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  • ASTRONOMY
  • 1985-1989
  • 1980-1984
  • 1975-1979  (426)
  • 1977  (213)
  • 1975  (213)
  • 1
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    Toward diffraction-limited seeing of dim astronomical objects from the Earth's surface using LIDAR (1977)
    In:  CASI
    Details
    Publication Date: 2005-02-28
    Keywords: ASTRONOMY
    Type: Res. in the Space Sci., Vol. 2, No. 1; 12 p
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  • 2
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    Infrared astronomy and high energy astrophysics (1977)
    In:  CASI
    Details
    Publication Date: 2006-08-09
    Description: Observations of the diffuse far-infrared flux from the galactic plane, as well as far-infrared measurements of the properties of dense molecular clouds, when combined with recent high-energy gamma-ray measurements and radio observations of carbon monoxide, yield information about the total mass of molecular clouds, the large-scale structure of the inner galaxy, and the density of cosmic rays.
    Keywords: ASTRONOMY
    Type: The Struct. and Content of the Galaxy and Galactic Gamma Rays; p 203-214
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  • 3
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    General-altitude transformations between geocentric and geodetic coordinates (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Formulas for the general-altitude (height above the ellipsoid) transformation from geocentric to geodetic coordinates and vice versa are derived. The set of four formulas is expressed in each of two useful forms: series expansions in powers of the earth's flattening and series expansions in powers of the earth's eccentricity. The error incurred in these expansions is of the order of one part in 30 million.-
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 12; Sept
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  • 4
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    La Posta Astrogeophysical Observatory (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An overview is presented of the equipment and data acquisition procedures at La Posta Astrogeophysical Observatory, located in the mountains, east of San Diego, Calif. It is a solar observatory, focusing on solar flares and the effect of solar activity on earth. It makes daily radio and optical observations of solar activity. Radio transmission in the earth atmosphere is monitored with VLF and HF equipment. A magnetometer monitors the state of the geomagnetic field.
    Keywords: ASTRONOMY
    Type: Solar Physics; 43; July 197
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  • 5
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    Airborne infrared astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: After a brief review of the general procedures involved in airborne infrared astronomy and of the historical background leading up to this important new technique, sources of infrared radiation, effects of the earth's atmosphere on this incoming radiation, methods of detection of infrared sources, and the development of airborne observatories are described. The discussion is on a lay level; the correlation of heat with infrared emission, the primary role played by CO2 and H2O in the opacity of the atmosphere in the IR above 18 microns, the use of a crystal to electronically detect radiation in the desired spectral region, and the Lear Jet telescope as mounted in a modified C-141 cargo jet are considered.
    Keywords: ASTRONOMY
    Type: Mercury; 4; July-Aug
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  • 6
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    High-energy gamma-ray astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The subject of gamma-ray astronomy is discussed with emphasis on celestial gamma rays with energies in excess of 10 MeV. Early observations of such gamma rays are reviewed, a gamma-ray spark-chamber telescope is described together with a gas Cerenkov-counter telescope, and the gamma-ray sky is delineated. It is shown that the diffuse high-energy gamma radiation from the galactic plane probably results primarily from cosmic-ray interactions with interstellar matter. Mechanisms for gamma-ray production are identified, and it is noted that the general galactic radiation may prove to be of great value in studies of galactic structure. Possible sources are considered for the diffuse celestial radiation, and discrete sources are described, including the Crab pulsar, the Vela remnant, the Cygnus region, and Gould's Belt. Future developments in gamma-ray astronomy are considered.
    Keywords: ASTRONOMY
    Type: Physics Today; 28; Sept
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  • 7
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    Mariner 9 observations of beta Cephei stars (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Ultraviolet spectra of three beta Cep variables and a nonvariable star of similar spectral type were observed by the ultraviolet spectrometer on Mariner 9. A significant light variation at 1400 A may have been detected for beta Cep. The variable stars have mean ultraviolet spectra similar to that of the nonvariable star and do not show any significant short-period spectral variations.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 8
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    Scientific instrumentation of the Radio-Astronomy-Explorer-2 satellite (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The instrumentation of the RAE-2 spacecraft is described. The instruments include a pair of long travelling-wave antennas, a 37-m dipole, two radiometers making one frequency scan every 144 sec, and two rapid-sampling total-power burst receivers which cover the range from 0.025 to 13.1 MHz in 32 discrete steps. Effects of terrestrial noise on RAE-1 and RAE-2 observations are discussed, and it is noted that RAE-2 is uniquely capable of observing repeated lunar occultations of strong radio sources at very low frequencies. Some observational programs are briefly noted, including observations of the galactic background distribution, measurements of lunar occultations of solar radio bursts, and searches for more radio sources among the planets, galactic objects, and extragalactic sources.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 40; 4, Ma; May 1975
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  • 9
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    Soft X-ray emission from Hercules X-1 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 10
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    Period changes in Centaurus X-3 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A number of mechanisms which can change the orbital period are applied to various models of Cen X-3. Only four models which give rise to feasible mechanisms are found. Possible observations which could distinguish between these models are suggested.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 11
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    The light curve of CV Serpentis, the sometimes-eclipsing Wolf-Rayet star (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: New photoelectric observations of the B-magnitude of CV Ser made in 1973 and 1974 show no clear evidence of an eclipse, but they establish night-to-night variability of several percent, a systematic brightness change of 0.035 mag during a portion of the single orbit observed in 1973, and irregular flaring in 1974. We made iris photometer measurements of Harvard patrol plates taken between 1905 June and 1953 July, and find no evidence of a very deep eclipse such as observed by Hjellming and Hiltner. We present several new light curves and discuss then in the light of the recent results of Cowley et al.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 15
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  • 12
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    The spectrum of HD 125823 /a Centauri/ (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 199; July 1
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  • 13
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    Conclusions from the discussions on observational results of heterodyne spectroscopy in astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Experimental results in astronomy obtained with the aid of infrared heterodyne detection techniques are considered, taking into account the detection of thermal emission with no dispersion at the intermediate frequency and observations involving molecular line detection. The tuning range of a heterodyne spectrometer and of a Fourier transform spectrometer is considered and attention is given to the selection of the appropriate technique for a specific investigative problem.-
    Keywords: ASTRONOMY
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  • 14
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    Heterodyne spectroscopy of astronomical and laboratory sources at 8.5 microns using diode laser local oscillators (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The first 8.5 microns infrared heterodyne spectrometer has been constructed using tuneable semiconductor (PbSe) diode lasers and was used to measure absorption line profiles of N2O in the laboratory, as well as black-body emission from the moon and from Mars. Spectral information was recorded over a 200 MHz bandwidth using an 8-channel filter bank. The resolution was 25 MHz (6 millionths of a micron), and the minimum detectable (black-body) power was approximately 1 times 10 to the minus 16th power W for 8 min of integration. The results demonstrate the usefulness of heterodyne spectroscopy for the study of remote and local sources in the infrared.
