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At least 325 records · Page 18

An Imaging Spectrometric Observatory (ISO)

The Imaging Spectrometric Observatory (ISO) is designed for low light level spectroscopy of both the day and night side of the earth. The instrument is composed of five spectrometers, each of which covers part of the total wavelength range of 30 to 1300 nm spanned by the instrument. Wavelength resolution varies between 0.2 and 0.6 nm over the spectral range. The five spectrometers are each optimized for a portion of the spectrum by the choice of mirror reflective coatings and detector photocathode materials. The full spectral range for each spectrometer is covered in a total of 11 grating steps. The Imaging Spectrometric Observatory was flown for the first time on the Spacelab 1 mission during which it acquired almost 40 hr of observations. The ISO investigation to be flown on the Atmospheric Laboratory for Applications and Science (ATLAS 1) mission will draw on the experience gained from the data gathered on Spacelab 1. The detector system in each spectrometer was upgraded to provide both higher sensitivity at low light levels and simultaneous imaging over larger spectral segments than was achieved on Spacelab 1. In addition, the instrument and the observing sequences were modified to allow observation of the sun in the extreme ultraviolet. A summary of ISO parameters for ATLAS 1 (scheduled for late 1990) is given.

Torr, M. R.↗

Multifrequency analysis of a decametric storm observed at Voyager 1 and ground-based observatories

Observations of a Jovian decametric non-Io-A noise storm made from Voyager 1, the University of Florida Radio Observatory, the University of Texas Radio Astronomy Observatory, and the Jupiter station at Goddard Space Flight Center at frequencies of 26.3, 22.2, 20.0, and 18.0 MHz were found to be correlated. The activity observed at the ground stations occurred 68 min after the corresponding activity at Voyager 1. After correction is made for propagation time differences, this delay is reduced to 34 min. It is demonstrated that at each frequency the envelope of the individual-event beams occurring during the storm (some or all of which are associated with dynamic spectral arcs) is a quasi-constant structure that corotates with the inner Jovian magnetosphere, and that the width of this envelope beam is frequency dependent. The width increases as frequency is decreased, mainly because of the change in position of the trailing-edge beam boundary. Evidence for a relatively slow temporal change in beam geometry is also presented.

Maeda, K.↗

The Einstein observatory stellar X-ray database - An overview

The paper presents the motivations for and the methodology followed in building the 'Einstein Observatory Stellar X-ray Database' based on the uniform analysis of all Einstein Observatory Imaging Proportional Counter fields obtained during the life of the HEAO-2 mission. The database has been implemented using the INGRES database system, so that statistical analyses of the properties of the full detection catalog are relatively easily and flexibly accomplished. Some illustrative examples will furnish a general view both of the kind and the amount of the archived information, and of the statistical approach used in analyzing the global properties of the data.

Sciortino, S.↗

21st century astronomical observatories on the moon

The advantages and disadvantages of building astronomical observatories on the moon are described. Several modest facilities that could be placed near an early lunar base are described, such as a 1-m optical telescope and a gamma-ray burst detector. Several more elaborate observatories are discussed, such as a lunar far-side very low frequency array, an optical interferometer, and a moon-earth ultralong baseline radio interferometer.

Burns, Jack O.↗

Stratospheric Observatory for Infrared Astronomy (SOFIA) system concept

The system concept for the Stratospheric Observatory for Infrared Astronomy (SOFIA), as developed by NASA Ames Research Center is described. The SOFIA facility is a 3-meter class optical/infrared/submillimeter telescope mounted in an open cavity in the forebody of a Boeing 747 aircraft, to be operational in 1992. It represents the next generation of Ames' existing airborne IR facilities, and is about ten times more sensitive than the Kuiper Airborne Observatory (KAO) with 3 times better angular resolution, and able to detect all the far-infrared point sources discovered by IRAS (Infrared Astronomical Satellite) survey in 1983. Major requirements and design attributes of the SOFIA telescope are presented, along with a brief description of the Ground Support/Operations System.

Wiltsee, Christopher B.↗

The Gamma-Ray Observatory

The scientific goals and the design of the NASA Gamma-Ray Observatory (GRO), planned for launch in mid-1990, are described together with the experiments to be performed on the GRO mission and the instruments to be flown on the Observatory. GRO contains a complement of four instruments to span the spectrum from 0.03 to 20,000 MeV in energy, three of which are optimized to make gamma-ray observations using either the photoelectric effect, the Compton scatter, or the pair production processes; the fourth instrument is optimized for high-sensitivity observations of transient events and time-variable sources. The instruments are the Oriented Scintillation Spectrometer Experiment, the Compton Telescope, the Energetic Gamma-Ray Experiment Telescope, and the Burst and Transient Source Experiment.

