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

40

The Revolution in Telescope Aperture C.M. Mountain and F.C. Gillett  

E-print Network

' The Revolution in Telescope Aperture C.M. Mountain and F.C. Gillett Gemini Observatory, 670 N. A that is often not recognised is the exponential growth in the total collecting area of large telescopes, materials and fabrication techniques ­­ these advances have facilitated the construction of telescopes

41

High-contrast visible nulling coronagraph for segmented and arbitrary telescope apertures  

NASA Astrophysics Data System (ADS)

Exoplanet coronagraphy will be driven by the telescope architectures available and thus the system designer must have available one or more suitable coronagraphic instrument choices that spans the set of telescope apertures, including filled (off-axis), obscured (e.g. with secondary mirror spiders and struts), segmented apertures, such as JWST, and interferometric apertures. In this work we present one such choice of coronagraph, known as the visible nulling coronagraph (VNC), that spans all four types of aperture and also employs differential sensing and control.

Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter

2014-08-01

42

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

43

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

44

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

Microsoft Academic Search

The 4m Advance Technology Solar Telescope (ATST) will be the most powerful solar telescope and the world's leading ground-based resource for studying solar magnetism that controls the solar wind, flares, coronal mass ejections and variability in the Sun's output. The project has successfully passed its final design review and the Environmental Impact Study for construction of ATST on Haleakala, Maui,

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

2010-01-01

45

A Balloon-borne Large Aperture Submillimeter Telescope  

E-print Network

A new generation of sub-orbital platforms will be operational in the next few years. These new telescopes will operate from airborne and balloon-borne platforms where the atmosphere is transparent enough to allow sensitive measurements to be made in the submillimeter bands. The telescopes will take advantage of state-of-the-art instrumentation including large format bolometer arrays and spectrometers. Other papers in this volume will deal specifically with the potential of these bands. In this paper will review the capabilities the BLAST balloon-borne telescope.

Mark J. Devlin

2000-12-14

46

Observation Scheduling for a Network of Small-Aperture Telescopes  

NASA Astrophysics Data System (ADS)

Over the past several years, a system for accepting, servicing and returning the results from a large number of imaging requests has been developed for use with automated optical telescopes. One of the primary goals of this project is to increase the accessibility of astronomy to school, college and university students. A key component of this system is a request scheduling engine, which produces schedules for each telescope for its current night. This engine is dynamic, adjusting schedules to accommodate new requests and rescheduling failed requests on a time scale of the order of ten minutes. If a telescope is unavailable for an extended period, imaging requests will be reallocated to other telescopes in the network. Various models of dynamic scheduling are considered, and the current implementation is explored with a number of numerical experiments.

Duncan, A. R.

2007-06-01

47

A stabilized large-aperture far-infrared telescope gondola  

Microsoft Academic Search

Description of a recently developed balloon-borne 1-m far-infrared telescope designed to carry out astronomical observations and to map radiation from selected areas of the sky. The telescope optical system consists of a conventional Cassegrain arrangement with an f\\/2 aluminum primary mirror, spherically figured, which feeds a pyrex secondary mirror to produce an f\\/13.8 beam at the focal plane with a

N. L. Hazen

1974-01-01

48

High-contrast imager for Complex Aperture Telescopes (HiCAT): 1. Testbed design  

E-print Network

Searching for nearby habitable worlds with direct imaging and spectroscopy will require a telescope large enough to provide angular resolution and sensitivity to planets around a significant sample of stars. Segmented telescopes are a compelling option to obtain such large apertures. However, these telescope designs have a complex geometry (central obstruction, support structures, segmentation) that makes high-contrast imaging more challenging. We are developing a new high-contrast imaging testbed at STScI to provide an integrated solution for wavefront control and starlight suppression on complex aperture geometries. We present our approach for the testbed optical design, which defines the surface requirements for each mirror to minimize the amplitude-induced errors from the propagation of out-of-pupil surfaces. Our approach guarantees that the testbed will not be limited by these Fresnel propagation effects, but only by the aperture geometry. This approach involves iterations between classical ray-tracing o...

N'Diaye, Mamadou; Pueyo, Laurent; Elliot, Erin; Perrin, Marshall D; Wallace, J Kent; Groff, Tyler; Carlotti, Alexis; Mawet, Dimitri; Sheckells, Matt; Shaklan, Stuart; Macintosh, Bruce; Kasdin, N Jeremy; Soummer, Rémi

2014-01-01

49

Could SAFE concept be applied for designing a new synthetic aperture telescope?  

PubMed

Synthetic aperture with Fresnel elements (SAFE) is an incoherent holographic imaging system in which the complete hologram is a mosaic of several holograms captured from different points of view. In this paper we investigate a new scheme of SAFE which may be used as a basis for designing a new type of synthetic aperture telescopes. Laboratory in-door experiments may provide the proof of concept for such a new design. PMID:21445128

Katz, Barak; Rosen, Joseph

2011-03-14

50

Advanced Technology Large-Aperture Space Telescope (ATLAST): A Technology Roadmap for the Next Decade  

E-print Network

The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a set of mission concepts for the next generation of UVOIR space observatory with a primary aperture diameter in the 8-m to 16-m range that will allow us to perform some of the most challenging observations to answer some of our most compelling questions, including "Is there life elsewhere in the Galaxy?" We have identified two different telescope architectures, but with similar optical designs, that span the range in viable technologies. The architectures are a telescope with a monolithic primary mirror and two variations of a telescope with a large segmented primary mirror. This approach provides us with several pathways to realizing the mission, which will be narrowed to one as our technology development progresses. The concepts invoke heritage from HST and JWST design, but also take significant departures from these designs to minimize complexity, mass, or both. Our report provides details on the mission concepts, shows the extraordinary s...

Postman, Marc

2009-01-01

51

ADVANCED TECHNOLOGY LARGE-APERTURE SPACE TELESCOPE (ATLAST)  

E-print Network

Investigator Space Telescope Science Institute Co-Investigators Vic Argabright1 , Bill Arnold11 , David Korechoff8 , John Krist8 , John Mather3 , Chuck Lillie7 , Amy Lo7 , Rick Lyon3 , Scot McArthur1 , Peter Mc , George Sonneborn3 , David Spergel10 , Phil Stahl2 , Karl Stapelfeldt8 , Harley Thronson3 , Gary Thronton2

Sirianni, Marco

52

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

53

Design of a telescope pointing and tracking subsystem for the Big Bear Solar Observatory New Solar Telescope  

E-print Network

Design of a telescope pointing and tracking subsystem for the Big Bear Solar Observatory New Solar Telescope J. R. Varsika and G.Yangb aBig Bear Solar Observatory, 40386 North Shore Lane, Big Bear City Telescope at Big Bear Solar Observatory will use a distributed system to control the telescope, dome

54

The Balloon-borne Large Aperture Submillimeter Telescope Peter Adea, Itziar Aretxagab, James Bockc, Jaspaul Chungd, Mark Devline, Simon Dickere,  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) Peter Adea, Itziar Aretxagab with unprecedented image fidelity. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) will be one of the first experiments to make full use of this new capability. The high altitude ( 35 km) of the balloon

Aretxaga, Itziar

55

LAPCAT: the Large Antarctic Plateau Clear-Aperture Telescope John Storeya*  

E-print Network

technologies in an Antarctic environment, LAPCAT also paves the way for the eventual construction of a secondLAPCAT: the Large Antarctic Plateau Clear-Aperture Telescope John Storeya* , Roger Angelb , Jon, and that the design of precision instruments to work under Antarctic conditions is possible. Dome C (75 O 6 south, 123

Ashley, Michael C. B.

56

Could SAFE concept be applied for designing a new synthetic aperture telescope?  

E-print Network

. 46(6), 993­1000 (2007). 9. B. Katz and J. Rosen, "Super-resolution in incoherent optical imaging," Nat. Photonics 2(3), 190­195 (2008). 13. B. Katz, D. Wulich, and J. Rosen, "Optimal noise suppressionCould SAFE concept be applied for designing a new synthetic aperture telescope? Barak Katz

Rosen, Joseph

57

Dynamics and control of a 25-meter aperture virtual structure Gossamer telescope in GEO  

NASA Technical Reports Server (NTRS)

In this paper we conduct a feasibility analysis of a 25-meter aperture virtual-structure space telescope example concept based on formation control of separated free-flying optical modules orbiting the Earth at GEO. We develop a Formation Flying implementation approach, and design and analyze the dynamics, control, metrology and estimation methods.

Mettler, E.; Quadrelli, M.; Breckenrisge, W.

2002-01-01

58

The balloon-borne large-aperture submillimeter telescope for polarimetry: BLAST-Pol  

Microsoft Academic Search

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry\\u000a(BLAST-Pol) is a suborbital mapping experiment designed to study the role\\u000aplayed by magnetic fields in the star formation process. BLAST-Pol is the\\u000areconstructed BLAST telescope, with the addition of linear polarization\\u000acapability. Using a 1.8 m Cassegrain telescope, BLAST-Pol images the sky onto a\\u000afocal plane that consists of 280 bolometric

G. Marsden; Peter A. R. Ade; S. Benton; J. J. Bock; Edward L. Chapin; J. Chung; M. J. Devlin; S. Dicker; L. Fissel; M. Griffin; J. O. Gundersen; M. Halpern; P. C. Hargrave; D. H. Hughes; J. Klein; A. Korotkov; C. J. MacTavish; P. G. Martin; T. G. Martin; T. G. Matthews; P. Mauskopf; L. Moncelsi; C. B. Netterfield; G. Novak; E. Pascale; L. Olmi; G. Patanchon; M. Rex; G. Savini; D. Scott; C. Semisch; N. Thomas; M. D. P. Truch; C. Tucker; G. S. Tucker; M. P. Viero; D. Ward-Thompson; D. V. Wiebec

2008-01-01

59

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100-hour flight from northern Sweden in June 2005 (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W 75N, and Mrk 231. One additional source, Arp 220, was observed and used as our primary calibrator. Details of the overall BLAST05 calibration procedure are discussed here. The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. The 250, 350, and 500 um BLAST data can provide useful constraints to the amplitude and slope of the submillimeter continuum, which in turn may be useful for the improved calibration of other submillimeter instruments.

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

2008-03-31

60

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

NASA Technical Reports Server (NTRS)

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 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 milliarcsecond angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, 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 current generation observatory-class space missions. Keywords: Advanced Technology Large-Aperture Space Telescope (ATLAST); ultraviolet/optical space telescopes; astrophysics; astrobiology; technology development.

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

2011-01-01

61

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

62

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

63

A 16-m Telescope for the Advanced Technology Large Aperture Telescope (ATLAST) Mission  

NASA Astrophysics Data System (ADS)

Future space observatories will require increasingly large telescopes to study the earliest stars and galaxies, as well as faint nearby objects. Technologies now under development will enable telescopes much larger than the 6.5-meter diameter James Webb Space Telescope (JWST) to be developed at comparable costs. Current segmented mirror and deployable optics technology enables the 6.5 meter JWST telescope to be folded for launch in the 5-meter diameter Ariane 5 payload fairing, and deployed autonomously after reaching orbit. Late in the next decade, when the Ares V Cargo Launch Vehicle payload fairing becomes operational, even larger telescope can be placed in orbit. In this paper we present our concept for a 16-meter JWST derivative, chord-fold telescope which could be stowed in the 10-m diameter Ares V fairing, plus a description of the new technologies that enable ATLAST to be developed at an affordable price.

Lillie, Charles F.; Dailey, D. R.; Polidan, R. S.

2010-01-01

64

Polarimetric Calibration of Large-Aperture Telescopes I: The Beam-Expansion Method  

E-print Network

This paper describes a concept for the high-accuracy absolute calibration of the instrumental polarization introduced by the primary mirror of a large-aperture telescope. This procedure requires a small aperture with polarization calibration optics (e.g., mounted on the dome) followed by a lens that opens the beam to illuminate the entire surface of the mirror. The Jones matrix corresponding to this calibration setup (with a diverging incident beam) is related to that of the normal observing setup (with a collimated incident beam) by an approximate correction term. Numerical models of parabolic on-axis and off-axis mirrors with surface imperfections are used to explore its accuracy.

H. Socas-Navarro

2004-10-23

65

Astron. Nachr. / AN 331, No. 6, 636 639 (2010) / DOI 10.1002/asna.201011390 Scientific instrumentation for the 1.6 m New Solar Telescope in Big Bear  

E-print Network

structures drive us to build large-aperture solar telescopes and state-of-the-art facility- class instruments come for building meters-class solar telescopes. New Jersey Institute of Technology (NJIT), in collab instrumentation for the 1.6 m New Solar Telescope in Big Bear W. Cao1,2, , N. Gorceix2 , R. Coulter2 , K. Ahn3 , T

66

Cornell Caltech Atacama Telescope (CCAT): a 25-m aperture telescope above 5000-m altitude  

Microsoft Academic Search

Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 mum. The telescope is designed to deliver high efficiency

Thomas A. Sebring; Riccardo Giovanelli; Simon Radford; Jonas Zmuidzinas

2006-01-01

67

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

68

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

NASA Astrophysics Data System (ADS)

Large-aperture telescopes require adaptive optics in order to compensate for atmospheric turbulence which would otherwise negate the resolution advantages of using large apertures. This investigation analyzes the impacts of misalignments and failures, in the deformable mirror actuators, upon the performance of such systems. A numerical simulation of a standard adaptive optics system is used to generate characteristic optical transfer function (OTF) and signal-to-noise ratio (SNR) performance metrics. The performance impacts of the misalignments are shown to be dependent upon the Fried parameter (effective telescope diameter), the source object brightness, and the control system time delay. The degree of performance degradation is directly related to the relative value of the Fried parameter to the deformable mirror displacement (misalignment cases) and the effective actuator spacing (actuator failure cases). The results indicate that the impact of misalignments and failures is small when seeing conditions are good or the percentage misalignments and failures are small.

Hogan, Timothy D.

1993-12-01

69

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

70

Solar optical telescope primary mirror controller  

NASA Technical Reports Server (NTRS)

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

Brown, R. J.; Liu, D.

1980-01-01

71

Large-aperture radiant solar energy concentrators  

Microsoft Academic Search

The relation between the maximum concentration factor and the number and form of facets of a paraboloid mirror used for solar energy concentration is analyzed. The three-step approach begins by describing, in terms of differential geometry, the ray deflections associated with a facet system approximating an ideal paraboloid reflector. Then the formation of the receiver irradiation field is represented by

I. V. Baum

1978-01-01

72

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

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 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

74

Cornell Caltech Atacama Telescope (CCAT): a 25-m aperture telescope above 5000-m altitude  

NASA Astrophysics Data System (ADS)

Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 ?m. The telescope is designed to deliver high efficiency images at that wavelength with a total one-half wavefront error of about 10 ?m. With a 20 arc min field of view, CCAT will be able to accommodate large format bolometer arrays and will excel at carrying out surveys as well as resolving structures to the 2 arc sec resolution level. The telescope will be an ideal complement to ALMA. Initial instrumentation will include both a wide field bolometer camera and a medium resolution spectrograph. Studies of the major telescope subsystems have been performed as part of an initial Feasibility Concept Study. Novel aspects of the telescope design include kinematic mounting and active positioning of primary mirror segments, high bandwidth secondary mirror segment motion control for chopping, a Calotte style dome of 50 meter diameter, a mount capable of efficient scanning modes of operation, and some new approaches to panel manufacture. Analysis of telescope performance and of key subsystems will be presented to illustrate the technical feasibility and pragmatic cost of CCAT. Project plans include an Engineering Concept Design phase followed by detailed design and development. First Light is planned for early 2012.

Sebring, Thomas A.; Giovanelli, Riccardo; Radford, Simon; Zmuidzinas, Jonas

2006-06-01

75

Cornell Caltech Atacama Telescope (CCAT): a 25 m aperture telescope above 5000 m altitude  

E-print Network

Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 micron. The telescope is designed to deliver high efficiency images at that wavelength with a total 1/2 wavefront error of about 10 microns. With a 20 arc min field of view, CCAT will be able to accommodate large format bolometer arrays and will excel at carrying out surveys as well as resolving structures to the 2 arc sec. resolution level. The telescope will be an ideal complement to ALMA. Initial instrumentation will include both a wide field bolometer camera and a medium resolution spectrograph. Studies of the major telescope subsystems have been performed as part of an initial Feasibility Concept Study. Novel aspects of the telescope design include kinematic mounting and active positioning of primary mirror segments, high bandwidth secondary mirror segment motion control for chopping, a Calotte style dome of 50 meter diameter, a mount capable of efficient scanning modes of operation, and some new approaches to panel manufacture. Analysis of telescope performance and of key subsystems will be presented to illustrate the technical feasibility and pragmatic cost of CCAT. Project plans include an Engineering Concept Design phase followed by detailed design and development. First Light is planned for early 2012.

Thomas A. Sebring; Riccardo Giovanelli; Simon Radford; Jonas Zmuidzinas

2006-10-17

76

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

NASA Astrophysics Data System (ADS)

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

Zhang, Lifang; Zhao, Weirui; Li, Yimin

2013-08-01

77

Cornell Caltech Atacama Telescope (CCAT): a 25 m aperture telescope above 5000 m altitude  

E-print Network

Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 micron. The telescope is designed to deliver high efficiency images at that wavelength with a total 1/2 wavefront error of about 10 microns. With a 20 arc min field of view, CCAT will be able to accommodate large format bolometer arrays and will excel at carrying out surveys as well as resolving structures to the 2 arc sec. resolution level. The telescope will be an ideal complement to ALMA. Initial instrumentation will include both a wide field bolometer camera and a medium resolution spectrograph. Studies of the major telescope subsystems have been performed as part of an initial Feasibility Concept Study. Novel aspects of the telescope design include kinematic mounting and active positioning of pr...

Sebring, T A; Radford, S; Zmuidzinas, J; Sebring, Thomas A.; Giovanelli, Riccardo; Radford, Simon; Zmuidzinas, Jonas

2006-01-01

78

The New Swedish Solar Telescope Control System  

NASA Astrophysics Data System (ADS)

This paper describes the new Swedish solar telescope control system which is currently in the final phases of testing and tuning. The telescope has two current controlled motors per axis and encoder resolution of 0.0016 arcsecond per pulse. The servo consists of a cascaded position-velocity loop system implemented on a Compaq Alpha workstation class computer. The servo position correction loop runs at a frequency of 100 Hz whilst the faster velocity loop runs at 1KHz. This choice of servo allows a methodical tuning of gains because each gain is correcting a seperate frequency range. We shall describe the mechanical design employed in the telescope and the computer control. The real time requirements of the control servo will be explained along with how we have used standard commercial hardware and operating system to achieve this.

Dettori, Peter M.; Hosinsky, Göran

2002-12-01

79

Review of the Solar Array Telescopes David A. Smith  

E-print Network

Review of the Solar Array Telescopes David A. Smith Centre d'Etudes Nucl´eaires de Bordeaux, described as an `Arizona mesa' in the text. 68 #12;Review of the Solar Array Telescopes David A. Smith 2 Wavefront Sampling with Solar Mirror Arrays 2.1 The ABC's Figure 1 illustrates the principle of a solar

Paris-Sud XI, Université de

80

Review of the Solar Array Telescopes  

E-print Network

For several years the only experiments sensitive to astrophysical gamma rays with energies beyond the reach of EGRET but below that of the Cherenkov imaging telescopes have been the "solar tower" detectors. They use >2000 m2 mirror areas to sample the Cherenkov wavefront generated by <100 GeV gamma rays, obtaining Crab sensitivities of more than 6$\\sigma$ in one ON-source hour. I will review the history of the solar tower Cherenkov experiments from 1992 to the present and their key design features. I will describe some successful analysis strategies, then summarize the principal results obtained.

David A. Smith

2006-08-11

81

Solar rejection for an orbiting telescope  

NASA Technical Reports Server (NTRS)

The present work discusses some of the constraints that the optical designer must deal with in optimizing spaceborne sensors that must look at or near the sun. Analytical techniques are described for predicting the effects of stray radiation from sources such as mirror scatter, baffle scatter, diffraction, and ghost images. In addition, the paper describes a sensor design that has been flown on the Apollo Telescope Mount (Skylab) to aid astronauts in locating solar flares. In addition to keeping stray radiation to a minimum, the design had to be nondegradable by the direct solar heat load.

Rehnberg, J. D.

1975-01-01

82

High-contrast Imager for Complex Aperture Telescopes (HICAT): II. Design overview and first light results  

NASA Astrophysics Data System (ADS)

We present a new high-contrast imaging testbed designed to provide complete solutions in wavefront sensing, control and starlight suppression with complex aperture telescopes. The testbed was designed to enable a wide range of studies of the effects of such telescope geometries, with primary mirror segmentation, central obstruction, and spiders. The associated diffraction features in the point spread function make high-contrast imaging more challenging. In particular the testbed will be compatible with both AFTA-like and ATLAST-like aperture shapes, respectively on-axis monolithic, and on-axis segmented telescopes. The testbed optical design was developed using a novel approach to define the layout and surface error requirements to minimize amplitude­ induced errors at the target contrast level performance. In this communication we compare the as-built surface errors for each optic to their specifications based on end-to-end Fresnel modelling of the testbed. We also report on the testbed optical and optomechanical alignment performance, coronagraph design and manufacturing, and preliminary first light results.

N'Diaye, Mamadou; Choquet, Elodie; Egron, Sylvain; Pueyo, Laurent; Leboulleux, Lucie; Levecq, Olivier; Perrin, Marshall D.; Elliot, Erin; Wallace, J. Kent; Hugot, Emmanuel; Marcos, Michel; Ferrari, Marc; Long, Chris A.; Anderson, Rachel; DiFelice, Audrey; Soummer, Rémi

2014-08-01

83

ATLAST-9.2: A Deployable Large Aperture UVOIR Space Telescope  

NASA Technical Reports Server (NTRS)

We present the results of a study of a deployable version of the Advanced Technology Large Aperture Space Telescope (ATLAST) that could be launched on an Evolved Expendable Launch Vehicle (EELV). ATLAST is a concept for a next-generation UVOIR observatory to follow HST and JWST. The observatory retains significant heritage from JWST, thereby taking advantage of technologies and engineering already developed for that mission. At the same time, we have identified several design changes to the JWST architecture, some of which are required due to the demanding wavefront error requirements at visible wavelengths. The optical telescope assembly has a segmented 9.2-meter aperture and consists of 36 hexagonal glass mirrors, each of which is I.3l5m in size (flat-to-flat). The telescope can be folded to fit in the 6.5m fairing on the planned upgrade to the Delta-IV heavy launch vehicle. Near-real time wavefront sensing and control is performed on-board the telescope using stars in the field of view to deliver diffraction limited imaging performance at 500nm wavelength. The optical design of the telescope provides an 8x20 arcmin FOV in which 4-5 instruments can be accommodated, plus fine guidance and wavefront sensors. Unlike JWST, the OTA sits at the end of a multi-gimbaled arm, allowing pitch and roll motion, and is isolated from the sunshield and spacecraft bus by an active isolation system. Our design permits servicing in order to extend the life of the observatory.

Oegerle, William R.; Feinberg, L.; Purves, L.; Hyde, T.; Thronson, H.; Townsend, J.; Postman, M.; Bolcar, M.; Budinoff, J.; Dean, B.; Clampin, N.; Ebbets, D.; Gong, Q.; Gull, T.; Howard, J.; Jones, A.; Lyon, R.; Pasquale, B.; Perrygo, C.; Smith, S.; Thompson, P.; Woodgate, B.

2010-01-01

84

1.8-M solar telescope in China: the CLST  

NASA Astrophysics Data System (ADS)

For better understanding and forecasting of the solar activity and the corresponding impacts human technologies and life on earth, the high resolution observations for Sun are needed. The Chinese Large Solar Telescope (CLST) with 1.8 m aperture is being built. The CLST is a classic Gregorian configuration telescope with open structure, alt-azimuth mount, retractable dome, and a large mechanical de-rotator. The optical system with all reflective design has the field of view of larger than 3 arc-minute. The 1.8 m primary mirror is a honeycomb sandwiches fused silica lightweight mirror with ULE material and active cooling. The adaptive optics system will be developed to provide the capability for diffraction limited observations at visible wavelengths. The CLST design and development phase began in 2011 and 2012 respectively. We plan for the CLST's starting of commission in 2017. A multi-wavelength tomographic imaging system with seven wavelengths range from visible to near-infrared wavelength is considered as the first light scientific instruments. In this paper the main system configuration and the corresponding post focal instruments are described. Furthermore, the latest progress and current status of the CLST are also reported.

Rao, Changhui; Gu, Naiting; Zhu, Lei; Liu, Yangyi; Huang, Jinlong; Li, Cheng; Cheng, Yuntao; Cao, Xuedong; Zhang, Ming; Zhang, Lanqiang; Liu, Hong; Wan, Yongjian; Xian, Hao; Ma, Wenli; Bao, Hua; Zhang, Xiaojun; Guan, Chunlin; Chen, Donghong; Li, Mei

2014-07-01

85

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.

86

Overview and Status Report on the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

87

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

88

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

89

Multiple Etalon Systems for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

Multiple etalon systems are discussed that meet the science requirements for a narrow-passband imaging system for the 4-meter National Solar Observatory (NSO)/Advance Technology Solar Telescope (ATST). A multiple etalon system can provide an imaging interferometer that works in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, an intermediate-band imager, and broadband high-resolution imager. Specific dual and triple etalon configurations are described that provide a spectrographic passband of 2.0-3.5 pm and reduce parasitic light levels to 10-4 as required for precise polarization measurement, e.g., Zeeman measurements of magnetic sensitive lines. A TESOS-like (Telecentric Etalon SOlar Spectrometer) triple etalon system provides a spectral purity of 10-5. The triple designs have the advantage of reducing the finesse requirement on each etalon; allow the use of more stable blocking filters, and have very high spectral purity. A dual-etalon double-pass (Cavallini-like) system can provide a competing configuration. Such a dual-etalon design can provide high contrast. The selection of the final focal plane instrument will depend on a trade-off between an ideal instrument and practical reality. The trade study will include the number of etalons, their aperture sizes, complexities of the optical train, number of blocking filters, configuration of the electronic control system, computer interfaces, temperature controllers, etalon controllers, and their associated feedback electronics. The heritage of single and multiple etalon systems comes from their use in several observatories, including the Marshall Space Flight Center (MSFC) Solar Observatory, Sacramento Peak Observatory (NSO), and Kiepenheuer-Institut für Sonnenphysik (KIS, Germany), Mees Solar Observatory (University of Hawaii), and Arcetri Astrophysical Observatory (Italy). The design of the ATST multiple etalon system will benefit from the experience gained at these observatories.

Gary, G. A.; Balasubramaniam, K. S.; Sigwarth, Michael

2003-02-01

90

Multiple Etalon Systems for the Advanced Technology Solar Telescope  

NASA Technical Reports Server (NTRS)

Multiple etalons systems are discussed that meet the 4-meter NSO/Advance Technology Solar Telescope (http://www.nso.edu/ATST/index.html) instrument and science requirements for a narrow bandpass imaging system. A multiple etalon system can provide an imaging interferometer working in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, and a wide-band and broad-band high-resolution imager. Specific dual and triple etalon configurations will be described that provides spectrographic passband of 2.0-3.5nm and reduces parasitic light levels to 1/10000 as required by precise polarization measurement, e.g., Zeeman measurements of magnetic sensitive lines. A TESOS-like triple etalon system provides for spectral purity of 100 thousandths. The triple designs have the advantage of reducing the finesse requirement on each etalon, allowing much more stable blocking filters, and can have very high spectral purity. A dual-etalon double-pass Cavallini-like configuration can provide a competing configuration. This design can provide high contrast with only a double etalon. The selection of the final focal plan instrument will depend on a trade-off of the ideal instrument versus reality, the number of etalons, the aperture of etalons, the number of blocking filters the electronic control system and computer interfaces, the temperature control and controllers for the etalons and the electronics. The use of existing experience should provide significant cost savings. The heritage of use of etalons and multiple etalon systems in solar physics come from a number of observatories, which includes MSFC Solar Observatory (NASA), Sac Peak Observatory (NSO), and Kiepenheuer Institute for Solar Physics (Germany), Mees Solar Observatory (University of Hawaii), and Arcetri Astrophysical Observatory (Italy). The design of the ATST multiple etalon system will reply on the existing experience from these observatories.