    Keywords: ASTRONOMY
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  • 15
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    Studies of the infrared source CRL 2688 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Infrared, optical, and radio observation are described of a newly discovered galactic infrared source. Most of the radiation comes from a 1.''5 diameter infrared source at a temperature of about 150 K, but some visible emission in the form of a symmetrical highly polarized reflection nebulosity is also seen. The object could represent either a very early or a very late stage in stellar evolution.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 198; June 15
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  • 16
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    The eclipsing binary CW Eridani (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results of three-color photoelectric observations of CW Eridani are presented which were made with a 30-inch telescope over the three-year period from 1970 to 1973. The times of minima are computed, solutions of the light curves are obtained, and theoretical light curves are computed from the solutions. The period is determined to be 2.72837 days, and the orbital and photoelectric elements are derived from solutions based on the idealized Russell model.
    Keywords: ASTRONOMY
    Type: Acta Astronomica; 25; 2, 19; 1975
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  • 17
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    Shadow of the head of Comet Kohoutek (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An earlier reported shadow of the head of Comet Kohoutek (1973f) was not found in later photographs of the comet. However, linear dark areas were seen and are described as the space between the plasma and the dust tails. The discrepancy in earlier observations is attributed to low resolution in them. Observation of a shadow is also discounted in terms of cometary physics, due to low dust content and the weakness and curvature of the dust tail.
    Keywords: ASTRONOMY
    Type: Nature; 253; Feb. 20
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  • 18
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    A statistical technique for processing radio interferometer data (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The output of a radio interferometer is the Fourier transform of the object under investigation. Due to the limited coverage of the Fourier plane, the reconstruction of the image of the source is blurred by the beam of the synthesized array. A maximum-likelihood processing technique is described which uses the statistical properties of the received noise-like signals. This technique has been used extensively in the processing of large-aperture seismic arrays. This inversion method results in a synthesized beam that is more uniform, has lower sidelobes, and higher resolution than the normal Fourier transform methods. The maximum-likelihood method algorithm was applied successfully to very long baseline and short baseline interferometric data.
    Keywords: ASTRONOMY
    Type: IEEE Transactions on Antennas and Propagation; AP-23; Jan. 197
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  • 19
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    Stabilization of Kepler's problem (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A regularization of Kepler's problem due to Moser (1970) is used to stabilize the equations of motion. In other words, a particular solution of Kepler's problem is imbedded in a Liapunov stable system. Perturbations can be introduced into the stabilized equations.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 16; Sept
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  • 20
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    Aperture averaging effects in stellar scintillation (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Stellar scintillation has been measured for apertures as low as 0.012 m by using photoncounting techniques. The scintillation measurements have been made for various aperture sizes in quick succession in order to determine experimentally the effects of aperture averaging. The results of the experiment are compared with the predictions of a model proposed earlier in the literature to quantify the phenomenon.
    Keywords: ASTRONOMY
    Type: Optics Communications; 22; Sept
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  • 21
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    Far-infrared scans of the Galactic plane (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results are reported for balloon-borne scans of the Galactic plane between longitudes of 348 and 32.5 deg, which were made in two broad spectral bands from 60 to 300 microns and from 150 to 300 microns. These results indicate that there are many bright H II regions embedded in a diffuse underlying band of emission in the examined longitude range, that the color temperatures range from 30 to 90 K, and that the width of the plane is at least 2 deg of arc in both spectral bands. A lower-limit IR luminosity of the order of 1 billion suns is computed for both the bright complex of sources at the nucleus and the underlying diffuse emission out to about + or -15 deg of arc from the nucleus. The strong relationship between far-IR emission and radio continuum expected for discrete sources is illustrated, and the results are compared with those of previous studies. It is concluded that the total far-IR luminosity of the central part of the Galaxy is understandable solely in terms of known distributions of stars and dust.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 214
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  • 22
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    90-GHz flux-density measurements of variable radio sources (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results are presented for measurements of the flux densities of 10 variable extragalactic sources at 85.2 or 90 GHz, which were made over a period of almost seven years with the NRAO 36-ft millimeter-wave antenna. The primary flux-density calibration standards used include Jupiter, Saturn, Mars, and the small-diameter Galactic source DR 21. Measured flux densities are given as a function of time (in years) for the sources 3C 84, NRAO 150, 3C 120, OJ 287, 4C 39.25, 3C 273, 3C 279, 3C 345, BL Lac, and 3C 454.3. No statistically meaningful flux-density changes during an observing interval (1 to 3 days) are detected for any source, and a high degree of correlation between flux-density variations at 85.2 or 90 GHz and those observed at lower frequencies is found in all 10 sources. Some variations observed at different frequencies in several individual sources are briefly discussed.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 82; Apr. 197
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  • 23
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    Copernicus observations of the Ap star Epsilon Ursae Majoris (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Spectral scans of the Ap star Epsilon UMa made with the Copernicus satellite show strong line blanketing from profuse Cr II and Fe II lines. In the spectral region covering 1900 to 3000 A, about 500 lines are present which suppress the apparent continuum by at least 15-30%. An accurate line-identification list is compiled showing Eu II present in addition to Mn II and Ni II. The identification of Eu II, however, rests on very stringent identification limits for Fe II. If these are relaxed, the existence of Eu II is dubious. There are no broad features in this spectral region which would suggest strong photoionization discontinuities by metals, but one feature near 2137 A might contain the photoionization edge due to Cr I 5S lying 0.94 eV above the ground level. However, a significant correlation between the line-blanketing strength and the amplitude of the OAO-2 ultraviolet light curves was found such that both monotonically increase in the same proportion toward shorter wavelengths. This gives additional strength to the suggestion that variations in the metal line-blanketing cause the observed photometric variations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 33; Jan. 197
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  • 24
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    5 GHz observations of galactic supernova remnants (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Brightness and polarization distributions over several galactic supernova remnants have been observed at a wavelength of 6 cm. These observations have confirmed the nonthermal nature of most of the observed sources. It is suggested, however, that the objects G33.1-0.1 (KES 78), G35.6-0.0, G37.6-0.1, G37.7+0.1, and G37.9-0.4 are thermal. The results of these observations are presented in the form of total intensity contour maps with superimposed polarization vectors.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 55; 1, Fe; Feb. 197
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  • 25
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    Far-ultraviolet imagery of the Barnard Loop Nebula (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An electrographic Schmidt camera carried on a sounding rocket has yielded far-ultraviolet (1050-2000 A and 1230-2000 A) images of the Barnard Loop Nebula and of the general background in the Orion region due to scattering of ultraviolet starlight by interstellar dust particles. The total intensity in the Barnard Loop region agrees well with OAO-2 measurements, but the discrete Loop structure contributes only some 15% of the total. The measurements are consistent with a relatively high albedo for the dust grains in the far-ultraviolet.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 212
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  • 26
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    Apollo-16 far-ultraviolet spectra in the Large Magellanic Cloud (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Spectra in the wavelength ranges from 900 to 1600 A and 1050 to 1600 A of some OB associations in the Large Magellanic Cloud were obtained from the lunar surface by the Apollo-16 far-ultraviolet camera/spectrograph on April 22, 1972. The observed spectral distributions appear consistent with a stellar model having an effective temperature of 30,000 K, reddened by E(B-V) = 0.3, and characterized by the average far-ultraviolet extinction curve of Bless and Savage (1972). However, the absolute intensity of the far-ultraviolet spectrum of the associations NGC 2050 and 2055 seems somewhat too bright in comparison with ground-based photometry.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 211
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  • 27
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    Far infrared observations of IRC + 10216 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results are reported for measurements of IRC + 10216 at 100 microns made with the 91-cm telescope of NASA's Kuiper Airborne Infrared Observatory. The IR photometer employed consisted of a gallium-doped germanium photoconductive detector with a MOSFET preamplifier and load resistor. Signals obtained from the source at modulation frequencies of 30 and 100 Hz are plotted, and the 100-micron flux measurements are shown to be in agreement with previous bolometric measurements. It is noted that the sensitivity of the photoconductive detection system is comparable to that of the conventional bolometers that have been used in airborne IR observations.
