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  • ASTRONOMY
  • 1985-1989
  • 1980-1984
  • 1975-1979  (213)
  • 1975  (213)
  • 1
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    General-altitude transformations between geocentric and geodetic coordinates (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.-
    Schlagwort(e): ASTRONOMY
    Materialart: Celestial Mechanics; 12; Sept
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  • 2
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    La Posta Astrogeophysical Observatory (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Solar Physics; 43; July 197
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  • 3
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    Airborne infrared astronomy (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Mercury; 4; July-Aug
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  • 4
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    High-energy gamma-ray astronomy (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Physics Today; 28; Sept
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  • 5
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    Mariner 9 observations of beta Cephei stars (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
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  • 6
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    Scientific instrumentation of the Radio-Astronomy-Explorer-2 satellite (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomy and Astrophysics; 40; 4, Ma; May 1975
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  • 7
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    Soft X-ray emission from Hercules X-1 (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; July 15
    Format: text
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  • 8
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    Period changes in Centaurus X-3 (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; July 15
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  • 9
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    The light curve of CV Serpentis, the sometimes-eclipsing Wolf-Rayet star (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; July 15
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  • 10
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    The spectrum of HD 125823 /a Centauri/ (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; July 1
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  • 11
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    Conclusions from the discussions on observational results of heterodyne spectroscopy in astronomy (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.-
    Schlagwort(e): ASTRONOMY
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  • 12
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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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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
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  • 13
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    Studies of the infrared source CRL 2688 (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 198; June 15
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  • 14
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    The eclipsing binary CW Eridani (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Acta Astronomica; 25; 2, 19; 1975
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  • 15
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    Shadow of the head of Comet Kohoutek (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Nature; 253; Feb. 20
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  • 16
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    A statistical technique for processing radio interferometer data (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: IEEE Transactions on Antennas and Propagation; AP-23; Jan. 197
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  • 17
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    The SAS-3 X-ray observatory (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: APL Technical Digest; 14; Oct
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  • 18
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    UBV and JHKL photometry of the radio star UX Ari = HD 21242 (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Materialart: Acta Astronomica; 25; 2, 19; 1975
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  • 19
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    Observing prospects for Halley's comet (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Sky and Telescope; 49; June 197
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  • 20
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    Photometric detection of extrasolar planets using L.S.T.-type telescopes (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: British Interplanetary Society; vol. 28
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  • 21
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    Binary galaxy orbit statistics. I - Fixed mass and major axis (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; May 1
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  • 22
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    Photometry of a bright filament in the Orion nebula (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
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  • 23
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    Interstellar scintillation of extragalactic radio sources (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; Apr. 1
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  • 24
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    Aperture synthesis observations of galactic H II-regions (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomy and Astrophysics; 38; 1, Ja; Jan. 197
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  • 25
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    On angular momentum transfer in binary systems (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.-
    Schlagwort(e): ASTRONOMY
    Materialart: Royal Astronomical Society; vol. 170
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  • 26
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    Gamma ray astronomy (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
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  • 27
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    Counterglow from the earth-moon libration points (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
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  • 28
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    X-ray and gamma-ray astronomy (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Significant Accomplishments in Sci. and Technol.; p 34-91
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  • 29
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    Cometary Physics (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Significant Accomplishments in Sci. and Technol.; p 2-33
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  • 30
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    Fourier spectroscopy in planetary research (1975)
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Space Science Reviews; 18; Nov. 197