Gary, G. Allen; Balasubramaniam, K. S.; Sigwarth, Michael; Six, N. Frank (Technical Monitor)

2002-01-01

91

Multiple-etalon systems for the Advanced Technology Solar Telescope  

NASA Technical Reports Server (NTRS)

Multiple etalon systems are discussed that meet the science requirements for a narrow-passband imaging system for the 4-meter National Solar Observatory (NSO)/Advance Technology Solar Telescope (ATST). A multiple etalon system can provide an imaging interferometer that works in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, an intermediate-band imager, and broadband high-resolution imager. Specific dual and triple etalon configurations are described that provide a spectrographic passband of 2.0-3.5 micron and reduce parasitic light levels to 10(exp -4) as required for precise polarization measurement, e.g., Zeeman measurements of magnetic sensitive lines. A TESOS-like (Telecentric Etalon SOlar Spectrometer) triple etalon system provides a spectral purity of 10(exp -5). The triple designs have the advantage of reducing the finesse requirement on each etalon; allow the use of more stable blocking filters, and have very high spectral purity. A dual-etalon double-pass (Cavallini-like) system can provide a competing configuration. Such a dual-etalon design can provide high contrast. The selection of the final focal plane instrument will depend on a trade-off between an ideal instrument and practical reality. The trade study will include the number of etalons, their aperture sizes, complexities of the optical train, number of blocking filters, configuration of the electronic control system, computer interfaces, temperature controllers, etalon controllers, and their associated feedback electronics. The heritage of single and multiple etalon systems comes from their use in several observatories, including the Marshall Space Flight Center (MSFC) Solar Observatory, Sacramento Peak Observatory (NSO), and Kiepenheuer-Institut fur Sonnenphysik (KIS, Germany), Mees Solar Observatory (University of Hawaii), and Arcetri Astrophysical Observatory (Italy). The design of the ATST multiple etalon system will benefit from the experience gained at these observatories.

Gary, G. Allen; Balasubramaniam, K. S.; Sigwarth, Michael

2003-01-01

92

The balloon-borne large-aperture submillimeter telescope for polarimetry: BLAST-Pol  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLAST-Pol) is a suborbital mapping experiment designed to study the role played by magnetic fields in the star formation process. BLAST-Pol is the reconstructed BLAST telescope, with the addition of linear polarization capability. Using a 1.8 m Cassegrain telescope, BLAST-Pol images the sky onto a focal plane that consists of 280 bolometric detectors in three arrays, observing simultaneously at 250, 350, and 500 um. The diffraction-limited optical system provides a resolution of 30'' at 250 um. The polarimeter consists of photolithographic polarizing grids mounted in front of each bolometer/detector array. A rotating 4 K achromatic half-wave plate provides additional polarization modulation. With its unprecedented mapping speed and resolution, BLAST-Pol will produce three-color polarization maps for a large number of molecular clouds. The instrument provides a much needed bridge in spatial coverage between larger-scale, coarse resolutio...

Fissel, Laura M; Angile, Francesco E; Benton, Steven J; Chapin, Edward L; Devlin, Mark J; Gandilo, Natalie N; Gundersen, Joshua O; Hargrave, Peter C; Hughes, David H; Klein, Jeffrey; Korotkov, Andrei L; Marsden, Galen; Matthews, Tristan G; Moncelsi, Lorenzo; Mroczkowski, Tony K; Netterfield, C Barth; Novak, Giles; Olmi, Luca; Pascale, Enzo; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A; Soler, Juan Diego; Thomas, Nicholas E; Truch, Matthew D P; Tucker, Carole E; Tucker, Gregory S; Ward-Thompson, Derek; Wiebe, Donald V

2010-01-01

93

Moon Dust Telescopes, Solar Concentrators, and Structures  

NASA Astrophysics Data System (ADS)

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

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

2008-05-01

94

Thermal design and performance of the balloon-borne large aperture submillimeter telescope for polarimetry BLASTPol  

NASA Astrophysics Data System (ADS)

We present the thermal model of the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). This instrument was successfully own in two circumpolar flights from McMurdo, Antarctica in 2010 and 2012. During these two flights, BLASTPol obtained unprecedented information about the magnetic field in molecular clouds through the measurement of the polarized thermal emission of interstellar dust grains. The thermal design of the experiment addresses the stability and control of the payload necessary for this kind of measurement. We describe the thermal modeling of the payload including the sun-shielding strategy. We present the in-flight thermal performance of the instrument and compare the predictions of the model with the temperatures registered during the flight. We describe the difficulties of modeling the thermal behavior of the balloon-borne platform and establish landmarks that can be used in the design of future balloon-borne instruments.

Soler, J. D.; Ade, P. A. R.; Angilè, F. E.; Benton, S. J.; Devlin, M. J.; Dober, B.; Fissel, L. M.; Fukui, Y.; Galitzki, N.; Gandilo, N. N.; Klein, J.; Korotkov, A. L.; Matthews, T. G.; Moncelsi, L.; Mroczkowski, A.; Netterfield, C. B.; Novak, G.; Nutter, D.; Pascale, E.; Poidevin, F.; Savini, G.; Scott, D.; Shariff, Jamil A.; Thomas, N. E.; Truch, M. D.; Tucker, C. E.; Tucker, G. S.; Ward-Thompson, D.

2014-07-01

95

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

96

Thermal design and performance of the balloon-borne large aperture submillimeter telescope for polarimetry BLASTPol  

E-print Network

We present the thermal model of the Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry (BLASTPol). This instrument was successfully flown in two circumpolar flights from McMurdo, Antarctica in 2010 and 2012. During these two flights, BLASTPol obtained unprecedented information about the magnetic field in molecular clouds through the measurement of the polarized thermal emission of interstellar dust grains. The thermal design of the experiment addresses the stability and control of the payload necessary for this kind of measurement. We describe the thermal modeling of the payload including the sun-shielding strategy. We present the in-flight thermal performance of the instrument and compare the predictions of the model with the temperatures registered during the flight. We describe the difficulties of modeling the thermal behavior of the balloon-borne platform and establish landmarks that can be used in the design of future balloon-borne instruments.

Soler, J D; Angilè, F E; Benton, S J; Devlin, M J; Dober, B; Fissel, L M; Fukui, Y; Galitzki, N; Gandilo, N N; Klein, J; Korotkov, A L; Matthews, T G; Moncelsi, L; Mroczkowski, A; Netterfield, C B; Novak, G; Nutter, D; Pascale, E; Poidevin, F; Savini, G; Scott, D; Shariff, J A; Thomas, N E; Truch, M D; Tucker, C E; Tucker, G S; Ward-Thompson, D

2014-01-01

97

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

NASA Astrophysics Data System (ADS)

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

Dong, Bing; Qin, Shun; Hu, Xinqi

2013-09-01

98

Obtaining Flat Field images for the HASTA solar telescope  

NASA Astrophysics Data System (ADS)

We compare the different methods implemented to obtain flat field images for the Halpha Solar telescope for Argentina (HASTA). This telescope observes the solar chromosphere in Halpha line center (656.3 nm) and wings. Four synthetic and instrumental methods were analyzed and compared considering the quality of the corrected images and practical and instrumental aspects. FULL TEXT IN SPANISH

Leuzzi, L.; Francile, C.

99

The Balloon-borne Large-Aperture Submillimeter Telescope for Polarization: BLAST-pol  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital experiment designed to study the process of star formation in local galaxies (including the Milky Way) and in galaxies at cosmological distances. Using a 2-m Cassegrain telescope, BLAST images the sky onto a focal plane, which consists of 270 bolometric detectors split between three arrays, observing simultaneously in 30% wide bands, centered at 250, 350, and 500 microns. The diffraction-limited optical system provides a resolution of 30" at 250 microns. The pointing system enables raster-like scans with a positional accuracy of ~30", reconstructed to better than 5" rms in post-flight analysis. BLAST had two successful flights, from the Arctic in 2005, and from Antarctica in 2006, which provided the first high-resolution and large-area (~0.8-200 deg^2) submillimeter surveys at these wavelengths. As a pathfinder for the SPIRE instrument on Herschel, BLAST shares with the ESA satellite similar focal plane technology and scientific...

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

2008-01-01

100

The Balloon-borne Large-Aperture Submillimeter Telescope for Polarization: BLAST-pol  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a sub-orbital experiment designed to study the process of star formation in local galaxies (including the Milky Way) and in galaxies at cosmological distances. Using a 2-m Cassegrain telescope, BLAST images the sky onto a focal plane, which consists of 270 bolometric detectors split between three arrays, observing simultaneously in 30% wide bands, centered at 250, 350, and 500 microns. The diffraction-limited optical system provides a resolution of 30" at 250 microns. The pointing system enables raster-like scans with a positional accuracy of ~30", reconstructed to better than 5" rms in post-flight analysis. BLAST had two successful flights, from the Arctic in 2005, and from Antarctica in 2006, which provided the first high-resolution and large-area (~0.8-200 deg^2) submillimeter surveys at these wavelengths. As a pathfinder for the SPIRE instrument on Herschel, BLAST shares with the ESA satellite similar focal plane technology and scientific motivation. A third flight in 2009 will see the instrument modified to be polarization-sensitive (BLAST-Pol). With its unprecedented mapping speed and resolution, BLAST-Pol will provide insights into Galactic star-forming nurseries, and give the necessary link between the larger, coarse resolution surveys and the narrow, resolved observations of star-forming structures from space and ground based instruments being commissioned in the next 5 years.

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

2008-05-28

101

Aperture synthesis  

Microsoft Academic Search

The article reviews the principles of aperture synthesis theory, with emphasis on earth rotation aperture synthesis, and the main data processing techniques for aperture synthesis telescope systems. A derivation is given for the formula giving the brightness distribution recorded by a continuum aperture synthesis system which samples the complex autocorrelation function of the electric field. The basic formulas are presented

W. N. Brouw

1975-01-01

102

High-contrast imager for Complex Aperture Telescopes (HiCAT): 2. Design overview and first light results  

E-print Network

We present a new high-contrast imaging testbed designed to provide complete solutions in wavefront sensing, control and starlight suppression with complex aperture telescopes. The testbed was designed to enable a wide range of studies of the effects of such telescope geometries, with primary mirror segmentation, central obstruction, and spiders. The associated diffraction features in the point spread function make high-contrast imaging more challenging. In particular the testbed will be compatible with both AFTA-like and ATLAST-like aperture shapes, respectively on-axis monolithic, and on-axis segmented telescopes. The testbed optical design was developed using a novel approach to define the layout and surface error requirements to minimize amplitude-induced errors at the target contrast level performance. In this communication we compare the as-built surface errors for each optic to their specifications based on end-to-end Fresnel modeling of the testbed. We also report on the testbed optical and optomechani...

N'Diaye, Mamadou; Egron, Sylvain; Pueyo, Laurent; Leboulleux, Lucie; Levecq, Olivier; Perrin, Marshall D; Elliot, Erin; Wallace, J Kent; Hugot, Emmanuel; Marcos, Michel; Ferrari, Marc; Long, Chris A; Anderson, Rachel; DiFelice, Audrey; Soummer, Rémi

2014-01-01

103

Results of aperture area comparisons for exo-atmospheric total solar irradiance measurements.  

PubMed

Exo-atmospheric solar irradiance measurements made by the solar irradiance community since 1978 have incorporated limiting apertures with diameters measured by a number of metrology laboratories using a variety of techniques. Knowledge of the aperture area is a critical component in the conversion of radiant flux measurements to solar irradiance. A National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) sponsored international comparison of aperture area measurements of limiting apertures provided by solar irradiance researchers was performed, the effort being executed by the National Institute of Standards and Technology (NIST) in coordination with the EOS Project Science Office. Apertures that had institutional heritage with historical solar irradiance measurements were measured using the absolute aperture measurement facility at NIST. The measurement technique employed noncontact video microscopy using high-accuracy translation stages. We have quantified the differences between the participating institutions' aperture area measurements and find no evidence to support the hypothesis that preflight aperture area measurements were the root cause of discrepancies in long-term total solar irradiance satellite measurements. Another result is the assessment of uncertainties assigned to methods used by participants. We find that uncertainties assigned to a participant's values may be underestimated. PMID:24513747

Johnson, B Carol; Litorja, Maritoni; Fowler, Joel B; Shirley, Eric L; Barnes, Robert A; Butler, James J

2013-11-20

104

Daniel K. Inouye Solar Telescope system safety  

NASA Astrophysics Data System (ADS)

System safety for the Daniel K. Inouye Solar Telescope (DKIST) is the joint responsibility of a Maui-based safety team and the Tucson-based systems engineering group. The DKIST project is committed to the philosophy of "Safety by Design". To that end the project has implemented an aggressive hazard analysis, risk assessment, and mitigation system. It was initially based on MIL-STD-882D, but has since been augmented in a way that lends itself to direct application to the design of our Global Interlock System (GIS). This was accomplished by adopting the American National Standard for Industrial Robots and Robot Systems (ANSI/RIA R15.06) for all identified hazards that involve potential injury to personnel. In this paper we describe the details of our augmented hazard analysis system and its use by the project. Since most of the major hardware for the DKIST (e.g., the enclosure, and telescope mount assembly) has been designed and is being constructed by external contractors, the DKIST project has required our contractors to perform a uniform hazard analysis of their designs using our methods. This paper also describes the review and follow-up process implemented by the project that is applied to both internal and external subsystem designs. Our own weekly hazard analysis team meetings have now largely turned to system-level hazards and hazards related to specific tasks that will be encountered during integration, test, and commissioning and maintenance operations. Finally we discuss a few lessons learned, describing things we might do differently if we were starting over today.

Hubbard, Robert P.; Bulau, Scott E.; Shimko, Steve; Williams, Timothy R.

2014-08-01

105

New Vacuum Solar Telescope and Observations with High Resolution  

E-print Network

The New Vacuum Solar Telescope (NVST) is a 1 meter vacuum solar telescope that aims to observe the fine structures on the Sun. The main tasks of NVST are high resolution imaging and spectral observations, including the measurements of solar magnetic field. NVST is the primary ground-based facility of Chinese solar community in this solar cycle. It is located by the Fuxian Lake of southwest China, where the seeing is good enough to perform high resolution observations. In this paper, we first introduce the general conditions of 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 solar photosphere and chromosphere are also shown.

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

2014-01-01

106

Multi-Spectral Solar Telescope Array. V - Temperature diagnostic response to the optically thin solar plasma  

NASA Technical Reports Server (NTRS)

The compact soft X-ray/EUV/FUV multilayer coated telescopes developed for solar chromosphere, corona, and corona/solar-wind interface studies permit the use of conventional (Cassegrain, Herschelian, etc.) configurations. The multilayer coatings also allow a narrow-wavelength band to be selected for imaging. NASA's Multi-Spectral Solar Telescope Array is composed of 17 of these compact telescopes; attention is given to their ability to obtain temperature-diagnostic information concerning the solar plasma.

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

1991-01-01

107

Integrating Seeing Measurements into the Operations of Solar Telescopes  

E-print Network

years, experimental solar physics has seen renewed efforts to design, build and operate the nextIntegrating Seeing Measurements into the Operations of Solar Telescopes C. Denker and A. P. Verdoni New Jersey Institute of Technology, Center for Solar-Terrestrial Research 323 Martin Luther King Blvd

108

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

109

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

Microsoft Academic Search

Large astronomical telescope or extremely enormous astronomical telescope servo tracking technique will be one of crucial technology that must be solved in researching and manufacturing. To control technique feature of large astronomical telescope or extremely enormous astronomical telescope, this paper design a sort of large astronomical telescope servo tracking control system. This system composes a principal and subordinate distributed control

Wei Hu; Zhenchao Zhang; Daxing Wang

2008-01-01

110

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

111

Daniel K. Inouye Solar Telescope: integration testing and commissioning planning  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope (DKIST), formerly the Advanced Technology Solar Telescope (ATST), has been in its construction phase since 2010, anticipating the onset of the integration, test, and commissioning (IT&C) phase late in 2016, and the commencement of science verification in early 2019. In this paper we describe the planning of the Integration, Testing and Commissioning (IT&C) phase of the project.

Craig, Simon; Bulau, Scott E.; Gonzales, Kerry; Hansen, Eric; Goodrich, Bret; Hubbard, Robert P.; Johansson, Eric; Liang, Chen; Kneale, Ruth A.; McBride, William; Sekulic, Predrag; Williams, Timothy R.

2014-08-01

112

Polarization Calibration of the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) will be the World's largest solar polarimeter with a number of polarimetric instruments simultaneously sharing the ATST light beam. Polarization calibration requires determination of the polarization properties of the telescope optics that are shared by all instruments and the polarization response of each instrument. Hundreds of parameters are required to fully specify the telescope optics but by grouping successive optical elements separated at the Gregorian focus, the elevation rotation, and the Coudé - azimuth rotation and performing calibrations over the course of a day, it is possible to infer the polarization properties of each of the groups, and the instruments themselves with many fewer parameters.

Elmore, D. F.

2014-10-01

113

Extreme adaptive optics imaging with a clear and well-corrected off-axis telescope sub-aperture  

E-print Network

Rather than using an adaptive optics (AO) system to correct a telescope s entire pupil, it can instead be used to more finely correct a smaller sub-aperture. Indeed, existing AO systems can be used to correct a sub-aperture 1/3 to 1/2 the size of a 5-10 m telescope to extreme adaptive optics (ExAO) levels. We discuss the potential performance of a clear off-axis well-corrected sub-aperture (WCS), and describe our initial imaging results with a 1.5 m diameter WCS on the Palomar Observatory s Hale telescope. These include measured Strehl ratios of 0.92-0.94 in the infrared (2.17 microns), and 0.12 in the B band, the latter allowing a binary of separation 0.34 arc sec to be easily resolved in the blue. Such performance levels enable a variety of novel observational modes, such as infrared ExAO, visible-wavelength AO, and high-contrast coronagraphy. One specific application suggested by the high Strehl ratio stability obtained (1%) is the measurement of planetary transits and eclipses. Also described is a simple dark-hole experiment carried out on a binary star, in which a comatic phase term was applied directly to the deformable mirror, in order to shift the diffraction rings to one side of the point spread function.

E. Serabyn; K. Wallace; M. Troy; B. Mennesson; P. Haguenauer; R. Gappinger; R. Burruss

2007-02-21

114

Solar radioastronomy with the LOFAR (LOw Frequency ARray) radio telescope  

E-print Network

Solar radioastronomy with the LOFAR (LOw Frequency ARray) radio telescope Stephen M. White Array (LOFAR) will be a radio astronomy interferometric array operating in the approximate fre­ quency of high solar activity the Sun will be a prominent (and highly variable) feature of the low­frequency sky

White, Stephen

115

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

116

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

Microsoft Academic Search

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

A. Steinfeld; M. Schubnell

1993-01-01

117

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

NASA Astrophysics Data System (ADS)

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

Hassebo, Yasser; El Sayed, Khaled

2007-02-01

118

Daniel K. Inouye Solar Telescope systems engineering update  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope (DKIST), formerly the Advanced Technology Solar Telescope (ATST), has been in its construction phase since 2010, anticipating the onset of integration, test, and commissioning (IT and C) phase late in 2016, and the commencement of science verification in early 2019. In this paper we describe the role of Systems Engineering during these final phases of the project, and present some of the tools, techniques, and methods in use for these purposes. The paper concludes with a brief discussion of lessons learned so far including things we might do differently next time.

Craig, Simon; Hansen, Eric; Hubbard, Robert P.; Kneale, Ruth

2014-08-01

119

Analysis of fratricide effect observed with GeMS and its relevance for large aperture astronomical telescopes  

NASA Astrophysics Data System (ADS)

Large aperture ground-based telescopes require Adaptive Optics (AO) to correct for the distortions induced by atmospheric turbulence and achieve diffraction limited imaging quality. These AO systems rely on Natural and Laser Guide Stars (NGS and LGS) to provide the information required to measure the wavefront from the astronomical sources under observation. In particular one such LGS method consists in creating an artificial star by means of fluorescence of the sodium atoms at the altitude of the Earth's mesosphere. This is achieved by propagating one or more lasers, at the wavelength of the Na D2a resonance, from the telescope up to the mesosphere. Lasers can be launched from either behind the secondary mirror or from the perimeter of the main aperture. The so-called central- and side-launch systems, respectively. The central-launch system, while helpful to reduce the LGS spot elongation, introduces the so-called "fratricide" effect. This consists of an increase in the photon-noise in the AO Wave Front Sensors (WFS) sub-apertures, with photons that are the result of laser photons back-scattering from atmospheric molecules (Rayleigh scattering) and atmospheric aerosols (dust and/or cirrus clouds ice particles). This affects the performance of the algorithms intended to compute the LGS centroids and subsequently compute and correct the turbulence-induced wavefront distortions. In the frame of the Thirty Meter Telescope (TMT) project and using actual LGS WFS data obtained with the Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS), we show results from an analysis of the temporal variability of the observed fratricide effect, as well as comparison of the absolute magnitude of fratricide photon-flux level with simulations using models that account for molecular (Rayleigh) scattering and photons backscattered from cirrus clouds.

Otarola, Angel; Neichel, Benoit; Wang, Lianqi; Boyer, Corinne; Ellerbroek, Brent; Rigaut, François

2013-12-01

120

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

NASA Technical Reports Server (NTRS)

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 dynamic power systems are viable for future space applications such as the International Space Station (ISS). The major components of the system include a solar receiver, a closed Brayton cycle power conversion unit, a power conditioning and control unit, a solar concentrator, a radiator, a thermal control system, and a Space Shuttle carrier. Unfortunately, the mission was demanifested from the ISS Phase 1 Space Shuttle Program in 1996. However, NASA Lewis is proposing to use the fabricated flight hardware as part of an all-American flight demonstration on the ISS in 2002. The present paper concerns the design and analysis of the solar receiver aperture shield assembly. The aperture shield assembly comprises the front face of the cylindrical receiver and is located at the focal plane of the solar concentrator. The aperture shield assembly is a critical component that protects the solar receiver structure from highly concentrated solar fluxes during concentrator off-pointing events. A full-size aperture shield assembly was fabricated. This unit was essentially identical to the flight configuration, with the exception of materials substitution. In addition, a thermal shock test aperture shield assembly was fabricated. This test article utilized the flight materials and was used for high-flux testing in the solar simulator test rig at NASA Lewis. This testing is described in a companion paper.

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

1997-01-01

121

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

SciTech Connect

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 the system include a solar receiver, a closed Brayton cycle power conversion unit, a power conditioning and control unit, a solar concentrator, a radiator, a thermal control system, and a Space Shuttle carrier. Unfortunately, the mission was demanifested from the ISS Phase 1 Space Shuttle Program in 1996. However, NASA Lewis is proposing to use the fabricated flight hardware as part of an all-American flight demonstration on the ISS in 2002. The present paper concerns the design and analysis of the solar receiver aperture shield assembly. The aperture shield assembly comprises the front face of the cylindrical receiver and is located at the focal plane of the solar concentrator. The aperture shield assembly is a critical component that protects the solar receiver structure from highly concentrated solar fluxes during concentrator off-pointing events. A full-size aperture shield assembly was fabricated. This unit was essentially identical to the flight configuration, with the exception of materials substitution. In addition, a thermal shock test aperture shield assembly was fabricated. This test article utilized the flight materials and was used for high-flux testing in the solar simulator test rig at NASA Lewis. This testing is described in a companion paper.

Strumpf, H.J.; Trinh, T.; Westelaken, W.; Krystkowiak, C.; Avanessian, V. [AlliedSignal Aerospace Equipment Systems, Torrance, CA (United States); Kerslake, T.W. [NASA Lewis Research Center, Cleveland, OH (United States)

1997-12-31

122

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

123

Polarization Calibration of the Solar Optical Telescope onboard Hinode  

Microsoft Academic Search

The Solar Optical Telescope (SOT) onboard Hinode aims to obtain vector magnetic fields on the Sun through precise spectropolarimetry of solar spectral lines with a spatial\\u000a resolution of 0.2?–?0.3 arcsec. A photometric accuracy of 10?3 is achieved and, after the polarization calibration, any artificial polarization from crosstalk among Stokes parameters is\\u000a required to be suppressed below the level of the statistical noise

K. Ichimoto; B. Lites; D. Elmore; Y. Suematsu; S. Tsuneta; Y. Katsukawa; T. Shimizu; R. Shine; T. Tarbell; J. Kiyohara; K. Shinoda; G. Card; A. Lecinski; K. Streander; M. Nakagiri; M. Miyashita; M. Noguchi; C. Hoffmann; T. Cruz

2008-01-01

124

Adaptive optics system for the new Swedish solar telescope  

NASA Astrophysics Data System (ADS)

The 1-meter Swedish solar telescope is a new solar telescope that was put in operation on the island of La Palma in the Canary Islands at the end of May 2002. The goal of this telescope is to reach its diffraction limited resolution of 0.1 arcsec in blue light. This has already been achieved by use of a low-order adaptive optics (AO)system. This paper describes the AO system initially developed for the former 50-cm Swedish Vacuum Solar Telescope (SVST) and further improved for the new telescope. Both systems use a combination of bimorph modal mirrors and Shack-Hartmann wavefront sensors. Unique to these systems are that they rely on a single workstation or a PC to do all the computations required to extract and pre-process the images, measure their positions using cross correlation techniques and for controlling the deformable mirror. This is in the present system possible by using the PERR instruction available on Compaq's Alpha architecture and in the new system using the PSADDBW instruction, available on Pentium 4 and Athlon processors. We describe both these systems with an emphasis on the performance, the ease of support and upgrades of performance. We also describe the optimization of the electrode geometry for the new 37-electrode bimorph mirror, supplied by AOPTIX Technologies, Inc., for controlling Karhunen--Loeve modes. Expected performance, based on closed-loop simulations, is discussed.

Scharmer, Goran B.; Dettori, Peter M.; Lofdahl, Mats G.; Shand, Mark

2003-02-01

125

The science case and data processing strategy for the Thinned Aperture Light Collector (TALC): a project for a 20m far-infrared space telescope  

NASA Astrophysics Data System (ADS)

The future of far-infrared observations rests on our capacity to reach sub-arcsecond angular resolution around 100 ?m, in order to achieve a significant advance with respect to our current capabilities. Furthermore, by reaching this angular resolution we can bridge the gap between capacities offered by the JWST in the near infrared and those allowed by ALMA in the submillimeter, and thus benefit from similar resolving capacities over the whole wavelength range where interstellar dust radiates and where key atomic and molecular transitions are found. In an accompanying paper,1 we present a concept of a deployable annular telescope, named TALC for Thinned Aperture Light Collector, reaching 20m in diameter. Being annular, this telescope features a main beam width equivalent to that of a 27m telescope, i.e. an angular resolution of 0.92" at 100 ?m. In this paper we focus on the science case of such a telescope as well on the aspects of unconventional data processing that come with this unconventional optical configuration. The principal science cases of TALC revolve around its imaging capacities, that allow resolving the Kuiper belt in extra-solar planetary systems, or the filamentary scale in star forming clouds all the way to the Galactic Center, or the Narrow Line Region in Active Galactic Nuclei of the Local Group, or breaking the confusion limit to resolve the Cosmic Infrared Background. Equipping this telescope with detectors capable of imaging polarimetry offers as well the extremely interesting perspective to study the influence of the magnetic field in structuring the interstellar medium. We will then present simulations of the optical performance of such a telescope. The main feature of an annular telescope is the small amount of energy contained in the main beam, around 30% for the studied configuration, and the presence of bright diffraction rings. Using simulated point spread functions for realistic broad-band filters, we study the observing performance of TALC in typical situations, i.e a field of point sources, and fields with emission power at every physical scales, taken to represent an extragalactic deep field observation and an interstellar medium observation. We investigate different inversion techniques to try and recover the information present in the input field. We show that techniques combining a forward modeling of the observation process and a reconstruction algorithm exploiting the concept of sparsity (i.e. related to the more general field of compressed sensing) represent a promising avenue to reach the angular resolution promised by the main beam of TALC.