    Keywords: ASTRONOMY
    Type: Nature; 265; Feb. 10
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  • 28
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    The SAS-3 X-ray observatory (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The experiment section of the Small Astronomy Satellite-3 (SAS-3) launched in May 1975 is an X-ray observatory intended to determine the location of bright X-ray sources to an accuracy of 15 arc-seconds; to study a selected set of sources over a wide energy range, from 0.1 to 55 keV, while performing very specific measurements of the spectra and time variability of known X-ray sources; and to monitor the sky continuously for X-ray novae, flares, and unexpected phenomena. The improvements in SAS-3 spacecraft include a clock accurate to 1 part in 10 billion, rotatable solar panels, a programmable data format, and improved nutation damper, a delayed command system, improved magnetic trim and azimuth control systems. These improvements enable SAS-3 to perform three-axis stabilized observations of any point on the celestial sphere at any time of the year. The description of the experiment section and the SAS-3 operation is followed by a synopsis of scientific results obtained from the observations of X-ray sources, such as Vela X-1 (supposed to be an accreting neutron star), a transient source of hard X-ray (less than 36 min in duration) detected by SAS-3, the Crab Nebula pulsar, the Perseus cluster of galaxies, and the Vela supernova remnant.
    Keywords: ASTRONOMY
    Type: APL Technical Digest; 14; Oct
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  • 29
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    UBV and JHKL photometry of the radio star UX Ari = HD 21242 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Acta Astronomica; 25; 2, 19; 1975
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  • 30
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    Observing prospects for Halley's comet (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The expected path and brightness development of Halley's comet soon before and after its perihelion on February 9, 1986 are described. It is concluded that the comet will prove disappointing to most U.S. observers, since it is not expected to equal Kohoutek in peak magnitude (and since this latter comet was disappointing to the general public). Moreover, Halley's comet will be brightest (3rd magnitude) in the southern hemisphere, and increased outdoor lighting by the year 1986 will probably obscure its tail near cities.
    Keywords: ASTRONOMY
    Type: Sky and Telescope; 49; June 197
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  • 31
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    Photometric detection of extrasolar planets using L.S.T.-type telescopes (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Detection of planets similar to the earth and Jupiter that might be circling nearby stars is possible with the large space telescope (LST), or modifications of this instrument. The use of the moon as an occulter to increase the signal-to-noise ratio and the expected photon fluxes from hypothetical planetary companions to alpha Centauri A and B, tau Ceti, and epsilon Eridani are discussed. Because Barnard's Star is a red dwarf of visual apparent magnitude 9.5, photometric detection of its hypothetical Jupiter-like companion would be difficult using the LST-occulter system described in this paper.
    Keywords: ASTRONOMY
    Type: British Interplanetary Society; vol. 28
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  • 32
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    Binary galaxy orbit statistics. I - Fixed mass and major axis (1975)
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    Publication Date: 2011-08-16
    Description: Averages for the projected separation, squared radial velocity difference, and the product of these, are presented for a binary galaxy system of fixed mass and major axis, but any orbital eccentricity. The average of the product varies by a factor about 3 for eccentricities from 0 to 1.0. For circular orbits, the results agree with those of Page (1952, 1960, 1961), but for linear orbits his mass estimate is too small by a factor 6. The mutual regressions of the velocity and separation on each other are calculated, and are presented in such a way as to exhibit the relative likelihood of occupation of the different parts of the regression curves. 'Isopleths' for the probability distribution are presented for a few values of the eccentricity to illustrate the underlying cause of pileup at certain parts of the regression curves. It is concluded that previous analyses were inadequate for failing to take into account that the regression curves represent in many cases a distribution that is almost wholly depopulated through most of the range. It is evident that the data are insufficient to draw a firm conclusion about the distribution of eccentricities.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 197; May 1
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  • 33
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    Photometry of a bright filament in the Orion nebula (1975)
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    Publication Date: 2011-08-16
    Description: The spectrum of a bright filament in the outer portion of the Orion nebula, 14 min from the Trapezium, was studied. The temperature of the filament, derived from /N II/ lambda 5755/6583 ratio, is 9560 K. The electron density (from /S II/ lambda 6717, 6731) is low: 360 plus or minus 150 per cu cm. The ionic abundances of He(+), N(+), O(++), and S(-) are about the same as Peimbert and Costero (1969) found in regions in Orion closer to the Trapezium. It is concluded that the filament is photoionized, presumably by the Trapezium, rather than a shock front, as had originally been suspected.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 34
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    Interstellar scintillation of extragalactic radio sources (1975)
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    Publication Date: 2011-08-16
    Description: Observations of 12 compact extragalactic sources were made at 2695 and 8085 MHz in order to detect weak intensity fluctuations caused by interstellar scintillation. Pulsar data are used to estimate the parameters of the interstellar medium needed to interpret the measured upper limits in terms of source angular diameters which are much larger than the scintillation cutoff diameter. It is shown that the observed source rms brightness temperatures are less than 10 to the 15th K and 10 to the 14th K at 2695 and 8085 MHz, respectively, making self-absorbed proton-synchroton radiation and high-brightness coherent mechanisms unlikely. If the sources are composed of 'point' components, each source can contain no fewer than 10,000 such components.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 197; Apr. 1
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    Aperture synthesis observations of galactic H II-regions (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Aperture synthesis observations at 2.695 GHz and 8.085 GHz of the H II regions NRAO 591, NGC 6857, NGC 7538, M8, W3 and W49A made with the NRAO interferometer are presented. A set of Gaussian functions is derived to describe the radiation distribution of each H II region at each frequency. Fine structure is found in all regions. With the exception of the extended source in W49A, all previously known sources with high excitation parameters are resolved into smaller sources. The electron densities of individual sources range from 100 per cu cm up to 100,000 per cu cm. In NGC 6857, NGC 7538 and W49A, continuum sources smaller than 4 arc sec and with electron densities exceeding 10,000 per cu cm are found close to the known class II OH emission sources. In M8, we find a ring which seems to be split at the position of the O-star Herschel 36.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 38; 1, Ja; Jan. 197
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  • 36
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    On angular momentum transfer in binary systems (1975)
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    Publication Date: 2011-08-16
    Description: The maximum limit for the conversion of orbital angular momentum into rotational angular momentum of the mass-gaining component in a close binary system is derived. It is shown that this conversion process does not seriously affect the rate of orbital period change and can be neglected in computing the mass transfer rate. Integration of this limit over the entire accretion process results in a value for the maximum accumulated rotational angular momentum that is 3 to 4 times larger than that implied by the observed underluminosity of stars in such systems as Mu(1) Sco, V Pup, SX Aur, and V356 Sgr. It is suggested that shell stars and emission-line stars in binary systems may be produced when the core angular momentum is transferred into an envelope having a rotational angular momentum close to the maximum limit.-
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 170
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  • 37
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    Gamma ray astronomy (1975)
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    Publication Date: 2011-08-16
    Description: A survey of the instruments developed for gamma ray astronomy is given together with a brief summary of the current status of the observational results. These include the studies of galactic gamma ray emission, the diffuse, presumably extragalactic, gamma radiation, and localized gamma ray sources. The study of the spatial distribution of galactic gamma radiation is beginning to provide a new means for the study of galactic structure and dynamics. The diffuse emission may provide evidence of gamma ray emission in the cosmological past, although improved observations must be obtained before the picture can be clarified. The study of localized sources has shown NP0532, the Crab radio pulsar, to be a gamma ray pulsar also and strong emission from Vela may be due to supernova produced cosmic rays interacting with the remnant gas.