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  • 31
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    Filter wedge spectroscopy in the region 3-6 microns (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Materialart: Nature; 257; Oct. 23
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  • 32
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    Interstellar scattering of pulsar radiation. I - Scintillation (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomy and Astrophysics; 43; 3, Oc; Oct. 197
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  • 33
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    Eclipses by an elliptical torus (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Journal; 80; Sept
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  • 34
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    Variations in Gegenschein polarization (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomy and Astrophysics; 41; 3-4,; July 197
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  • 35
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    A search for optical pulsations from X-ray sources near 4640-4650 A and 4686 A (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 200; Aug. 15
    Format: text
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  • 36
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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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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Format: text
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  • 37
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    Aplanatic two-mirror telescopes - A systematic study. III - The Schwarzschild-Couder configuration (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Schlagwort(e): ASTRONOMY
    Materialart: Applied Optics; 14; Apr. 197
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  • 38
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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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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Optical Engineering; 14; Nov
    Format: text
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  • 39
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    The night sky brightness at McDonald Observatory (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
    Format: text
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  • 40
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    Search for extreme ultraviolet radiation from selected stars (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomy and Astrophysics; 45; 1, De; Dec. 197
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  • 41
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    The rocket-ultraviolet spectrum of the planetary nebula NGC 7027 (1975)
    In:  Other Sources
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    Publikationsdatum: 2011-08-16
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 202; Dec. 1
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  • 42
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    Distance to Cygnus X-1 (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-01-25
    Schlagwort(e): ASTRONOMY
    Materialart: Res. in the Space Sci., vol. 2, no.2; 70 p
    Format: text
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  • 43
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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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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; Apr. 15
    Format: text
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  • 44
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    The diffuse interstellar features studied in HD 21389 by polarimetry and spectrophotometry (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 195; Jan. 15
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  • 45
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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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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 195; Jan. 1
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  • 46
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    A decametric wavelength radio telescope for interplanetary scintillation observations (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-143176 , U-OF-IOWA-75-12
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  • 47
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    An upper limit to the low-energy X-ray flux from beta Persei (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: 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.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Letters; 16; 1975
    Format: text
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  • 48
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    Centaurus X-3 - New low- and medium-energy X-ray observations (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Low- and medium-energy X-ray observations of Cen X-3 during two pointed sounding-rocket experiments are discussed. The lack of low-energy emission from Cen X-3 is consistent with the identification of Krzeminski's star as the optical counterpart of Cen X-3 and normal reddening, in contrast to an earlier measurement by Bleeker et al (1973).
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; Apr. 15
    Format: text
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  • 49
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    The X-ray, optical, and radio behavior of Scorpius X-1 - The 1972 coordinated observations (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; Apr. 15
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  • 50
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    Polar motion spectra based upon Doppler IPMS and BIH data (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: In comparing polar motion spectra, an oscillation was found at 1.3 cpy which might be due to an Eulerian motion of the solid inner core. An extended 15-year data set was filtered and analyzed to yield a Chandler peak with a period 430.8 solar days and a full width at half-maximum of 0.7 days (Q-600). The data was reanalyzed in overlapping 3-year segments and indicates that the excitation of the Chandler wobble is a discrete process and that periods as long as three years occur in which the driving mechanism is essentially quiescent.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-70924 , X-921-75-157
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  • 51
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    Treatment of atomic and molecular line blanketing by opacity sampling (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: An opacity sampling (OS) technique for treating the radiative opacity of large numbers of atomic and molecular lines in cool stellar atmospheres is presented. Tests were conducted and results show that the structure of atmospheric models is accurately fixed by the use of 1000 frequency points, and 500 frequency points is often adequate. The effects of atomic and molecular lines are separately studied. A test model computed by using the OS method agrees very well with a model having identical atmospheric parameters computed by the giant line (opacity distribution function) method.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-143097
