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  • ASTRONOMY  (129)
  • INSTRUMENTATION AND PHOTOGRAPHY  (51)
  • 1985-1989
  • 1980-1984  (180)
  • 1970-1974
  • 1982  (180)
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  • 1985-1989
  • 1980-1984  (180)
  • 1970-1974
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  • 1
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    Tunable diode-laser heterodyne spectrometer for remote observations near 8 microns (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A diode-laser-based, ultrahigh resolution IR heterodyne spectrometer for laboratory and field use has been developed for operation between 7.5 and 8.5 microns. The local oscillator is a PbSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed-cycle cooler. The laser output frequency is controlled and stabilized using a high-precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. The system largely employs reflecting optics to minimize losses from internal reflection and absorption and to eliminate chromatic effects. Spectral analysis of the diode-laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the IR spectral regions over which useful heterodyne operation can be achieved. Observations have been made of atmospheric N2O, O3, and CH4 between 1170 and 1200/cm, using both a single-frequency swept IF channel and a 64-channel RF spectral line receiver with a total IF coverage of 1600 MHz.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Jan. 15
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    NASA TECHNICAL REPORTS
  • 2
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    The excitation and distribution of CO (J = 6-5) emission in the Orion Nebula (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations of the 691-GHz (J = 6-5) transition of CO in the BN/KL region of Orion obtained in February 1981, at the IR Telescope Facility at Mauna Kea are reported. The system employs a heterodyne receiver with an overall noise temperature of 3900 K DSB at 432 microns, 64 5-MHz IF-filter-bank channels, and a chopping secondary with 120-arcsec excursion, and has 35-arcsec resolution. Sample data are presented graphically and analyzed using a rate equation and a kinetic model. A 35 x 45-arcsec core with hot broad plateau emission (antenna temperature 180 + or - 36 K) surrounded by an area of strong narrow-line 120-K emission is found. It is suggested that the plateau emission originates in a wide thin sheet after a shock wave, with H2 density at least 10 to the 6th/cu cm and gas kinetic temperature greater than 500 K.
    Keywords: ASTRONOMY
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    NASA TECHNICAL REPORTS
  • 3
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    Arcsecond positions for milliarcsecond VLBI nuclei of extragalactic radio sources. I - 546 sources (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: (Previously announced in STAR as N82-16109)
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 87; Mar. 198
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  • 4
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    Tunable diode laser heterodyne spectrometer for remote observations near 8 microns (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Infrared heterodyne spectroscopy is a passive technique employing coherent optical detection for the study of spectral features in remote sources. It employs optical components such as mirrors and lenses normally associated with incoherent optics, but because of it's coherent nature, it offers the advantages of ultrahigh spectral resolving power, high frequency precision, and diffraction limited field-of-view. Attention is given to the development of an ultrahigh resolution diode laser heterodyne spectrometer for observational and laboratory use. The instrument is designed for operation in the spectral range from 7.5 to 8.5 microns. A PbSe tuneable diode laser (TDL) is employed as local oscillator. A closed-cycle cooler is employed to keep the oscillator at operating temperatures in the range from 12 to 60 K. Attention is given to factors determining the TDL heterodyne sensitivity, the spectrometer design, and a survey of 8 micron observations, SiO could be detected in the sunspot spectrum.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Instrumentation in astronomy IV; Fourth Conference; Mar 08, 1982 - Mar 10, 1982; Tucson, AZ
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  • 5
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    The wide field/planetary camera (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A wide site of potential astronomical and solar system scientific studies using the wide field planetary camera on space telescope are described. The expected performance of the camera as it approaches final assembly and testing is also detailed.