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  • 38
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    Counterglow from the earth-moon libration points (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results from the OSO-6 Rutgers Zodiacal Light Analyzer experiment show photometric perturbations above the background in the antisun line of sight. Sixteen successive lunations were examined, and the accumulated perturbations show a maximum value in the direction of the L4 and L5 earth-moon libration points. This is interpreted as a counterglow from a cloud of particles at the libration points. The average brightness of these libration clouds is 20 S10 Vis. The average angular size of the libration clouds is approximately 6 degrees. Their position varies from one lunation to the next, within an ellipsoidal zone centered on the libration-point direction, with its semimajor axis, of approximately 6 degrees, nominally in the ecliptic and its semiminor axis, of approximately 2 degrees perpendicular to the ecliptic. The position of these clouds with respect to the Lagrangian L4 and L5 points is towards the moon in the northern summer and away from the moon in the northern winter.
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  • 39
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    X-ray and gamma-ray astronomy (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Accomplishments in the fields of X-ray and gamma ray astronomy are discussed. Data obtained from IMP and OGO satellites are analyzed to determine the sources of interplanetary radiation bursts. The energy spectrum of cosmic gamma ray bursts as observed by IMP-6 is described. The application of cooling blackbody techniques as a method for examining cosmic gamma ray bursts is reported. The experimental results and theoretical interpretation of high energy diffuse gamma rays are investigated. The structure of the SAS-2 satellite is depicted and the accomplishments are examined. Other sources of gamma radiation to include galactic fermi, Cygnus X-1, supernovae, and the planet Jupiter are proposed. Data obtained from the Pioneer 10 space probe are presented in graph form.
    Keywords: ASTRONOMY
    Type: Significant Accomplishments in Sci. and Technol.; p 34-91
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  • 40
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    Cometary Physics (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A history of comets and cometary observations is presented. Emphasis is placed on the observations and characteristics of the Comet Kohoutek. A schematic drawing of a comet is included to show the structure of the nucleus, coma, dust tail, ion tail, and natural hydrogen cloud. A joint observatory for cometary research, located in New Mexico, is described. Observations of magnetic fields in comets are analyzed. Infrared spectral observations of comet structure in the 10 micron atmospheric window are reported.
    Keywords: ASTRONOMY
    Type: Significant Accomplishments in Sci. and Technol.; p 2-33
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  • 41
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    Far-ultraviolet imagery of the Orion Nebula (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Two electrographic cameras carried on a sounding rocket have yielded useful-resolution far-ultraviolet (1000-2000 A) imagery of the Orion Nebula. The brightness distribution in the images is consistent with a primary source which is due to scattering of starlight by dust grains, although an emission-line contribution, particularly in the fainter outer regions, is not ruled out. The results are consistent with an albedo of the dust grains that is high in the far-ultraviolet and which increases toward shorter wavelengths below 1230 A.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 217
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  • 42
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    OSO-8 X-ray observations of AM Herculis (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Results are reported for hard X-ray observations of the binary system AM Her, which were coincident with soft X-ray and ground-based optical measurements. In the 2-60-keV band, variability was detected with an eclipse during phases 0.5 to 0.7 with respect to the 0.12892-day optical minima, synchronous with the known soft X-ray eclipse. The 2-60-keV uneclipsed flux was 9.5 by 10 to the -10th power erg/sq cm per sec, of which 86% lies above 10 keV. Thus, AM Her contains a hard source located near the similarly eclipsed soft X-ray source. The X-ray data are interpreted in terms of thermal bremsstrahlung from accretion onto a white dwarf.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 43
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    The far-infrared spectrum of the core of Sagittarius B2 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A Michelson interferometer aboard NASA's Kuiper Airborne Observatory has been used to measure the spectrum of Sgr B2 from 40 to 200 kaysers with 5-kayser resolution in a 1.4-arcmin beam. The measured spectrum is smooth and featureless with a broad maximum at about 85 kaysers. The data can be fitted analytically with a model corresponding to thermal emission by a uniform sla of dust filling the beam, with an average temperature of approximately 32 K, an optical depth at 100 microns of about 1.6, and a spectral index of the dust emissivity about 1.5. The absence of features implies either that the source is optically thick or that the emission spectrum of the individual grains is smooth in the passband. The possible physical significance of this model is discussed.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 44
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    X-ray spectra of Hercules X-1. II - The pulse (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 45
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    A1540-53, an eclipsing X-ray binary pulsator (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An eclipsing X-ray binary pulsator consistent with the location of A1540-53 has been observed. The source pulse period was 528.93 + or - 0.10 s. The binary nature is confirmed by a Doppler curve for the pulsation period. The eclipse angle of 30.5 + or - 3 deg and the 4-hour transition to and from eclipse suggest an early-type giant or supergiant primary star.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 46
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    The spectral development of Nova Cygni 1975 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Optical and near-infrared (0.3-2.5 microns) observations of Nova Cygni 1975 made during the period from August 30 to December 11, 1975, are reported. The persistent strength of O I at 8446 and 11,287 A is shown to be due to L-beta fluorescence in clouds with high (greater than 1000) H-alpha optical depth. A simple model of the nova ejecta is presented and shown to be consistent with the observed evolution of the nova spectrum.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 216
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  • 47
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    Radar detectability of asteroids - A survey of opportunities for 1977 through 1987 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The study of asteroids by earth-based radar during the period 1977 to 1987 is discussed. Detection modeling, including backscattering laws, limits of detectability, and in particular, measurement of center frequency, center-to-limb bandwidth, and areal spectral density, is reviewed. The number of detectable objects and detectable events falling into various 5-decibel radar target loss slots is estimated; a total of 60 different asteroids should be observable on about 130 occasions by either the Goldstone or Arecibo radar systems during the decade considered. Furthermore, the detectability margins for many objects should be large enough to permit more refined analysis of the radar spectrograms. Data acquired during the ten-year period may be used to find the radius, average surface roughness, rotation rate, direction of polar axis, and estimates of the Doppler frequency offsets for many of the asteroids. Also, information about radar albedos and orbital parameters may be obtainable in a number of cases.
    Keywords: ASTRONOMY
    Type: Icarus; 31; Aug. 197
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  • 48
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    UBV photometry of small and distant asteroids (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Photoelectric magnitudes and colors on the ultraviolet (UBV) system are presented for 65 minor planets, including four Mars crossers, six Trojans, and main-belt objects down to 6 km in diameter. The Trojans all have very similar colors not characteristic of the main-belt population. A paucity of S-type asteroids at the smallest diameters, predicted from trends seen at larger sizes, is not observed. The newly available color data for small objects ranging from 1.0 to 5.2 astronomic units in heliocentric distance show the main belt to be a transition zone between predominantly silicate and carbonaceous compositions.