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  • 52
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    Pulsar average waveforms and hollow cone beam models (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: An analysis of pulsar average waveforms at radio frequencies from 40 MHz to 15 GHz is presented. The analysis is based on the hypothesis that the observer sees one cut of a hollow-cone beam pattern and that stationary properties of the emission vary over the cone. The distributions of apparent cone widths for different observed forms of the average pulse profiles (single, double/unresolved, double/resolved, triple and multiple) are in modest agreement with a model of a circular hollow-cone beam with random observer-spin axis orientation, a random cone axis-spin axis alignment, and a small range of physical hollow-cone parameters for all objects.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-70917 , X-693-75-138
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  • 53
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    The spectral energy distribution of NGC 1275 (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: An analysis of absolute spectral energy distributions of interstellar gas for a galaxy (NGC 1275) is presented. Infrared spectra data shows heavy reddening. It is proposed that the interstellar gas may be ionized by shock waves or by nonthermal or stellar radiation. It is suggested, that high velocity, emission-line knots are H2 regions in a Perseus cluster galaxy or intergalactic gas cloud seen in projection against NGC 1275.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-143039
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  • 54
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    Far infrared spectroscopy of the Orion Nebula (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A coarse resolution spectrum of the Orion Nebula between 65 and 125 microns is presented which closely fits the color dependence of a 75 K blackbody. A high resolution search for O III at 88.16 microns yields an upper limit below theoretical predictions. Observations were carried out in November, 1974, using the 31 cm gyrostabilized telescope mounted in the NASA Lear jet. The instrument employed was a fully liquid helium cooled grating spectrometer with a 3 mm entrance slit that gave a square beam on the sky, 5 arc minutes in diameter. The results are presented.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142697
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  • 55
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    Scattering by dust and the photographic appearance of eta Carinae (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 202; Dec. 1
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  • 56
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    Observations of an isolated compact infrared source in Perseus (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 202; Dec. 1
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  • 57
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    Detection of the O III 88.16-micron forbidden line in M17 (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: This paper reports the detection of the fine-structure forbidden line of O III at 88.16 microns in emission from M 17 (the Omega Nebula), which is an optically bright galactic H II region and a strong thermal radio source. The observations were made using an airborne 30-cm telescope and a liquid helium-cooled grating spectrometer with Ge:Ga photoconductive detectors. The line intensity is found to be 2.2 (+1.0, -0.7) by 10 to the -15th power W/sq cm. The results are compared with those of a search for the present line in M 42 as well as with theoretical predictions of the line intensity.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 202; Nov. 15
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  • 58
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    Ultraviolet photometry and spectrophotometry of Algol (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: OAO-2 blue and UV light curves and spectrophotometric observations are used to establish effective temperatures and luminosities for the three components of the eclipsing Algol (beta Persei) system. An essentially complete energy distribution is given for Algol, and the fundamental properties - geometrical quantities, wavelength-dependent quantities and derived astrophysical quantities - are presented for the star.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
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  • 59
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    Study of Permanent Magnet Focusing for Astronomical Camera Tubes (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: A design is developed of a permanent magnet assembly (PMA) useful as the magnetic focusing unit for the 35 and 70 mm (diagonal) format SEC tubes. Detailed PMA designs for both tubes are given, and all data on their magnetic configuration, size, weight, and structure of magnetic shields adequate to screen the camera tube from the earth's magnetic field are presented. A digital computer is used for the PMA design simulations, and the expected operational performance of the PMA is ascertained through the calculation of a series of photoelectron trajectories. A large volume where the magnetic field uniformity is greater than 0.5% appears obtainable, and the point spread function (PSF) and modulation transfer function(MTF) indicate nearly ideal performance. The MTF at 20 cycles per mm exceeds 90%. The weight and volume appear tractable for the large space telescope and ground based application.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-143716
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  • 60
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    On the oscillation of the laterally heterogeneous earth, 1 (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The perturbative effects, as cause by lateral inhomogeneities in the earth structure and by Coriolis force, contaminate the originally toroidal and spheroidal earth's oscillations, making them of mixed type. For this reason, in order to make the computation of the perturbations more uniform and homogeneous, it was suggested that the earth's free oscillations be expanded into a series in terms of generalized harmonics familiar from the theory of angular momentum in quantum mechanics. Making use of Gibbsian symbolism and of some operators from the theory of angular momentum, explicit expressions were deduced for the perturbative terms in the differential equation of the earth's free oscillations. Decomposition of the strain tensor in terms of canonical vectors was also obtained.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-70869 , X-920-75-62
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  • 61
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    A timeline algorithm for astronomy missions (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: An algorithm is presented for generating viewing timelines for orbital astronomy missions of the pointing (nonsurvey/scan) type. The algorithm establishes a target sequence from a list of candidate targets in a way which maximizes total viewing time. Two special cases are treated. One concerns dim targets which, due to lighting constraints, are scheduled only during the antipolar portion of each orbit. They normally require long observation times extending over several revolutions. A minimum slew heuristic is employed to select the sequence of dim targets. The other case deals with bright, or short duration, targets, which have less restrictive lighting constraints and are scheduled during the portion of each orbit when dim targets cannot be viewed. Since this process moves much more rapidly than the dim path, an enumeration algorithm is used to select the sequence that maximizes total viewing time.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-64921
