Search NASA⌕ Search

SEARCH · Search NASA

Results for “all-sky”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

IRAS observations of binaries with compact objects

The infrared emission data, obtained on 260 binary systems by the all-sky IRAS survey in wavelengths between 12 and 100 microns, are reported. Of all the 260 sources, which contained compact objects including white dwarfs, neutron stars, or possibly black holes, only 32 contained detectable IR radiation. The X-ray emitting Be-type stars (gamma-Cas and X Per) were found to have their energy flux proportional to frequency in the range of the log nu values of 12.7-14.7. However, the GS304-1 flux distribution is unique, in that its flux rises by several orders of magnitude as the wavelength changes from 4000 A to 60 microns. A static dust cloud was detected, with a radius of about 1 AU, which has formed around the classical nova RR Pic since its 1925 eruption. The post-eruption far-IR light curve of a classical nova provides strong evidence for IR emissions from both dust grains formed during the eruption and dust grains existing from previous eruptions.

Schaefer, B. E.↗
NASA NTRS1987

The joint NASA/Goddard-University of Maryland research program in charged particle and high energy photon detector technology

The first measurements of Fe charge states in two coronal hole-association high speed streams, using the sensor on ISEE-3, are presented. Eight event intervals from the January to June 1983 timeframe were chosen for the study of magnetotail dynamics and its relationship to substorm activity and the possible formation of plasmoids. Techniques are being explored for measurement of secondary electrons which are characteristically emitted when ions hit a target material. Efforts are continuing to understand kilometer wavelength shock associated radio events. An all-sky survey of fast X-ray transients of duration of 5 to 10,000 s was completed. Research using high resolution gamma-ray spectroscopy of celestial sources in the 20 keV to 20 MeV range to search for and study narrow lines in low-energy gamma-ray spectrum continues. Research in high energy radiation from pulsars is being conducted.

Source record↗
NASA NTRS1987

Origin and propagation of galactic cosmic rays

The study of systematic trends in elemental abundances is important for unfolding the nuclear and/or atomic effects that should govern the shaping of source abundances and in constraining the parameters of cosmic ray acceleration models. In principle, much can be learned about the large-scale distributions of cosmic rays in the galaxy from all-sky gamma ray surveys such as COS-B and SAS-2. Because of the uncertainties in the matter distribution which come from the inability to measure the abundance of molecular hydrogen, the results are somewhat controversial. The leaky-box model accounts for a surprising amount of the data on heavy nuclei. However, a growing body of data indicates that the simple picture may have to be abandoned in favor of more complex models which contain additional parameters. Future experiments on the Spacelab and space station will hopefully be made of the spectra of individual nuclei at high energy. Antiprotons must be studied in the background free environment above the atmosphere with much higher reliability and presion to obtain spectral information.

Cesarsky, Catherine J.↗
NASA NTRS1986

Preliminary analysis of the IRAS solar system dust data

The structure of the solar system dust cloud as revealed by IRAS all-sky survey data is discussed. Fourier analysis was used to separate the smooth, large-scale zodiacal background from the narrower dust lanes. The geometry of the background zodiacal cloud appears to show features associated with both the forced inclinations and the forced eccentricities of the dust particle orbits. The ecliptic latitude of the peak of the background zodiacal emission varies nearly sinusoidally with ecliptic longitude with an amplitude of 2.1 + or -0.2 degrees. However, there are marked displacements, both in latitude and longitude, between the leading or ascending curve and the trailing or descending curve, implying that the curves exhibit significant deviations from a simple sinusoidal variation. It is suggested that the plane of symmetry of the background cloud is inclined to the ecliptic by 1.47 + or -0.10 degrees with a descending node of 230 + or -4 degrees, and that the sun is not at the center of symmetry of the cloud.

Dermott, S. F.↗
NASA NTRS1986

Arcsecond positions for milliarcsecond VLBI nuclei of extragalactic radio sources. IV - Seventeen sources

VLBI measurements of time delay and delay rate at 2.29 and 8.42 GHz on baselines of 10,000 km have been used to determine the positions of the milliarcsecond nuclei in 17 extragalactic radio sources with estimated accuracies of 0.1 to 0.3 arcsec. The observed sources are part of an all-sky VLBI catalog of milliarcsecond radio sources. In addition, slightly improved positions are presented for 101 sources originally reported by Morabito et al. (1983). Arcsecond positions have now been determined for 836 sources.