Kniffen, Donald A.↗

Wind tunnel study of an observatory dome with a circular aperture

Results of a wind tunnel test of a new concept in observatory dome design, the Fixed Shutter Dome are presented. From an aerodynamic standpoint, the new dome configuration is similar in overall shape to conventional observatory domes, with the exception of the telescope viewing aperture. The new design consists of a circular aperture of reduced area in contrast to conventional domes with rectangular or slotted openings. Wind tunnel results of a side-by-side comparison of the new dome with a conventional dome demonstrate that the mean and fluctuating velocity through the aperture and in the center of the new dome configuration are lower than those of conventional domes, thus reducing the likelihood of telescope flow-induced vibration.

Zilliac, Gregory G.↗

Geomagnetic model investigations for 1980 - 1989: A model for strategic defense initiative particle beam experiments and a study in the effects of data types and observatory bias solutions

Two suites of geomagnetic field models were generated at the request of Los Alamos National Lab. concerning Strategic Defense Initiative (SDI) research. The first is a progression of five models incorporating MAGSAT data and data from a sequence of batches as a priori information. The batch sequence is: post 1979.5 observatory data, post 1980 land survey and selected aeromagnetic and marine survey data, a special White Sands (NM) area survey by Project Magnet with some additional post 1980 marine survey data, and finally DE-2 satellite data. These models are of 13th deg and order in their main field terms, and deg and order 10 in their first derivative temporal terms. The second suite consists of four models based solely upon post 1983.5 observatory and survey data. They are of deg and order 10 in main field and 8 in a first deg Taylor series. A comprehensive error analysis was applied to both series, which accounted for error sources such as the truncated core and crustal fields, and the neglected Sq and low deg crustal fields. Comparison of the power spectrum of the MGST (10/81) model with those of this series show good agreement.

Langel, Robert A.↗

SOFIA: The Stratospheric Observatory For Infrared Astronomy

SOFIA, an airborne observatory intended to be carried aboard a Boeing 747 high performance aircraft, is described. The observatory is predicted to provide a threefold greater aperture than that of the Kuiper telescope. The Boeing aircraft will carry the 2.5 diameter telescope and its observers to altitudes of 14,000 and above where the atmosphere is very nearly transparent at all wavelengths. Various aspects and specific missions of the SOFIA project, a cooperative venture of the U.S. and Germany, are described.

Hildebrand, Roger H.↗

The Advanced Solar Observatory

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.↗

The chopping secondary mirror for the Kuiper Airborne Observatory

This paper reports on the design, construction, and implementation of a new chopping secondary mirror system for the Kuiper Airborne Observatory. This observatory facility maintains a 0.91 m diameter telescope in a modified C-141 aircraft at the NASA Ames Research Center. This telescope is routinely used at stratospheric altitudes for astronomical observations at infrared and submillimeter wavelengths that are inaccessible from the ground.

Downey, Charles H.↗

Building a lunar observatory - An engineer's time table

This paper shows the feasibility of constructing a 400 ft diameter steerable parabolic radio dish-type observatory on the moon. A structural configuration and the construction procedure are presented. The estimated earth weight of the proposed structure, assuming that graphite-epoxy-invar is used, is about 42 tons. An engineering construction timeline is also presented. The proposed structural configuration of the observatory is shown to be realistic and attainable.

Chua, Koon Meng↗

Fiber-coupled high resolution infrared array spectrometer for the Kuiper Airborne Observatory

A novel cryogenic grating spectrometer (FCAS) is being designed for observations of volatiles in cometary and planetary atmospheres, and in newly forming planetary systems. The instrument features two-dimensional detector arrays coupled to a high-dispersion echelle by infrared fibers, and will achieve a spectral resolving power of about 40,000. The primary observational platform for this instrument will be the Kuiper Airborne Observatory, but it will also be configured for use at ground-based observatories. Initially, the spectrometer will use a 58 x 62, 1- to 5-micron InSb array. Larger-format IR arrays and arrays of different composition, will later be incorporated as they become available. The instrument will be used in two modes. The first uses a large format IR array in the spectral image plane for the customary one-dimensional spectral-one-dimensional spatial coverage. In the second mode, a massive, coherent bundle of infrared transmitting ZrF4 fibers will be installed after the dispersive element, to reformat the two-dimensional array into an elongated one-dimensional array for wide spectral coverage, allowing multiple lines to be measured in a single integration with high sensitivity. The overall instrument design is discussed, and the system sensitivity is estimated.