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  • 62
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    A table of semiempirical gf values. Part 3: Wavelengths: 599.4004 nm to 9997.2746 nm (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: For abstract, see N75-24599.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142881 , SAO-SPECIAL-REPT-362-PT-3
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  • 63
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    A table of semiempirical gf values. Part 2: Wavelengths: 272.3395 nm to 599.3892 nm (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: For abstract, see N75-24599.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142880 , SAO-SPECIAL-REPT-362-PT-2
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  • 64
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    A table of semiempirical gf values. Part 1: Wavelengths: 5.2682 nm to 272.3380 nm (1975)
    In:  CASI
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    Publikationsdatum: 2019-06-27
    Beschreibung: The gf values for 265,587 atomic lines selected from the line data used to calculate line-blanketed model atmospheres are tabulated. These data are especially useful for line identification and spectral synthesis in solar and stellar spectra. The gf values are calculated semiempirically by using scaled Thomas-Fermi-Dirac radial wavefunctions and eigenvectors found through least-squares fits to observed energy levels. Included in the calculation are the first five or six stages of ionization for sequences up through nickel. Published gf values are included for elements heavier than nickel. The tabulation is restricted to lines with wavelengths less than 10 micrometers.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142879 , SAO-SPECIAL-REPT-362-PT-1
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  • 65
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    Infrared spectroscopy of Comet Kohoutek (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Interferometry observations from 90-in. and 61-in. telescopes tracking the Comet Kohoutek are summarized. Laboratory reflection studies of ices potentially useful for future cometary work were conducted. The frosts studied included: H2O, CO2 NH3, H2S, CH4, NH4HS, and ammonia polysulfide. The frost spectra show remarkable changes with the temperatures, particularly in the case of hydrogen sulfide. Additional analysis found the variation in the H2S ice spectrum to be due to a phase change from a low temperature tetragonal unit cube to a higher temperature face-centered cubic structure. The spectra data indicate that if frost spectra are required for comparison with observed cometary or planetary absorption, the temperature of the frost must be matched.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142809
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  • 66
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    Spectral variability of Cyg X-3 (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The 1.7-40 keV spectra of Cyg X-3 obtained about a year apart, using the same rocket payload, show large spectral differences. The two observations suggest that while the luminosity of this source remains roughly the same, its spectrum can vary from a featureless blackbody distribution to a flat spectrum which includes strong iron line emission at approximately 6.7 keV. The flux in the line corresponds to an equivalent continuum width of 1.2 keV.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-70891 , X-661-75-98
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  • 67
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    Copernicus observations of Betelgeuse and Antares (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Copernicus observations of the M-supergiants, alpha Ori and alpha Sco, are presented. The MgII h and k resonance lines are strongly in emission in both stars. The k line is highly asymmetric in both stars but the h line is symmetric. Upper limits for several other resonance lines are given for alpha Ori. The possibility is explored that the k line asymmetry is caused by overlying resonance lines of MnI and FeI formed in the cool circumstellar gas shells around these stars. Observations of the MnI 4030-4033 A lines are used to show that circumstellar shell absorption is too weak to explain the asymmetry. It is suggested that the absorption occurs in a cool turbulent region between the base of the circumstellar shell and the top of the chromosphere.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142815
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  • 68
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    The rocket ultraviolet spectrum of the planetary nebula NGC 7027 (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: An ultraviolet spectrum of NGC 7027 was obtained with a rocket-borne telescope. The observed fluxes are given on an absolute basis and upper limits are given for the strongest predicted lines which were not observed. The extinction correction was made on the basis of the observed and calculated line ratios for the hydrogenic recombination line of He 2 at 1640A to H beta. The extinction is in agreement with ground based determinations. When corrected for extinction the C 4 resonance line at 1549A is in good agreement with the intensity calculated from models, but the C 3 intercombination line at 1909A is a factor of ten too bright. The addition of dielectronic recombination to the models sufficiently changes the C 3 concentration to reduce the discrepancy to a factor of four. The abundance of carbon is assumed to be 2 x 0.0001 that of hydrogen. Using carbon abundances for the sun, this discrepancy disappears and there must be attenuation in the C 4 line. Since the optical depth is approximately 10,000 at the line center, no appreciable number of absorbing grains can exist in the C 4 producing region of the nebula.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-TM-X-70892 , X-672-75-113
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  • 69
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    Development and evaluation of infrared sensitive image sensors for space astronomy (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The experimental development and evaluation of infrared vidicons for use in solving high precision high flux broadband astronomical problems are discussed. Data cover the EOS, silicon, and doped germanium vidicons. Results are graphed and problems encountered using the vidicons in electrical cameras are reported.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-142928
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  • 70