Sauvage, Marc; Chanial, Pierre; Durand, Gilles A.; Rodriguez, Louis R.; Starck, Jean-Luc; Ronayette, Samuel; Aussel, Hervé; Minier, Vincent; Motte, Frédérique; Pantin, Eric J.; Sureau, Florent; Terrisse, Robin

2014-08-01

126

Innovative enclosure dome\\/observing aperture system design for the MROI Array Telescopes  

Microsoft Academic Search

The close-pack array of the MROI necessitated an original design for the Unit Telescope Enclosure (UTE) at Magdalena Ridge Observatory. The Magdalena Ridge Observatory Interferometer (MROI) is a project which comprises an array of up to ten (10) 1.4m diameter mirror telescopes arranged in a \\

A. Busatta; G. Marchiori; S. Mian; I. Payne; M. Pozzobon

2010-01-01

127

Hubble Space Telescope solar array: A thermally induced disturbance torque  

Microsoft Academic Search

The thermoelastic behavior of one solar array wing of the Hubble Space Telescope (HST) as it enters sunlight (or eclipse) was investigated by taking a simplified model of the blanket longitudinal elasticity and a Coulomb friction model within the drum bearings at one end and within the spreader bar compensator mechanism at the other end of the blanket. A temperature

D. Poelaert; W. R. Burke

1987-01-01

128

Solar radioastronomy with the LOFAR (LOw Frequency ARray) radio telescope  

E-print Network

Solar radioastronomy with the LOFAR (LOw Frequency ARray) radio telescope Stephen M. Whitea, Namir, USA bRemote Sensing Div., Naval Research Lab., Washington D.C., USA ABSTRACT The Low Frequency Array (LOFAR) will be a radio astronomy interferometric array operating in the approximate fre- quency range 10

129

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

130

Thermal analysis of the baffle structure of the Solar Space Telescope  

NASA Astrophysics Data System (ADS)

The SST (Space Solar Telescope) is an astronomical telescope with a primary mirror of 1 m in diameter. It observes the sun 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). Surrounding the small view field is still the sun, which is an intense source of both heat and stray light. The baffles (the main baffle, the aperture, and the outer baffle), which are used to eliminate the stray light, will change the thermal flux in the SST and will weaken the effect of the thermal control design. In this study, the compatibility analysis of the thermal effect of baffle structures in SST is performed. The GCF (Geometry Composing Function) and BRDF (Bidirectional Reflectance Distribution Function), which are two inherent related parameters in the compatibility analysis, are derived. The objective and method of the compatibility analysis are determined. With the thermal analysis software, the temperature fields are calculated for different lengths of the main baffle, different radii of apertures, different lengths of the outer baffle with a 3' tilt angle and 16' tilt angle, and different tilt angles of the outer baffle with a 200 mm length. A series of configurations and sizes of the baffles are studied with the goals of both thermal control and elimination of stray light. The design of the baffle structure of SST is achieved: the main baffle of length 4100 mm, the internal shield of radius 494 mm, the outer baffle of length 200 mm, and the outer baffle of tilt angle 3' are successfully designed. This paper presents the relationship between the thermal control design and stray light elimination plan in the SST. The aims of the optimal design of the baffle structure of SST are reached. The thoughts and methods of the optimal analysis are also useful for similar optical telescopes designed for solar observation.

Li, Rong; Wang, Sen

2010-09-01

131

The pier and building of the European Solar Telescope (EST) F.C.M. Bettonvil*a  

E-print Network

The pier and building of the European Solar Telescope (EST) F.C.M. Bettonvil*a , R. Codinab , A surrounded by an open framework. Keywords: Telescope pier, building, solar telescope, CFD analysis, tower. ABSTRACT EST (European Solar Telescope) is a 4-m class solar telescope, which is currently

Rutten, Rob

132

Aperture synthesis polarimetry: Application to the Dominion Radio Astrophysical Observatory synthesis telescope  

Microsoft Academic Search

Aperture synthesis is a powerful technique for imaging the radio sky and can be used to make images in all four Stokes parameters, providing a complete measurement of the polarization state of the received radiation. In centimeter-wavelength continuum astronomy the received signals are generally partially linearly polarized, with a negligibly small fraction of circular polarization. For this application the preferred

R. J. Smegal; T. L. Landecker; J. F. Vaneldik; D. Routledge; P. E. Dewdney

1997-01-01

133

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

134

Advanced electrostatically clean solar array panel design using reflective aperture grids  

Microsoft Academic Search

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

T. G. Stern

2002-01-01

135

SolarB X-Ray Telescope (XRT)  

NASA Astrophysics Data System (ADS)

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

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

2004-12-01

136

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

137

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

138

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

139

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry-BLASTPol: performance and results from the 2012 Antarctic flight  

NASA Astrophysics Data System (ADS)

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping experiment, designed to study the role played by magnetic fields in the star formation process. BLASTPol observes polarized light using a total power instrument, photolithographic polarizing grids, and an achromatic half-wave plate to modulate the polarization signal. During its second flight from Antarctica in December 2012, BLASTPol made degree scale maps of linearly polarized dust emission from molecular clouds in three wavebands, centered at 250, 350, and 500 ?m. The instrumental performance was an improvement over the 2010 BLASTPol ight, with decreased systematics resulting in a higher number of confirmed polarization vectors. The resultant dataset allows BLASTPol to trace magnetic fields in star-forming regions at scales ranging from cores to entire molecular cloud complexes.

Galitzki, N.; Ade, P. A. R.; Angilè, F. E.; Benton, S. J.; Devlin, M. J.; Dober, B.; Fissel, L. M.; Fukui, Y.; Gandilo, N. N.; Klein, J.; Korotkov, A. L.; Matthews, T. G.; Moncelsi, L.; Netterfield, C. B.; Novak, G.; Nutter, D.; Pascale, E.; Poidevin, F.; Savini, G.; Scott, D.; Shariff, J. A.; Soler, J. D.; Tucker, C. E.; Tucker, G. S.; Ward-Thompson, D.

2014-07-01

140

The Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers, Technology Developments, and Synergies with Other Future Facilities  

NASA Technical Reports Server (NTRS)

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 astrophysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, high stability in wavefront sensing and control). We will also discuss the synergy between ATLAST and other anticipated future facilities (e.g., TMT, EELT, ALMA) and the priorities for technology development that will enable the construction for a cost that is comparable to current generation observatory-class space missions.

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

2011-01-01

141

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry-BLASTPol: Performance and results from the 2012 Antarctic flight  

E-print Network

The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) is a suborbital mapping experiment, designed to study the role played by magnetic fields in the star formation process. BLASTPol observes polarized light using a total power instrument, photolithographic polarizing grids, and an achromatic half-wave plate to modulate the polarization signal. During its second flight from Antarctica in December 2012, BLASTPol made degree scale maps of linearly polarized dust emission from molecular clouds in three wavebands, centered at 250, 350, and 500 microns. The instrumental performance was an improvement over the 2010 BLASTPol flight, with decreased systematics resulting in a higher number of confirmed polarization vectors. The resultant dataset allows BLASTPol to trace magnetic fields in star-forming regions at scales ranging from cores to entire molecular cloud complexes.

Galitzki, N; Angilé, F E; Benton, S J; Devlin, M J; Dober, B; Fissel, L M; Fukui, Y; Gandilo, N N; Klein, J; Korotkov, A L; Matthews, T G; Moncelsi, L; Netterfield, C B; Novak, G; Nutter, D; Pascale, E; Poidevin, F; Savini, G; Scott, D; Shariff, J A; Soler, J D; Tucker, C E; Tucker, G S; Ward-Thompson, D

2014-01-01

142

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

143

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

E-print Network

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 (NST) at Big Bear Solar Observatory (BBSO) and with a broad-band 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.$"$0375) augmented by the very high image contrast (15.5$\\pm$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...

Abramenko, Valentyna; Goode, Philip; Kitiashvili, Irina; Kosovichev, Alexander

2012-01-01

144

Construction status of the Daniel K. Inouye Solar Telescope  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope (DKIST, renamed in December 2013 from the Advanced Technology Solar Telescope) will be the largest solar facility built when it begins operations in 2019. Designed and developed to meet the needs of critical high resolution and high sensitivity spectral and polarimetric observations of the Sun, the observatory will enable key research for the study of solar magnetism and its influence on the solar wind, flares, coronal mass ejections and solar irradiance variations. The 4-meter class facility will operate over a broad wavelength range (0.38 to 28 microns, initially 0.38 to 5 microns), using a state-of-the-art adaptive optics system to provide diffraction-limited imaging and the ability to resolve features approximately 25 km on the Sun. Five first-light instruments will be available at the start of operations: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter (ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF; Kiepenheuer Institut für Sonnenphysik), Diffraction Limited Near InfraRed SpectroPolarimeter (DL-NIRSP; University of Hawai'i, Institute for Astronomy) and the Cryogenic Near InfraRed SpectroPolarimeter (Cryo-NIRSP; University of Hawai'i, Institute for Astronomy). As of mid-2014, the key subsystems have been designed and fabrication is well underway, including the site construction, which began in December 2012. We provide an update on the development of the facilities both on site at the Haleakal? Observatories on Maui and the development of components around the world. We present the overall construction and integration schedule leading to the handover to operations in mid 2019. In addition, we outline the evolving challenges being met by the project, spanning the full spectrum of issues covering technical, fiscal, and geographical, that are specific to this project, though with clear counterparts to other large astronomical construction projects.

McMullin, Joseph P.; Rimmele, Thomas R.; Martínez Pillet, Valentin; Berger, Thomas E.; Casini, Roberto; Craig, Simon C.; Elmore, David F.; Goodrich, Bret D.; Hegwer, Steve L.; Hubbard, Robert P.; Johansson, Erik M.; Kuhn, Jeffrey R.; Lin, Haosheng; McVeigh, William; Schmidt, Wolfgang; Shimko, Steve; Tritschler, Alexandra; Warner, Mark; Wöger, Friedrich

2014-07-01

145

Observing Solar System Targets with the James Webb Space Telescope  

NASA Astrophysics Data System (ADS)

With its anticipated launch date in October 2018, the James Webb Space Telescope will tremendously advance astronomy in the near- and mid-infrared, offering sensitivity and spatial/spectral resolution greatly surpassing its predecessors. We have developed a white paper that explores observations of Solar System targets with JWST, with the goals of highlighting anticipated Solar System capabilities, motivation of potential observers, and encouragement of further interest and discussion. This paper presents the most current information available concerning JWST instrument properties and observing techniques relevant to planetary science. It also illustrates example observing scenarios for a wide variety of Solar System objects, including the giant planets, Kuiper Belt objects, Europa, Titan, and more. We are also collaborating with a set of focus groups that have expanded upon this work, producing a series of further white papers dealing with individual subdisciplines. This work has been supported by NASA Grant NAG5-12457.

Norwood, James; Hammel, Heidi; Milam, Stefanie; Stansberry, John; Lunine, Jonathan; Chanover, Nancy; Hines, Dean; Sonneborn, George; Tiscareno, Matthew; Brown, Michael; Ferruit, Pierre

2014-11-01

146

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

147

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

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

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

150

The design, construction and testing of the optics for a 147-cm-aperture telescope  

NASA Technical Reports Server (NTRS)

Geodetic optics research for the Air Force Cambridge Research Laboratories (AFCRL) is described. The work consisted mainly of the fabrication of the optical components for a telescope with a 152-cm-diam (60-in.) primary mirror masked down to 147-cm-diam for use by the AFCRL for a lunar ranging experiment. Among the achievements of this contract were the following: completion of the primary and secondary mirrors for a high-quality 147-cm-diam telescope system in eight months from the start of edging the primary; manufacture and testing of a unique center mount for the primary according to an AFCRL design that allowed for a thin-edged and therefore less-massive mirror; and development of a quantitative analysis of the wire test for calculating the departure of the mirror figure from the design figure quickly and accurately after each polishing step. This analysis method in conjunction with a knowledge of polishing rates for given weights and diameters of tools, mirror, and polishing materials should considerably reduce the polishing time required for future large mirrors.

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

1972-01-01

151

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

152

Properties of 16 Sunspots Observed with Hinode Solar Optical Telescope  

E-print Network

We studied 16 sunspots with different sizes and shapes using the observations with the Hinode Solar Optical Telescope. The ratio of G-band and CaII H images reveal rich structures both within the umbra and penumbra of most spots. The striking features are the compact blob at the foot point of the umbra side of the penumbral fibrils with disk center-limb side asymmetry. In this paper, we present properties of these features using the spectropolarimetry and images in G-band, CaII and blue filters. We discuss the results using the contemporary models of the sunspots.

Choudhary, Debi Prasad; Toshifumi,

2010-01-01

153

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

E-print Network

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 {\\mu}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,...

Matthews, Tristan G; 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

2013-01-01

154

Progress on the 1.6-meter New Solar Telescope at Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

The New Solar Telescope (NST) project at Big Bear Solar Observatory (BBSO) now has all major contracts for design and fabrication in place and construction of components is well underway. NST is a collaboration between BBSO, the Korean Astronomical Observatory (KAO) and Institute for Astronomy (IfA) at the University of Hawaii. The project will install a 1.6-meter, off-axis telescope at BBSO, replacing a number of older solar telescopes. The NST will be located in a recently refurbished dome on the BBSO causeway, which projects 300 meters into the Big Bear Lake. Recent site surveys have confirmed that BBSO is one of the premier solar observing sites in the world. NST will be uniquely equipped to take advantage of the long periods of excellent seeing common at the lake site. An up-to-date progress report will be presented including an overview of the project and details on the current state of the design. The report provides a detailed description of the optical design, the thermal control of the new dome, the optical support structure, the telescope control systems, active and adaptive optics systems, and the post-focus instrumentation for high-resolution spectro-polarimetry.

Denker, C.; Goode, P. R.; Ren, D.; Saadeghvaziri, M. A.; Verdoni, A. P.; Wang, H.; Yang, G.; Abramenko, V.; Cao, W.; Coulter, R.; Fear, R.; Nenow, J.; Shoumko, S.; Spirock, T. J.; Varsik, J. R.; Chae, J.; Kuhn, J. R.; Moon, Y.; Park, Y. D.; Tritschler, A.

2006-06-01

155

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

156

8-m UV\\/visible\\/IR space telescope  

Microsoft Academic Search

This paper presents a conceptual design of a next generation large space telescope. A 8-m aperture telescope orbiting Earth at an altitude of 134,000 km would offer dramatic improvements over the Hubble Space Telescope (HST) in sensitivity, resolution, spectral range (1.2 micrometers - 40 micrometers ), sky coverage, and viewing efficiency. The proposed design is characterized by an effective solar

Antoni K. Jakubowski; P. Mohan; R. K. Kapania; Paul Crisafulli; Daniel Hammerand

1995-01-01

157

Electron-Proton and High Energy Telescopes for Solar Orbiter  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

158

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

159

Performance of the Multi-Spectral Solar Telescope Array. III - Optical characteristics of the Ritchey-Chretien and Cassegrain telescopes  

NASA Technical Reports Server (NTRS)

The Multi-Spectral Solar Telescope Array (MSSTA), which is a sounding-rocket-borne observatory for investigating the sun in the soft X-ray/EUV and FUV regimes of the electromagnetic spectrum, utilizes single reflection multilayer coated Herschelian telescopes for wavelengths below 100 A, and five doubly reflecting multilayer coated Ritchey-Chretien and two Cassegrain telescopes for selected wavelengths in the EUV region between 100 and 1000 A. The paper discusses the interferometric alignment, testing, focusing, visible light testing, and optical performance characteristics of the Ritchey-Chretien and Cassegrain telescopes of MSSTA. A schematic diagram of the MSSTA Ritchey-Chretien telescope is presented together with diagrams of the system autocollimation testing.

Hoover, Richard B.; Baker, Phillip C.; Hadaway, James B.; Johnson, R. B.; Peterson, Cynthia; Gabardi, David R.; Walker, Arthur B., Jr.; Lindblom, J. F.; Deforest, Craig; O'Neal, R. H.

1991-01-01

160

HUBBLE SPACE TELESCOPE SPECTROPHOTOMETRY AND MODELS FOR SOLAR ANALOGS  

SciTech Connect

Absolute flux distributions for seven solar analog stars are measured from 0.3 to 2.5 {mu}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 and 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 {sub 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 {approx}1%; and the modeled flux distributions of these G stars have an estimated ensemble accuracy of 2% out to 30 {mu}m.

Bohlin, R. C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: bohlin@stsci.edu

2010-04-15

161

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

162

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

163

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

164

Latest results and prospects of the CERN Axion Solar Telescope  

NASA Astrophysics Data System (ADS)

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 now immersed in the data taking with 3He, to be finished in 2011. The status of the experiment will be presented, including a preliminary exclusion plot of the first 3He data. CAST is currently sensitive to realistic QCD axion models at the sub-eV scale, and with axion-photon couplings down to the ~ 2 × 10-10 GeV-1, compatible with solar life limits. Future plans include revisiting vaccuum and 4He configurations with improved sensitivity, as well as possible additional search for non-standard signals from chamaleons, paraphotons or other WISPs. For the longer term, we study the feasibility of an altogether improved version of the axion helioscope concept, with a jump in sensitivity of about one order of magnitude in ga? beyond CAST.

Irastorza, I. G.; 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.; 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.; 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.; Soufli, R.; Stewart, L.; Tomás, A.; Tsagri, M.; van Bibber, K.; Vafeiadis, T.; Villar, J.; Vogel, J. K.; Yildiz, S. C.; Zioutas, K.

2011-08-01

165

Upgraded Siberian Solar Radio Telescope: new opportunities to diagnose energetic particles in solar flares  

NASA Astrophysics Data System (ADS)

Energetic electrons are a key factor of solar flares and therefore knowing their parameters is highly important for understanding the flare mechanisms and verifying the flare models. Radio emission offers multiple promising diagnostic tools, because this emission is produced by these energetic particles in the corona, at or near the particle acceleration sites. However, high diagnostic potential of radio observations has not yet been fully utilized due to two main reasons: (1) lack of well-calibrated observations with high spatial, spectral, and temporal resolutions and (2) lack of accurate and reliable theoretical models and fast numerical tools capable of recovering the emission source parameters from the radio data. Here we report on the recent and anticipated progress in both these science components - instrumentation and modeling. To this end the Siberian Solar Radio Telescope (Badary, Russia) is now being significantly upgraded in order to convert this instrument into a multi-wavelength imaging spectropolarimetry radioheliograph. At stage 1, the instrument will produce two-dimensional images of the Sun with high temporal and spatial resolution at five frequencies simultaneously in the 4-8 GHz range; this stage will be completed in 2015. Final (stage 2) configuration of the Upgraded Siberian Solar Radio Telescope (expected to be completed in 2019) will perform imaging observations at 15 frequencies in the 3-24 GHz range. At the same time, we are developing new theoretical methods and computer codes to analyze and interpret the anticipated observational data; the recent achievements include the "fast gyrosynchrotron codes", gyroresonance codes, and the 3D simulation tool "GX Simulator" freely available via the SSW distribution. In this presentation, we discuss the approaches to diagnosing the solar energetic particles with radio observations, including the recent advances and the opportunities coming from the construction of the Multiwavelength Siberian Solar Radio Telescope. We also discuss some unsolved problems in this field, which require cooperative efforts of the solar physics community.

Kuznetsov, Alexey; Altyntsev, Alexander; Sergey, Lesovoi; Fleishman, Gregory

166

Future Diagnostic Capabilities: The 4-meter Daniel K. Inouye Solar Telescope  

NASA Astrophysics Data System (ADS)

We discuss the observational capabilities of the Daniel K. Inouye Solar Telescope (DKSIT), formerly known as the Advanced Technology Solar Telescope (ATST), currently under construction on Haleakala Mountain on the island of Maui, Hawaii, with first light anticipated in mid-2019. The DKIST will be a 4-meter aperture Gregorian telescope with advanced environmental control and adaptive optics capable of producing diffraction-limited resolution in visible light of 0.03" or about 20 km in the solar photosphere. The first light instrument suite will include the Visible Broadband Imager (VBI), an interference filter-based instrument capable of 30 Hz imaging of photospheric and chromospheric magnetic structures in the 380 to 800 nm wavelength range. All VBI images will be reconstructed in near-real-time using the KISIP speckle reconstruction algorithm adapted to the DKIST optical and AO configuration. The Visible Spectropolarimeter (ViSP) instrument being fabricated by the High Altitude Observatory (HAO) will enable high-precision slit-spectropolarimetery in any three spectral regions from 380 to 900 nm. The ViSP instrument will be the highest precision spectropolarimeter ever produced with a spatial resolution of approximately 40 km at 600 nm and temporal resolution of 10s to achieve 1e-03 polarimetric precision. The Visible Tunable Filter (VTF) instrument under fabrication at the Kiepenheuer Institute for Solar Physics (KIS) is a triple-etalon Fabry-Perot imaging spectropolarimeter instrument capable of diffraction limited measurements of the Fe I 630.2 nm and Ca II 854.2 nm spectral lines for Doppler and magnetic measurements in the photosphere and chromosphere, respectively. The VTF will also enable the highest spatial and temporal resolution observations yet achieved in the H-alpha line for detailed studies of chromospheric dynamics in response to photospheric magnetic drivers. The Diffraction-Limited Near-IR Spectropolarimeter (DL-NiRSP) and the Cryogenic Near-IR Spectropolarimeter (Cryo-NiRSP) instruments, both under fabrication at the University of Hawaii, will enable polarimetric and spectroscopic investigations in the largely unexplored infra-red spectral region. The DL-NiRSP will span 900 nm to 2.5 microns in wavelength and include a novel fiber-optic "Integral Field Unit" (IFU) for true imaging spectropolarimetry in three simultaneous spectral regions over a variable field of view. This instrument will enable revolutionary measurements of prominence magnetic fields and will also, in the wider field mode, enable coronal polarimetric studies. The Cryo-NiRSP instrument spans the 1--5 micron wavelength range and will make near-diffraction limited 0.3" resolution slit-scan measurements of the coronal magnetic field out to 1.3 solar radii with temporal resolution measured in minutes. The DKIST facility will undergo extensive polarimetric calibration to ensure that the ultimate goal of 5e-04 polarimetic precision is obtainable under the best conditions. All of the data from the DKIST will be transmitted to the central DKIST data center in Boulder, Colorado where automated reduction and calibration pipelines will rapidly provide the community with calibrated data products for use in science investigations. The DKIST will also be operated in a "Service Mode" access model in which investigators will not be required to travel to the telescope to accomplish their science observations.

Berger, Thomas; Reardon, Kevin; Elmore, David; Woeger, Friedrich; Tritschler, Alexandra; Rimmele, Thomas

167

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

168

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

169

The Daniel K. Inouye Solar Telescope first light instruments and critical science plan  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope is a 4-meter-class all-reflecting telescope under construction on Haleakal? mountain on the island of Maui, Hawai'i. When fully operational in 2019 it will be the world's largest solar telescope with wavelength coverage of 380 nm to 28 microns and advanced Adaptive Optics enabling the highest spatial resolution measurements of the solar atmosphere yet achieved. We review the first-generation DKIST instrument designs, select critical science program topics, and the operations and data handling and processing strategies to accomplish them.

Elmore, David F.; Rimmele, Thomas; Casini, Roberto; Hegwer, Steve; Kuhn, Jeff; Lin, Haosheng; McMullin, Joseph P.; Reardon, Kevin; Schmidt, Wolfgang; Tritschler, Alexandra; Wöger, Friedrich

2014-07-01

170

Solar Physics, Space Weather, and Wide-field X-ray Telescopes  

E-print Network

Solar Physics, Space Weather, and Wide-field X-ray Telescopes CREOL & FPCE: The College of Optics of the Earth). The detrimental effects of solar storm induced "space weather" ranges from disruption of our. The National Oceanic & Atmospheric Administration (NOAA) and NASA are cooperating on a Solar X-ray Imager (SXI

Van Stryland, Eric

171

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

172

Opportunities for Follow-Up Observations of Solar System Objects with 50/70 cm Schmidt Telescope  

E-print Network

Opportunities for Follow-Up Observations of Solar System Objects with 50/70 cm Schmidt Telescope, akostov@astro.bas.bg Introduction The 50/70 cm Schmidt telescope is one of the four telescopes in National are obtained every clear dark night, for exceptional events moon nights are used, also. Telescopes schedules

Boyer, Edmond

173

Observation and Modeling of the Solar Transition Region. 1; Multi-Spectral Solar Telescope Array Observations  

NASA Technical Reports Server (NTRS)

We report on observations of the solar atmosphere in several extreme-ultraviolet and far-ultraviolet bandpasses obtained by the Multi-Spectral Solar Telescope Array, a rocket-borne spectroheliograph, on flights in 1987, 1991, and 1994, spanning the last solar maximum. Quiet-Sun emission observed in the 171-175 Angstrom bandpass, which includes lines of O v, O VI, Fe IX, and Fe X, has been analyzed to test models of the temperatures and geometries of the structures responsible for this emission. Analyses of intensity variations above the solar limb reveal scale heights consistent with a quiet-Sun plasma temperature of 500,000 less than or equal to T (sub e) less than or equal to 800,000 K. The structures responsible for the quiet-Sun EUV emission are modeled as small quasi-static loops. We submit our models to several tests. We compare the emission our models would produce in the bandpass of our telescope to the emission we have observed. We find that the emission predicted by loop models with maximum temperatures between 700,000 and 900,000 K are consistent with our observations. We also compare the absolute flux predicted by our models in a typical upper transition region line to the flux measured by previous observers. Finally, we present a preliminary comparison of the predictions of our models with diagnostic spectral line ratios from previous observers. Intensity modulations in the quiet Sun are observed to occur on a scale comparable to the supergranular scale. We discuss the implications that a distribution of loops of the type we model here would have for heating the local network at the loops' footpoints.

Oluseyi, Hakeem M.; Walker, A. B. C., II; Porter, Jason; Hoover, Richard B.; Barbee, Troy W., Jr.

1999-01-01

174

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

175

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

176

The Thermal Control of the New Solar Telescope at Big Bear Observatory  

E-print Network

The Thermal Control of the New Solar Telescope at Big Bear Observatory Angelo P. Verdonia and Carsten Denkera aNew Jersey Institute of Technology, Center for Solar-Terrestrial Research, 323 Martin Luther King Blvd, Newark, NJ 07102, US ABSTRACT We present the basic design of the THermal Control System

177

Observations in H-alfa with very high temporal resolution in the HASTA solar telescope  

NASA Astrophysics Data System (ADS)

We present the design of a routine for automatic observation of solar flares with very high time resolution in H-alpha for the HASTA solar telescope. This allows to acquire several images per second during the impulsive phase of the flare in order to correlate his temporal evolution with observations of other instruments. FULL TEXT IN SPANISH

Leuzzi, L.; Francile, C.

178

Filters for soft X-ray solar telescopes  

NASA Technical Reports Server (NTRS)

Soft X-ray telescopes require filters that block visible and infrared light and have good soft X-ray transmission. The optical properties of possible materials are discussed, and the fabrication and testing methods for the filters used in a 10-inch normal incidence telescope for 63 A are described. The best performances in the 44-114-A wavelength range are obtained with foils of carbon and rhodium.