Morabito, D. D.↗
NASA NTRS1986

A VLA survey of unidentified HEAO-1 X-ray sources

Radio observations toward 47 unidentified sources from the HEAO-1 all-sky X-ray survey (Wood et al., 1984), obtained at 1.418 GHz using the C configuration of the VLA on May 11-14, 1983 are reported. Of the 238 radio sources detected at flux density 1-3 mJy or greater, 26 are found to be within 5 arcsec of optical objects, which are thereby considered to be candidate X-ray sources. Tentative classifications of the candidates include five RS CVn systems, three AGNs, three galaxy or cluster sources, and two X-ray binaries.

Schmelz, J. T.↗
NASA NTRS1986

The Extreme Ultraviolet Explorer and the local interstellar medium

The EUV Explorer (EUVE) mission is described, with emphasis on the overall capabilities of the instrumentation and the relevance of the mission to determining parameters of the local interstellar medium. The primary purpose of the mission is to search the celestial sphere for astronomical sources of EUV radiation (100-1000 A). The search will be accomplished with the use of three EUV telescopes, sensitive to different segments of the EUV band. A fourth telescope will perform a high-sensitivity search of a limited sample of the sky in the shortest-wavelength bands. The all-sky survey will be carried out in the first six months of the mission. The second six months of the mission, conducted entirely by Guest Investigators selected by NASA, will be devoted to spectroscopic observations of selected EUV sources. The instrumentation is now well developed. The best mirror has full-width/half-energy spread of 8 arcsec and a surface finish of 20 A. Prototype thin-film bandpass filters have been flown on the Space Shuttle and their performance optimized. Prototype detectors have been developed which have 600 by 600-pixel imaging capability and up to 80-percent quantum efficiency in parts of the EUV band.

Bowyer, Stuart↗
NASA NTRS1986

The NASA SETI program - An overview

The development and objectives of the NASA SETI program are reviewed. The search strategy for the program is two phase, an all-sky survey and a targeted search; the capabilities and hardware for the searches are discussed. The use of a spectrum analyzer to search the GHz of the spectrum, and of a multichannel spectrum analyzer to detect pulses are examined; the designs and functions of the analyzers are described. A new method for detecting a drifting CW signal is proposed. A diagram of the automated SETI system is presented.

Oliver, Bernard M.↗
NASA NTRS1987

Search for orbital X-ray variation in Scorpius X-1

All 5 yr of 3-6 keV monitoring of Sco X-1 by the Ariel 5 all-sky monitor have been reanalyzed to search more sensitively for variation at the 0.787313 d orbital period. The best limits on orbital variations come from data selected to exclude active episodes. Any narrow absorption dip has an average depth less than 1.0 percent (0.1/Delta Phi), where Delta Phi is the width in units of the orbital period (2 sigma confidence level). A weak (0.4 percent) sinusoidal modulation, with 3.2 sigma significance, reaching minimum at phase 0.59 + or - 0.06 with respect to superior conjunction of the optical emission-line source is observed. In any case, the upper limit to a sinusoidal orbital modulation is 0.7 percent. Sco X-1 never - at least not for more than 2 hrs - dipped below its normal quiescent level.

Priedhorsky, W. C.↗
NASA NTRS1987

The IRAS bright galaxy sample. II - The sample and luminosity function

A statistically complete sample of 324 of the brightest infrared galaxies discovered at 60 microns in the IRAS all-sky survey is described. The results show that far-infrared emission is a significant luminosity component in the local universe, representing 25 percent of the luminosity emitted by stars in the same volume. Above 10 to the 11th solar luminosities, the infrared luminous galaxies are the dominant population of objects in the universe, being as numerous as the Seyfert galaxies and more numerous than quasars at higher luminosities. The infrared luminosity appears to be independent of the optical luminosity of galaxies. Most infrared bright galaxies appear to require much of the interstellar matter to be contributing to the observed infrared luminosity. Approximately 60-80 percent of the far-infrared luminosity of the local universe can be attributed, directly or indirectly, to recent or ongoing star formation.

Soifer, B. T.↗
NASA NTRS1986

Calibration of the thin film filters to be used on the Extreme Ultraviolet Explorer Satellite

The methods of calibrating the filters used on the Extreme Ultraviolet Explorer (EUVE) astronomical satellite are described. EUVE will conduct the first all-sky survey in the entire EUV band. The measurement of the filters' transmission properties from the soft X-ray to the far UV using a grazing incidence monochromator is discussed. A particle ingress test to determine the ability of the filters to inhibit energetic particles in earth orbit from entering the detector and increasing the background is described. Problems encountered in calibrating these four filters are also presented.