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    Turbulence effects in radio occultation studies of atmospheric scale heights (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Atmospheric scale heights derived from radio occultation measurements of a turbulent planetary atmosphere would be accurate if the average angle of refraction through the turbulent atmosphere were equal to the refraction angle for the corresponding quiescent atmosphere. These two angles are not equal (although their difference may not be large enough to cause significant error). If necessary, it should be possible to correct for the systematic error introduced by this inequality by using measurements of signal spectra to determine characteristics of the turbulence. Sensitive dual-frequency measurements could help define the effects of turbulence in future radio occultation experiments. It does not appear that the angular offset due to turbulence has been important in past experiments, although it may become significant and require corrective analysis when improved equipment is used to probe deep into turbulent atmospheres with greater measurement precision.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-146823 , SU-TR-3208-5 , SU-SEL-75-030
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  • 71
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    Further observations of the lambda 10830 He line in stars and their significance as a measure of stellar activity (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Measurements of the lambda 1030 He line in 198 stars are given along with data on other features in that spectral range. Nearly 80% of all G and K stars show some lambda 10830; of these, half are variable and 1/4 show emission. It was confirmed that lambda 10830 is not found in M stars, is weak in F stars, and is particularly strong in close binaries. The line is found in emission in extremely late M and S stars, along with P gamma, but P gamma is not in emission in G and K stars with lambda 10830 emissions. Variable He emission and Ti I emission are found in the RV Tauri variables R Scuti and U Mon. In R Aqr the Fe XIII coronal line lambda 10747 and a line at lambda 11012 which may be singlet He or La II are found, as well as lambda 10830 and P gamma. The nature of coronas or hot chromospheres in the various stars is discussed. It was concluded that the lambda 10830 intensity must be more or less proportional to the energy deposited in the chromosphere corona by non-thermal processes.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-145974 , BBSO-0150
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  • 72
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    Further joint X-ray, infrared and radio observations of Cygnus X-3 (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Observations of Cygnus X-3 were carried out at 2.5 - 7.5 keV, 2.2 micron, 8.1 GHz and 2.7 GHz over a two week period. The X-ray data show the periodic structure which is typical of Cyg X-3. At times the X-ray and infrared measurements show very similar periodic structure, both in phase and shape, while at other times the infrared data show no periodic variability. The radio fluxes were usually low during the period of observation; both the daily average radio flux levels and spectral index remained nearly constant.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-143536
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  • 73
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    Mass loss in red giants and supergiants (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The circumstellar envelopes surrounding late-type giants and supergiants were studied using high resolution, photoelectric scans of strong optical resonance lines. A method for extracting the circumstellar from the stellar components of the lines allowed a quantitative determination of the physical conditions in the envelopes and the rates of mass loss at various positions in the red giant region of the HR diagram. The observed strengthening of the circumstellar spectrum with increasing luminosity and later spectral type is probably caused by an increase in the mass of the envelopes. The mass loss rate for individual stars is proportional to the visual luminosity; high rates for the supergiants suggest that mass loss is important in their evolution. The bulk of the mass return to the interstellar medium in the red giant region comes from the normal giants, at a rate comparable to that of planetary nebulae.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-145435 , PREPRINT-165
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  • 74
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    Observations of the Circinus X-1 region (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The X-ray telescope on board the OSO-7 satellite has provided observations of the Cir X-1 region for over 110 days between December 1971 and March 1973. Although statistically significant fluctuations in the 7- to 11-keV flux were measured, no periodicities in the range between 5 hours and 100 days were found to an upper limit of about 40 percent amplitude. Intensities in the 7- to 57-keV range show variability by a factor of approximately 25 and changes in the spectral shape reflected by a number spectral index varying from about 1.1 to about 3.0. There is a positive correlation between intensity and spectral shape, with a steeper spectrum at times of peak intensity. Although power-law, exponential, and blackbody spectral shapes are equally good fits to these data alone, examination of all the available data appears to rule out a simple blackbody spectrum, at least at times of maximum intensity.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 198; June 1
    Format: text
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  • 75
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    Absolute spectrophotometry in M31 and M32 (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: For a number of places in the bulge of M31, and for two places in M32, photometric scans from lambda = 3300 A to lambda = 10,600 A have been obtained with the multichannel spectrometer on the 5-m Hale telescope. The scans show that in both objects the color temperature (particularly shortward of 5000 A) decreases toward the center, and that the strength of the CN bands increases toward the center in both objects, in agreement with other earlier observations. The new data can all be interpreted in terms of an increase of heavy-element abundance toward the center in both objects by a factor probably less than 2, and by an excess of heavy elements in M31 compared with M32 by a factor probably greater than 2, in qualitative agreement with earlier conclusions of other observers.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 198; May 15
    Format: text
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  • 76
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    The Celescope survey and the galactic distribution of interstellar absorption (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The instrumentation and data-reduction techniques used in the Celescope experiment conducted on board OAO-2 are reviewed. A brief summary is presented of the principles of UV astronomy, the Celescope optical package and bay E4 electronic module assembly are described, and the distribution of the Celescope pictures is plotted in galactic coordinates. Described data-reduction techniques include the determination of the U-B and B-V colors, removal of interstellar extinction effects, and construction of model atmospheres for the observed stars. Some difficulties and apparent contradictions encountered in the data interpretation are noted.