Spiller, Eberhard; Grebe, Kurt; Golub, Leon

1990-01-01

179

The Solar Electron and Proton Telescope for the STEREO Mission  

Microsoft Academic Search

The Solar Electron and Proton Telescope (SEPT), one of four instruments of the Solar Energetic Particle (SEP) suite for the\\u000a IMPACT investigation, is designed to provide the three-dimensional distribution of energetic electrons and protons with good\\u000a energy and time resolution. This knowledge is essential for characterizing the dynamic behaviour of CME associated and solar\\u000a flare associated events. SEPT consists of

R. Müller-Mellin; S. Böttcher; J. Falenski; E. Rode; L. Duvet; T. Sanderson; B. Butler; B. Johlander; H. Smit

2008-01-01

180

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

181

The space instrument SODISM, a telescope to measure the solar diameter  

NASA Astrophysics Data System (ADS)

PICARD is a satellite dedicated to the simultaneous measurement of the solar diameter, the solar shape, the solar irradiance and the solar interior. These measurements obtained throughout the mission will allow study of their variations as a function of solar activity. The objectives of the PICARD mission are to improve our knowledge of the functioning of our star through new observations and the influence of the solar activity on the climate of the Earth. PICARD was launched on June 15, 2010 on a Dnepr-1 launcher. SODISM (SOlar Diameter Imager and Surface Mapper), an instrument of the PICARD payload, is a high resolution imaging telescope. It was built on an innovative technological concept. SODISM allows us to measure the solar diameter and shape with an accuracy of a few milliarcseconds, and to perform helioseismologic observations to probe the solar interior. SODISM provides continuous observations of the Sun since mid-July 2010. A brief comparison of measurements of solar diameter since the seventeenth century and solar diameter variability are described. In this article, we present the instrumental concept and design and we give an overview of the thermal stability of the telescope. First results from the SODISM experiment are briefly reported (housekeeping and image).

Meftah, M.; Irbah, A.

2011-09-01

182

NGLT - A Solar System Survey Telescope for the Coming Decade  

NASA Astrophysics Data System (ADS)

Exploring the extent, content, and dynamical make-up of the Kuiper Belt is arguably the most exciting opportunity confronting groundbased planetary astronomy in the coming decade. Similarly, we must meet the Congressional mandate to fill out the inventory of NEOs and we should extend the NEO survey to those objects whose impacts, while not globally catastrophic, would still cause regional devastation. We describe a planned telescope designed for efficient surveys of both the Kuiper Belt and the Near-Earth Object population. NGLT is a 4-meter telescope with a 2-degree-diameter field of view at prime focus for optical imaging. The telescope can be quickly reconfigured as an F/6 Ritchey-Chretien instrument for optical and near-IR spectroscopy or wide-field IR imaging. NGLT will permit imaging approximately 250 square degrees of sky to 25th mag in R within a single 10-hr dark night. Adopting the same observing protocol as the current Deep Ecliptic Survey, one could expect with NGLT to discover of order 200 KBOs per night. Similarly, this telescope would permit an increase in the NEO discovery rate by a factor of 25 over that of the most effective current surveys; NEOs could be detected at a rate of about 500 per night. Approximately half the cost of this \\$30M project will be provided by Lowell Observatory; a governmental or private partner is being sought for the balance.

Millis, R. L.; Dunham, E. W.; Bowell, E.; Smith, C. H.; Blanco, D. R.

2001-11-01

183

Large-aperture telescopic laser system with phase-conjugation compensation of distortions of a segmented main mirror  

Microsoft Academic Search

A telescopic laser system with phase-conjugation compensation of distortions of a segmented main mirror (diameter 30 cm, focal length 1.2 m) was constructed. Experimental results agreed with numerical modeling and demonstrated the feasibility of forming a diffraction-quality image when the segments of the main mirror were tilted at angles up to 1.5 × 10 ? 4 rad and longitudinal displacements

Michail V Vasilev; Vladimir Yu Venediktov; Alexey A Leshchev; P M Semenov; V G Sidorovich; O V Solodyankin

1991-01-01

184

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

185

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

186

Extracting Information from the Data Flood of New Solar Telescopes: Brainstorming  

NASA Astrophysics Data System (ADS)

Extracting magnetic and thermodynamic information from spectropolarimetric observations is a difficult and time consuming task. The amount of science-ready data that will be generated by the new family of large solar telescopes is so large that we will be forced to modify the present approach to inference. In this contribution, I propose several possible ways that might be useful for extracting the thermodynamic and magnetic properties of solar plasmas from such observations quickly.

Asensio Ramos, A.

2012-12-01

187

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

Microsoft Academic Search

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

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

2005-01-01

188

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

Microsoft Academic Search

A Post-Flight Investigation was initiated by the European Space Agency to analyze impact fluxes on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600 km altitude. The solar cells were deployed during servicing mission SM-1 (December 1993), and retrieved by shuttle orbiter Columbia in March 2002 (SM-3B). A sub-panel of 2 m2

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

2004-01-01

189

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

Microsoft Academic Search

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

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

2005-01-01

190

Chemical analysis of hypervelocity impacts on the solar cells of the Hubble Space Telescope with EPMA-EDX and SIMS  

Microsoft Academic Search

The Technical University Darmstadt received 20 solar cell samples of the retrieved Hubble Space Telescope solar wing for chemical characterization of hypervelocity impact residues in and around all impacts. The solar cells were analyzed by electron probe microanalysis with energy dispersive X-ray detection (EPMA-EDX) and secondary ion mass spectrometry (SIMS). Because of the complexity of the solar cells it was

C. H. Heiss; F. J. Stadermann

1997-01-01

191

Residue Analysis Reports Report on the Chemical Analysis of Hypervelocity Impacts on Solar Cells from the Hubble Space Telescope  

Microsoft Academic Search

The Technical University of Darmstadt received 20 solar cell samples of the retrieved Hubble Space Telescope solar wing. The objective was the chemical characterization of hypervelocity impact residues in the in all impacts. The solar cells were analyzed with EPMA-EDX and SIMS. Because of the complexity of the solar cells it was extremely difficult to unequivocally identify fragments of space

Christian H. Heiss; Frank J. Stadermann

192

Performance of polarization modulation and calibration optics for the Daniel K. Inouye Solar Telescope  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope (formerly Advanced Technology Solar Telescope) will be the world's largest solar telescope and polarimeter when completed in 2019. Efficient use of the telescope to address key science priorities calls for polarization measurements simultaneously over broad wavelength ranges and calibration of the telescope and polarimeters to high accuracy. Broadband polarization modulation and calibration optics utilizing crystal optics have been designed for this application. The performance of polarization modulators and calibration retarders is presented along with a discussion of the unique challenges of this application. Polarimeters operate over the ranges of 0.38-1.1 microns, 0.5-2.5 microns, and 1.0-5.0 microns. Efficient polarization modulation over these broad ranges led to modulators utilizing multiple wave plates and that are elliptical, rather than linear, retarders. Calibration retarders are linear retarders and are constructed from the same sub-component wave plate pairs as the polarization modulators. Polarization optics must address efficiency over broad wavelength ranges while meeting beam deflection, transmitted wave front error, and thermal constraints and doing so with designs that, though large in diameter, can be affordably manufactured.

Elmore, David F.; Sueoka, Stacey R.; Casini, Roberto

2014-07-01

193

The chemical composition of micrometeoroids impacting upon the solar arrays of the Hubble Space Telescope  

Microsoft Academic Search

Analytical scanning electron microscopy of solar cells returned from the Hubble Space Telescope (HST) at the end of HST Service Missions SM-1 (1993) and SM-3B (2002) has revealed abundant remains of micrometeoroids. We have documented the most common residue compositions, and in this paper we suggest how they relate to mineral phases, and show how it is possible to estimate

A. T. Kearsley; G. A. Graham; J. A. M. McDonnell; E. A. Taylor; G. Drolshagen; R. J. Chater; D. McPhail; M. J. Burchell

2007-01-01

194

The chemical composition of micrometeoroids impacting upon the solar arrays of the Hubble Space Telescope  

Microsoft Academic Search

Analytical scanning electron microscopy of solar cells returned from the Hubble Space Telescope (HST) at the end of HST Service Missions SM-1 (1993) and SM-3B (2002) has revealed abundant remains of micrometeoroids. Hypervelocity impact craters of greater than 30 mu m diameter usually contain micrometeoroid residue of variable quantity and quality, dependant upon the preservation of the central melt pit

A. T. Kearsley; G. A. Graham; J. A. M. McDonnell; E. A. Taylor; G. Drolshagen; R. J. Chater; D. McPhail; M. J. Burchell

2004-01-01

195

On the Use of Cherenkov Telescopes for Outer Solar System Body Occultations  

E-print Network

Imaging Atmosphere Cherenkov Telescopes (IACT) are arrays of very large optical telescopes that are well-suited for rapid photometry of bright sources. I investigate their potential in observing stellar occultations by small objects in the outer Solar System, Transjovian Objects (TJOs). These occultations cast diffraction patterns on the Earth. Current IACT arrays are capable of detecting objects smaller than 100 meters in radius in the Kuiper Belt and 1 km radius out to 5000 AU. The future Cherenkov Telescope Array (CTA) will have even greater capabilities. Because the arrays include several telescopes, they can potentially measure the speeds of TJOs without degeneracies, and the sizes of the TJOs and background stars. I estimate the achievable precision using a Fisher matrix analysis. With CTA, the precisions of these parameter estimations will be as good as a few percent. I consider how often IACTs can observe occultations by members of different TJO populations, including Centaurs, Kuiper Belt Objects (KB...

Lacki, Brian C

2014-01-01

196

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

197

Solar Polar ORbit Telescope (SPORT): A Potential Heliophysics 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 and the first mission that could measure solar high-latitude magnetism. 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, Ying

198

Commissioning and First Operation of the Cryogenics for the CERN Axion Solar Telescope (CAST)  

NASA Astrophysics Data System (ADS)

A new experiment, the CERN Axion Solar Telescope (CAST) was installed and commissioned in 2002. Its aim is to experimentally prove the existence of an as yet hypothetical particle predicted by theory as a solution of the strong CP problem and possible candidate for galactic dark matter. The heart of the detector consists of a decommissioned 10-m long LHC superconducting dipole prototype magnet, providing a magnetic field of up to 9.5 T. The whole telescope assembly is aligned with high precision to the core of the sun. If they exist, axions could be copiously produced in the core of the sun and converted into photons within the transverse magnetic field of the telescope. The converted low-energy solar axion spectrum, peaked around a mean energy of 4.4 keV, can then be focused by a special x-ray mirror system and detected by low-background photon detectors, installed on each end of the telescopes twin beam pipes. This paper describes the external and proximity cryogenic system and magnet commissioning as well as the first operational experience with the overall telescope assembly.

Barth, K.; Delikaris, D.; Passardi, G.; Pezzetti, M.; Pirotte, O.; Stewart, L.; Vullierme, B.; Walckiers, L.; Zioutas, K.

2004-06-01

199

Solar EUV, XUV and soft X-ray telescope facilities  

NASA Technical Reports Server (NTRS)

Facility class, high resolution instrumentation can enable maximum spatial, spectral and temporal resolutions and provide understanding of the complex physical conditions in the outer solar atmosphere and the mechanisms responsible for these conditions. The scientific rationale for facility class instruments operating in the EUV, XUV, and soft X ray spectral ranges are discussed. Possible configurations for these facilities and priorities for their development are considered.

Withbroe, G. L.

1982-01-01

200

The SOLAR-C Mission: Plan B Payload Concept  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

201

The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: A 4 sq. deg Galactic Plane Survey in Vulpecula (l=59)  

E-print Network

We present the first results from a new 250, 350, and 500 micron Galactic Plane survey taken with the Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) in 2005. This survey's primary goal is to identify and characterize high-mass proto-stellar objects (HMPOs). The region studied here covers 4 sq. deg near the open cluster NGC 6823 in the constellation Vulpecula (l=59). We find 60 compact sources (0) velocities combined with a variety of other velocity and morphological data in the literature. In total, 49 sources are associated with a molecular cloud complex encompassing NGC 6823 (distance ~2.3kpc), 10 objects with the Perseus Arm (~8.5kpc) and one object is probably in the outer Galaxy (~14kpc). Near NGC 6823, the inferred luminosities and masses of BLAST sources span ~40-10^4 L_\\odot, and ~15-700 M_\\odot, respectively. The mass spectrum is compatible with molecular gas masses in other high-mass star forming regions. Several luminous sources appear to be Ultra Compact HII regions powered by early B stars. However, many of the objects are cool, massive gravitationally-bound clumps with no obvious internal radiation from a protostar, and hence excellent HMPO candidates.

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

2007-11-21

202

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

203

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

204

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

205

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

206

Features of the solar array drive mechanism for the space telescope  

NASA Technical Reports Server (NTRS)

The solar array drive mechanism for the Space Telescope embodies several features not customarily found on solar array drives. Power and signal transfer is achieved by means of a flexible wire harness for which the chosen solution, consisting of 168 standard wires, is described. The torque performance data of the harness over its temperature range are presented. The off load system which protects the bearings from the launch loads is released by a trigger made from Nitinol, the memory alloy. The benefits of memory alloy and the caveats for the design are briefly discussed. The design of the off load system is described and test experience is reported.

Hostenkamp, R. G.

1985-01-01

207

STS-31 Hubble Space Telescope (HST) solar array panel deploy aboard OV-103  

NASA Technical Reports Server (NTRS)

Held in appendage deploy position by Discovery's, Orbiter Vehicle (OV) 103's, remote manipulator system (RMS), the Hubble Space Telescope's (HST's) starboard solar array (SA) bistem cassette is released from its stowed position on the Support System Module (SSM) forward shell. The spreader bar and bistem begin to unfurl the SA wing. View was taken by an STS-31 crewmember through an overhead window and is backdropped against the surface of the Earth.

1990-01-01

208

Solar far-infrared observations with a balloon-borne telescope  

Microsoft Academic Search

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

H.-C. Zou

1984-01-01

209

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

210

Prototype Tests for the CELESTE Solar Array Gamma--Ray Telescope  

E-print Network

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

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

1998-03-17

211

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

212

MuSICa image slicer prototype at 1.5-m GREGOR solar telescope  

NASA Astrophysics Data System (ADS)

Integral Field Spectroscopy is an innovative technique that is being implemented in the state-of-the-art instruments of the largest night-time telescopes, however, it is still a novelty for solar instrumentation. A new concept of image slicer, called MuSICa (Multi-Slit Image slicer based on collimator-Camera), has been designed for the integral field spectrograph of the 4-m European Solar Telescope. This communication presents an image slicer prototype of MuSICa for GRIS, the spectrograph of the 1.5-m GREGOR solar telescope located at the Observatory of El Teide. MuSICa at GRIS reorganizes a 2-D field of view of 24.5 arcsec into a slit of 0.367 arcsec width by 66.76 arcsec length distributed horizontally. It will operate together with the TIP-II polarimeter to offer high resolution integral field spectropolarimetry. It will also have a bidimensional field of view scanning system to cover a field of view up to 1 by 1 arcmin.

Calcines, A.; López, R. L.; Collados, M.; Vega Reyes, N.

2014-07-01

213

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

214

High Contrast Imaging with Gaussian Aperture Pupil Masks (GAPMs)  

E-print Network

Gaussian aperture pupil masks (GAPMs) can in theory achieve the contrast requisite for directly imaging an extrasolar planet around a nearby solar type star. We outline the process of designing, fabricating, and testing a GAPM for use on current telescopes and specifically the Penn State near-IR Imager and Spectrograph (PIRIS) at the Mt. Wilson 100$^{\\prime\\prime}$ telescope. We find that the initial prototype observations are quite successful, achieving a contrast similar to a traditional Lyot coronagraph without blocking any light from a central object and useful for finding faint companions to nearby young solar analogues. In the lab we can reproduce the expected PSF reasonably well and with a single aperture design which achieves $\\sim4 \\times 10^{-5}$ contrast at 10$\\lambda/D$. We find that small inaccuracies in the mask fabrication process and insufficient correction of the atmosphere contribute the most degradation to contrast at these levels.

J. H. Debes; J. Ge

2004-06-16

215

The wavefront correction control system for the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

216

On the use of Cherenkov Telescopes for outer Solar system body occultations  

NASA Astrophysics Data System (ADS)

Imaging Atmospheric Cherenkov Telescopes (IACTs) are arrays of very large optical telescopes that are well-suited for rapid photometry of bright sources. I investigate their potential in observing stellar occultations by small objects in the outer Solar system, Transjovian Objects (TJOs). These occultations cast diffraction patterns on the Earth. Current IACT arrays are capable of detecting objects smaller than 100 m in radius in the Kuiper Belt and 1 km radius out to 5000 au. The future Cherenkov Telescope Array (CTA) will have even greater capabilities. Because the arrays include several telescopes, they can potentially measure the speeds of TJOs without degeneracies, and the sizes of the TJOs and background stars. I estimate the achievable precision using a Fisher matrix analysis. With CTA, the precisions of these parameter estimations will be as good as a few per cent. I consider how often detectable occultations occur by members of different TJO populations, including Centaurs, Kuiper Belt Objects (KBOs), Oort Cloud objects, and satellites and Trojans of Uranus and Neptune. The great sensitivity of IACT arrays means that they likely detect KBO occultations once every O(10) hours when looking near the ecliptic. IACTs can also set useful limits on many other TJO populations.

Lacki, Brian C.

2014-12-01

217

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

218

Control and operation of the 1.6 m New Solar Telescope in Big Bear  

NASA Astrophysics Data System (ADS)

The 1.6m New Solar Telescope (NST) has developed a modern and comprehensive suite of instruments which allow high resolution observations of the Sun. The current instrument package comprises diffraction limited imaging, spectroscopic and polarimetric instruments covering the wavelength range from 0.4 to 5.0 microns. The instruments include broadband imaging, visible and near-infrared scanning Fabry-Perot interferometers, an imaging spectropolarimeter, a fast visible-light imaging spectrograph, and a unique new scanning cryogenic infrared spectrometer/spectropolarimeter that is nearing completion. Most instruments are operated with a 308 subaperture adaptive optics system, while the thermal-IR spectrometer has a correlation tracker. This paper reports on the current observational programs and operational performance of the telescope and instrumentation. The current control, data processing, and archiving systems are also briefly discussed.

Varsik, J.; Plymate, C.; Goode, P.; Kosovichev, A.; Cao, W.; Coulter, R.; Ahn, K.; Gorceix, N.; Shumko, S.

2014-08-01

219

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

220

The Thermal Environment of the Fiber Glass Dome for the New Solar Telescope at Big Bear Solar Observatory  

E-print Network

The New Solar Telescope (NST) is a 1.6-meter off-axis Gregory-type telescope with an equatorial mount and an open optical support structure. To mitigate the temperature fluctuations along the exposed optical path, the effects of local/dome-related seeing have to be minimized. To accomplish this, NST will be housed in a 5/8-sphere fiberglass dome that is outfitted with 14 active vents evenly spaced around its perimeter. The 14 vents house louvers that open and close independently of one another to regulate and direct the passage of air through the dome. In January 2006, 16 thermal probes were installed throughout the dome and the temperature distribution was measured. The measurements confirmed the existence of a strong thermal gradient on the order of 5 degree Celsius inside the dome. In December 2006, a second set of temperature measurements were made using different louver configurations. In this study, we present the results of these measurements along with their integration into the thermal control system (ThCS) and the overall telescope control system (TCS).

A. P. Verdoni; C. Denker; J. R. Varsik; S. Shumko; J. Nenow; R. Coulter

2007-08-04

221

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

222

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

NASA Astrophysics Data System (ADS)

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

1999-10-01

223

The multi-conjugate adaptive optics system of the New Solar Telescope at Big Bear Solar Observatory  

NASA Astrophysics Data System (ADS)

We report on the multi-conjugate adaptive optics (MCAO) system of the New Solar Telescope (NST) at Big Bear Solar Observatory which has been integrated in October 2013 and is now available for MCAO experiments. The NST MCAO system features three deformable mirrors (DM), and it is purposely flexible in order to offer a valuable facility for development of solar MCAO. Two of the deformable mirrors are dedicated to compensation of field dependent aberrations due to high-altitude turbulence, whereas the other deformable mirror compensates field independent aberrations in a pupil image. The opto-mechanical design allows for changing the conjugate plane of the two high-altitude DMs independently between two and nine kilometers. The pupil plane DM can be placed either in a pupil image upstream of the high-altitude DMs or downstream. This capability allows for performing experimental studies on the impact of the geometrical order of the deformable mirrors and the conjugate position. The control system is flexible, too, which allows for real-world analysis of various control approaches. This paper gives an overview of the NST MCAO system and reveals the first MCAO corrected image taken at Big Bear Solar Observatory.

Schmidt, Dirk; Gorceix, Nicolas; Zhang, Xianyu; Marino, Jose; Coulter, Roy; Shumko, Sergey; Goode, Phil; Rimmele, Thomas; Berkefeld, Thomas

2014-07-01

224

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

225

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.

2008-02-01

226

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.

2008-02-01

227

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

228

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

229

An Overview of the Electron-Proton and High Energy Telescopes for Solar Orbiter  

NASA Astrophysics Data System (ADS)

The Energetic Particle Detector (EPD) suite for ESA's Solar Orbiter will provide key measurements to address particle acceleration at and near the Sun. The EPD suite consists of four sensors (STEP, SIS, EPT, and HET). The University of Kiel in Germany is responsible for the design, development, and building of STEP, EPT and HET. This poster will focus on the last two. The Electron Proton Telescope (EPT) is designed to cleanly separate and measure electrons in the energy range from 20 - 400 keV and protons from 20 - 7000 keV. To separate electrons and protons EPT relies on the magnet/foil-technique. EPT is intended to close the gap between the supra-thermal particles measured by STEP and the high energy range covered by HET. The High-Energy Telescope (HET) will measure electrons from 300 keV up to about 30 MeV, protons from 10 to 100 MeV, and heavy ions from ~20 to 200 MeV/nuc. To achieve this performance HET consists of a series of silicon detectors in a telescope configuration with a scintillator calorimeter to stop high energy protons and ions. It uses the dE/dx vs. total E technique . In this way HET covers an energy range which is of interest for studies of the space radiation environment and will perform measurements needed to understand the origin of high-energy particle events at the Sun. EPT and HET share a common Electronics Box, there are two EPT-HET sensors on Solar Orbiter to allow rudimentary pitch-angle coverage. Here we present the current development status of EPT-HET units and calibration results of demonstration models as well as plans for future activities.

Boden, Sebastian; Kulkarni, Shrinivasrao R.; Tammen, Jan; Steinhagen, Jan; Martin, César; Wimmer-Schweingruber, Robert F.; Böttcher, Stephan I.; Seimetz, Lars; Ravanbakhsh, Ali; Elftmann, Robert; Rodriguez-Pacheco, Javier; Prieto Mateo, Manuel; Gomez Herrero, Rául

2014-05-01

230

The soft x-ray photon-counting telescope for solar observations  

NASA Astrophysics Data System (ADS)

We present overview and development activities of a soft X-ray photon-counting spectroscopic imager for the solar corona that we conceive as a possible scientific payload for future space solar missions including Japanese Solar-C. The soft X-ray imager will employ a Wolter I grazing-incidence sector mirror with which images of the corona (1 MK to beyond 10 MK) will be taken with the highest-ever angular resolution (0.5"/pixel for a focal length of 4 m) as a solar Xray telescope. In addition to high-resolution imagery, we attempt to implement photon-counting capability for the imager by employing a backside-illuminated CMOS image sensor as the focal-plane device. 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 with the soft X-ray imager will provide a noble probe for investigating mechanism(s) of magnetic reconnection and generation of supra-thermal (non-thermal) electrons associated with flares. Ongoing development activities in Japan towards the photon-counting imager is described with emphasis on that for sub-arcsecond-resolution grazing-incidence mirrors.

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

2014-07-01

231

Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons  

NASA Astrophysics Data System (ADS)

Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry-Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up, in conjunction with a 15 cm Carl Zeiss Coud\\'e solar telescope. The etalons were calibrated for the solar spectral lines FeI 6173 {\\AA}, and CaII 8542 {\\AA}. In this work, we discuss the characterization of the Fabry-Perot etalons, specifically the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We also present solar images obtained using the system parameters. We also present solar images obtained using the system.

Raja Bayanna, A.; Mathew, Shibu K.; Venkatakrishnan, P.; Srivastava, N.

2014-10-01

232

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

NASA Technical Reports Server (NTRS)

The Mass Spectrometer Telescope (MAST) on SAMPEX 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 about 10 to several hundred MeV/nuc. During large solar flares MAST will measure the isotopic abundances of solar energetic particles to determine directly the composition of the solar corona, while during solar quiet times MAST will study the isotopic composition of galactic cosmic rays. In addition, MAST will measure the isotopic composition of both interplanetary and trapped fluxes of anomalous cosmic rays, believed to be a sample of the nearby interstellar medium.

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

1993-01-01

233

Similitude modeling of natural convection heat transfer through an aperture in passive solar heated buildings  

NASA Astrophysics Data System (ADS)

An experimental study of natural convection heat transfer through a doorway in a two room passive solar heated building is described. Similitude modeling was the method used to measure natural convection heat transfer coefficients (h/sub NC/) in a model geometrically scaled down by a factor of 5. Freon gas was used as the working fluid to obtain dynamic similarity within the model. A temperature difference was maintained between the two rooms by a heated vertical wall which simulated a Trombe wall in one room, and by a cooled vertical wall which simulated a thermal storage wall in the other room. Heat transfer through the doorway was measured as a function of a characteristic temperature differential and the geometry of the doorway.

Weber, D. D.

1980-06-01

234

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

235

Feasibility study of a layer-oriented wavefront sensor for solar telescopes: comment.  

PubMed

The future generation of telescopes will be equipped with multi-conjugate adaptive-optics (MCAO) systems in order to obtain high angular resolution over large fields of view. MCAO comes in two flavors: star- and layer-oriented. Existing solar MCAO systems rely exclusively on the star-oriented approach. Earlier we suggested a method to implement the layer-oriented approach, and in view of recent concerns by Marino and Wöger [Appl. Opt.53, 685 (2014)10.1364/AO.53.000685APOPAI1559-128X], we now explain the proposed scheme in further detail. We note that in any layer-oriented system one sensor is conjugated to the pupil and the others are conjugated to higher altitudes. For the latter, not all the sensing surface is illuminated by the entire field of view. The successful implementation of nighttime layer-oriented systems shows that the field reduction is no crucial limitation. In the solar approach the field reduction is directly noticeable because it causes vignetting of the Shack-Hartmann subaperture images. It can be accounted for by a suitable adjustment of the algorithms to calculate the local wavefront slopes. We discuss a further concern related to the optical layout of a layer-oriented solar system. PMID:25402984

Kellerer, Aglaé

2014-11-10

236

To appear in Proc. SPIE 4853-52, Innovative Telescopes and Instrumentation for Solar Astrophysics, Keil & Avakyan, eds., Waikoloa, Hawaii, USA, August 2002. Adaptive optics system for the new Swedish solar telescope  

E-print Network

, Keil & Avakyan, eds., Waikoloa, Hawaii, USA, August 2002. Adaptive optics system for the new Swedish of a low-order adaptive optics (AO) system. This paper describes the AO system initially developed, optics, wavefront sensing, adaptive optics 1. INTRODUCTION The 1-meter Swedish solar telescope2

Löfdahl, Mats

237

Chemical analysis of hyper velocity impacts on the solar cells of the hubble space telescope with epma-edx and SIMS  

Microsoft Academic Search

The Technical University Darmstadt received 20 solar cell samples of the retrieved Hubble Space Telescope solar wing for chemical characterization of hypervelocity impact residues in and around all impacts. The solar cells were analyzed by electron probe microanalysis with energy dispersive X-ray detection (EPMA-EDX) and secondary ion mass spectrometry (SIMS). Because of the complexity of the solar cells it was

C. H. Heiss; F. J. Stadermann

1997-01-01

238

Dutch Open Telescope: status, results, prospects  

NASA Astrophysics Data System (ADS)

The Dutch Open Telescope (DOT) on La Palma is a revolutionary telescope achieving high-resolution imaging of the solar surface. The DOT combines a pioneering open design at an excellent wind-swept site with image restoration through speckle interferometry. Its open principle is now followed in major solar-telescope projects elsewhere. In the past three years the DOT became the first solar telescope to regularly obtain 0.2" resolution in extended image sequences, i.e., reaching the diffraction limit of its 45-cm primary mirror. Our aim for 2003-2005 is to turn the DOT into a 0.2" tomographic mapper of the solar atmosphere with frequent partnership in international multi-telescope campaigns through student-serviced time allocation. After 2005 we aim to triple the DOT resolution to 0.07" by increasing the aperture to 140 cm and to renew the speckle cameras and the speckle pipeline in order to increase the field size and sequence duration appreciably. These upgrades will maintain the DOT's niche as a tomographic high-resolution mapper in the era when GREGOR, Solar-B and SDO set the stage.