Vallerga, John↗
NASA NTRS1987

The advanced X-ray astrophysics facility - An overview

This paper presents an overview of NASA's Advanced X-Ray Astrophysics Facility (AXAF), which is planned for launch in the 1990s and is expected to operate in space for at least 15 years. The design of the X-ray telescope is discussed and the instruments that may fly at the start of the AXAF mission, the principal investigator of each instrument, and the instrument performance parameters are listed. The AXAF instruments will include low-energy and high-energy transimission gratings, a Bragg crystal spectrometer, CCD imagers, an X-ray calorimeter, and a microchannel plate imager. The long lifetime of the AXAF will make it possible to follow up on the HEAO-2/Einstein results, the more recent X-ray observations performed by European and Japanese satellites, and the future ROSAT all-sky survey. The long lifetime of the AXAF, together with the servicing capability that will be offered by the Space Station, will also provide the opportunity of incorporating other instruments into the observatory.

Weisskopf, Martin C.↗
NASA NTRS1987

Contamination control approach for the Extreme Ultraviolet Explorer satellite instrumentation

The Extreme Ultraviolet Explorer will perform an all-sky survey and spectroscopic observations over the wavelength range 80-900A. Hydrocarbon and particulate contamination will potentially affect the throughput and signal to noise ratio of the signal detected by the instruments. A witness sample program is here used to investigate and monitor the effects of specific contaminants on EUV reflectivity. Witness samples were intentionally contaminated with thin layers of pump oil. An oil layer 150 A thick was applied and found to evaporate over 8 hours. The EUV reflectivity and imaging properties were then measured and found to be acceptable for grazing angles between 5 and 30 deg. In a second test, layers 500 A thick were deposited and then allowed to evaporate in vacuum; once the oil had evaporated to at least 350 A, the final sample reflectivity was degraded less than 10 percent, but the image was degraded severely by scattering. An outline of the contamination control program is also presented.

Mrowka, Stan↗
NASA NTRS1987

Prospective EUV observations of hot DA white dwarfs with the EUV Explorer

The Extreme Ultraviolet Explorer (EUVE) will perform a high sensitivity EUV all-sky survey. A major category of sources which will be detected with the EUVE instruments consists of hot white dwarfs. Detailed preliminary studies of synthetic EUV observations of white dwarfs have been carried out using the predicted EUVE instrumental response functions. Using available information regarding space densities of white dwarfs and the distribution of neutral hydrogen in the interstellar medium, the numbers of DA white dwarfs which will be detectable in the different EUV bandpasses have been estimated.

Finley, David S.↗
NASA NTRS1986

Studies of an x ray selected sample of cataclysmic variables

Just prior to the thesis research, an all-sky survey in hard x rays with the HEAO-1 satellite and further observations in the optical resulted in a catalog of about 700 x-ray sources with known optical counterparts. This sample includes 43 cataclysmic variables, which are binaries consisting of a detached white-dwarf and a Roche lobe filling companion star. This thesis consists of studies of the x-ray selected sample of catalcysmic variables.

Silber, Andrew D.↗
NASA NTRSDate not supplied

A Radiometric Consistent Spectral Fingerprinting Algorithm for Continuity Products of Hyperspectral Sounders

A radiometric consistent climate fingerprinting methodology has been developed to derive long-term temperature, water vapor, cloud, trace gases, and surface skin temperature anomaly time series from the hyper-spectral sounder measurements of multiple platforms. The spectral fingerprinting methodology requires the use of radiative kernels that are radiometrically consistent with observations. Radiative kernels are built using space-time averaged Jacobians that are physically retrieved from observations under all sky conditions. The physical retrieval algorithm uses the Principal Component based Radiative Transfer Model (PCRTM) for the forward simulation. The incorporation of multiple scattering simulation in PCRTM allows the direct radiative relationship between single field-of-view (FOV) radiance observations and corresponding thermal dynamic variables including cloud properties to be established. Therefore, radiance ?closure? can be achieved under all-sky conditions by the fingerprinting scheme. This methodology has been used to derive climate anomalies from the space-time averaged spectra of AIRS/AMSU and CrIS/ATMS. The use of a consistent fingerprinting scheme provides an effective mean of generating continuity product by merging observations from different platforms and therefore facilitating the long-term climate trend study.

Wan Wu↗