    Schlagwort(e): ASTRONOMY
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  • 77
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    Time-dependent effects in the radially streaming particle model (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The radially streaming particle model for broad quasar and Seyfert galaxy emission features is modified to include sources of time dependence. The results seem to correlate with reported observations of multiple components, variability, and transient features in the wings of Seyfert and quasi-stellar emission lines.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 198; May 15
    Format: text
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  • 78
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    Design and construction of prototype radio antenna for shortest radio wavelengths (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: A paraboloid radio antenna of 10.4 meters diameter, 0.41 meter focal length was constructed and its successful completion is described. The surface accuracy of the antenna is at least four times better than any existing antenna in its class size (50 micrometers rms). Antenna design specifications (i.e., for mounting, drive motors, honeycomb structures) are discussed and engineering drawings and photographs of antenna components are shown. The antenna will be used for millimeter-wave interferometry and sub-millimeter wave radiometry over a full frequency range (up to approximately 860 GHz). The antenna will also be moveable (for interferometric use) between reinforced concrete pads by rail. The effects of the weather and gravity on antenna performance are briefly discussed.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-146304
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  • 79
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    Far Infrared Spectroscopy of H II Regions (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: The far infrared spectra of H II regions are investigated. A liquid helium cooled grating spectrometer designed to make observations from the NASA Lear Jet is described along with tests of the instrument. The observing procedure on the Lear Jet telescope is described and the method of data analysis is discussed. Results are presented from a search for the (O III) 88.16 micron line. An upper limit on the emission in this line is obtained and line detection is described. Results are compared to theoretical predictions, and future applications of fine structure line observations are discussed. Coarse resolution results are given along with calibration problems. The spectra obtained are compared to models for dust emission.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-145960 , CRSR-613
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  • 80
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    On the Laplace relation among the satellites of Uranus (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Three of Uranus' satellites are involved in an interaction similar to the Laplace relation among the Galilean satellites of Jupiter. However, there are no pair-wise commensurabilities in the Uranus system as there are among the Galilean satellites. Thus analysis by Fourier expansion of disturbing functions becomes too unwieldy for practical calculation. Instead, the unexpanded perturbations are numerically averaged over a time scale short compared to the important variations in the Laplace relation. Perturbations of Miranda's orbit are estimated to be of observable magnitude for reasonable masses of Ariel and Umbriel.
    Schlagwort(e): ASTRONOMY
    Materialart: Royal Astronomical Society; vol. 173
    Format: text
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  • 81
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    Observations of nine supernova remnants at 10.6 GHz (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Intensity contour and polarization observation maps of nine supernova remnants at a microwave frequency are presented and discussed. The data provided are the highest-frequency (10.6 GHz) measurements to date for several of these sources and should therefore be useful in determining their spectra. Polarization ranges from 2 or 3% to as high as 40-50%. Integrated fluxes for the sources vary from about 3 to more than 25.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Journal; 80; Sept
    Format: text
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  • 82
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    Ultraviolet observations of alpha Aurigae from Copernicus (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Emission lines of L-alpha (1215.67 A) and O VI (1031.94 A) were detected in the spectroscopic binary alpha Aur (Capella) with the Princeton experiment on Copernicus. Temperatures of the emitting regions are inferred to be in excess of 300,000 K. The temperature and emission measure are consistent with a variable source of soft X-rays. If the emission is attributed to the primary star (G5 III), the atmosphere is expanding with velocities of about 20-100 km/s. Such expansion can lead to material within the binary system. The density of interstellar hydrogen inferred from absorption of stellar L-alpha appears to be approximately 0.01 hydrogen atoms per cu cm.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 200; Aug. 15
    Format: text
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  • 83
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    Short-term variability of gamma-2 Velorum (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Photoelectric spectrum scans of gamma-2 Velorum in the spectral range 4600-4720 A were analyzed to study the short-term variability of brightness and of emission line strengths. The emission strengths of He II (4686 A) and C III-IV (4650 A) show rms variations of 3 and 2 per cent, respectively. These variations have time scales of 1 minute and longer. Night-to-night variations were also found. The continuum radiation also shows small-amplitude variations. No periodic variations attributable to this star were detected on any of the nights on which these observations were made.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 200; Aug. 15