    Keywords: ASTRONOMY
    Type: Icarus; 31; Aug. 197
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  • 49
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    Effect of the Shuttle contaminant environment on a sensitive infrared telescope (1977)
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    Publication Date: 2011-08-17
    Description: A sensitive IR telescope on the Space Shuttle Orbiter will be limited in its performance by fluctuations in the IR radiation from the natural environment and the contaminant atmosphere. Models of the Orbiter's contaminant atmosphere were used to predict its spectral radiance from 3 to 300 microns. At 350 km, statistical fluctuations in the radiation from a water vapor column, and a noise equivalent power were measured. This noise is somewhat smaller than the expected contribution from zodiacal light from 5 to 30 microns. The column density of all IR emitting molecules can be kept low only if restrictions on rocket firings and liquid vents are maintained. The relatively low frequency of particle sightings from Skylab, coupled with improvements in Orbiter venting techniques, indicate that sightings of particles 2 microns and larger in radius will not seriously hamper telescope performance provided that liquid vents and rocket firings are properly restricted.
    Keywords: ASTRONOMY
    Type: Applied Optics; 16; Aug. 197
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  • 50
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    A new optical supernova remnant in Cygnus (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The letter reports the discovery of a filamentary emission-line structure at right ascension 19 hr 31 min and declination +31 deg 10 min (1950) during an emission-line survey of the Milky Way. This structure is classified as a supernova remnant on the basis of its similarity to several other SNRs, but is shown not to be part of the Gamma Cygni complex. A physical diameter of about 70 pc is obtained for this SNR along with a distance of approximately 1200 pc, a shock velocity of at least 50 km/s, an initial density of about 0.5 per cu cm, and an age of approximately 300,000 yr.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 215
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  • 51
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    The ultraviolet spectra of four binaries observed with the S59 spectrometer (1977)
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    Publication Date: 2011-08-17
    Description: Ultraviolet spectra of Omicron And, Alpha CrB, Eta Ori A, and Alpha Vir, which were obtained with the S59 spectrometer at a resolution of 1.7 A in three 100-A-wide regions centered at 2110, 2454, and 2825 A, have been studied for the presence or absence of effects due to their binary nature. As may have been anticipated from their orbital and other characteristics, no indication of strong binary interactions were seen in these observations. However, there are certain spectral peculiarities suggesting the possibility of modifications of spectral classifications for some of these objects. A rather unusual spectral behavior in Alpha Vir is also noted. In addition, based primarily on a review of available literature, attention is drawn to a remarkable property of the third component in Eta Ori A.
    Keywords: ASTRONOMY
    Type: Astrophysics and Space Science; 46; Feb. 197
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  • 52
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    Spectroscopic studies of very old hot stars. II - Spectral classification, absolute magnitudes, and distances of O-type planetary nuclei (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 215
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  • 53
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    Orbital evolution (1977)
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    Publication Date: 2011-08-17
    Description: The orbital evolution of a large satellite is governed primarily by tidal interactions between the satellite and the planet it orbits. Tides raised on a planet by a satellite transfer energy and angular momentum to the satellite orbit; this changes the semimajor axes of satellite orbits, increasing the size of those orbits where the satellite mean motion is smaller than the planetary angular velocity, and decreasing those where the opposite is true. Substantial changes caused by such tides for satellites of the terrestrial planets may explain the absence of satellites about Mercury and Venus. For Jovian and Saturnian satellites, such tides probably are only important in bringing about some of the observed orbital resonances. Tides raised on satellites generally cause decreasing orbital eccentricities, indicating why close satellites always have nearly circular orbits. Different processes of orbital evolution dominate for small bodies; their effects probably are critical in positioning material in the primordial dust cloud so that satellite coagulation may occur. A qualitative description is given of the orbital results of gas drag, radiation pressure, Poynting-Robertson drag and electromagnetic forces.
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  • 54
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    Black holes and relativitic gravity theories (1977)
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    Publication Date: 2011-08-17
    Description: All presently known relativistic gravitation theories were considered which have a Riemannian background geometry and possess exact static, spherically symmetric solutions which are asymptotically flat. Each theory predicts the existence of trapped surfaces (black holes). For a general static isotropic metric, MACSYMA was used to compute the Newman-Penrose equations, the black hole radius, the impact parameter, and capture radius for photon accretion. These results were then applied to several of the better known gravitation theories.
    Keywords: ASTRONOMY
    Type: NASA. Langley Res. Center Proc. of the 1977 MACSYMA Users' Conf. (NASA); p 97-107
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  • 55
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    Gamma-ray astronomy in the medium energy (10-50 MeV) range (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: To observe the medium energy component of the intense galactic center gamma-ray emission, two balloon flights of a medium energy gamma-ray spark chamber telescope were flown in Brazil in 1975. The results indicate the emission is higher than previously thought and above the predictions of a theoretical model proposed.
    Keywords: ASTRONOMY
    Type: ESA Recent Advan. in Gamma-Ray Astronomy; p 117-124
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  • 56
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    Survey of the BY Draconis syndrome among dMe stars (1977)
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    Publication Date: 2011-08-17
    Description: Results are reported for a BVr photometric survey of 22 dK, dKe, dM, and dMe stars conducted to search for slow quasi-sinusoidal fluctuations in V (the BY Draconis syndrome). The (B-V) and (V-r) color indices are determined in an attempt to detect wavelength-dependent color changes produced by starspots and to infer starspot temperatures. It is found that nine of the stars exhibit variations in V of the order of 0.05 to 0.10 magnitude on a time scale of days or weeks, that at least three more display changes in mean light level over a period of years, that the stars generally tend to become redder at minimum light, and that some of the stars show no detectable color changes over their photometric cycle. The color data are taken to suggest a probable temperature difference of about 200 to 500 K between the stellar photospheres and starspots if the V variations are attributed to dark spots. It is concluded that the BY Draconis syndrome is clearly a very common occurrence among dMe stars.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 82; Nov. 197
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  • 57
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    Antenna concepts for interstellar search systems (1977)
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    Publication Date: 2011-08-17
    Description: An evaluation is made of microwave receiving systems designed to search for signals from extraterrestrial intelligence. Specific design concepts are analyzed parametrically to determine whether the optimum antenna system location is on earth, in space, or on the moon. Parameters considered include the hypothesized number of transmitting civilizations, the number of stars that must be searched to give any desired probability of receiving a signal, the antenna collecting area, the search time, the search range, and the cost. This analysis suggests that (1) search systems based on the moon are not cost-competitive, (2) if the search is extended only a few hundred light years from the earth, a Cyclops-type array on earth may be the most cost-effective system, (3) for a search extending to 500 light years or more, a substantial cost and search-time advantage can be achieved with a large spherical reflector in space with multiple feeds, (4) radio frequency interference shields can be provided for space systems, and (5) cost can range from a few hundred million to tens of billions of dollars, depending on the parameter values assumed.
    Keywords: ASTRONOMY
    Type: Radio Science; 12; Sept
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  • 58
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    Fourier spectroscopy in planetary research (1975)
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    Publication Date: 2011-08-16
    Description: The application of Fourier Transform Spectroscopy (FTS) to planetary research is reviewed. The survey includes FTS observations of the sun, all the planets except Uranus and Pluto, The Galilean satellites and Saturn's rings. Instrumentation and scientific results are considered. The prospects and limitations of FTS for planetary research in the forthcoming years are discussed.