    Keywords: ASTRONOMY
    Type: Space Telescope Science Inst. The Space Telescope Obs.; p 28-39
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  • 6
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    Magnetospheres and winds of the helium strong stars: Dependence on rotation (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Large aperture, low resolution spectra of 24 stars of types 05, 04, and 03 were obtained, and from these the energy distribution between 1200 and 3200 angstrom was derived in absolute units. The energies were combined with energies deduced from uvby and UBV photometry and corrected for interstellar extinction. Angular diameters and effective temperatures are also derived. The effective temperatures range from 24800K to 63000K. There is no correlation between effective temperature and spectral type or luminosity class for the early 0 stars. The size of the expected errors are also studied.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 589-592
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  • 7
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    Distribution of gas in the halo of the galaxy (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Results are presented from a high-resolution, ultraviolet study of interstellar gas situated away from the plane of the Milky Way Galaxy, using the nuclei of Seyfert galaxies Mkn 509 and F9 as background probes. In these directions, low-velocity, galactic gas were detected as well as two extragalactic clouds, one probably associated with the Magellanic Stream and the other with Mkn 509. These data were combined with results from other lines of sight to show that the ultraviolet species extend about 10 kpc from the plane, assuming the high-latitude gas corotates with the galactic disk. Complimentary observations of the optical Ca II and Na I species suggests that these do not extend as far - perhaps 2 to 3 kpc from the plane. Further, the exceedingly complex velocity structure found only in Magellanic Cloud directions suggests that these sight-lines are not typical of high-latitude gas in general.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 359-362
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  • 8
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    On the detection of other planetary systems by astrometric techniques (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A quantitative method for astrometrically detecting perturbations induced in a star's motion by the presence of a planetary object is described. A periodogram is defined, wherein signals observed from a star show exactly periodic variations, which can be extracted from observational data using purely statistical methods. A detection threshold is defined for the frequency of occurrence of some detectable signal, e.g., the Nyquist frequency. Possible effects of a stellar orbital eccentricity and multiple companions are discussed, noting that assumption of a circular orbit assures the spectral purity of the signal described. The periodogram technique was applied to 12 yr of astrometric data from the U.S. Naval Observatory for three stars with low mass stellar companions. Periodic perturbations were confirmed. A comparison of the accuracy of different astrometric systems shows that the detection accuracy of a system is determined by the measurement accuracy and the number of observations, although the detection efficiency can be maximized by minimizing the number of data points for the case when observational errors are proportional to the square root of the number of data points. It is suggested that a space-based astrometric telescope is best suited to take advantage of the method.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 263
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    NASA TECHNICAL REPORTS
  • 9
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    A digital optical torquemeter for high rotational speed applications (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A digital optical torquemeter system designed for applications at high rotational speeds was fabricated and tested for zero stability at speeds up to 20,000 rpm. Data obtained in a spin rig and with simulated inputs demonstrate that the system is capable of measuring torque bar twist to within 0.03 degrees at speeds of 30,000 rpm. The optical system uses fiber optic bundles to transmit light to the torque bar and to silicon avalanche detectors. The system is microcomputer based and provides measurements of average torque and torque as a function of angular shaft position. The torquemeter requires no bearings or other contact between the rotating torque bar and the nonrotating optics, and tolerates movement of the torque bar as large as 1 mm relative to the optics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-82914 , E-1189 , NAS 1.15:82914
    Format: application/pdf
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  • 10
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    IUE observations of lines of sight with peculiar ultraviolet extinction (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Low resolution IUE data were used to derive UV extinction curves for a group of stars known to have peculiar extinction parameters from ANS data. The resulting curves have a wide range of appearances. Although the ratio E(BUMP)/E(B-V) differs by a factor of three in the extreme cases, the wavelength of maximum absorption does not appear to change. No evidence for new fine structure in UV extinction was found. The structure near 62 micrometers in the existing mean extinction curves appears to be the result of luminosity mismatch errors. The new extinction curves have shapes that separate into two distinct classes; those associated with clear field extinction and those associated with extinction in dense nebular environments. The range of variation in the curves is so large, the common practice of ironing out the bump can produce enormous errors in the resultant UV energy distributions when E(B-V) 0.3.
    Keywords: ASTRONOMY
    Type: NASA. Goddard Space Flight Center Advan. in Ultraviolet Astron.; p 409-412
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