Rutten, Robert J.; Sütterlin, Peter; de Wijn, Alfred G.; Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Hoogendoorn, Piet W.; Jägers, Aswin P. L.

2002-12-01

239

Radio Telescopes  

NASA Astrophysics Data System (ADS)

``Radio Telescopes" starts with a brief historical introduction from Jansky's1931 discovery of radio emission from the Milky Way through the development ofradio telescope dishes and arrays to aperture synthesis imaging. It includessufficient basics of electromagnetic radiation to provide some understanding of thedesign and operation of radio telescopes. The criteria such as frequencyrange, sensitivity, survey speed, angular resolution, and field of view thatdetermine the design of radio telescopes are introduced. Because it is soeasy to manipulate the electromagnetic waves at radio frequencies, radiotelescopes have evolved into many different forms, sometimes with "wire"structures tuned to specific wavelengths, which look very different from anykind of classical telescope. To assist astronomers more familiar with otherwavelength domains, the appendix A.1. includes a comparison of radioand optical terminology. Some of the different types of radio telescopesincluding the filled aperture dishes, electronically steered phased arrays, andaperture synthesis radio telescopes are discussed, and there is a sectioncomparing the differences between dishes and arrays. Some of the morerecent developments including hierarchical beam forming, phased arrayfeeds, mosaicing, rotation measure synthesis, digital receivers, and longbaseline interferometers are included. The problem of increasing radiofrequency interference is discussed, and some possible mitigation strategies areoutlined.

Ekers, Ron; Wilson, Thomas L.

240

Opto-thermal analysis of a lightweighted mirror for solar telescope  

E-print Network

In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account for the radiative heating and energy exchange of the mirror with surroundings. The numerical simulations show the non-uniform temperature distribution and associated thermo-elastic distortions of the mirror blank clearly mimicking the underlying discrete geometry of the lightweighted substrate. The computed mechanical deformation data is analyzed with surface polynomials and the optical quality of the mirror is evaluated with the help of a ray-tracing software. The thermal print-through distortions are further shown to contribute to optical figure changes and mid-spatial frequency errors of the mirror surface. A comparative study presented for three commonly used substrate materials, namely, Zerodur, Pyrex and Silicon Carbide (SiC) is relevant to vast area of large optics requirements in gro...

Banyal, Ravinder K; Chatterjee, S

2013-01-01

241

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

242

The Italian contribution to the design study of the European Solar Telescope EST: current status and future steps  

NASA Astrophysics Data System (ADS)

The EST (European Solar Telescope) is a 4-m class telescope, four times larger than any existing high resolution solar telescope. It is designated with the highest priority among the ground-based, medium term (2016-2020) new projects in the ASTRONET Roadmap (Panel C). The EST will be equipped with a suite of instruments to perform spectropolarimetric and imaging observations at high spatial and temporal resolution in the range UV-NIR. The conceptual design study, which has been funded from EU in the framework of FP7, started on February 2008. We summarize the Italian participation to the EST project, which includes detailed design of various subsystems affecting the opto-mechanical structure, the suite of post-focus instruments, the data handling, and the control system.

Zuccarello, F.; EST Team

243

FPGA-based real time processing of the plenoptic wavefront sensor for the european solar telescope (EST)  

Microsoft Academic Search

This paper describes the development of the plenoptic wave front sensor for an adaptive optics systems proposed for the future EST Solar telescope. The plenoptic sensor offers additional optical information compared to traditional sensors at the expense of a significant increase in the image processing. This paper will concentrate on the processing required to develop a viable plenoptic sensor, describing

Y. Martin; L. F. Rodriguez-Ramos; J. Garcia; J. M. Rodriguez-Ramos

2010-01-01

244

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

245

Similitude Modeling of Natural Convection Heat Transfer Through AN Aperture in Passive Solar Heated Buildings.  

NASA Astrophysics Data System (ADS)

This dissertation was an experimental study of natural convection heat transfer through a doorway in a two room passive solar heated building. Similitude modeling was the method used to measure natural convection heat transfer coefficients (h(,NC)) in a model geometrically scaled down by a factor of 5. Freon gas was used as the working fluid to obtain dynamic similarity within the model. A temperature difference was maintained between the two rooms by a heated vertical wall which simulated a Trombe wall in one room, and by a cooled vertical wall which simulated a thermal storage wall in the other room. Heat transfer through the doorway was measured as a function of a characteristic temperature differential ((DELTA)T(,ave)) and the geometry of the doorway. The geometric factors investigated were the door height to ceiling height ratio (AHR) and the door width to partition width ratio (AWR). For building design considerations, (DELTA)T(,ave) was chosen to be the difference between volume weighted temperature averages of the two rooms. Relationships between h(,NC) and (DELTA)T(,ave) were expressed in terms of the non-dimensional similarity numbers for natural convection systems, the Nusselt number (Nu), the Grashof number (Gr), and the Prandtl number (Pr), in the form Nu/Pr = C(Gr)('a). A general relationship for h(,NC) was written in the form Nu = K(AHR)('b)(AWR)('c)Gr('a) for the variables investigated here. Similarity numbers were calculated using the ceiling height H as the characteristic length to evaluate the influence of AHR and AWR on h(,NC). For comparison with previous works, and with a theoretical expression developed in this work, the doorway height d was used as the characteristic length. Heat transfer rates were measured for values of the Grashof number Gr(,d) in the range 1.3 x 10('8) (LESSTHEQ) Gr(,d) (LESSTHEQ) 1.3 x 10('9). The dependence on AHR was found to be strong, and the AWR dependence was weak. A comparison of the results of this work with previous full scale studies and with the theory shows good correlation. Deviations of the Gr dependence from the theoretical predictions were caused by errors in assumptions of the relationship between (DELTA)T(,ave) and the temperature differences in the doorway. Velocity and temperature profiles measured in the doorway allowed a critical examination of these assumptions. Measurements were made using three Freon gases having different Prandtl numbers to experimentally determine the influence of Prandtl number on Nu. Data are presented but the results are inconclusive.

Weber, Dennis David

246

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

247

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

248

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

249

Narrow-Band Imaging System for the Multi-application Solar Telescope at Udaipur Solar Observatory: Characterization of Lithium Niobate Etalons  

E-print Network

Multi-application Solar Telescope is a 50 cm off-axis Gregorian telescope that has been installed at the lake site of Udaipur Solar Observatory. For quasi-simultaneous photospheric and chromospheric observations, a narrow-band imager has been developed as one of the back-end instruments for this telescope. Narrow-band imaging is achieved using two lithium niobate Fabry-Perot etalons working in tandem as a filter. This filter can be tuned to different wavelengths by changing either voltage, tilt or temperature of the etalons. To characterize the etalons, a Littrow spectrograph was set up, in conjunction with a 15 cm Carl Zeiss Coud\\'e solar telescope. The etalons were calibrated for the solar spectral lines FeI 6173 {\\AA}, and CaII 8542 {\\AA}. In this work, we discuss the characterization of the Fabry-Perot etalons, specifically the temperature and voltage tuning of the system for the spectral lines proposed for observations. We present the details of the calibration set-up and various tuning parameters. We al...

Bayanna, A Raja; Venkatakrishnan, P; Srivastava, N

2014-01-01

250

Compilation of flares and transients observed by the S-056 solar X-ray telescope during the Skylab missions  

NASA Technical Reports Server (NTRS)

During the manned operation of the Skylab Apollo Telescope Mount, the Marshall Space Flight Center/The Aerospace Corporation solar X-ray telescope (S-056) observed many solar flares and transient solar phenomena. Those X-ray observations are correlated with events reported by H-alpha observers and those recorded by integrating X-ray satellite detectors. Data included for individual events are: (1) type of H-alpha activity; (2) H-alpha begin, maximum, and end times; (3) SOLRAD 9 or VELA X-ray (1 to 8 A) peak flux and time of peak flux; (4) begin time of S-056 observations; (5) approximate heliographic location; and (6) Boulder and McMath active region numbers.

Speich, D. M.; Smith, J. B., Jr.; Reichmann, E. J.; Mcguire, J. P.; Vorpahl, J. A.; Mckenzie, D. L.

1976-01-01

251

Silicon carbide pointing mirror and telescope for the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)  

NASA Astrophysics Data System (ADS)

SSG Precision Optronics, Inc. has delivered a silicon carbide (SiC) pointing mirror and telescope for NASA's Geostationary Imaging Fourier Transform Spectrometer (GIFTS) project. The 28 x 45 cm SiC pointing mirror is part of SSG's two-axis gimbaled mirror assembly that will provide object-space pointing and jitter control. The 24 cm aperture telescope is an off-axis afocal three mirror anastigmat that is the collection aperture for the GIFTS instrument. Silicon carbide was selected for the GIFTS pointing mirror and telescope in order to minimize weight, provide athermal optical performance from room temperature to 190 Kelvin, and maintain image quality and line-of-sight stability in the presence of partial or full solar loading (minimizing solar outages). Both subsystems were successfully designed, fabricated, and subjected to testing prior to being delivered to Utah State University's Space Dynamics Laboratory for integration. This paper describes the pointing mirror and telescope design and hardware results.

Schwalm, Mark; Dibiase, Dan; Landry, Dave; Rider, Brian; Ugolini, Virginia

2005-08-01

252

Assembly of a large modular optical telescope (ALMOST)  

E-print Network

Future space telescope programs need to assess in-space robotic assembly of large apertures at GEO and ESL2 to support ever increasing aperture sizes. Since such large apertures will not fit within a fairing, they must ...

Mohan, Swati

253

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

NASA Astrophysics Data System (ADS)

A Post-Flight Investigation was initiated by the European Space Agency to analyze impacts on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600 km altitude. The solar cells deployed during the first Service Mission (SM-1 in December 1993) were retrieved in March 2002 as part of Service Mission 3B (SM-3B). A sub-panel of 2 m 2 was cut from the arrays for subsequent selection and removal of individual solar cells for analysis. Six cells (4.8 × 10 -3 m 2) were surveyed for flux of all craters of sizes greater than 5 microns. Analytical scanning electron microscopy was used to analyse residues in 111 features of 3-4000 micron conchoidal detachment diameter ( Dco), examined on 23 solar cells. Eighty three show identifiable residue: 38 are Space Debris impacts and 45 Micrometeoroid impacts. Of the remaining 28, 2 contain residue of ambiguous origin, 1 is probably a minor manufacturing flaw, 1 is obscured by contamination, and 24 are unresolved, lacking recognizable residue. The majority of space debris impacts on the SM-3B cells are less than 80 microns Dco, dominated by Al-rich residue, probably of solid rocket motor origin, although three may be due to sodium metal droplet impacts. Three larger features include paint pigment and binder, ferrous alloy, and possible carbon-fibre composite material debris. Micrometeoroid residues are found across the entire crater size range and dominate features of between 100 and 1000 microns, their residues are similar to those found in earlier SM-1 surveys. Fe- and Mg-rich silicates dominate; Fe sulphides are common and there are occasional vesicular Ni- and S-bearing mafic silicates of hydrous phyllosilicate origin. A single sodium aluminosilicate residue and one Fe Ni metal residue were found; as well as enigmatic Mg- and S-bearing residues, all considered as probably of micrometeoroid origin. A few Fe-, O- and C-bearing residues were classified as of ambiguous origin.

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

254

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

255

Forbush decreases and solar events seen in the 10 - 20GeV energy range by the Karlsruhe Muon Telescope  

E-print Network

Since 1993, a muon telescope located at Forschungszentrum Karlsruhe (Karlsruhe Muon Telescope) has been recording the flux of single muons mostly originating from primary cosmic-ray protons with dominant energies in the 10 - 20 GeV range. The data are used to investigate the influence of solar effects on the flux of cosmic-rays measured at Earth. Non-periodic events like Forbush decreases and ground level enhancements are detected in the registered muon flux. A selection of recent events will be presented and compared to data from the Jungfraujoch neutron monitor. The data of the Karlsruhe Muon Telescope help to extend the knowledge about Forbush decreases and ground level enhancements to energies beyond the neutron monitor regime.

I. Braun; J. Engler; J. R. Hörandel; J. Milke

2008-10-27

256

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

257

The Planet Pipeline: Enabling Data Mining and Citizen Science with Hubble Space Telescope Solar System Images  

NASA Astrophysics Data System (ADS)

In 15 years of service, the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope (HST) obtained over 10,000 frames of Solar System data. Since HST's standard data reduction pipelines are not optimized for moving target data, our "planet pipeline" will uniformly reprocess and catalog this WFPC2 image collection to make it more immediately science-ready. Some of our processing steps will utilize citizen scientists to perform visual inspections. Our "Planet Investigators" website, built on CosmoQuest infrastructure, will allow people to assist us in verifying our artifact rejections and assemble object catalogs. It is now easily possible to have each image inspected multiple times, and set up iterative processes that can converge on the optimal output with greater confidence. Our corresponding database will enable robust queries which are more specific to planetary science, helping archival researchers quickly find and utilize the prepared images within our collection for a wide range of scientific analyses. Our processed images and associated catalogs will be made available as High Level Science Products (HLSP) in the Multimission Archive at STScI (MAST): http://archive.stsci.edu/prepds/planetpipeline

Deustua, S.; Mutchler, M.; Conti, A.; Viana, A.; Wong, M. H.; Gay, P.

2012-12-01

258

Opto-thermal analysis of a lightweighted mirror for solar telescope.  

PubMed

In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account for the radiative heating and energy exchange of the mirror with surroundings. The numerical simulations show the non-uniform temperature distribution and associated thermo-elastic distortions of the mirror blank clearly mimicking the underlying discrete geometry of the lightweighted substrate. The computed mechanical deformation data is analyzed with surface polynomials and the optical quality of the mirror is evaluated with the help of a ray-tracing software. The thermal print-through distortions are further shown to contribute to optical figure changes and mid-spatial frequency errors of the mirror surface. A comparative study presented for three commonly used substrate materials, namely, Zerodur, Pyrex and Silicon Carbide (SiC) is relevant to vast area of large optics requirements in ground and space applications. PMID:23546089

Banyal, Ravinder K; Ravindra, B; Chatterjee, S

2013-03-25

259

Plate coil thermal test bench for the Daniel K. Inouye Solar Telescope (DKIST) carousel cooling system  

NASA Astrophysics Data System (ADS)

Analyses have shown that even a white-painted enclosure requires active exterior skin-cooling systems to mitigate dome seeing which is driven by thermal nonuniformities that change the refractive index of the air. For the Daniel K. Inouye Solar Telescope (DKIST) Enclosure, this active surface temperature control will take the form of a system of water cooled plate coils integrated into the enclosure cladding system. The main objective of this system is to maintain the surface temperature of the enclosure as close as possible to, but always below, local ambient temperature in order to mitigate this effect. The results of analyses using a multi-layer cladding temperature model were applied to predict the behavior of the plate coil cladding system and ultimately, with safety margins incorporated into the resulting design thermal loads, the detailed designs. Construction drawings and specifications have been produced. Based on these designs and prior to procurement of the system components, a test system was constructed in order to measure actual system behavior. The data collected during seasonal test runs at the DKIST construction site on Haleakal? are used to validate and/or refine the design models and construction documents as appropriate. The test fixture was also used to compare competing hardware, software, components, control strategies, and configurations. This paper outlines the design, construction, test protocols, and results obtained of the plate coil thermal test bench for the DKIST carousel cooling system.

Phelps, LeEllen; Murga, Gaizka; Montijo, Guillermo; Hauth, David

2014-08-01

260

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

261

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

NASA Astrophysics Data System (ADS)

A Post-Flight Investigation was initiated by the European Space Agency to analyze impact fluxes on solar arrays of the Hubble Space Telescope (HST), exposed to space for 8.25 years at approximately 600 km altitude. The solar cells were deployed during servicing mission SM-1 (December 1993), and retrieved by shuttle orbiter Columbia in March 2002 (SM-3B). A sub-panel of 2 m2 was cut from the --V2 wing and cells were selected for in-depth analysis. Twelve cells (9.6x10-3 m2) were surveyed for flux of all craters of sizes greater than 5 microns Dco; six at the NHM, and six at ONERA. Cumulative flux plots reveal slightly greater abundance of very small craters than in a comparable survey of SM-1 cells. Analytical scanning electron microscopy was used to locate impact features and to analyse residues at the NHM. 103 features of 3 -- 4000 micron conchoidal detachment diameter (Dco) were located on a total of 17 solar cells. 78 features show identifiable residue: 36 are Space Debris impacts and 42 Micrometeoroid impacts. Of the remaining 25: 4 contain residue of ambiguous origin, 1 is a minor manufacturing flaw, 1 is obscured by contamination, and 19 are unresolved, lacking recognizable residue. Space debris impacts on the SM-3B cells are all less than 80 microns Dco, dominated by Al- rich residue, probably of solid rocket motor origin, some may be unburnt fuel. Three craters may be sodium metal droplet impacts. No residues from paint pigment, aluminium or ferrous alloys, or copper- and tin-bearing metal were found. All craters larger than 100 microns are of micrometeoroid origin, or unresolved. Most residues are magnesium-iron silicate or iron sulfide. A few craters show vesicular Mg, S, Fe and Ni residue. A single Fe Ni metal residue was found, as well as enigmatic Mg- and S-bearing residues, all considered of micrometeoroid origin. A few Fe-, O- and C-bearing residues were classified as of ambiguous origin. The quality and quantity of residue is clearly linked to the crater pit morphology, with oval pit features containing more identifiable residue, perhaps due to lower peak shock pressures experienced in these oblique-incidence impacts.

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

262

Production of the 4.26 m ZERODUR mirror blank for the Advanced Technology Solar telescope (ATST)  

NASA Astrophysics Data System (ADS)

The Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope, ATST) will be the most powerful solar telescope in the world. It is currently being built by the Association of Universities for Research in Astronomy (AURA) in a height of 3000 m above sea level on the mountain Haleakala of Maui, Hawaii. The primary mirror blank of diameter 4.26 m is made of the extremely low thermal expansion glass ceramic ZERODUR® of SCHOTT AG Advanced Optics. The DKIST primary mirror design is extremely challenging. With a mirror thickness of only 78 to 85 mm it is the smallest thickness ever machined on a mirror of 4.26 m in diameter. Additionally the glassy ZERODUR® casting is one of the largest in size ever produced for a 4 m class ZERODUR® mirror blank. The off axis aspherical mirror surface required sophisticated grinding procedures to achieve the specified geometrical tolerance. The small thickness of about 80 mm required special measures during processing, lifting and transport. Additionally acid etch treatment was applied to the convex back-surface and the conical shaped outer diameter surface to improve the strength of the blank. This paper reports on the challenging tasks and the achievements on the material property and dimensional specification parameter during the production of the 4.26 m ZERODUR® primary mirror blank for AURA.

Jedamzik, Ralf; Werner, Thomas; Westerhoff, Thomas

2014-07-01

263

A search for small solar-system bodies near the earth using a ground-based telescope - Technique and observations  

NASA Technical Reports Server (NTRS)

A large, previously undetected flux of small bodies near earth is identified by employing the standard technique of detection of an individual object in two consecutive frames. The observational periods and viewing coordinates for the search for small bodies are presented. A null test is performed in order to further demonstrate that the signatures in the images are not due to instrumental artifacts. The observed fluxes, orbital motions, and radii of the small bodies detected are in agreement with those for the small cometlike objects previously reported. It is pointed out that the radii of the small bodies would be in the range of meters. Since an alternative interpretation of the small bodies is possible, it is suggested that the use of a telescope with larger aperture and/or array detectors with lesser noise levels is necessary to confirm the present observations.

Frank, L. A.; Sigwarth, J. B.; Yeates, C. M.

1990-01-01

264

Phasing rectangular apertures.  

PubMed

Several techniques have been developed to phase apertures in the context of astronomical telescopes with segmented mirrors. Phasing multiple apertures, however, is important in a wide range of optical applications. The application of primary interest in this paper is the phasing of multiple short pulse laser beams for fast ignition fusion experiments. In this paper analytic expressions are derived for parameters such as the far-field distribution, a line-integrated form of the far-field distribution that could be fit to measured data, enclosed energy or energy-in-a-bucket and center-of-mass that can then be used to phase two rectangular apertures. Experimental data is taken with a MEMS device to simulate the two apertures and comparisons are made between the analytic parameters and those derived from the measurements. Two methods, fitting the measured far-field distribution to the theoretical distribution and measuring the ensquared energy in the far-field, produced overall phase variance between the 100 measurements of less than 0.005 rad(2) or an RMS displacement of less than 12 nm. PMID:19997175

Baker, K L; Homoelle, D; Utterback, E; Jones, S M

2009-10-26

265

Angle-of-arrival anemometry by means of a large-aperture Schmidt-Cassegrain telescope equipped with a CCD camera.  

PubMed

The frequency spectrum of angle-of-arrival (AOA) fluctuations of optical waves propagating through atmospheric turbulence carries information of wind speed transverse to the propagation path. We present the retrievals of the transverse wind speed, upsilon b, from the AOA spectra measured with a Schmidt-Cassegrain telescope equipped with a CCD camera by estimating the "knee frequency," the intersection of two power laws of the AOA spectrum. The rms difference between 30 s estimates of upsilon b retrieved from the measured AOA spectra and 30s averages of the transverse horizontal wind speed measured with an ultrasonic anemometer was 11 cm s(-1) for a 1 h period, during which the transverse horizontal wind speed varied between 0 and 80 cm s(-1). Potential and limitations of angle-of-arrival anemometry are discussed. PMID:17975575

Cheon, Yonghun; Hohreiter, Vincent; Behn, Mario; Muschinski, Andreas

2007-11-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

267

Receive Transmit Telescope Telescope  

E-print Network

Receive Transmit Telescope Telescope Acquisition, Tracking, and Pointing Technology Development technologies. BRMS utilizes two optically coupled telescopes to relay a laser source from the ground telescope is attached to the spacecraft bus with navigation and attitude control subsystems. The BRMS

268

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

269

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

270

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

271

The design of a large aperture infrared optical system  

Microsoft Academic Search

The paper considers the optical design of a large aperture telescope for near infrared imaging onto a linear array of detectors. The design must satisfy a number of optical system variables which include aperture, obscuration, field of view, image quality, focal surface, color correction, system throughput, off-axis energy rejection, and maximum mirror dimension. The ring field infrared telescope design uses

R. R. Altenhof

1975-01-01

272

Radon approach to shaped and apodized apertures for imaging exoplanets  

Microsoft Academic Search

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

C. Aime

2005-01-01

273

Astrometric and Photometric Observations of Solar System Bodies with Telescopes of Pulkovo Observatory  

E-print Network

with MTM-500M telescope, placed on Mount Astronomical Station of Pulkovo observatory (Northern Caucasus in the Mount Astronomical station of Pulkovo Observatory at Northern Caucasus ( = 42° 40', = 43° 44', h = 2070

Boyer, Edmond

274

CCD camera systems and support electronics for a White Light Coronagraph and X-ray XUV solar telescope  

NASA Technical Reports Server (NTRS)

Two instruments, a White Light Coronagraph and an X-ray XUV telescope built into the same housing, share several electronic functions. Each instrument uses a CCD as an imaging detector, but due to different spectral requirements, each uses a different type. Hardware reduction, required by the stringent weight and volume allocations of the interplanetary mission, is made possible by the use of a microprocessor. Most instrument functions are software controlled with the end use circuits treated as peripherals to the microprocessor. The instruments are being developed for the International Solar Polar Mission.

Harrison, D. C.; Kubierschky, K.; Staples, M. H.; Carpenter, C. H.

1980-01-01

275

Method for digitizing paper archive of solar radio observations made with Large Pulkovo Radio Telescope  

NASA Astrophysics Data System (ADS)

Valuable large archive of solar radio observations has been accumulated by the Pulkovo solar radio group. But big part of data is recorded on paper. We describe a method and software for transferring data recorded on paper to FITS format.

Abramov-Maximov, Vladimir E.

276

Formation metrology and control for large separated optics space telescopes  

NASA Technical Reports Server (NTRS)

In this paper we present formation flying performance analysis initial results for a representative large space telescope composed of separated optical elements [Mett 02]. A virtual-structure construct (an equivalent rigid body) is created by unique metrology and control that combines both centralized and decentralized methods. The formation may be in orbit at GEO for super-resolution Earth observation, as in the case of Figure 1, or it may be in an Earth-trailing orbit for astrophysics, Figure 2. Extended applications are envisioned for exo-solar planet interferometric imaging by a formation of very large separated optics telescopes, Figure 3. Space telescopes, with such large apertures and f/10 to f/100 optics, are not feasible if connected by massive metering structures. Instead, the new virtual-structure paradigm of information and control connectivity between the formation elements provides the necessary spatial rigidity and alignment precision for the telescope.

Mettler, E.; Quadrelli, M.; Breckenridge, W.

2002-01-01

277

Adaptive membrane for large lightweight space telescopes  

Microsoft Academic Search

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

Dimitry Gorinevsky; T. Tupper Hyde

2002-01-01

278

Development of Solar Scintillometer  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

279

Direct imaging of extra-solar planetary systems with the Circumstellar Imaging Telescope (CIT)  

NASA Technical Reports Server (NTRS)

In a joint study conducted by the Jet Propulsion Laboratory and the Perkin-Elmer Corporation it was found that an earth orbital, 1.5 meter diameter low scattered light coronagraphic telescope can achieve a broad range of scientific objectives including the direct detection of Jupiter-sized planets around the nearby stars. Recent major advances in the understanding of coronagraphic performance and in the field of super smooth mirror fabrication allow such an instrument to be designed and built within current technology. Such a project, called the Circumstellar Imaging Telescope (CIT), is currently being proposed.

Terrile, Richard J.

1988-01-01

280

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

281

NEAT: an astrometric space telescope to search for habitable exoplanets in the solar neighborhood  

NASA Astrophysics Data System (ADS)

The last decade has witnessed a spectacular development of exoplanet detection techniques, which led to an exponential number of discoveries and a great diversity of known exoplanets. However, it must be noted that the quest for the holy grail of astrobiology, i.e. a nearby terrestrial exoplanet in habitable zone around a solar type star, is still ongoing and proves to be very hard. Radial velocities will have to overcome stellar noise if there are to discover habitable planets around stars more massive than M ones. For very close systems, transits are impeded by their low geometrical probability. Here we present an alternative concept: space astrometry. NEAT (Nearby Earth Astrometric Telescope) is a concept of astrometric mission proposed to ESA which goal is to make a whole sky survey of close (less then 20 pc) planetary systems. The detection limit required for the instrument is the astrometric signal of an Earth analog (at 10 pc). Differential astrometry is a very interesting tool to detect nearby habitable exoplanets. Indeed, for F, G and K main sequence stars, the astrophysical noise is smaller than the astrometric signal, contrary to the case for radial velocities. The difficulty lies in the fact that the signal of an exo-Earth around a G type star at 10 pc is a tiny 0.3 micro arc sec, which is equivalent to a coin on the moon, seen from the Earth: the main challenge is related to instrumentation. In order to reach this specification, NEAT consists of two formation flying spacecraft at a 40m distance, one carries the mirror and the other one the focal plane. Thus NEAT has a configuration with only one optical surface: an off-axis parabola. Consequently, beamwalk errors are common to the whole field of view and have a small effect on differential astrometry. Moreover a metrology system projects young fringes on the focal plane, which can characterize the pixels whenever necessary during the mission. NEAT has two main scientific objectives: combined with radial velocities and direct imaging, it will explore in a quasi systematic way the nearby planetary systems. The resulting catalog of planetary systems will be very useful to constrain planetary formation models. The second objective is to find very close Earth analogs. These will be top priority targets for a spectroscopic mission aimed at detecting biomarquers. The current activities related to NEAT revolve around 3 themes: i) a lab demonstration: an optical bench replicates the NEAT optical configuration and metrology system in order to demonstrate the feasibility of measuring centroids with a differential accuracy of 5 µpixels (corresponding to 0.3 micro arc sec on sky) ii) a definition phase study of the NEAT mission done by CNES (the "French Space Agency") iii) an end to end simulation of the NEAT data reduction pipeline: from astrometric and RVs measurements to planets All of these activities are focused on the need to answer the next ESA call for M class missions in 2014 with an improved NEAT concept.