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  • 84
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    Optical and X-ray observations of the PSR 1913 + 16 field (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: We have obtained medium-resolution spectra in the yellow of seven stars in the error box of the binary radio pulsar PSR 1913 + 16, using the image-tube scanner at the Lick 3-m telescope. None of the objects is spectroscopically abnormal and thus a strong candidate for membership in the system. The data are used to establish the extinction in the field, which is modest for this low galactic latitude. For three of the stars, limits of the order V exceeding 23 mag on optical pulsations with the frequency of the radio pulsar are derived. X-ray observations of the field have been obtained in the 2.5-7.5 keV band, using the UCL experiment aboard OAO Copernicus. No source is detected, with a 2 sigma upper limit on the time-averaged flux of 1.0 times 10 to the -10th power ergs per sq cm per sec.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 200; Aug. 15
    Format: text
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  • 85
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    A fully automated digitally controlled 30-inch telescope (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A fully automated 30-inch (75-cm) telescope has been successfully designed and constructed from a military surplus Nike-Ajax radar mount. Novel features include: closed-loop operation between mountain telescope and campus computer 30 km apart via microwave link, a TV-type sensor which is photon shot-noise limited, a special lightweight primary mirror, and a stepping motor drive capable of slewing and settling one degree in one second or a radian in fifteen seconds.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
    Format: text
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  • 86
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    On the color indices of giants and subgiants in globular clusters (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The globular-cluster metal-abundance parameter, which is the intrinsic color index at the intersection of the horizontal and subgiant branch in the color-magnitude diagram, is shown to be tightly correlated with the concentration ratio of Fe/H.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Society of the Pacific; vol. 87
    Format: text
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  • 87
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    Spectrophotometry of CRL 2688 from 2 to 24 microns (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Infrared spectrophotometric observations (2 to 24 microns) are reported for CRL 2688, an IR source in Cygnus associated with twin symmetric reflection nebulae. The entire spectrum from 3 to 24 microns is shown to be a generally featureless continuum and to be too broad to be fit by a single blackbody. No evidence is found for ice absorption near 3.1 microns, and the data suggest a possible emission feature near 3.3 microns.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; Aug. 1
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  • 88
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    Skylab ultraviolet stellar spectra - The Wolf-Rayet stars (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; Aug. 1
    Format: text
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  • 89
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    A high-resolution map of the W3 region at far-infrared wavelengths (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: The area in the vicinity of the H II region W3 is mapped at an effective wavelength of 69 microns with high angular resolution (1 min) using the 102-cm balloon-borne telescope. The main continuum source, W3, shows a partially resolved complex structure with a FWHM size of 1.8 min. The radio sources W3(OH) and G133.8 + 1.4 are also observed as well as three faint sources not associated with known radio emission.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; Aug. 1
    Format: text
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  • 90
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    A jet in the galaxy identified with the radio source DA 240 (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; Aug. 1
    Format: text
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  • 91
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    The rotation curve of NGC 3115 (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A rotation curve is derived for the S0 galaxy NGC 3115 from its absorption-line spectrum. The central velocity is 728 (+ or - 9) km/sec. The rotation curve rises to 260 km/sec at 25 arc sec from the nucleus, and remains constant at that value to the limit of the measurements. A rough computation of the mass gives 24 billion solar masses out to 3.4 kpc, and a mass-to-light ratio of 20 to the same radius.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 199; Aug. 1
    Format: text
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  • 92
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    One-dimensional focusing X-ray telescope for stellar X-ray astronomy (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: A one-dimensional X-ray telescope of the Kirkpatrick-Baez design is described. The instrument consists of a grazing-incidence X-ray telescope and a multiwire proportional counter. The optics were provided with a gold reflecting surface to yield an energy response from below 0.25 to above 4.0 keV. The angular resolution of the system is 6 min by 9.5 deg over a 1.1 deg by 9.5 deg field of view.