    Keywords: ASTRONOMY
    Type: Space Science Reviews; 18; Nov. 197
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  • 59
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    Filter wedge spectroscopy in the region 3-6 microns (1975)
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Nature; 257; Oct. 23
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  • 60
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    Interstellar scattering of pulsar radiation. I - Scintillation (1975)
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    Publication Date: 2011-08-16
    Description: An investigation of the intensity fluctuations of 28 pulsars near 0.4 GHz indicates that spectra of interstellar scintillation are consistent with a Gaussian shape, that scintillation indices are near unity, and that the scintillation bandwidth depends linearly on dispersion measure. Observations at cm wavelengths show that the observer is in the near field of the scattering medium for objects with the lowest dispersion measures, and confirm the steep dependence of correlation bandwidth on dispersion measure found by Sutton (1971). The variations of scattering parameters with dispersion measure may indicate that the rms deviation of thermal electron density on the scale of 10 to the 11th cm grows with path length through the galaxy.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 43; 3, Oc; Oct. 197
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  • 61
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    Positions of three X-ray burst sources (1977)
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    Publication Date: 2011-08-17
    Description: Precise (20-30 arcsec) positions are reported for three steady X-ray sources that have been identified recently as X-ray burst sources: 4U (MXB) 1636-53, 4U 1728-33 (MXB 1728-34), and 4U (MXB) 1735-44. The positions were derived from data obtained with the SAS 3 rotating modulation collimators during a survey of the galactic plane. Possible optical counterparts are noted.
    Keywords: ASTRONOMY
    Type: Nature; 270; Nov. 24
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  • 62
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    High-resolution rocket spectra of the 1920-A and 1720-A features in the spectrum of Zeta Tauri (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: High-resolution ultraviolet spectrograms of the B-shell star Zeta Tau reveal two features characteristic of B supergiants, one at 1720 A and the other at 1920 A. The presence of these features in the spectrum of this object shows that they are indicative of an extended atmosphere - either the tenuous atmosphere of a supergiant or the envelope surrounding a rapidly rotating main-sequence star - and are therefore not purely luminosity criteria. The high spectral resolution allows an identification of the contributors to these features. The dominant contributor to the 1920-A feature is Fe III, while the primary contributor to the 1720-A feature is Al II.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 217
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  • 63
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    Trajectories and orbits from the NASA-NMSU Meteor Observatory. II (1977)
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    Publication Date: 2011-08-17
    Description: Trajectory data and orbital elements for 12 double-station meteors photographed by the NASA-NMSU Meteor Observatory during the winter of 1975-1976 are presented. Three of these are members of the Quadrantid stream. Photoelectric timing of meteors, uncertainties in the derived orbital elements, and monitoring of the night sky with a two-channel photometer are discussed.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 82; June 197
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  • 64
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    Optical contamination - Its prevention in the XUV spectrographs flown by the U.S. Naval Research Laboratory in the Apollo Telescope Mount (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: During construction and testing of the XUV spectrographs flown in the ATM by the Naval Research Laboratory, many problems associated with optical contamination were encountered. Solving these problems required setting up a contamination prevention program to select the materials used in constructing the instruments and to delineate procedures in assembling, testing, and storing the instruments. A brief description is given of methods of assessing the effects of contamination and of the procedures used to prevent contamination.
    Keywords: ASTRONOMY
    Type: Applied Optics; 16; Apr. 197
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  • 65
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    The high-energy celestial X-ray instrument on board OSO-8 (1977)
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    Publication Date: 2011-08-17
    Description: The 20 keV-3 MeV celestial X-ray detector on the OSO-8 is described. The primary objectives of this instrument are to measure the energy spectrum of cosmic X-ray sources above 20 keV and to search for time variations, both periodic and irregular, in the intensity of the sources detected. The detector consists of two optically isolated central crystals shielded by a large, active collimator. The sensitive area is 27.5 sq cm and the field-of-view is 5 deg FWHM. The instrument is mounted in the wheel section of OSO-8 with the axis of its field of view offset by 5 deg from the negative spin axis of the wheel. The minimum detectable intensity of a point source which is brought to within 5 deg of the negative spin axis for greater than one day is about 10 to the minus fifth power photons/sq cm-sec at 100 keV.
    Keywords: ASTRONOMY
    Type: Space Science Instrumentation; 3; Nov. 197
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  • 66
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    NH3 spectral line measurements on earth and Jupiter using a 10 micron superheterodyne receiver (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
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  • 67
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    Theory of thin-screen scintillations for a spherical wave (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A thin-screen scintillation theory for a spherical wave is presented under the 'quasi-optical' approximation. The 'scattering angle', the 'observed angle', the intensity correlation function, and the temporal pulse broadening are calculated for the random wave. It is found that as the wave propagates outward away from the phase screen, the correlation scale of the intensity fluctuation increases linearly while the 'observed angle' decreases linearly. The calculations are carried out for both Gaussian and power-law spectra of the turbulent medium. The results are applied to an analysis of the scattering data for the Crab Nebula's radiation.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 218
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  • 68
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    Apparent wavelength dependence of v sin i for Zeta Tauri (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: It was previously reported that the derived projected rotational velocity (v sin i) of the B shell star, Zeta Tau, appeared to depend on the wavelength of the line used in the analysis. This letter documents the apparent wavelength dependence of v sin i for Zeta Tau in order to provide an observational basis against which quantitative explanations can be tested. A value of 300 km/s is adopted for v sin i on the basis of an examination of the visual line spectrum, particularly the lines of He I at 4026 and 4471 A and Mg II at 4481 A. Analysis of the far-UV resonance lines of Si III at 1206 A and Si IV at 1393 and 1463 A in Copernicus spectrograms of Zeta Tau yields a representative value of no more than 150 km/s for v sin i. Gravity darkening of the star's atmosphere and distention of the atmosphere by rapid differential rotation are considered as possible explanations for the discrepancy between the v sin i values determined from the UV and visual lines.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 218
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  • 69
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    Positions of galactic X-ray sources Cir X-1, TrA X-1 and 3U1626-67 (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Keywords: ASTRONOMY
    Type: Nature; 269; Oct. 6
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  • 70
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    Eclipses by an elliptical torus (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A general procedure for computing the effects of eclipses by a torus, including both the outer horizon and the inner or hole horizon, was developed. The procedure can be used for any of the simple figures of revolution encountered in binary-star models. That is, the thickness can be made negligible to produce a thin ring, the hole radius can be set to zero to yield a thin disk, the radius to the center of the elliptical meridian section can be brought to zero to give an ellipsoid of revolution, or the equatorial axis of the elliptical meridian section can be made to equal zero to produce a section of a right circular cylinder.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 80; Sept
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  • 71
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    Variations in Gegenschein polarization (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Claims made by Bandermann and Wolstencroft (1974) that angular structure and day-to-day variations of the polarized component of the zodiacal light were observed near the antisolar point are shown to be unsubstantiated. The data obtained by Bandermann and Wolstencroft are reviewed together with the instruments they used. It is shown that the incorrect results reported were due to observation errors.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 41; 3-4,; July 197
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  • 72
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    A search for optical pulsations from X-ray sources near 4640-4650 A and 4686 A (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: We have searched for periodic optical pulsations from Cyg X-1, Cyg X-2, 3 U 1700 - 37, Her X-1, Sco X-1, Vela X-1, SMC X-1, WRA 977, and from the central region of the Cygnus Loop. Most observations were confined to the spectral features around 4640-4650 A and 4686 A, which are seen in most X-ray source counterparts, are known to be variable, and are likely to be associated with the X-ray emission. No optical pulsations were detected, but upper limits are established and related to the X-ray behavior.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 200; Aug. 15
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  • 73
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    Recent results in ultraviolet astronomy obtained by a wide field rocket camera and the French S 183 Skylab experiment (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
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  • 74
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    Aplanatic two-mirror telescopes - A systematic study. III - The Schwarzschild-Couder configuration (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Keywords: ASTRONOMY
    Type: Applied Optics; 14; Apr. 197
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  • 75
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    Analysis and experimental measurement of straylight suppression systems for the large space telescope (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: A computer program for straylight suppression system design and analysis was developed to analyze various proposed LST straylight suppression systems. Simultaneously, experimental measurements are being made on a simplified LST straylight suppression system in a unique facility. The experimental measurements are being used to verify and improve the computer program. The facility represents the state-of-the-art in straylight suppression measurements, and transmission factors of 10 to the minus 12th power have been measured.