Crouzier, A.; Malbet, F.; Kern, P.; Feautrier, P.; Preiss, O.; Martin, G.; Henault, F.; Stadler, E.; Lafrasse, S.; Behar, E.; Saintpe, M.; Dupont, J.; Potin, S.; Lagage, P.-O.; Cara, C.; Leger, A.; Leduigou, J.-M.; Shao, M.; Goullioud, R.

2014-03-01

282

Telescopes and space exploration  

NASA Technical Reports Server (NTRS)

The necessity for different types of telescopes for astronomical investigations is discussed. Major findings in modern astronomy by ground-based and spaceborne telescopes are presented. Observations of the Crab Nebula, solar flares, interstellar gas, and the Black Hole are described. The theory of the oscillating universe is explored. Operating and planned telescopes are described.

Brandt, J. C.; Maran, S. P.

1976-01-01

283

Characterisation of rear incident hypervelocity impact phenomena on hubble space telescope solar arrays  

Microsoft Academic Search

Impact damage on glass faced HST solar cells generated by rear-incident impactors represent over one-third of the total damage on the retrieved solar array. Analysis of such space and laboratory generated morphologies has revealed a means of discriminating between front and rear incident impact sites and enabled characterization through either impactor energy or a simplified indentation fracture model. Morphology is

M. K. Herbert

1999-01-01

284

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

NASA Technical Reports Server (NTRS)

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

285

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

286

A new large-aperture transportable lidar system for atmospheric measurements is being developed in the  

E-print Network

an array telescope with an equivalent aperture of 1.6 m, and will be housed in a 12 m transportable telescope primary mirrors, to yield an equivalent aperture of 1.6 m. Compared to other telescopes. The observatory is being built from a 12 m shipping container, and will have a retractable roof, a climate

Duck, Thomas J.

287

Solar filter for the Mars laser communication demonstration optical receiver  

Microsoft Academic Search

To maximize the cost-effectiveness of the Mars Laser Communication Demonstration (MLCD), the project is pursuing the use of ground-based astronomical telescopes as large-aperture optical receiving antennae. To facilitate communication as the spacecraft approaches solar conjunction, a large membrane filter is being considered to reject approximately 95% of the sun\\

Brian G. Patrick; Paul Gierow; David Sheikh; W. Tom Roberts

2004-01-01

288

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

289

Large bearings with incorporated gears, high stiffness, and precision for the Swedish Solar Telescope (SST) on La Palma  

NASA Astrophysics Data System (ADS)

The 1-meter Swedish Solar Telescope (SST) obtains images of the solar surface with an unprecedented resolution of 0.1 arcsec. It consists of a relatively slender tower with on top only the vacuum turret for reflecting downward the solar beam and no protective dome. This is a favourable situation to get good local seeing. Just in the case of some wind, seeing is best for daytime observations, therefore the precision bearings and drives of the elevation- and azimuth axis of the turret have to be stiff against wind. This requires line contact between the meshing teeth of the large gear wheel and the pinion. High preload forces to achieve line contact are not allowed because of appearing stick-slip effects. To reduce the risk on stick-slip a special design of the teeth for high stiffness combined with low friction and smooth transition from one tooth to the next was made. Furthermore, extreme precision in the fabrication was pursued such that relatively small contact forces give already line contact. This required a special order of the successive fabrication steps of the combination of bearing and gear teeth. An additional problem was the relatively thin section of the bearings required for a compact turret construction, needed for best local seeing and minimum wind load. Solutions for all these problems will be discussed. For the large gears the exceptional good DIN quality class 4 for the pitch precision and straightness plus direction of the teeth faces was achieved.

Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Scharmer, Göran B.

2006-06-01

290

The Advanced Solar Observatory  

NASA Technical Reports Server (NTRS)

A conceptual plan for the development of a comprehensive long duration solar space observatory, The Advanced Solar Observatory (ASO) is described. The ASO is intended to provide solar astronomers with the observational power necessary to address fundamental problems relating to the solar convection zone and activity cycle; the thermal and nonthermal processes that control the transport of energy, mass, and magnetic flux in the solar atmosphere; the generation of the solar wind; and the dynamics of the inner heliosphere. The ASO concept encompasses three proposed Space Station-based instrument ensembles: (1) the High Resolution Telescope Cluster, which includes far ultraviolet, extreme ultraviolet, and X-ray telescopes; (2) the Pinhole/Occulter Facility, which includes Fourier transform and coded aperture hard X-ray and gamma ray telescopes and occulted ultraviolet and visible light coronagraphs; and (3) the High Energy Facility, which contains neutron, gamma ray, and low frequency radio spectrometers. Two other facilities, the Orbiting Solar Laboratory, and a package of Global Dynamics Instrumentation, will, with the Space Station ensembles, form a comprehensive capability for solar physics. The scientific program of the ASO, current instrument concepts for the Space Station based ASO instrument ensembles, and plans for their accommodation on the Space Station are described.

Walker, Arthur B. C., Jr.; Bailey, Wayne; Chupp, Edward L.; Hudson, Hugh S.; Moore, Ronald; Roberts, William; Hoover, Richard B.

1990-01-01

291

Progress toward large-aperture membrane mirrors  

Microsoft Academic Search

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

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

2000-01-01

292

LOFAR: A digital aperture array radio telescope  

Microsoft Academic Search

Construction of the Low Frequency Array (LOFAR) is nearly complete. It consists of 48 stations, mostly concentrated within the Netherlands, and spreading into Europe. Each station has 48 or 96 dipole antennas and antenna tiles, optimized for 30-240 MHz. LOFAR uses a combination of true time delay and phased-array techniques. Digital beam-forming gives the system agility and allows rapid repointing

Andre W. Gunst; Michiel P. van Haarlem; Rene C. Vermeulen

2011-01-01

293

Shared Aperture Multiplexed (SAM) Lidar Telescopes  

NASA Technical Reports Server (NTRS)

A concept is introduced in which a single optic containing several holographic optical elements, are employed to effect multiple fields of view as an alternative to mechanically scanned lidar receivers.

Schwemmer, Geary K.

1999-01-01

294

Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode  

E-print Network

Exploiting high-resolution observations made by the Solar Optical Telescope onboard Hinode, we investigate the spatial distribution of power spectral density of oscillatory signal in and around NOAA active region 10935. The G-band data show that in the umbra the oscillatory power is suppressed in all frequency ranges. On the other hand, in Ca II H intensity maps oscillations in the umbra, so-called umbral flashes, are clearly seen with the power peaking around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with the spatial scale of the umbral flashes over most of the umbra but there is a region with suppressed power at the center of the umbra. The origin and property of this node-like feature remain unexplained.

Kaori Nagashima; Takashi Sekii; Alexander G. Kosovichev; Hiromoto Shibahashi; Saku Tsuneta; Kiyoshi Ichimoto; Yukio Katsukawa; Bruce W. Lites; Shin'ichi Nagata; Toshifumi Shimizu; Richard A. Shine; Yoshinori Suematsu; Theodore D. Tarbell; Alan M. Title

2007-09-05

295

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

SciTech Connect

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

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

2012-03-01

296

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

NASA Astrophysics Data System (ADS)

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

297

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

298

A Catalog of Solar X-Ray Plasma Ejections Observed by the Soft X-Ray Telescope on Board Yohkoh  

NASA Astrophysics Data System (ADS)

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

Tomczak, M.; Chmielewska, E.

2012-03-01

299

Large holographically corrected space telescopes  

Microsoft Academic Search

The next generation optical space telescopes with apertures > 10 m for imaging, lidar, communications and directed energy focusing will be unable to use conventional technologies which are impractical or too costly. Our solution is to construct a telescope from a lightweight, low-quality primary, which is holographically corrected for surface distortions, in situ. This scheme makes it possible to correct

Geoff Andersen; W. R. White; Randall J. Knize

1998-01-01

300

Ground based solar radio observations during solar maximum mission  

NASA Technical Reports Server (NTRS)

The Very Large Array (VLA) and the Westerbork Synthesis Radio Telescope (WSRT) were used for making aperture synthesis maps of solar active and flaring regions. Observations of the Flare buildup in the form of increased intensity and polarization were made. Ring structure associated with sunspots were interpreted as due to the existence of cool material above the spot. Model computations were performed to explain the total intensity and polarization structures of a continuous set of active region maps.

Kundu, M. R.

1983-01-01

301

Opportunities for Follow-Up Observations of Solar System Objects with 50/70 cm Schmidt Telescope of National Astronomical Observatory Rozhen, Bulgaria  

NASA Astrophysics Data System (ADS)

The 50/70 cm Schmidt telescope is one of the four telescopes in National Astronomical Observatory, Rozhen. The Observatory is situated in the Rozhen area of Rhodopes Mountain, at an altitude of 1750 m and away from big cities. Due to good location of observatory and high altitude light pollution is minimized and there is sufficient number of clear observational nights per year. Observations are obtained every clear dark night, for exceptional events moon nights are used, also. Telescopes schedules are allocated for 6 months ahead and the scientific teams know their dates of observations in advance. Nevertheless, changes of observational schedules (especially for small telescopes) and observations of targets of opportunity are common practice in the observatory. In addition the scientific team is experienced, with skills and background in observations of Solar system objects.

Kostov, Andon

2011-06-01

302

Occultation systems in space-borne telescopes dedicated to the observation of the solar corona  

NASA Astrophysics Data System (ADS)

The observation of the solar corona in white light is a challenging task because of the poor contrast of the signal (i.e., the solar corona) to the stray light noise. The main task a coronagraph or heliospheric imager designer shall face is the reduction of the stray light. This is particularly important in space-borne instruments with an external occultation. A large part of the field literature is dedicated to the optimization of the occulting system in order to reduce the total amount of stray light on the instrument focal plane. From the pioneering work of Newkirk and Bohlin in 1965, several solutions have been elaborated in optimizing the occulters shape. Despite a series of classical optimizing shapes has been employed in many solar missions, each optimization shall fit the constraint of the instrument design and of the mission characteristics. Forthcoming solar space missions such as ASPIICS on PROBA3 (formation flight) and Solar Orbiter (approaching the Sun with a perihelion of 0.28 AU) will introduce considerable technological innovations and their characteristics impose demanding efforts on the scientific payloads in order to be compliant with the constraints. This work reviews the most effective occultation systems that have been employed by past coronagraphs, spectrographs and heliospheric imagers. Moreover, it illustrates the innovative solutions that are going to be adopted by the missions to come.

Landini, Federico; Fineschi, Silvano; Moses, Daniel; Romoli, Marco

303

Debris production from solar array surface impact spallation: Results from the Hubble Space Telescope  

Microsoft Academic Search

Impacts on exposed spacecraft surfaces generate vapour, liquid and solid ejecta particles. Unless this encounters other parts of the spacecraft it escapes into space. On the HST spacecraft, meteoroid and space debris impacts produced thousands of craters visible to the naked eye (spallation diameter > 100 ?m) on the solar arrays. On the front surfaces these craters liberated solid spall-type

A. D. Griffiths; J. A. M. McDonnell; G. Drolshagen

1997-01-01

304

Debris production from solar array surface impact spallation: results from the hubble space telescope  

Microsoft Academic Search

Impacts on exposed spacecraft surfaces generate vapour, liquid and solid ejecta particles. Unless this encounters other parts of the spacecraft it escapes into space. On the HST spacecraft, meteoroid and space debris impacts produced thousands of craters visible to the naked eye (spallation diameter > 100 mum) on the solar arrays. On the front surfaces these craters liberated solid spall-type

A. D. Griffiths; J. A. M. McDonnell; G. Drolshagen

1997-01-01

305

Power Challenges of Large Scale Research Infrastructures: the Square Kilometer Array and Solar Energy Integration; Towards a zero-carbon footprint next generation telescope  

E-print Network

The Square Kilometer Array (SKA) will be the largest Global science project of the next two decades. It will encompass a sensor network dedicated to radioastronomy, covering two continents. It will be constructed in remote areas of South Africa and Australia, spreading over 3000Km, in high solar irradiance latitudes. Solar Power supply is therefore an option to power supply the SKA and contribute to a zero carbon footprint next generation telescope. Here we outline the major characteristics of the SKA and some innovation approaches on thermal solar energy Integration with SKA prototypes.

Barbosa, Domingos; Ruiz, Valeriano; Silva, Manuel; Verdes-Montenegro, Lourdes; Santander-Vela, Juande; Maia, Dalmiro; Antón, Sonia; van Ardenne, Arnold; Vetter, Matthias; Kramer, Michael; Keller, Reinhard; Pereira, Nuno; Silva, Vitor

2012-01-01

306

Mission design for the Space Infrared Telescope Facility (SIRTF)  

NASA Astrophysics Data System (ADS)

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

Kwok, Johnny H.; Osmolovsky, Michael G.

1991-12-01

307

Improved magnetogram calibration of Solar Magnetic Field Telescope and its comparison with the Helioseismic and Magnetic Imager  

NASA Astrophysics Data System (ADS)

In this paper, we try to improve the magnetogram calibration method of the Solar Magnetic Field Telescope (SMFT). The improved calibration process fits the observed full Stokes information, using six points on the profile of Fe I 5324.18 Å line, and the analytical Stokes profiles under the Milne-Eddington atmosphere model, adopting the Levenberg-Marquardt least-squares fitting algorithm. In comparison with the linear calibration methods, which employs one point, there is a large difference in the strength of longitudinal field Bl and transverse field Bt, caused by the non-linear relationship, but the discrepancy is little in the case of inclination and azimuth. We conclude that it is better to deal with the non-linear effects in the calibration of Bl and Bt using six points. Moreover, in comparison with Solar Dynamics Observatory/Helioseismic and Magnetic Imager (HMI), SMFT has larger stray light and acquires less magnetic field strength. For vector magnetic fields in two sunspot regions, the magnetic field strength, inclination and azimuth angles between SMFT and HMI are roughly in agreement, with the linear fitted slopes of 0.73/0.7, 0.95/1.04 and 0.99/1.1. In the case of pores and quiet regions (Bl < 600 G), the fitted slopes of the longitudinal magnetic field strength are 0.78 and 0.87, respectively.

Bai, X. Y.; Deng, Y. Y.; Teng, F.; Su, J. T.; Mao, X. J.; Wang, G. P.

2014-11-01

308

Design of a space telescope for vibration control  

Microsoft Academic Search

The end of the Cold War has made large-aperture telescope technologies from the U.S. Strategic Defense Initiative program available for non-defense missions. Now, a four-meter aperture space telescope, a seventy percent larger aperture than that of the Hubble space telescope, has been proposed for a dual military and astronomical mission. An important part of the preliminary design work was to

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

1994-01-01

309

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

310

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.

311

High-Resolution Observations of Limb Spicules from the Transition Region and Coronal Explorer and the Swedish Solar Telescope  

NASA Astrophysics Data System (ADS)

We observed spicules at the solar limb with TRACE and the Swedish Solar Telescope on La Palma for four-day intervals in 2004 and 2005 as well as simultaneous SUMER/SOHO observations in 2004. We are evaluating the apparent motion of individual spicules to infer chromospheric heat flow and mass transfer and to improve the statistics of basic spicule parameters including height, velocity, and inclination. We use the highest available cadence to measure height vs. time curves, using parabolic and linear fits to extract average maximum heights and apparent velocities of rise and descent. Our semiautomatic measurements of several dozen individual Ca II H spicules find an average height of 7610 ± 20 km based on ballistic fits and 7990 ± 80 km based on linear fits, with average velocities 8.7 ± 0.2 km/s ascending and 5.6 ± 0.1 km/s descending. Our TRACE data include observations at 1600 Å, 171 Å, and Lyman-alpha; our SST observations using Lockheed Martin's SOUP include H-alpha (four wing wavelengths to measure velocities) and Ca II H. We are investigating the relationships between spicule height and intensity to search for evidence of sheathed vs. monolithic spicule models, and analyzing ionization fadeout vs. velocity reversals for limiting spicule heights. A third yearly session of simultaneous TRACE/SST observations is scheduled.We thank S. P. Souza, B. De Pontieu, L. Golub, and J. Cirtain; earlier collaboration by D. B. Seaton, J. P. Shoer, D. L. Butts, and J. W. Gangestad; as well as the Royal Swedish Academy of Sciences. Support was provided by a NASA/Solar-Terrestrial Guest Investigator Grant for TRACE (NNG04GK44G), from Sigma Xi, and from the NASA/Massachusetts Space Grant.

Westbrook, Owen; Pasachoff, J. M.; Kozarev, K. A.; Yee, J.

2006-06-01

312

Design, Implementation and Control of a Sparse Aperture Imaging Satellite  

E-print Network

in designing and building a sparse aperture array, the challenge of building a white light Golay-3 telescope optics using interferometry. In order to better understand the technological difficulties involved

313

Journal of Atmospheric and Solar-Terrestrial Physics 67 (2005) 11711177 Modelling high-power large-aperture radar meteor trails  

E-print Network

-aperture radar meteor trails Lars P. Dyrud�, Licia Ray, Meers Oppenheim, Sigrid Close, Kelly Denney Center see high-power large-aperture (HPLA) radar observations of meteor phenomena called head echoes and non demonstrating that meteor trails are unstable to growth of Farley­Buneman gradient-drift (FBGD) waves

Oppenheim, Meers

314

Very high resolution space telescope using the Earth atmosphere as the objective lens  

Microsoft Academic Search

Telescopes are critical elements of NASA's space program. Very high resolution telescopes are needed to study planets of neighboring stellar systems and life beyond earth. Telescope resolution is limited by aperture diameter but current technology limits telescope apertures to about 10- meters in diameter. The Earth's atmosphere refracts sunlight such that the sun's image appears about a half degree above

Yu Wang

1998-01-01

315

Interface Region Imaging Spectrograph (IRIS) entrance aperture design  

NASA Astrophysics Data System (ADS)

The Interface Region Imaging Spectrograph (IRIS) is a complementary follow-on to Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO-AIA) and funded as a member of the NASA SMEX program. This paper presents the thermal design of the IRIS telescope front end, with a focus on the IRIS door and entrance aperture assembly. The challenge of the IRIS entrance aperture, including the door design, was to manage the solar flux, both before and after the door was opened. This is especially a problem with instruments that are permanently pointed directly at the sun. Though there is an array of effective flux-rejecting coatings, they are expensive, hard to apply, harder to measure, delicate, prone to unpredictable performance decay with exposure, and very often a source of contamination. This paper presents a thermal control and protection method based on robust, inexpensive coatings and materials, combined to produce high thermal and structural isolation. The end result is a first line of thermal protection whose performance is easy to predict and well isolated from the instrument it is protecting.

Cheimets, P.; Park, S.; Bergner, H.; Chou, C.; Gates, R.; Honsa, M.; Podgorski, W.; Yanari, C.

2014-07-01

316

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

317

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

318

Phase diversity for segmented and multi-aperture systems  

Microsoft Academic Search

As telescopes become larger, segmented and multi-aperture designs are being implemented to meet cost, size and weight constraints. These systems require alignment of the segments or sub-apertures to within fractions of a wavelength. We investigate the performance of phase diversity, a technique of image-based wavefront sensing, for characterizing and aligning segmented and multi-aperture systems. Supporting work developing the core phase-diversity

Matthew R. Bolcar

2009-01-01

319

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

320

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

NASA Astrophysics Data System (ADS)

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

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

1993-05-01

321

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

NASA Technical Reports Server (NTRS)

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, A.; Cirtain, J.; Golub, L.; DeLuca, E.; Savage, S.; Alexander, C.; Schuler, T.

2014-01-01

322

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

NASA Technical Reports Server (NTRS)

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 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 percent 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, A.; Cirtain, J.; Golub, L.; DeLuca, E.; Savage, S.; Alexander, C.; Schuler, T.

2014-01-01

323

Optical synthetic aperture imaging with spatial heterodyne interferometry  

Microsoft Academic Search

Experimental demonstrations of optical synthetic aperture imaging using spatial heterodyne interferometry have been achieved at the Lockheed Martin Advanced Technology Center in Palo Alto, CA. In laboratory experiments, a reflective binary star scene and an Air Force resolution bar target were illuminated and imaged by a 532 nm laser and an afocal telescope. The real aperture diffraction limit in the

Mel S. Ni; J. Wes Irwin

2009-01-01

324

Aperture masking behind AO systems  

NASA Astrophysics Data System (ADS)

Sparse Aperture-Mask Interferometry (SAM or NRM) behind Adaptive Optics (AO) has now come of age, with more than a dozen astronomy papers published from several 5-10m class telescopes around the world. I will describe the reasons behind its success in achieving relatively high contrasts ( 1000:1 at lambda/ D) and repeatable binary astronomy at the diffraction limit, even when used behind laser-guide star adaptive optics. Placed within the context of AO calibration, the information in an image can be split into pupil-plane phase, Fourier amplitude and closure-phase. It is the closure-phase observable, or its generalisation to Kernel phase, that is immune to pupil-plane phase errors at first and second-order and has been the reason for the technique's success. I will outline the limitations of the technique and the prospects for aperture-masking and related techniques in the future.

Ireland, Michael J.

2012-07-01

325

Attempt to detect Aflven waves with Solar Optical Telescope aboard Hinode  

NASA Astrophysics Data System (ADS)

Flux tube on the sun may carry linear and torsional Alfven waves generated by photospheric motion. Photospheric motion of 2 km/s would provide magnetic fluctuation of 40G for 1KG tube and for the Alfven speed of 50km/s. This may be close to the detection limit of the Stokes Q and U signals for flux tubes located in the sun center. However, for flux tubes located near the limb, the fluctuation would be seen in the Stokes V signal, and can be detectable. We also may be able to confirm the 90 degree phase shift between magnetic fluctuation and velocity fluctuation, which is easier to observe for flux tubes near the limb. Detection of waves would be important in terms of coronal heating and solar wind acceleration. An attempt to detect waves along flux tubes will be reported.

Tsuneta, Saku; Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.; Nagata, S.; Orozco Suárez, D.; Lites, B.; Shine, D.; Tarbell, T.; Title, A.

2007-05-01

326

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

327

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

328

The Change in Cosmic Ray Intensity Variation with the Solar Wind Velocity (Using GRAPES3 muon narrow angle telescopes and Kiel neutron monitor)  

Microsoft Academic Search

GRAPES-3 experiment is situated at Ooty in South India 76.7 East 11.4 North. Effective observation area of our muon telescopes is 560 m2. They are the largest detector in the world of its kind. There were several reports that increase of the solar wind velocity suppresses the intensity of cosmic rays. But there are few which studied qualitatively. We have

H. Kojima; Y. Hayashi; K. Hayashi

2008-01-01

329

Solar semidiurnal anisotropy of galactic cosmic ray intensity observed by the two-hemisphere network of surface-level muon telescopes  

Microsoft Academic Search

Observations made by the two-hemisphere network of surface-level, multidirectional muon telescopes at Hobart (Tasmania, Australia) and Nagoya (Aichi, Japan) are used to examine the origin of the solar semidiurnal variation in cosmic ray intensity. The network allows us to precisely determine the asymmetry of the variation across both hemispheres. It is shown that the variation is consistent with the north-south

K. Munakata; T. Kitawada; S. Yasue; S. Mori; C. Kato; M. Koyama; S. Akahane; D. L. Hall; Z. Fujii; K. Fujimoto; J. E. Humble; A. G. Fenton; K. B. Fenton; M. L. Duldig

1998-01-01

330

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

331

Large lightweight deployable telescopes with active surface correction  

Microsoft Academic Search

The future of space-based telescopes will inevitably incorporate large apertures made from lightweight, stable materials that deploy from small volumes and actively adjust for maximum efficiency. These types of telescopes are directly applicable toward imaging and non-imaging applications. Techniques to remove wavefront error via surface correction are currently being studied and are highly applicable towards deployable telescopes. Imaging telescopes require

Mark K. Pryor

2000-01-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

333

SYSTEMATIC MOTION OF FINE-SCALE JETS AND SUCCESSIVE RECONNECTION IN SOLAR CHROMOSPHERIC ANEMONE JET OBSERVED WITH THE SOLAR OPTICAL TELESCOPE/HINODE  

SciTech Connect

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

Singh, K. A. P.; Nishida, K.; Shibata, K. [Kwasan and Hida Observatories, Graduate School of Science, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Isobe, H., E-mail: singh@kwasan.kyoto-u.ac.jp [Unit for Synergetic Study for Space, Kyoto University, Yamashina, Kyoto 607-8471 (Japan)

2012-11-20

334

Optical design of the Big Bear Solar Observatory's multi-conjugate adaptive optics system  

NASA Astrophysics Data System (ADS)

A multi-conjugate adaptive optics (MCAO) system is being built for the world's largest aperture 1.6m solar telescope, New Solar Telescope, at the Big Bear Solar Observatory (BBSO). The BBSO MCAO system employs three deformable mirrors to enlarge the corrected field of view. In order to characterize the MCAO performance with different optical configurations and DM conjugated altitudes, the BBSO MCAO setup also needs to be flexible. In this paper, we present the optical design of the BBSO MCAO system.

Zhang, Xianyu; Gorceix, Nicolas; Schmidt, Dirk; Goode, Philip R.; Cao, Wenda; Rimmele, Thomas R.; Coulter, Roy

2014-07-01

335

Simulation of synthetic aperture imaging ladar (SAIL) for three-dimensional target model  

Microsoft Academic Search

In conventional imaging laser radar, the resolution of target is constrained by the diffraction-limited, which includes the beamwidth of the laser in the target plane and the telescope's aperture. Synthetic aperture imaging Ladar (SAIL) is an imaging technique which employs aperture synthesis with coherent laser radar, the resolution is determined by the total frequency spread of the source and is

Ning Yi; Zhen-Sen Wu

2010-01-01

336

LUTE telescope structural design  

NASA Technical Reports Server (NTRS)

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 constraints. This study uses the results from our previous studies on LUTE as a basis for further developing the LUTE structural architecture. After summarizing our results in Section 2, Section 3 begins with the overall logic we used to determine which telescope 'structural form' should be adopted for further analysis and weight estimates. Specific telescope component analysis showing calculated fundamental frequencies and how they compare with our derived requirements are included. 'First-order' component stress analyses to ensure telescope optical and structural component (i.e. mirrors & main bulkhead) weights are realistic are presented. Layouts of both the primary and tertiary mirrors showing dimensions that are consistent with both our weight and frequency calculations also form part of Section 3. Section 4 presents our calculated values for the predicted thermally induced primary-to-secondary mirror despace motion due to the large temperature range over which LUTE must operate. Two different telescope design approaches (one which utilizes fused quartz metering rods and one which assumes the entire telescope is fabricated from beryllium) are considered in this analysis. We bound the secondary mirror focus mechanism range (in despace) based on these two telescope configurations. In Section 5 we show our overall design of the UVTA (Ultraviolet Telescope Assembly) via an 'exploded view' of the sub-system. The 'exploded view' is annotated to help aid in the understanding of each sub-assembly. We also include a two view layout of the UVTA from which telescope and telescope component dimensions can be measured. We conclude our study with a set of recommendations not only with respect to the LUTE structural architecture but also on other topics related to the overall feasibility of the LUTE telescope sub-system.

