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  • 11
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    Halos around planetary nebulae (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Preliminary results of a CCD survey designed to detect and investigate faint halos around planetary nebulae are reported. A TI 800 x 800 pixel CCD was used to take deep exposures of 44 planetary nebulae. The exposures were obtained through an H-alpha filter at the Cassegrain focus of the Palomar 1.5 m telescope. Spatial resolutions of 1 to 2 arcsec were obtained across 400 arcsec wide fields. The images, which are in many cases considerably deeper than any previously taken, reveal numerous planetary nebula halos. About two-thirds of the studied nebulae possess extensive outer halos, here defined as any extended emission beyond the 10 percent isophote. Ionized sulphur electron density measurements show that in some nebulae, the mass in the halo is comparable to the mass contained in the primary H II region. The data have been used to place constraints on the mode of origin of the halos. It is likely that the halos originate either by dynamical separation of a single ejected shell of gas or by the ejection of two or more such shells from the central star. It is possible but less likely that the halos are caused by excitation of the preplanetary stellar wind and improbable that the halos represent reflection nebulae.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 302; 727-736
    Format: text
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    NASA TECHNICAL REPORTS
  • 12
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    Voyager 1 imaging and IRIS observations of Jovian methane absorption and thermal emission: Implications for cloud structure (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Images from three filters of the Voyager 1 wide angle camera are used to measure the continuum reflectivity and spectral gradient near 6000 A and the 6190 A band methane/continuum ratio for a variety of cloud features in Jupiter's atmosphere. The dark barge features in the North Equatorial Belt have anomalously strong positive continuum spectral gradients suggesting unique composition. Methane absorption is shown at unprecedented spatial scales for the Great Red Spot and its immediate environment, for a dark barge feature in the North Equatorial Belt, and for two hot spot and plume regions in the North Equatorial Belt. Methane absorption and five micrometer emission are correlated in the vicinity of the Great Red Spot but are anticorrelated in one of the plume hot spot regions. Methane absorption and simultaneous maps of five micrometer brightness temperature is quantitatively compared to realistic cloud structure models which include multiple scattering at five micrometer as well as in the visible. Variability in H2 quadrupole lines are also investigated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: NASA-CR-173567 , NAS 1.26:173567
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 13
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    Voyager 1 imaging and IRIS observations of Jovian methane absorption and thermal emission - Implications for cloud structure (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Images from three filters of the Voyager 1 wide angle camera are used to measure the continuum reflectivity and spectral gradient near 6000 A and the 6190 A band methane/continuum ratio for a variety of cloud features in Jupiter's atmosphere. The dark barge features in the North Equatorial Belt have anomalously strong positive continuum spectral gradients suggesting unique composition. Methane absorption is shown at unprecedented spatial scales for the Great Red Spot and its immediate environment, for a dark barge feature in the North Equatorial Belt, and for two hot spot and plume regions in the North Equatorial Belt. Methane absorption and five micrometer emission are correlated in the vicinity of the Great Red Spot but are anticorrelated in one of the plume hot spot regions. Methane absorption and simultaneous maps of five micrometer brightness temperature are quantitatively compared to realistic cloud structure models which include multiple scattering at five micrometer as well as in the visible. Variability in H2 quadrupole lines are also investigated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 61; 311-342
    Format: text
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    NASA TECHNICAL REPORTS
  • 14
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    Variability of the optical intensity and plane polarization of OJ 287. (1972)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Photometric and plane polarimetric observations of the radio source Oj 287 have been made in the optical region. The photometric data show variations of 0.10 mag with a timescale of 6-7 days superposed on a total decrease of approximately 0.5 mag during February 1972. The polarimetric data, which exhibit a similar decrease in plane polarization during this same period, suggest the possibility of a periodicity with a timescale of the order of 30 days.
    Keywords: SPACE SCIENCES
    Type: Astrophysical Journal; 174; June 1
    Format: text
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  • 15
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    Discovery of currently active extraterrestrial volcanism (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Two volcanic plumes were discovered on an image of Io taken as part of the Voyager optical navigation effort. This is the first evidence of active volcanism on any body in the solar system other than earth.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 204; June 1
    Format: text
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    NASA TECHNICAL REPORTS
  • 16
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    Two-dimensional photometry of planetary nebulae (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Monochromatic images of three planetary nebulae, NGC 6720, NGC 7662 and NGC 2392, were taken using narrow band interference filters centered on the forbidden emission lines of Oxygen I, II, III, Nitrogen II, Sulfur II and the permitted emission lines of Hydrogen I, Helium I and Helium II. The data was taken with a silicon intensified vidicon using the Palomar 1.5 meter telescope and was recorded digitally to an encoding level of 12 bits. The data was processed at the Image Processing Laboratory of the Jet Propulsion Laboratory. The calibrated images were used to investigate the three dimensional structure of the nebulae and to generate two-dimensional electron and temperature maps.
    Keywords: ASTRONOMY
    Type: Conference on Applications of Digital Image Processing to Astronomy; Aug 20, 1980 - Aug 22, 1980; Pasadena, CA
    Format: text
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    NASA TECHNICAL REPORTS
  • 17
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    Imaging spectrometer - An advanced multispectral imaging concept (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The concept of an imaging spectrometer, which is being studied as a potential Space Shuttle experiment, is evaluated as a 'push-broom' imager that includes a spectrometer to disperse each line of imaging information into its spectral components. Using this instrument, the dispersed energy falls upon a two-dimensional focal plane array that detects both spatial and spectral information. As the line field of view is advanced over the earth by the motion of the spacecraft, the focal plane is read out constantly, which produces 'push-broom' images at multiple wavelengths. Ground instantaneous fields of view of 10 m in the visual and 20 m in the infrared are provided by the system, at a spectral resolution of 20 nm over the range from 0.4-2.5 microns. The system utilizes a triple-pass Schmidt optical system with a mosaic focal plane. A subset of the data stream is selected and encoded for transmission by the use of onboard processing.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: 1982 International Geoscience and Remote Sensing Symposium; Jun 01, 1982 - Jun 04, 1982; Munich
    Format: text
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    NASA TECHNICAL REPORTS
  • 18
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    Discovery of Currently Active Extraterrestrial Volcanism (1979)
    American Association for the Advancement of Science
    Details
    Publication Date: 1979-06-01
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science
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    PAPER CURRENT
  • 19
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    Discovery of Currently Active Extraterrestrial Volcanism (1979)
    American Association for the Advancement of Science
    Details
    Publication Date: 1979-06-01
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science
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