    Keywords: ASTRONOMY
    Type: Optical Engineering; 14; Nov
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  • 76
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    The night sky brightness at McDonald Observatory (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Baseline observations of the night sky brightness in B and V are presented for McDonald Observatory. In agreement with earlier work by Elvey and Rudnick (1937) and Elvey (1943), significant night-to-night and same-night variations in sky brightness are found. Possible causes for these variations are discussed. The largest variation in sky brightness found during a single night is approximately a factor of two, a value which corresponds to a factor-of-four variation in airglow brightness. The data are used to comment on the accuracy of previously published surface photometry of M 81.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 87
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  • 77
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    Search for extreme ultraviolet radiation from selected stars (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: Results are reported for a search for EUV radiation between 140 and 430 A from selected objects which was conducted with a rocket-borne EUV filter photometer. The candidate objects included the bright planetary nebula NGC 2392 and the stars gamma Gem, alpha CMa, omicron-prime CMa, and gamma-2 Vel. Upper limits (2-sigma level) to the flux near 200 A are determined for the five objects, and estimates of the expected 200-A helium-continuum flux are derived for two of the stars on the basis of the hot-corona model. It is found that the calculated upper limits are at least two orders of magnitude higher than plausible flux estimates based on the hot-corona model. However, it is noted that uncertainties in the flux estimates are great enough to make the upper limits useful.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics; 45; 1, De; Dec. 197
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  • 78
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    The rocket-ultraviolet spectrum of the planetary nebula NGC 7027 (1975)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: An ultraviolet spectrum of NGC 7027, obtained with a rocket-borne telescope, is analyzed. Absolute values are presented for the observed fluxes, and upper limits are given for the strongest predicted lines that were not observed. The results are corrected for interstellar extinction using the observed and calculated line ratios between H-beta and the hydrogenic recombination line of He II at 1640 A. The corrected C IV resonance line at 1549 A is found to be in good agreement with the intensity calculated from models, but the intercombination line of C III at 1909 A is found to be too bright by a factor of 10. This discrepancy is reduced to a factor of 4 by taking dielectric recombination into account and is eliminated by using the solar carbon abundance, which implies attenuation in the C IV line. It is shown that no appreciable number of absorbing grains can exist in the C IV-producing region of the nebula since the optical depth is of the order of 10,000 at the line center.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 202; Dec. 1
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  • 79
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    An element formulation for perturbed motion about the center of mass (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The perturbed motion of a rigid body about its center of mass, is formulated in terms of the six elements: l, the magnitude of the angular momentum vector; h, the total energy; delta and epsilon, two linear functions of the independent variable; and psi(1) and theta (1), two Euler angles that orientate the inertial frame with respect to the unperturbed solution. Solutions from the element formulation and the original Euler equations are numerically compared using shuttle-type data. For applied torques smaller than a given magnitude, the element formulation produced the following results: (1) larger step sizes in the numerical integration of the differential equations, resulting in an overall computational time-saving, and (2) more significant figures of accuracy in the computation of the variables describing the state of the rigid body.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 16; Nov. 197
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  • 80
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    The Tidbinbilla interferometer (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: This paper describes a technique to detect and identify weak, small-diameter radio sources with flux densities in the millijansky range. An interferometer system is proposed which will use existing 64 m and 24 m antennas of the Tidbinbilla Deep Space Network near Canberra. Design parameters of the system are described, and a schematic is presented with attention to low-noise traveling wave masers, and phase oscillation devices.
    Keywords: ASTRONOMY
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  • 81
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    Analysis of penumbral eclipse data (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two days of data from the ATS-6 1976 eclipse season were analyzed to determine the effects of varying photoelectron flux on spacecraft potential. Particular emphasis was placed on the variation in potential as the satellite entered the earth's penumbra. Measurements from the AE-C satellite of the solar UV radiation were used to construct a model of atmospheric attenuation. This model was found to be consistent with direct measurements of the variations in photoelectron flux as Injun 5 passed into eclipse. Applying the model to the ATS-6 data gave the time dependency of the solar illumination/photoelectron flux as the satellite was eclipsed. This relationship, when combined with the ATS-6 measurements of satellite potential, revealed a nearly linear relation between the solar illumination/photoelectron flux and the logarithm of the satellite potential.
    Keywords: ASTRONOMY
    Type: NASA. Lewis Res. Center Proc. of the Spacecraft Charging Technol. Conf.; p 191-201
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  • 82
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    Distance to Cygnus X-1 (1975)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Keywords: ASTRONOMY
    Type: Res. in the Space Sci., vol. 2, no.2; 70 p
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  • 83
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    X-ray burst sources (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Current knowledge of sources of X-ray bursts, defined as having rise times of less than a few seconds, durations of a few seconds to a few minutes and a generally regular recurrence pattern, is reviewed. An examination of the galactic distribution of X-ray burst sources, which has been confirmed by SAS-3 rotating modulation collimator observations, reveals that the burst sources are spread along the galactic equator and clustered near low galactic longitudes, unlike the distribution of globular clusters. At least four X-ray burst sources have been associated with steady X-ray sources based on positional coincidence, and it has been found that the X-ray bursts are less intense but harder than steady X-ray emission from these sources. Individual burst sources, including MXB1659-29, which has not been identified with a steady X-ray source, the source in NGC6624 which has been identified with 3U1820-30, MXB1837+05, associated with Ser X-1, three burst sources near the galactic center and the rapid burster MXB1730-335 are briefly discussed.
    Keywords: ASTRONOMY
    Type: New York Academy of Sciences; vol. 302
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  • 84
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    On the orbital dependence of the asteroidal collision process (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Collision of asteroids with the main-belt asteroid population is considered with the effect of the impact kinetic energy taken into account. It is found that objects in eccentric orbits have a larger probability of destructive collision as compared to objects in orbits with mean values of eccentricity (equal to 0.15) and inclination (equal to 10 deg); also orbits with small semimajor axes (about 2.3 AU) are found to have peak values of the probability of destructive collision.