Ruthven, Gregory

1993-01-01

337

Optical sparse aperture imaging  

Microsoft Academic Search

The resolution of a conventional diffraction-limited imaging system is proportional to its pupil diameter. A primary goal of sparse aperture imaging is to enhance resolution while minimizing the total light collection area; the latter being desirable, in part, because of the cost of large, monolithic apertures. Performance metrics are defined and used to evaluate several sparse aperture arrays constructed from

Nicholas J. Miller; Matthew P. Dierking; Bradley D. Duncan

2007-01-01

338

Detection of zero anisotropy at 5.2 AU during the November 1998 solar particle event: Ulysses Anisotropy Telescopes observations  

E-print Network

Detection of zero anisotropy at 5.2 AU during the November 1998 solar particle event: Ulysses words: Interplanetary physics (energetic particles) ± Solar physics, astrophysics and astronomy in solar activity towards solar maximum, several large energetic particle events were detected

Paris-Sud XI, Université de

339

DUTCH OPEN TELESCOPE PUBLICATIONS JUNE 16, 2014 Panasenco, O., Martin, S. F., and Velli, M.: 2014, "Apparent Solar Tornado-Like Prominences", Solar Phys. 289, 603622  

E-print Network

, "Apparent Solar Tornado-Like Prominences", Solar Phys. 289, 603­622 Joshi, A. D., Srivastava, N., Mathew, S. K., and Martin, S. F.: 2013, "Rapid Formation and Disappearance of a Filament Barb", Solar Phys

Rutten, Rob

340

Deployable reflector configurations. [for space telescope  

NASA Technical Reports Server (NTRS)

Both the theoretical reasons for considering a non-circular format for the Large Deployable Reflector, and a potentially realizable concept for such a device, are discussed. The optimum systems for diffraction limited telescopes with incoherent detection have either a single filled aperture, or two such apertures as an interferometer to synthesize a larger aperture. For a single aperture of limited area, a reflector in the form of a slot can be used to give increased angular resolution. It is shown how a 20 x 8 meter telescope can be configured to fit the Space Shuttle bay, and deployed with relatively simple operations. The relationship between the sunshield design and the inclination of the orbit is discussed. The possible use of the LDR as a basic module to permit the construction of supergiant space telescopes and interferometers both for IR/submm studies and for the entire ultraviolet through mm wave spectral region is discussed.

Meinel, A. B.; Meinel, M. P.; Woolf, N. J.

1983-01-01

341

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

342

Spitzer Space Telescope evidence in NGC 6791: no super-mass-loss at super-solar metallicity to explain helium white dwarfs?  

E-print Network

We use archival Spitzer Space Telescope photometry of the old, super-solar metallicity massive open cluster NGC 6791 to look for evidence of enhanced mass loss, which has been postulated to explain the optical luminosity function and low white dwarf masses in this benchmark cluster. We find a conspicuous lack of evidence for prolificacy of circumstellar dust production that would have been expected to accompany such mass loss. We also construct the optical and infrared luminosity functions, and demonstrate that these fully agree with theoretical expectations. We thus conclude that there is no evidence for the mass loss of super-solar metallicity red giants to be sufficiently high that they can avoid the helium flash at the tip of the red giant branch.

Jacco Th. van Loon; Martha L. Boyer; Iain McDonald

2008-04-29

343

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

344

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

345

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

346

Telescopes for Future UV/Optical Astronomy  

NASA Astrophysics Data System (ADS)

Future UV/Optical telescopes will require increasingly large apertures to answer the questions raised by HST, JWST, Planck and Herschel, and to complement the 30-m ground-based telescopes that will be coming on line in the next decade. Large aperture telescopes are required to provide the spatial resolution and sensitivity needed to perform frontier measurements of the future. These include stellar photometry and archaeology of distant galaxies, ultraviolet spectroscopy of the cosmic web, and high resolution imaging that will probe the formation and structure of the first galaxies, the properties of dark matter, and the evolutionary phases of pre-planetary systems. Low-cost, lightweight optics are required to enable the development of such large aperture UV / Optical telescopes in the 2020 decade. Technologies are therefore required that provide a high degree of thermal and dynamic stability, and wave front sensing and control, while minimizing the factors which drive the cost of flagship missions -- complexity, testing challenges, and mass.

Martin, Christopher D.

2012-01-01

347

CRTF Real-Time Aperture Flux system  

SciTech Connect

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

Davis, D.B.

1980-01-01

348

Variable-aperture screen  

DOEpatents

Apparatus for separating material into first and second portions according to size including a plurality of shafts, a plurality of spaced disks radiating outwardly from each of the shafts to define apertures and linkage interconnecting the shafts for moving the shafts toward or away from one another to vary the size of the apertures while the apparatus is performing the separating function.

Savage, George M. (Richmond, CA)

1991-01-01

349

THE INFRARED SPECTROGRAPH1 (IRS) ON THE SPITZER SPACE TELESCOPE  

E-print Network

THE INFRARED SPECTROGRAPH1 (IRS) ON THE SPITZER SPACE TELESCOPE J. R. Houck,2 T. L. Roellig,3 J science instruments on the Spitzer Space Telescope. The IRS comprises four separate spectrograph modules sensitivity given the 85 cm aperture of the Spitzer Space Telescope (Werner et al. 2004) and the then

Galis, Frietson

350

Applications of MEMS in segmented mirror space telescopes  

Microsoft Academic Search

Development of space telescopes, such as the Hubble Space Telescope and the James Webb Telescope has been very challenging in terms of cost, schedule, and performance. For several future space missions, larger aperture and lightweight deployable mirrors, in the range of 10-20 meters in diameter with high surface accuracy, are required. In order to achieve lightweight, reduce cost for development

Brij Agrawal; Joel Kubby

2011-01-01

351

The Pan-STARRS Survey Telescope Project  

NASA Astrophysics Data System (ADS)

The Institute for Astronomy at the University of Hawaii is developing a large optical/near-IR survey telescope system; the Panoramic Survey Telescope and Rapid Response System. Pan-STARRS will employ 1.8m optical imagers very large (7 square degree) field of view and revolutionary 1.4 billion pixel CCD cameras with low noise and rapid read-out to provide broad band imaging from 400-1000nm wavelength. The project is proceeding in two phases: PS1 is a single aperture system that has been deployed on Haleakala on Maui and the full 4-aperture system PS4 will be sited on Mauna Kea and is scheduled to become operational in late 2010. The data from Pan-STARRS will be reduced in near real time to produce both a cumulative image of the static sky and difference images, from which transient, moving and variable objects can be detected. Pan-STARRS will be able to scan the entire visible sky to approximately 24th magnitude in less than a week, and this unique combination of sensitivity and cadence will open up many new possibilities in time domain astronomy. A major goal for the project is to survey potentially dangerous asteroids, where Pan-STARRS will be able to detect most objects down to 300m size, much smaller than the km size objects accessible to existing search programs. In addition, the Pan-STARRS data will provide a dramatic leap in data quality and extent over existing wide-field image durvey data that will be used to advance our understanding of the formation of the Solar System, the Galaxy, and the Cosmos at large. In this talk I will describe the science drivers for the project; review the technical design and performance metrics for various scientific gols; and give an update on the current status and future time-line of the project.

Kaiser, N.

352

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

353

Studies of expolanets and solar systems with SPICA  

NASA Astrophysics Data System (ADS)

The SPace Infrared telescope for Cosmology and Astrophysics (SPICA) is a proposed mid-to-far infrared (4-200?m) astronomy mission, scheduled for launch in 2017. A single, 3.5 m aperture telescope would provide superior image quality at 5-200?m, and its very cold (˜5K) instrumentation would provide superior sensitivity in the 25-200 ?m wavelength regimes. This would provide a breakthrough opportunity for studies of exoplanets, protoplanetary and debris disk, and small solar system bodies. This paper summarizes the potential scientific impacts for the proposed instrumentation.

Takami, Michihiro; Tamura, Motohide; Enya, Keigo; Ootsubo, Takafumi; Fukagawa, Misato; Honda, Mitsuhiko; Okamoto, Yoshiko; Sako, Shigehisa; Yamashita, Takuya; Hasegawa, Sunao; Kataza, Hirokazu; Matsuhara, Hideo; Nakagawa, Takao; Goicoechea, Javier R.; Isaak, Kate; Swinyard, Bruce

2010-04-01

354

Large fully retractable telescope enclosures still closable in strong wind  

E-print Network

Large fully retractable telescope enclosures still closable in strong wind Felix C.M. Bettonvil a built for the high-resolution solar telescopes DOT (Dutch Open Telescope) and GREGOR, both located the telescopes are in operation. The telescopes and enclosures also operate in hard wind. The prototypes

Rutten, Rob

355

High Contrast Imaging with an Arbitrary Aperture: Active Correction of Aperture Discontinuities  

E-print Network

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of Deformable Mirror Surfaces that yield high contrast Point Spread Functions is not linear, and non-linear methods are needed to find the true minimum in the optimization topology. We solve the highly non-linear Monge-Ampere equation that is the fundamental equation describing the physics of phase induced amplitude modulation. We determine the optimum configuration for our two sequential Deformable Mirror system and show that high-throughput and high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries si...

Pueyo, Laurent

2012-01-01

356

Imaging interplanetary CMEs at radio frequency from solar polar orbit  

NASA Astrophysics Data System (ADS)

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

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

2011-09-01

357

Combining visibilities from the giant meterwave radio telescope and the Nancay radio heliograph. High dynamic range snapshot images of the solar corona at 327 MHz  

NASA Astrophysics Data System (ADS)

We report first results from an ongoing program of combining visibilities from the Giant Meterwave Radio Telescope (GMRT) and the Nancay Radio Heliograph (NRH) to produce composite snapshot images of the sun at meter wavelengths. We describe the data processing, including a specific multi-scale CLEAN algorithm. We present results of a) simulations for two models of the sun at 327 MHz, with differing complexity b) observations of a complex noise storm on the sun at 327 MHz on Aug. 27, 2002. Our results illustrate the capacity of this method to produce high dynamic range snapshot images when the solar corona has structures with scales ranging from the image resolution of 49'' to the size of the whole sun. We emphasize that snapshot images of a complex object such as the sun, obtained by combining data from both instruments, are far better than images from either instrument alone, because their uv-coverages are very complementary.

Mercier, C.; Subramanian, P.; Kerdraon, A.; Pick, M.; Ananthakrishnan, S.; Janardhan, P.

2006-03-01

358

Monolithic versus segmented primary mirror concepts for space telescopes  

NASA Astrophysics Data System (ADS)

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

Kendrick, Stephen E.

2009-08-01

359

Occultation studies with small telescopes  

NASA Astrophysics Data System (ADS)

The data which can be acquired by observing occultations of stars by asteroids, the Pluto-Charon system, and comets using small telescopes are reviewed. A network of small telescopes may be the only possible means of observing a few specific types of occultations. The occultations are usually sufficiently bright so that small aperture telescopes can easily obtain high signal/noise ratios. The techniques and equipment are accessible to both professional, amateur and student astronomers, which is a favorable situation since only a small percentage of the nearly-hourly occurrence of occultations of stars by minor and distant planetary bodies are ever observed. Techniques employed for measuring the dimensions of asteroids by combining chords measured by distributed small telescopes are described and examples are provided of asteroids for which complete or incomplete size/density mappings have been made.

Millis, Robert L.

360

Why not exposed extreme large telescopes?  

NASA Astrophysics Data System (ADS)

In designing and building extreme large optical telescopes of sizes above 10m main aperture diameter, the effort for protecting the telescope against environmental influences gets remarkable large in engineering efforts as well as in costs. Large radio telescopes of similar size are built in "exposed" design, which means, that the protections for the sensitive components are integrated into the telescope itself. Long ranging experience even for sub-millimeter wavelength radio telescopes is available. Why not thinking the unthinkable and design exposed extreme large optical telescopes? The paper describes methods to protect the optics, to protect the structures and mechanics, and to overcome the wind and temperature induced disturbances during operations. It shows also means to integrate large and comfortable rooms for the science instruments with free access during operations into the protected area of the telescope.

Kärcher, Hans J.; Süss, Martin

2006-06-01

361

Minimizing high spatial frequency residual in active space telescope mirrors  

E-print Network

The trend in future space telescopes is towards large apertures and lightweight, rib-stiffened, and actively controlled deformable mirrors. These mirror architectures permit the development of segmented and deployed primary ...

Gray, Thomas, S.M. (Thomas L.) Massachusetts Institute of Technology

2008-01-01

362

Super-Resolution in a Synthetic Aperture Imaging System  

Microsoft Academic Search

Large telescopes have reached a limit of practical realization, restricted by the high costs of manufacturing large and precise optics. To overcome these limitations, images can be collected from a strip aperture which rotates to synthesize a circular one. Variations of a Poisson maximum a priori (PMAP) algorithm are applied to the collection of frames to reconstruct and super-resolve the

J. J. Green; Bobby R. Hunt

1997-01-01

363

Fluorescence and hybrid detection aperture of the Pierre Auger Observatory  

SciTech Connect

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

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

2005-07-01

364

THE DUTCH OPEN TELESCOPE Robert J. Rutten  

E-print Network

Chapter 1 THE DUTCH OPEN TELESCOPE Robert J. Rutten Sterrekundig Instituut Utrecht Postbus 80 000, NL-3508 TA Utrecht, The Netherlands R.J.Rutten@astro.uu.nl Abstract The Dutch Open Telescope (DOT) is an innovative optical solar telescope at the Roque de los Muchachos Observatory in the Canary Islands. Its

Rutten, Rob

365

6Hinode Discovers the Origin of White Light Flares White light emissions were observed by the Hinode Solar Optical Telescope  

E-print Network

on the solar surface where electrons were being accelerated to over 40% the speed of light! This means meters is given by the formula E = 40,000 B 2 V where B is the magnetic field strength in units of Gauss, and where E is in units of ergs. What is the stored energy in this flaring region if B = 150 Gauss? Problem

366

Present status of the 7–10 m telescope of CANGAROO II  

Microsoft Academic Search

The Cherenkov telescope of the CANGAROO II project will start operation in 1999 in Woomera, South Australia, with a 7 m aperture using 60 plastic mirrors. The telescope, which can potentially be extended to a 10 m aperture, will be used to observe gamma-ray sources with an energy threshold of the order of 100 GeV in the southern sky.

T. Yoshikoshi; S. A. Dazeley; S. Gunji; S. Hara; T. Hara; J. Holder; J. Jimbo; A. Kawachi; T. Kifune; H. Kubo; J. Kushida; S. Le Bohec; Y. Matsubara; Y. Mizumoto; M. Mori; M. Moriya; H. Muraishi; Y. Muraki; T. Naito; K. Nishijima; J. R. Patterson; M. D. Roberts; G. P. Rowell; K. Sakurazawa; R. Susukita; T. Tamura; T. Tanimori; S. Yanagita; T. Yoshida; A. Yuki

1999-01-01

367

A Low-Frequency Distributed Aperture Array for Radio Astronomy in Space  

NASA Astrophysics Data System (ADS)

The frequency band below 30 MHz is one of the last unexplored bands in radio astronomy. This band is well suited for studying the early cosmos at high hydrogen redshifts, the so-called dark ages, extragalactic surveys, (extra) solar planetary bursts, and high energy particle physics. In addition, space research such as space weather tomography, are also areas of scientific interest. Due to ionospheric scintillation (below 30MHz) and its opaqueness (below 15MHz), earth-bound radio astronomy observations in these bands are either severely limited in sensitivity and spatial resolution or entirely impossible. A radio telescope in space obviously would not be hampered by the Earth's ionosphere. In the past, several (limited) studies have been conducted to explore possibilities for such an array in space. These studies considered aperture synthesis arrays in space, at the back-side of the Moon, or a satellite constellation operating in a coherent mode. In 2009 an ESA project, Distributed Aperture Array for Radio Astronomy in Space (DARIS), set out to investigate the space-based radio telescope concept. The focus of this feasibility study is on a moderate size three-dimensional satellite constellation operating as a coherent large aperture synthesis array. This aperture synthesis array would consist of 5 to 50 antennas (satellites) having a maximum separation of 100 km. This study considers the main aspects of such a distributed system in more detail than previous studies. This conference contribution aims at presenting an overview of the DARIS project and at discussing the main results. The project selected extra-galactic surveys and the search for transient radio sources as the best suited science cases within the DARIS concept, and it investigated the scientific and technical requirements for such an array. Several antenna concepts were considered and simulated. An active antenna dipole array concept would be well suited, and a moderate 5 m tip-tip antenna system would lead to a sky noise limited system. Multiple digital signal processing scenarios were considered. Ultimately, although a distributed signal processing approach would be fa-vorable in terms of reliability and scalability, for complexity reasons the project has chosen to have several (5 to 50) identical receiving nodes, and one centralized processing node i.e. the correlator. Analysis has shown that with current technologies, one MHz bandwidth can be processed with full duty cycle. The limiting factor is the inter-satellite link bandwidth. Several deployment locations, such as Moon orbit, Earth-Moon L2, and dynamic Solar orbits were investigated. Each of those locations has its pro's and con's such as interference levels from the Earth (which drive the number of sampling bits), relative speed-vectors of the satellite nodes (influencing maximum correlator integration times, and the need for orbit maintenance), and achievable down-link bandwidth to Earth. Two preferred deployment location were selected: Moon orbit and dynamic Solar orbit. The main advantage of the Moon orbit is that the syn-thetic aperture is filled more rapidly, making it more suitable for transient science than the dynamic Solar orbit. The project also studied the relation between the three-dimensional satellite configuration, the deployment location and the quality of the sky maps. The conclusion is that for the science cases under consideration, sufficient independent aperture sampling points can be obtained in a 1 MHz limited band (with 1 kHz channels) by using bandwidth synthesis. It is expected that, as a result, up to about one million astronomical sources can be detected in a five year duration mission.

Boonstra, Albert-Jan; Saks, Noah; Falcke, Heino; Klein-Wolt, Marc; Bentum, Ark; Thilak Rajan, Raj; Wijnholds, Ir. Stefan J.; Arts, Michel; van-T Klooster, Kees; Belien, Frederik

368

Fe XI Emission Lines in a High-Resolution Extreme-Ultraviolet Active Region Spectrum Obtained by the Solar Extreme Ultraviolet Research Telescope and Spectrograph  

NASA Astrophysics Data System (ADS)

New calculations of radiative rates and electron impact excitation cross sections for Fe XI are used to derive emission-line intensity ratios involving 3s23p4-3s23p33d transitions in the 180-223 Å wavelength range. These ratios are subsequently compared with observations of a solar active region obtained during the 1995 flight of the Solar Extreme Ultraviolet Research Telescope and Spectrograph (SERTS). The version of SERTS flown in 1995 incorporated a multilayer grating that enhanced the instrumental sensitivity for features in the ~170-225 Å wavelength range, observed in second order between 340 and 450 Å. This enhancement led to the detection of many emission lines not seen on previous SERTS flights, which were measured with the highest spectral resolution (0.03 Å) ever achieved for spatially resolved active region spectra in this wavelength range. However, even at this high spectral resolution, several of the Fe XI lines are found to be blended, although the sources of the blends are identified in the majority of cases. The most useful Fe XI electron density diagnostic line intensity ratio is I(184.80 Å)/I(188.21 Å). This ratio involves lines close in wavelength and free from blends, and it varies by a factor of 11.7 between Ne=109 and 1011 cm-3 yet shows little temperature sensitivity. An unknown line in the SERTS spectrum at 189.00 Å is found to be due to Fe XI, the first time (to our knowledge) this feature has been identified in the solar spectrum. Similarly, there are new identifications of the Fe XI 192.88, 198.56, and 202.42 Å features, although the latter two are blended with S VIII/Fe XII and Fe XIII, respectively.

Keenan, F. P.; Aggarwal, K. M.; Ryans, R. S. I.; Milligan, R. O.; Bloomfield, D. S.; Brosius, J. W.; Davila, J. M.; Thomas, R. J.

2005-05-01

369

Optical Technology Needs for Future Space Telescopes  

E-print Network

Optical Technology Needs for Future Space Telescopes H. Philip Stahl, Ph.D. #12;Prelude instruments & sensors. Future Space Telescopes will operate over broad spectrum: Gamma Rays, X-Rays, XUV Structure #12;NASA's Science Missions Directorate Themes: Earth Science Sun-Solar System Connection Solar

Van Stryland, Eric

370

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

NASA Astrophysics Data System (ADS)

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

Pueyo, Laurent; Norman, Colin

2013-06-01

371

FalconSAT-7: a membrane space telescope  

NASA Astrophysics Data System (ADS)

The USAF Academy Department of Physics has built FalconSAT-7, a membrane solar telescope to be deployed from a 3U CubeSat in LEO. The primary optic is a 0.2m photon sieve - a diffractive element consisting of billions of tiny circular dimples etched into a Kapton sheet. The membrane, its support structure, secondary optics, two imaging cameras and associated control/recording electronics are all packaged within half the CubeSat volume. Once in space, the supporting pantograph structure is deployed, extending out and pulling the membrane flat under tension. The telescope will then be directed at the Sun to gather images at H-alpha for transmission to the ground. Due for launch in 2015, FalconSAT-7 will serve as a pathfinder for future surveillance missions consisting of a 0.3m aperture deployed from a 12U satellite. Such a telescope would be capable of providing sub-meter resolution of ground-based objects.

Andersen, Geoff P.; Asmolova, Olha

2014-08-01

372

Planetary Remote Sensing Science Enabled by MIDAS (Multiple Instrument Distributed Aperture Sensor)  

NASA Technical Reports Server (NTRS)

The science capabilities and features of an innovative and revolutionary approach to remote sensing imaging systems, aimed at increasing the return on future space science missions many fold, are described. Our concept, called Multiple Instrument Distributed Aperture Sensor (MIDAS), provides a large-aperture, wide-field, diffraction-limited telescope at a fraction of the cost, mass and volume of conventional telescopes, by integrating optical interferometry technologies into a mature multiple aperture array concept that addresses one of the highest needs for advancing future planetary science remote sensing.

Pitman, Joe; Duncan, Alan; Stubbs, David; Sigler, Robert; Kendrick, Rick; Chilese, John; Lipps, Jere; Manga, Mike; Graham, James; dePater, Imke

2004-01-01

373

Optical sparse aperture imaging.  

PubMed

The resolution of a conventional diffraction-limited imaging system is proportional to its pupil diameter. A primary goal of sparse aperture imaging is to enhance resolution while minimizing the total light collection area; the latter being desirable, in part, because of the cost of large, monolithic apertures. Performance metrics are defined and used to evaluate several sparse aperture arrays constructed from multiple, identical, circular subapertures. Subaperture piston and/or tilt effects on image quality are also considered. We selected arrays with compact nonredundant autocorrelations first described by Golay. We vary both the number of subapertures and their relative spacings to arrive at an optimized array. We report the results of an experiment in which we synthesized an image from multiple subaperture pupil fields by masking a large lens with a Golay array. For this experiment we imaged a slant edge feature of an ISO12233 resolution target in order to measure the modulation transfer function. We note the contrast reduction inherent in images formed through sparse aperture arrays and demonstrate the use of a Wiener-Helstrom filter to restore contrast in our experimental images. Finally, we describe a method to synthesize images from multiple subaperture focal plane intensity images using a phase retrieval algorithm to obtain estimates of subaperture pupil fields. Experimental results from synthesizing an image of a point object from multiple subaperture images are presented, and weaknesses of the phase retrieval method for this application are discussed. PMID:17694146

Miller, Nicholas J; Dierking, Matthew P; Duncan, Bradley D

2007-08-10

374

SCIENTIFIC EFFICIENCY OF GROUND-BASED TELESCOPES  

SciTech Connect

I scanned the six major astronomical journals of 2008 for all 1589 papers that are based on new data obtained from ground-based optical/IR telescopes worldwide. Then I collected data on numbers of papers, citations to them in 3+ years, the most-cited papers, and annual operating costs. These data are assigned to four groups by telescope aperture. For instance, while the papers from telescopes with an aperture >7 m average 1.29 more citations than those with an aperture of 2 to <4 m, this represents a small return for a factor of four difference in operating costs. Among the 17 papers that have received {>=}100 citations in 3+ years, only half come from the large (>7 m) telescopes. I wonder why the large telescopes do so relatively poorly and suggest possible reasons. I also found that papers based on archival data, such as the Sloan Digital Sky Survey, produce 10.6% as many papers and 20.6% as many citations as those based on new data. Also, the 577.2 papers based on radio data produced 36.3% as many papers and 33.6% as many citations as the 1589 papers based on optical/IR telescopes.

Abt, Helmut A., E-mail: abt@noao.edu [Kitt Peak National Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States)

2012-10-01

375

Scanning holographic lidar telescope  

NASA Technical Reports Server (NTRS)

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

Schwemmer, Geary K.; Wilkerson, Thomas D.

1993-01-01

376

The development of the Schmidt telescope  

NASA Astrophysics Data System (ADS)

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

Wolfschmidt, G.

2009-06-01

377

Solar Site Survey for the Advanced Technology Solar Telecope. I. Analysis of the Seeing Data  

E-print Network

The site survey for the Advanced Technology Solar Telescope concluded recently after more than two years of data gathering and analysis. Six locations, including lake, island and continental sites, were thoroughly probed for image quality and sky brightness. The present paper describes the analysis methodology employed to determine the height stratification of the atmospheric turbulence. This information is crucial because day-time seeing is often very different between the actual telescope aperture (~30 m) and the ground. Two independent inversion codes have been developed to analyze simultaneously data from a scintillometer array and a solar differential image monitor. We show here the results of applying them to a sample subset of data from May 2003, which was used for testing. Both codes retrieve a similar seeing stratification through the height range of interest. A quantitative comparison between our analysis procedure and actual in situ measurements confirms the validity of the inversions. The sample d...

Socas-Navarro, H; Brandt, P; Briggs, J; Brown, T; Brown, W; Collados, M; Denker, C; Fletcher, S; Hegwer, S; Hill, F; Horst, T; Komsa, M; Kühn, J; Lecinski, A; Lin, H; Oncley, S; Penn, M; Rimmele, T; Streander, K

2005-01-01

378

Propagation of apertured Bessel beams  

NASA Astrophysics Data System (ADS)

The propagation features of several apertured Bessel beams are numerically calculated. The calculations show that the relations of axial intensity versus propagation distance are similar to the radial distribution of the aperture functions, which may be helpful in choosing the proper aperture functions in experiments.

Jiang, Zhiping; Lu, Qisheng; Liu, Zejin

1995-11-01

379

Concept for Solar Multi-Conjugate Adaptive Optics at Big Bear Observatory  

NASA Astrophysics Data System (ADS)

Solar observations are performed over an extended field of view and the isoplanatic patch over which conventional adaptive optics (AO) provides diffraction limited resolution is a severe limitation. The development of multi-conjugate adaptive optics (MCAO) for the large aperture solar telescopes ranging from 1.6 to 4 metres diameters is extremely important. The Sun is an ideal object for the development of MCAO since solar structure provides multiple "guide stars" in any desired configuration. We propose a concept for a new MCAO system at Big Bear Observatory. This MCAO system uses three deformable mirrors conjugated to the telescope entrance pupil and to two layers in the upper atmosphere. We present the detailed analysis of the performance of this system for large range of elevations as required in solar observations by using the Fractal Iterative Method (FrIM), which incorporates wide field correlating Shack-Hartmann wavefront sensors.