    Schlagwort(e): ASTRONOMY
    Materialart: Review of Scientific Instruments; 46; Aug. 197
    Format: text
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  • 93
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    Spectrophotometric observations of mu Cephei and the moon from 4 to 8 microns (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 198; May 15
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  • 94
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    Adiabatic invariants and phase equilibria for first-order orbital resonances (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: In the planar circular restricted three-body problem, the evolution of near-commensurable orbits is studied under change in the mass ratio, mu. The evolution involves preservation of two adiabatic invariants. Transition from circulation to libration may occur; such transitions are of two types. Type I transition occurs when the evolutionary track in phase space passes through near-zero eccentricity; as in the ordinary case (no transition), pre- and post-evolutionary states are linked by solution of a two-point boundary-value problem. Type II transition occurs when the evolutionary track encounters an unstable phase equilibrium or periodic orbit. There is then a discontinuous change in one adiabatic invariant, and pre- and post-evolutionary states are linked by solution of a three-point boundary-value problem. No evolutionary track can encounter a stable phase equilibrium, but the class of all stable phase equilibria is mapped into itself under mu change.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Journal; 80; June 197
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  • 95
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    Low-frequency radio maps and spectra of supernova remnants (1975)
    In:  Other Sources
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    Publikationsdatum: 2019-06-27
    Beschreibung: Low-frequency radio maps of 18 supernova remnants have been constructed from observations made at the Arecibo Observatory. The integrated flux densities have been combined with others in the literature to show that most of the sources have simple power-law spectra. None of the sources show features which would suggest changes in the spectrum spatially across the given source.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Journal; 80; June 197
    Format: text
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    Observations of compact radio nuclei in Cygnus A, Centaurus A, and other extended radio sources (1975)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Observations of Cygnus A show a compact radio core 2 milliarcsec in extent oriented in the same direction as the extended components. Other large double- or multiple-component sources, including Centaurus A, have also been found to contain compact radio nuclei with angular sizes in the range 1-10 milliarcsec.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 197; May 1
    Format: text
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  • 97
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    An image-stabilized telescope - Ten channel ultraviolet spectrometer for sounding rocket observations (1975)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Schlagwort(e): ASTRONOMY
    Materialart: Space Science Instrumentation; 1; Feb. 197
    Format: text
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  • 98
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    Multifrequency techniques for studying interplanetary scintillations (1975)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Rytov's approximation, or the method of smooth perturbations, is utilized to derive the temporal frequency spectra of the amplitude and phase fluctuations of multifrequency plane and spherical waves propagating in the interplanetary medium and solar corona. It is shown that multifrequency observations of interplanetary scintillations using either compact radio stars of spacecraft radio signals are desirable because the correlation of the multifrequency waves yields additional independent measurements of the solar wind and turbulence. Measurements of phase fluctuations are also desirable because, unlike amplitude fluctuations, they provide information on the full range of scale sizes for the electron-density fluctuations. It is also shown that a coherent dual-frequency radio system is particularly useful in making such measurements. In addition to providing a means for interpreting observations of multifrequency interplanetary scintillations, the present analysis is essential for estimating the effects of solar corona turbulence on the communications and navigation of a spacecraft whose line-of-sight path passes close to the sun.
    Schlagwort(e): ASTRONOMY
    Materialart: Astrophysical Journal; 201; Oct. 1
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
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    Asteroidal and planetary analysis (1975)
    In:  CASI
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Photometric, spectrophotometric, and radiometric investigations of asteroids and planets are reported. Profiles of the planetary disk were used to study the physical structure of the Uranus atmosphere, and thermal and photographic properties of Saturn rings were theoretically modelled. Ground-based Mars observations were made for long-term comparison with Mariner 9 results.
    Schlagwort(e): ASTRONOMY
    Materialart: NASA-CR-147983
    Format: application/pdf
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  • 100
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    Spectrophotometry of Comet Kohoutek /1973f = 1973XII/ (1975)
    In:  Other Sources
    Details
    Publikationsdatum: 2019-06-27
    Beschreibung: Spectrum scans have been obtained of Comet Kohoutek with a Fourier spectrometer at heliocentric distances from 0.55 to 1.05 AU. The useful spectral range is roughly 3800-8400 A and the resolution is about 10-15 A at 5000 A. Large variations occurred in the gas-to-dust ratio (pre- versus postperihelion) and in the relative strength of the NH2 bands (with heliocentric distance). There is a smaller change in the ratio of CN to C2 emission. The Swan bands of C2 show the customary anomaly in strengths implying highly non-Boltzmann distributions among vibrational levels. The red and violet CN system fluxes are in slightly better agreement with laboratory data on oscillator strengths than results on previous comets. Other species measured include Na, (O I), CH, and C3.
    Schlagwort(e): ASTRONOMY
    Materialart: Astronomical Journal; 80; Oct. 197
    Format: text
    Standort Signatur Erwartet Verfügbarkeit
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