    Keywords: ASTRONOMY
    Type: Icarus; 32; Nov. 197
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  • 85
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    Observations of NGC 4151 from Uhuru (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Uhuru X-ray observations of NGC 4151 over the energy range from 2 to 10 keV are reported. A best-fit exponential power-law spectrum with a constant of 0.0096 and a spectral index of -0.1 is determined for the cited energy range. A comparison with Ariel 5 results indicates that a previously reported intensity variation was accompanied by a change in spectral shape. It is suggested that the X-ray source might have two components.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 218
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  • 86
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    Infrared spectra of the WN stars HD 50896 and HD 151932 (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific; vol. 89
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  • 87
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    A note of expansions of functions of velocity in the two-body problem (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: Fourier expansions based on both the true anomaly and the mean anomaly are obtained for the functions of velocity in the two-body problem; the series of coefficients is written from classical formulae involving associated Legendre polynomials, Gegenbauer polynomials, or Bessel functions. The Fourier expansions are compared with the expansions in powers of eccentricity developed by Broucke (1974) through use of computerized Poisson series manipulation.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics; 15; Aug. 197
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  • 88
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    MK spectral classifications for southern OB stars (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 35; Sept
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  • 89
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    The Copernicus ultraviolet spectral atlas of Tau Scorpii (1977)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Description: An ultraviolet spectral atlas is presented for the B0 V star, Tau Scorpii. It has been scanned from 949 to 1560 A by the Princeton spectrometer aboard the Copernicus satellite. From 949 to 1420 A the observations have a nominal resolution of 0.05 A. At the longer wavelengths, the resolution is 0.1 A. The atlas is presented in both tables and graphs.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series; 35; Sept
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  • 90
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    The Copernicus ultraviolet spectral atlas Tau Scorpii (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An ultraviolet spectral atlas was presented for the B0 V star, Tau Scorpii. It was scanned from 949 to 1560 A by the Princeton spectrometer aboard the Copernicus satellite. From 949 to 1420 A the observations have a nominal resolution of 0.05 A. At the longer wavelengths, the resolution was 0.1 A. The atlas was presented in both tables and graphs.
    Keywords: ASTRONOMY
    Type: NASA-CR-156690
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  • 91
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    Extended observations of Vela X-1 by OSO-8 (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Goddard Space Flight Center Cosmic X-Ray Experiment aboard OSO-8 viewed the X-ray binary pulsar, Vela X-1, on three occasions from late 1975 through late 1976. The X-ray spectrum is well represented by a power law modified by photoelectric absorption, a high energy cutoff, and a line feature at approximately 6.8 keV. When combined with other observations, our measurements show that the pulse period is not decreasing monotonically. The three eclipses observed all indicate a significant eclipse flux.
    Keywords: ASTRONOMY
    Type: NASA-TM-78098
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  • 92
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    Study of an astronomical extreme ultraviolet rocket spectrometer for use on shuttle missions (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The adaptation of an extreme ultraviolet astronomy rocket payload for flight on the shuttle was studied. A sample payload for determining integration and flight procedures for experiments which may typically be flown on shuttle missions was provided. The electrical, mechanical, thermal, and operational interface requirements between the payload and the orbiter were examined. Of particular concern was establishing a baseline payload accommodation which utilizes proven common hardware for electrical, data, command, and possibly real time monitoring functions. The instrument integration and checkout procedures necessary to assure satisfactory in-orbit instrument performance were defined and those procedures which can be implemented in such a way as to minimize their impact on orbiter integration schedules were identified.
    Keywords: ASTRONOMY
    Type: NASA-CR-156655
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  • 93
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    Cygnus A at 99 GHz: Observations of the three principal components and interpretation of the central source (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The three principal emission components of Cygnus A were observed at 99 GHz, the highest frequency at which radio measurements of this source have been accomplished. The observations show no definite indication of a high-frequency cutoff in the spectrum of the compact central component, which perhaps may be attributed to an optically thin synchrotron source that peaks at a frequency of several hundred GHz.
    Keywords: ASTRONOMY
    Type: NASA-TM-78068 , X-685-77-272
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  • 94
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    Planetary astronomy program (1977)
    In:  CASI
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    Publication Date: 2019-06-27
    Description: A program was developed in which asteroids and two planets, namely, Saturn and Uranus, were investigated. This included: (1) asteroid spectrophotometry; (2) the nature of the Trojan asteroids; (3) an investigation to determine asteroid masses; (4) the photometry, structure, and dynamics of the rings surrounding the planet Saturn; and (5) aerosol distribution in the atmosphere of Uranus. Plans were finalized to obtain observations of the nucleus of the dying comet P/Arend-Rigaux. Further work was accomplished in asteroid data reduction. Data were entered into the TRIAD data file and a program generated classifications for over 560 different asteroids. A photoelectric area scanner was used to obtain UBV scans of the disk of the planet Saturn on several winter and spring nights in 1977. Intensity profiles show pronounced limb brightening in U, moderate limb brightening in B, and limb darkening in V. Narrow band photoelectric area-scanning photometry of the Uranus disk is also reported. Results are given.
    Keywords: ASTRONOMY
    Type: NASA-CR-154512
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  • 95
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    High-energy X-ray observations of a lunar occultation of the Crab Nebula (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 197; Apr. 15
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  • 96
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    The diffuse interstellar features studied in HD 21389 by polarimetry and spectrophotometry (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 195; Jan. 15
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  • 97
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    Ultraviolet photometry from the orbiting astronomical observatory. XVIII - The 1972 eclipse of 31 Cygni (1975)
    In:  Other Sources
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    Publication Date: 2019-06-27
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; 195; Jan. 1
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  • 98
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    A decametric wavelength radio telescope for interplanetary scintillation observations (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.
    Keywords: ASTRONOMY
    Type: NASA-CR-143176 , U-OF-IOWA-75-12
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  • 99
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    An upper limit to the low-energy X-ray flux from beta Persei (1975)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A region of the sky including the binary system Algol (beta Persei) was observed with a one-dimensional, grazing-incidence X-ray telescope sensitive in the energy range from 0.5 to 4.0 keV. No statistically significant flux was detected above that attributable to the diffuse and cosmic-ray induced backgrounds. This result allows an upper limit of .02 billionths of an erg/sq cm sec keV at 1.6 keV to be set for the X-ray emission from this source at the epoch of observation. The absence of detectable low-energy X-rays is consistent with a thermal radio source, on condition that no flares occurred at the time of observation.
    Keywords: ASTRONOMY
    Type: Astrophysical Letters; 16; 1975
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  • 100
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    Three-dimensional determination of the center of the Watts datum relative to the lunar center of mass (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The location of the origin of the Watts datum for the marginal zone of the moon is determined using results of 2770 photoelectric occultation observations obtained over an 18-yr period in combination with 1787 laser time-delay measurements carried out over a five-year period. The lunar ephemeris employed is an experimental one developed from a much shorter span of laser observations. The final solution is obtained by adopting LURE2 parameters and correcting 19 lunar orbital, solar orbital, and coordinate-system parameters. The offsets for the center of the Watts datum are found to be approximately +6.8 km for x1, -2.5 km for x2, and +0.06 km for x3 with respect to the lunar principal axes of inertia.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 82; Apr. 197
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