Glenar, D. A.↗

The Gamma Ray Observatory

The Gamma Ray Observatory (GRO), scheduled for launch by the Space Shuttle in April 1991, weighs 35,000 lbs and will offer 10 to 20 times better sensitivity than any previous gamma ray mission. The four instruments aboard GRO are described. The Burst and Transient Source Experiment (BATSE) will continuously monitor the entire sky for transient gamma-ray events using eight identical, wide-field detectors capable of measuring brightness variations lasting only milliseconds at energies from about 50,000 to 600,000 eV. The Oriented Scintillation Spectrometer Experiment (OSSE) will make comprehensive observations of discrete sources at energies from 100,000 to 10 million eV, where many radioactive elements have emission lines. The observatory's Imaging Compton Telescope will conduct a deep survey of the entire sky at gamma-ray energies between 1 and 30 MeV. The Energetic Gamma Ray Experiment Telescope will cover a broad high-energy spectral range, from about 20 million to 30 billion eV and conduct a sensitive all-sky survey with a wide field of view and good angular resolution.

Kniffen, Donald A.↗

A lunar based solar observatory - Rationale and concepts

The rationale for a lunar solar observatory is described and the requirements for various candidate instruments are developed. The unique characteristics of the lunar surface, its stability, low seismicity, and long unobstructed paths make it an ideal site for a large, high performance optical telescope. The capabilities of such an instrument is used, as an example (1) for the science that might be achieved from the lunar surface, (2) to identify the magnitude of the instrumentation, and (3) to indicate the technologies that must be developed if such an observatory is to become a reality.

Davis, John M.↗

NASA Marshall Space Flight Center solar observatory report, January - June 1991

Given here is a summary of the solar vector magnetic field, H-alpha, and white-light observations made at the NASA/Marshall Space Flight Center (MSFC) Solar Observatory during its daily periods of operation. The MSFC Solar Observatory facilities consist of the Solar Magnetograph, an f/13, 30-cm Cassegrain system with a 3.5-cm image of the Sun, housed on top of a 12.8-meter tower; a 12.5-cm Razdow H-alpha telescope housed at the base of the tower; an 18-cm Questar telescope with a full aperture white-light filter mounted at the base of the tower; a 30-cm Cassegrain telescope located in a second metal dome; and a 16.5-cm H-alpha telescope mounted on side of the Solar Vector Magnetograph. A concrete block building provides office space, a darkroom for developing film and performing optical testing, a workshop, video displays, and a computer facility for data reduction.

Smith, James E.↗

The Compton Observatory Science Workshop

The Compton Observatory Science Workshop was held in Annapolis, Maryland on September 23-25, 1991. The primary purpose of the workshop was to provide a forum for the exchange of ideas and information among scientists with interests in various areas of high energy astrophysics, with emphasis on the scientific capabilities of the Compton Observatory. Early scientific results, as well as reports on in-flight instrument performance and calibrations are presented. Guest investigator data products, analysis techniques, and associated software were discussed. Scientific topics covered included active galaxies, cosmic gamma ray bursts, solar physics, pulsars, novae, supernovae, galactic binary sources, and diffuse galactic and extragalactic emission.

Shrader, Chris R.↗

NASA Marshall Space Flight Center Solar Observatory report, July - December 1991

A summary is given of the solar vector magnetic field, H-alpha, and white light observations made at the NASA/Marshall Space Flight Center (MSFC) Solar Observatory during its daily periods of observation. The MSFC Solar Observatory facilities consist of the Solar Magnetograph, an f-13, 30 cm Cassegrain system with a 3.5 cm image of the Sun housed on top of a 12.8 meter tower, a 12.5 cm Razdow H-alpha telescope housed at the base of the tower, an 18 cm Questar telescope with a full aperture white-light filter mounted at the base of the tower, a 30 cm Cassegrain telescope located in a second metal dome, and a 16.5 cm H-alpha telescope mounted on the side of the Solar Vector Magnetograph. A concrete block building provides office space, a darkroom for developing film and performing optical testing, a workshop, video displays, and a computer facility for data reduction.

Smith, James E.↗