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  • 1
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    Hard X-ray imaging of the Galactic black hole candidate GX 339 - 4 (1992)
    Institute of Physics
    Details
    Publication Date: 1992-04-01
    Print ISSN: 0004-637X
    Electronic ISSN: 1538-4357
    Topics: Physics
    Published by Institute of Physics
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  • 2
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    Representation of functions as the Post-Widder inversion operator of generalized functions (1984)
    Hindawi
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    Publication Date: 1984-01-01
    Description: A study is made of the Post-Widder inversion operator to a class of generalized functions in the sense of distributional convergence. Necessary and sufficient conditions are proved for a given function to have the representation as therth operate of the Post-Widder inversion operator of generalized functions. Some representation theorems are also proved. Certain results concerning the testing function space and its dual are established. A fundamental theorem regarding the existence of the real inversion operator (1.6) withr=0is proved in section4. A classical inversion theory for the Post-Widder inversion operator with a few other theorems which are fundamental to the representation theory is also developed in this paper.
    Print ISSN: 0161-1712
    Electronic ISSN: 1687-0425
    Topics: Mathematics
    Published by Hindawi
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  • 3
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    Hard X-ray imaging of the Galactic black hole candidate GX 339 - 4 (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-08-14
    Description: Imaging and spectral observations in the energy range 25-250 keV of the black hole candidate GX 339 - 4 have been obtained with the Energetic X-ray Imaging Telescope Experiment. Observations were made during a balloon flight from Alice Springs, Australia on UT 1989 May 8-10. A single source of nearly 6-sigma significance is detected near the center of the 3.4-deg field of view with a position consistent with GX 339 - 4. This is the first imaging observation of GX 339 - 4 at hard X-ray energies. This result confirms previously reported results from nonimaging experiments showing significant hard X-ray flux up to greater than about 60 keV, with a power-law spectral fit similar to the other black hole candidates such as Cygnus X - 1. The source may have been in an outburst state similar to that recently detected with BATSE on GRO.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters (ISSN 0004-637X); 388; L65-L67
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  • 4
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    EXITE observation of the Galactic center - A new transient? (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: The balloon-borne Energetic X-ray Imaging Telescope Experiment observed the Galactic center on May 9, 1989. Within the 3.4-deg (FWHM) field of view, imaged with 22-arcmin resolution at 20-250 keV, two sources were detected: the 'Einstein source' (1E1740.7-2942) and a possible second source about 40 deg West (EXS1737.9-2952). This source was detected significantly at both 20-30 keV and 83-111 keV, suggesting a double-backscattered 511 keV line source at 102 keV and a soft excess, perhaps from a black hole candidate undergoing a transient outburst.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 97; 1; p. 155-158.
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  • 5
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    Techniques for removing non-uniform background in coded-aperture imaging on the energetic X-ray imaging telescope experiment (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: It is found that the subtractive flat field technique for nonuniform background illumination is generally effective at removing background systematics for stationary mask experiments such as the Energetic X-ray Imaging Experiment. The time dependence of intensity and the two-dimensional shape of the background detector image during the flight are explored. A flat field image is constructed from observations where X-ray sources were absent from the field of view. It is shown that this technique can successfully reduce rms fluctuations to within a few percent of ideal Poisson statistics. The quality of the flat field does not appear to be a strong function of radius and can be used effectively out to the edge of the detector to remove the strong background ring.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Nuclear Science (ISSN 0018-9499); 38; 591-596
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  • 6
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    A Hybrid Gas Detector/Phoswich for Hard X-ray Astronomy (1993)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A hybrid detector, which combines an optical avalanche chamber with a phoswich, is currently under development. The optical avalanche chamber - a proportional counter designed to give large quantities of light photons during charge multiplication, mounts on the front of the scintillator and gives response at low energies, while the solid scintillator takes over at energies where the gas becomes transparent (greater than 90 keV). Both sections of the hybrid will be read out by a common set of photomultipliers under the phoswich. The addition of the gas section to the phoswich improves the energy resolution of the instrument by a factor of 2.5 at 25 keV and the spatial resolution by a factor of 10 at the same energy. The net result is an instrument with broad band coverage and high sensitivity which will be used for coded aperture imaging on long duration balloon flights.
    Keywords: Astronomy
    Type: NASA-TM-112688 , NAS 1.15:112688 , EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy 4; 2006; 90-96|EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy 4; Jul 11, 1993 - Jul 12, 1993; San Diego, CA; United States
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  • 7
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    Development of a Hybrid Gas Detector/Phoswich for Hard X-Ray Astronomy (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A hybrid detector is under development for use as a balloon-borne instrument in hard x-ray astronomy. The detector provides broad band coverage by coupling an optical avalanche chamber to a phoswich. The optical avalanche chamber yields superior instrument response at low energies while the scintillator takes over at the higher energies where the gas becomes transparent: at 25 keV, the addition of the gas chamber improves the energy resolution by a factor of 2.5 and the spatial resolution by a factor of 10 as compared to the stand-alone response of the phoswich. A half-scale prototype instrument is being constructed for test purposes and to help resolve a number of design questions involving the coupling of the two components.
    Keywords: Astronomy
    Type: NASA-CR-203696 , NAS 1.26:203696 , EUV, X-Ray, and Gamma-Ray Instrumentation Meeting for Astronomy; Jul 27, 1994 - Jul 28, 1994; San Diego, CA; United States|SPIE Proceedings Series; 2280; 119-126
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