Langlois, Maud; Moretto, Gil; Béchet, Clémentine; Montilla, Icíar; Tallon, Michel; Goode, Philip; Gorceix, Nicolas; Shumko, Sergey

2013-12-01

380

Conically scanned lidar telescope using holographic optical elements  

Microsoft Academic Search

Holographic optical elements (HOE) using volume phase holograms make possible a new class of lightweight scanning telescopes having advantages for lidar remote sensing instruments. So far, the only application of HOE's to lidar has been a non-scanning receiver for a laser range finder. We introduce a large aperture, narrow field of view (FOV) telescope used in a conical scanning configuration,

Geary K. Schwemmer; Thomas D. Wilkerson

1992-01-01

381

Optical verification of the James Webb Space Telescope  

Microsoft Academic Search

The optical system of the James Webb Space Telescope (JWST) is split between two of the Observatory's element, the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM). The OTE optical design consists of an 18-hexagonal segmented primary mirror (25m2 clear aperture), a secondary mirror, a tertiary mirror, and a flat fine steering mirror used for fine guidance

Brian McComas; Rich Rifelli; Allison Barto; Adam Contos; Tony Whitman; Conrad Wells; John Hagopian

2006-01-01

382

The Cornell Caltech Atacama Telescope: progress and plans 2010  

Microsoft Academic Search

The CCAT Project is an effort to construct a 25 meter aperture telescope above 5600 meters altitude operating down to wavelengths as short as 200 mum. CCAT has developed some new and innovative approaches to telescope and optics design, added new partners to the project, and has plans for substantially increased activities over the next two years. Begun by Cornell

T. Sebring

2010-01-01

383

Architecture Concept for a 10m Class Space Telescope  

Microsoft Academic Search

NASA recently supported a Visions Mission study to develop the scientific justification and an implementation concept for a future large Optical and Ultraviolet Telescope. Our study, which we called the Modern Universe Space Telescope, identified scientific goals that require the angular resolution expected from a 10m aperture in visible light and the sensitivity provided by 50m2 of collecting area. The

D. C. Ebbets; J. DeCino; J. Green

2005-01-01

384

The synthesis telescope at the Dominion Radio Astrophysical Observatory  

Microsoft Academic Search

We describe an aperture synthesis radio telescope optimized for studies of the Galactic interstellar medium (ISM), providing the ability to image extended structures with high angular resolution over wide fields. The telescope produces images of atomic hydrogen emission using the 21-cm H I spectral line, and, simultaneously, continuum emission in two bands centred at 1420 MHz and 408 MHz, including

T. L. Landecker; P. E. Dewdney; T. A. Burgess; A. D. Gray; L. A. Higgs; A. P. Hoffmann; G. J. Hovey; D. R. Karpa; J. D. Lacey; N. Prowse; C. R. Purton; R. S. Roger; A. G. Willis; W. Wyslouzil; D. Routledge; J. F. Vaneldik

2000-01-01

385

A balloon borne telescope for infrared astronomy  

Microsoft Academic Search

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

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

1984-01-01

386

Aperture center energy showcase  

SciTech Connect

Sandia and Forest City have established a Cooperative Research and Development Agreement (CRADA), and the partnership provides a unique opportunity to take technology research and development from demonstration to application in a sustainable community. A project under that CRADA, Aperture Center Energy Showcase, offers a means to develop exhibits and demonstrations that present feedback to community members, Sandia customers, and visitors. The technologies included in the showcase focus on renewable energy and its efficiency, and resilience. These technologies are generally scalable, and provide secure, efficient solutions to energy production, delivery, and usage. In addition to establishing an Energy Showcase, support offices and conference capabilities that facilitate research, collaboration, and demonstration were created. The Aperture Center project focuses on establishing a location that provides outreach, awareness, and demonstration of research findings, emerging technologies, and project developments to Sandia customers, visitors, and Mesa del Sol community members.

Torres, J. J.

2012-03-01

387

Synthetic aperture confocal imaging  

Microsoft Academic Search

Confocal microscopy is a family of imaging techniques that employ focused patterned illumination and synchronized imaging to create cross-sectional views of 3D biological specimens. In this paper, we adapt confocal imaging to large-scale scenes by replacing the optical apertures used in microscopy with arrays of real or virtual video projectors and cameras. Our prototype implementation uses a video projector, a

Marc Levoy; Billy Chen; Vaibhav Vaish; Mark Horowitz; Ian McDowall; Mark T. Bolas

2004-01-01

388

Integrated electrochromic aperture diaphragm  

NASA Astrophysics Data System (ADS)

In the last years, the triumphal march of handheld electronics with integrated cameras has opened amazing fields for small high performing optical systems. For this purpose miniaturized iris apertures are of practical importance because they are essential to control both the dynamic range of the imaging system and the depth of focus. Therefore, we invented a micro optical iris based on an electrochromic (EC) material. This material changes its absorption in response to an applied voltage. A coaxial arrangement of annular rings of the EC material is used to establish an iris aperture without need of any mechanical moving parts. The advantages of this device do not only arise from the space-saving design with a thickness of the device layer of 50?m. But it also benefits from low power consumption. In fact, its transmission state is stable in an open circuit, phrased memory effect. Only changes of the absorption require a voltage of up to 2 V. In contrast to mechanical iris apertures the absorption may be controlled on an analog scale offering the opportunity for apodization. These properties make our device the ideal candidate for battery powered and space-saving systems. We present optical measurements concerning control of the transmitted intensity and depth of focus, and studies dealing with switching times, light scattering, and stability. While the EC polymer used in this study still has limitations concerning color and contrast, the presented device features all functions of an iris aperture. In contrast to conventional devices it offers some special features. Owing to the variable chemistry of the EC material, its spectral response may be adjusted to certain applications like color filtering in different spectral regimes (UV, optical range, infrared). Furthermore, all segments may be switched individually to establish functions like spatial Fourier filtering or lateral tunable intensity filters.

Deutschmann, T.; Oesterschulze, E.

2014-05-01

389

Quantum telescopes  

E-print Network

In the 20th century, quantum mechanics connected the particle and wave concepts of light and thereby made mechanisms accessible that had never been imagined before. Processes such as stimulated emission and quantum entanglement have revolutionized modern technology. But even though astronomical observations rely on novel technologies, the optical layout of telescopes has fundamentally remained unchanged. While there is no doubt that Huyghens and Newton would be astounded by the size of our modern telescopes, they would nevertheless understand their optical design. The time may now have come to consider quantum telescopes, that make use of the fundamental scientific changes brought along by quantum mechanics. While one aim is to entertain our reader, our main purpose is to explore the possible future evolution of telescopes.

Kellerer, Aglae

2014-01-01

390

SNAP telescope  

SciTech Connect

The SuperNova/Acceleration Probe (SNAP) mission will require a two-meter class telescope delivering diffraction limited images spanning a one degree field in the visible and near infrared wavelength regime. This requirement, equivalent to nearly one billion pixel resolution, places stringent demands on its optical system in terms of field flatness, image quality, and freedom from chromatic aberration. We discuss the advantages of annular-field three-mirror anastigmat (TMA) telescopes for applications such as SNAP, and describe the features of the specific optical configuration that we have baselined for the SNAP mission. We discuss the mechanical design and choice of materials for the telescope. Then we present detailed ray traces and diffraction calculations for our baseline optical design. We briefly discuss stray light and tolerance issues, and present a preliminary wavefront error budget for the SNAP Telescope. We conclude by describing some of tasks to be carried out during the upcoming SNAP research and development phase.

Lampton, Michael L.; Akerlof, C.W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E.; Bebek, C.; Bergstrom, L.; Bercovitz, J.; Bernstein, G.; Bester, M.; Bonissent, A.; Bower, C.; Carithers Jr., W.C.; Commins, E.D.; Day, C.; Deustua, S.E.; DiGennaro, R.; Ealet, A.; Ellis,R.S.; Eriksson, M.; Fruchter, A.; Genat, J.-F.; Goldhaber, G.; Goobar,A.; Groom, D.; Harris, S.E.; Harvey, P.R.; Heetderks, H.D.; Holland,S.E.; Huterer, D.; Karcher, A.; Kim, A.G.; Kolbe, W.; Krieger, B.; Lafever, R.; Lamoureux, J.; Levi, M.E.; Levin, D.S.; Linder, E.V.; Loken,S.C.; Malina, R.; Massey, R.; McKay, T.; McKee, S.P.; Miquel, R.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi,H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Pratt, R.; Prieto,E.; Refregier, A.; Rhodes, J.; Robinson, K.; Roe, N.; Sholl, M.; Schubnell, M.; Smadja, G.; Smoot, G.; Spadafora, A.; Tarle, G.; Tomasch,A.; von der Lippe, H.; Vincent, R.; Walder, J.-P.; Wang, G.; Wang, G.

2002-07-29

391

The front-end electronics of the Spectrometer Telescope for Imaging X-Rays (STIX) on the ESA Solar Orbiter satellite  

NASA Astrophysics Data System (ADS)

Solar Orbiter is an ESA mission to study the heliosphere in proximity to the Sun, scheduled for launch in January 2017. It carries a suite of ten instruments for comprehensive remote-sensing and in-situ measurements. The Spectrometer Telescope for Imaging X-Rays (STIX), one of the remote sensing instruments, images X-rays between 4 and 150keV using an Fourier technique. The angular resolution is 7 arcsec and the spectral resolution 1keV full-width-half-maximum at 6keV. X-ray detection uses pixelized Cadmium Telluride crystals provided by the Paul Scherrer Institute. The crystals are bonded to read-out hybrids developed by CEA Saclay, called Caliste-SO, incorporating a low-noise, low-power analog front-end ASIC IDeF-X HD. The crystals are cooled to -20°C to obtain very low leakage currents of less than 60pA per pixel, the prerequisite for obtaining the required spectral resolution. This article briefly describes the mission goals and then details the front-end electronics design and main challenges, resulting in part from the allocation limit in mass of 7kg and in power of 4W. Emphasis is placed on the design influence of the cooling requirement within the warm environment of a mission approaching the Sun to within the orbit of Mercury. The design for the long-term in-flight energy calibration is also explained.

Grimm, O.; Bednarzik, M.; Commichau, V.; Graczyk, R.; Gröbelbauer, H. P.; Hurford, G.; Krucker, S.; Limousin, O.; Meuris, A.; Orlea?ski, P.; Przepiórka, A.; Seweryn, K.; Skup, K.; Viertel, G.

2012-12-01

392

Novel large aperture EBCCD  

NASA Astrophysics Data System (ADS)

A novel large aperture electron bombardment charge coupled device (EBCCD) has been developed. The diameter of its photocathode is 10 cm and it is the first EBCCD with such a large aperture. Its gain shows good linearity as a function of applied voltage up to -12 kV, where the gain is 2400. The spatial resolution was measured using ladder pattern charts. It is better than 2 line pairs/mm, which corresponds to 3.5 times the CCD pixel size. The spatial resolution was also measured with a copper foil pattern on a fluorescent screen irradiated with X-rays (14 and 18 keV) and a 60 keV gamma-ray from an americium source. The result was consistent with the measurement using ladder pattern charts. The output signal as a function of input light intensity shows better linearity than that of image intensifier tubes (IIT) as expected. We could detect cosmic rays passing through a scintillating fiber block and a plastic scintillator as a demonstration for a practical use in particle physics experiments. This kind of large aperture EBCCD can, for example, be used as an image sensor for a detector with a large number of readout channels and is expected to be additionally applied to other physics experiments.

Suzuki, Atsumu; Aoki, Shigeki; Haba, Junji; Sakuda, Makoto; Suyama, Motohiro

2011-02-01

393

On choosing an aperture  

SciTech Connect

The most difficult part of choosing an aperture is choosing the right method of choosing, after that the choice simply requires work. We must find just which important of a good ring, of the type we are designing, makes the severest demand on field quality and hence specifies the largest aperture. For electron rings, beam loss at many sigma makes the greatest demand because of the total dominance of synchrotron radiation. Proton rings and particularly superconducting proton rings are not similar to electron rings. The Fermilab experience with the Doubler and with the Main Ring shows very clearly that workability'' is the dominant virtue. An aperture decision based solely on beam loss from a modest beam size will not produce a good superconducting proton ring; a decision based on workability will. Workability is the property that the Main Ring lacks. The Doubler on the other hand has excellent workability, in spite of the more complex operation necessary for superconducting rings --- for example correction elements must ramp to full field and generally will require different relative settings for injection, acceleration, and flat-top. Our problem is to express this quality concept in a numeric form.

Collins, T.L. (Fermi National Accelerator Lab., Batavia, IL (USA))

1985-04-01

394

Aperture excited dielectric antennas  

NASA Technical Reports Server (NTRS)

The results of a comprehensive experimental and theoretical study of the effect of placing dielectric objects over the aperture of waveguide antennas are presented. Experimental measurements of the radiation patterns, gain, impedance, near-field amplitude, and pattern and impedance coupling between pairs of antennas are given for various Plexiglas shapes, including the sphere and the cube, excited by rectangular, circular, and square waveguide feed apertures. The waveguide excitation of a dielectric sphere is modeled using the Huygens' source, and expressions for the resulting electric fields, directivity, and efficiency are derived. Calculations using this model show good overall agreement with experimental patterns and directivity measurements. The waveguide under an infinite dielectric slab is used as an impedance model. Calculations using this model agree qualitatively with the measured impedance data. It is concluded that dielectric loaded antennas such as the waveguide excited sphere, cube, or sphere-cylinder can produce directivities in excess of that obtained by a uniformly illuminated aperture of the same cross section, particularly for dielectric objects with dimensions of 2 wavelengths or less. It is also shown that for certain configurations coupling between two antennas of this type is less than that for the same antennas without dielectric loading.

Crosswell, W. F.; Chatterjee, J. S.; Mason, V. B.; Tai, C. T.

1974-01-01

395

Field optimization and CCD data simulation for the antarctic International Concordia Explorer Telescope (ICE-T)  

NASA Astrophysics Data System (ADS)

We performed extensive data simulations for the planned ultra-wide-field, high-precision photometric telescope ICE-T (International Concordia Explorer Telescope). ICE-T consists of two 60 cm-aperture Schmidt telescopes with a joint field of view simultaneously in two photometric bandpasses. Two CCD cameras, each with a single 10.3k×10.3k thinned back-illuminated device, would image a sky field of 65 square degrees. Given a location of the telescope at Dome C on the East Antarctic Plateau, we searched for the star fields that best exploit the technical capabilities of the instrument and the site. We considered the effects of diurnal air mass and refraction variations, solar and lunar interference, interstellar absorption, overexposing of bright stars and ghosts, crowding by background stars, and the ratio of dwarf to giant stars in the field. Using NOMAD, SSA, Tycho-2 and 2MASS-based stellar positions and BVIJH magnitudes for these fields, we simulated the effects of the telescope's point-spread-function, the integration, and the co-addition times. Simulations of transit light curves are presented for the selected star fields and convolved with the expected instrumental characteristics. For the brightest stars, we showed that ICE-T should be capable of detecting a 2 R_Earth Super Earth around a G2 solar-type star, as well as an Earth around an M0-star - if these targets were as abundant as hot Jupiters. Simultaneously, the telescope would monitor the host star's surface activity in an astrophysically interpretable manner.

Fügner, D.; Fuhrmann, C.; Strassmeier, K. G.

2009-04-01

396

Site survey for the Giant Segmented Mirror Telescope  

Microsoft Academic Search

The Giant Segmented Mirror Telescope (GSMT), along with other proposed Extremely Large Telescopes (ELT's) with apertures over 20-m, is likely to impose rather different site selection criteria than those for existing large telescopes. Advantageously, remote-sensing techniques allow rather more objective comparisons than was possible in the past, and the general task is aided by numerical modeling and new ground-based measurement

Alistair R. Walker; Robert D. Blum; Maxime Boccas; Edison Bustos; Hugo E. Schwarz; Nicholas B. Suntzeff; Andrei A. Tokovinin

2003-01-01

397

Phase-diverse adaptive optics for future telescopes  

NASA Astrophysics Data System (ADS)

Phase Diversity (PD) is a wavefront-sensing technology that offers certain advantages in an Adaptive-Optics (AO) system. Historically, PD has not been considered for use in AO applications because computations have been prohibitive. However, algorithmic and computational-hardware advances have recently allowed use of PD in AO applications. PD is an attractive candidate for AO applications for a variety of reasons. The optical hardware required is simple to implement and eliminates non-common path errors. In addition, PD has also been shown to work well with extended scenes that are encountered, for example, when imaging low-contrast solar granulation. PD can estimate high-order continuous aberrations as well as wavefront discontinuities characteristic of segmented-aperture or sparse-aperture telescope designs. Furthermore, the fundamental information content in a PD data set is shown to be greater than that of the correlation Shack-Hartmann wavefront sensor for the limiting case of unresolved objects. These advantages coupled with recent laboratory results (extended-scene closed-loop AO with PD sampling at 100 Hz) highlight the maturation of not only the PD concept and algorithm but the technology as an emerging and viable wavefront sensor for use in AO applications.

Paxman, Richard G.; Thelen, Brian J.; Murphy, Ryan J.; Gleichman, Kurt W.; Georges, James A., III

2007-09-01

398

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

SciTech Connect

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

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

2006-09-01

399

James Webb Space Telescope: large deployable cryogenic telescope in space  

NASA Astrophysics Data System (ADS)

The James Webb Space Telescope (JWST) is an infrared space telescope designed to explore four major science themes: first light and reionization, the assembly of galaxies, the birth of stars and protoplanetary systems, and planetary systems and origins of life. JWST is a segmented architecture telescope with an aperture of 6.6 m. It will operate at cryogenic temperature (40 K), achieved via passive cooling, in an orbit about the Earth-Sun second Lagrange point (L2). Passive cooling is facilitated by means of a large sunshield that provides thermal isolation and protection from direct illumination from the Sun. The large size of the telescope and spacecraft systems require that they are stowed for launch in a configuration that fits the Ariane 5 fairing, and then deployed after launch. Routine wavefront sensing and control measurements are used to achieve phasing of the segmented primary mirror and initial alignment of the telescope. A suite of instruments will provide the capability to observe over a spectral range from 0.6- to 27-?m wavelengths with imaging and spectroscopic configurations. An overview is presented of the architecture and selected optical design features of JWST are described.

Lightsey, Paul A.; Atkinson, Charles; Clampin, Mark; Feinberg, Lee D.

2012-01-01

400

Transit Detection with a Distributed Network of Telescopes  

NASA Technical Reports Server (NTRS)

The discovery since 1995 of more than 80 planets around nearby solar-like stars and the photometric detection of a transit of the planet orbiting HD 209458 (producing a more than 1% drop in brightness that lasts 3 hours) has heralded a new era in astronomy. It has now been demonstrated that small telescopes equipped with sensitive and stable electronic detectors can produce fundamental scientific discoveries regarding the frequency and nature of planets outside the solar system. The modest equipment requirements for the measurement of extrasolar planetary transits are achieved by commercial small aperture telescopes and CCD imagers common among amateur astronomers. With equipment already in hand and armed with target lists, observing techniques and software procedures developed b NASA's Ames Research Center and the University of California at Santa Cruz, non-professional astronomers can contribute significantly to the study of planets around others stars. Statistical analyses of the population of parent stars of the known extrasolar planets indicate that approximately one in ten metal-rich stars should harbor a short-period planet. Given the ten percent chance that a given short-period planet displays transits, we therefore expect that approximately 1% of the most metal rich stars will have a planetary companion detectable by this project. A catalog of 206 highly metal rich nearby F, G and K stars has been compiled, and this catalog will provide a rich source of targets. In addition, main sequence F, G, K and M stars identified to have "transit-like" features in the Hipparcos satellite photometry archive will also be monitored. A commercially available "amateur grade" telescope/CCD/software system acquired late during the 2001 "transit season" for HID 209458 has achieved 0.47% RMS precision for 13 minute time sampling from a suburban backyard under less than ideal observing conditions and a realistic range of airmass values.

Castellano, T.; DeVincenzi, Donald (Technical Monitor)

2002-01-01

401

A Wide-Field Infrared Camera for the Palomar 200-inch Telescope  

E-print Network

A Wide-Field Infrared Camera for the Palomar 200-inch Telescope J. C. Wilsona, S. S. Eikenberrya, C of both large aperture telescopes and large format near-infrared (NIR) detectors are making wide-field NIR that provides the Palomar 200-inch telescope with such an imaging capability. WIRC features a field-of-view (FOV

Galis, Frietson

402

Beginning Research with the 1.8-meter Spacewatch Telescope  

NASA Technical Reports Server (NTRS)

The purpose of this grant was to bring the Spacewatch 1.8-m telescope to operational status for research on asteroids and comets. This objective was achieved; first light with the telescope was in May 2000 and since then several tests and demonstrations of the facility's capability to observe Earth-approaching Asteroids (EAs) have been made, including the first observations to be incorporated into a peer-reviewed publication. The Spacewatch 1.8-m telescope will be the largest in the world dedicated full time to finding and doing astrometry of asteroids and comets. It will be used to search for asteroids and comets anywhere from the space near Earth to regions beyond the orbit of Neptune, and to do astrometry and lightcurves on the fainter of such objects that are already known. Its comparatively large aperture will permit faster discovery of the very small asteroids in Earthlike orbits, such as 1998 KY(sub 26), that are coveted for their accessibility as material resources in space, as well as recovery of EAs on their return apparitions when they tend to be more distant and fainter than they were at the times of their discoveries. It will also tend to find EAs when they do not happen to be close to Earth. Discoveries made under those circumstances allow the objects to be followed for longer intervals, providing better determinations of their orbits during their discovery apparitions. In addition to its size, the 1.8-m Spacewatch telescope will have the unique capability of long strip scanning in any direction, for example along the ecliptic (the plane of the solar system), and along the line of variation of EAs with uncertain orbits that are being targeted for recovery.

Gehrels, Tom; Lane, Lynn A.

2001-01-01

403

Vertical emitting aperture nanoantennas.  

PubMed

Herein we propose, theoretically investigate, and numerically demonstrate a compact design for a vertical emitter at a wavelength of 1.5 ?m based on nanophotonic aperture antennas coupled to a dielectric waveguide. The structure utilizes a plasmonic antenna placed above a Si3N4 waveguide with a ground plane for breaking the up-down symmetry and increasing the emission efficiency. Three-dimensional (3-D) finite-difference time-domain (FDTD) simulations reveal that up to 60% vertical emission efficiency is possible in a structure only four wavelengths long with a 3 dB bandwidth of over 300 nm. PMID:22555702

Yaacobi, Ami; Timurdogan, Erman; Watts, Michael R

2012-05-01

404

The LCOGT Network for Solar System Science  

NASA Astrophysics Data System (ADS)

Las Cumbres Observatory Global Telescope (LCOGT) network is a planned homogeneous network of over 35 telescopes at 6 locations in the northern and southern hemispheres. This network is versatile and designed to respond rapidly to target of opportunity events and also to do long term monitoring of slowly changing astronomical phenomena. The global coverage of the network and the apertures of telescope available make LCOGT ideal for follow-up and characterization of Solar System objects (e.g. asteroids, Kuiper Belt Objects, comets, Near-Earth Objects (NEOs)) and ultimately for the discovery of new objects. Currently LCOGT is operating the two 2m Faulkes Telescopes at Haleakala, Maui and Siding Spring Observatory, Australia and in March 2012 completed the install of the first member of the new 1m telescope network at McDonald Observatory, Texas. Further deployments of six to eight 1m telescopes to CTIO in Chile, SAAO in South Africa and Siding Spring Observatory are expected in late 2012-early 2013. I am using the growing LCOGT network to confirm newly detected NEO candidates produced by PanSTARRS (PS1) and other sky surveys and to obtain follow-up astrometry and photometry for radar-targeted objects. I have developed an automated system to retrieve new PS1 NEOs, compute orbits, plan observations and automatically schedule them for follow-up on the robotic telescopes of the LCOGT Network. In the future, LCOGT has proposed to develop a Minor Planet Investigation Project (MPIP) that will address the existing lack of resources for minor planet follow-up, takes advantage of ever-increasing new datasets, and develops a platform for broad public participation in relevant scientific exploration. We plan to produce a cloud-based Solar System investigation environment, a citizen science project (AgentNEO), and a cyberlearning environment, all under the umbrella of MPIP.

Lister, Tim

2012-10-01

405

Eyelid system for telescope protection  

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

406

A portable solar adaptive optics system: software and laboratory developments  

NASA Astrophysics Data System (ADS)

We present our recent process on a portable solar adaptive Optics system, which is aimed for diffraction-limited imaging in the 1.0 ~ 5.0-?m infrared wavelength range with any solar telescope with an aperture size up to 1.6 meters. The realtime wave-front sensing, image processing and computation are based on a commercial multi-core personal computer. The software is developed in LabVIEW. Combining the power of multi-core imaging processing and LabVIEW parallel programming, we show that our solar adaptive optics can achieve excellent performance that is competitive with other systems. In addition, the LabVIEW's block diagram based programming is especially suitable for rapid development of a prototype system, which makes a low-cost and high-performance system possible. Our adaptive optics system is flexible; it can work with any telescope with or without central obstruction with any aperture size in the range of 0.6~1.6 meters. In addition, the whole system is compact and can be brought to a solar observatory to perform associated scientific observations. According to our knowledge, this is the first adaptive optics that adopts the LabVIEW high-level programming language with a multi-core commercial personal computer, and includes the unique features discussed above.

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

2010-07-01

407

Complex aperture networks  

NASA Astrophysics Data System (ADS)

A complex network approach is proposed for studying the shear behavior of a rough rock joint. Similarities between aperture profiles are established, and a functional complex network-in each shear displacement-is constructed in two directions: parallel and perpendicular to the shear direction. We find that the growth of the clustering coefficient and that of the number of edges are approximately scaled with the development of shear strength and hydraulic conductivity, which could possibly be utilized to estimate and formulate a friction law and the evolution of shear distribution over asperities. Moreover, the frictional interface is mapped in the global-local parameter space of the corresponding functional friction network, showing the evolution path and, eventually, the residual stage. Furthermore, we show that with respect to shear direction, parallel aperture patches are more adaptable to environmental stimuli than perpendicular profiles. We characterize the pure-contact profiles using the same approach. Unlike the first case, the later networks show a growing trend while in the residual stage; a saturation of links is encoded in contact networks.

Ghaffari, H. O.; Sharifzadeh, M.; Young, R. Paul

2013-02-01

408

Radio Astronomy Transformed: Aperture Arrays - Past, Present & Future  

E-print Network

I review the early development of Aperture Arrays and their role in radio astronomy. The demise of this technology at the end of the 1960's, and the reasons for the rise of parabolic dishes is also considered. The parallels with the Antikythera mechanism (see these proceedings) as a lost technology are briefly presented. Aperture Arrays re-entered the world of radio astronomy as the idea to build a huge radio telescope with a collecting area of one square kilometre (the Square Kilometre Array, SKA) arose. Huge ICT technology advances had transformed Aperture Arrays in terms of their capability, flexibility and reliability. In the mid-1990s, ASTRON started to develop and experiment with the first high frequency aperture array tiles for radio astronomy - AAD, OSMA, THEA & EMBRACE. In the slipstream of these efforts, Phased Array Feeds (PAFs) for radio astronomy were invented and LOFAR itself emerged as a next generation telescope and a major pathfinder for the SKA. Meanwhile, the same advantages that apertu...

Garrett, Michael A

2012-01-01

409

Control of optical performance on the Space Telescope  

NASA Technical Reports Server (NTRS)

A large astronomical telescope, termed the Space Telescope, is expected to be placed in orbit in the early 1980's. It will be operated as an international observatory that will enable astronomers to detect electromagnetic radiation over a much broader spectrum than is possible from ground observatories. The image quality (not degraded by atmospheric effects) will be limited only by the quality of the optics and by aperture diffraction. This opportunity to approach diffraction-limited imagery on an astronomical telescope of this size (2.4-m aperture) sets unusually stringent tolerances on the optical quality. The budgeting and control of these qualities throughout the design, fabrication, assembly, and operation of the Space Telescope is described. A feedback control system which will maintain the telescope at peak performance in the orbital environment is examined.

Jones, C. O.

1977-01-01