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  • 1
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    Detection of silicate emission features in the 8- to 13-micron spectra of main belt asteroids (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A presentation is given of 8.0-13.0 micron spectra (Delta lambda/lambda = 0.02-0.03) for six main belt asteroids, which range from 58 to 220 km in diameter and sample the five principal taxonomic classes (C, S, M, R and E). Narrow, well-defined silicate emission features are present on two of the asteroids, the C-type 19 Fortuna and the M-type 21 Lutetia. No comparable emission features are observed on the S-types 11 Parthenope and 14 Irene, the R-type 349 Dembowska or the E-type 64 Angelina.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 56; 393-397
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  • 2
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    The evolution of the infrared emission from the Type II supernova 1980k in NGC 6946 - The dust formation model (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper presents 1-4 micron photometry of supernova 1980 k in NGC 6946 obtained over a period of 1 year following the outburst. During the period between 1980 November 1 and December 19, the infrared emission probably originated from the extended atmosphere of the expanding star. The JHKL colors and a 1.3-2.6-micron spectrum observed during this period correspond to those of a blackbody with an average temperature of about 5000 K. Observations around 1981 May 31 showed that the supernova developed an infrared excess after 1980 December. This infrared excess persisted through 1981 October and is consistent with the appearance of thermal emission from about 700 to 900 K dust in addition to a hotter photosphere. The similarity of this behavior to that of the infrared evolution of some novae suggests that dust formation may be occurring in the supernova ejecta. The hypothesis, that the emission arises from preexisting grains in a circumstellar shell which are heated by the supernova outburst, is also consistent with the data.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 168-174
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  • 3
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    Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. III - Reticon radial velocities (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Radial velocities for 72 stars, most of them known or suspected binaries with F - K giant-supergiant primaries, are derived from Reticon spectra in the region 6005-6235 A at a scale of 7 km/s per diode. Cross-correlation of the spectra normally produces results accurate to better than 1.0 km/s. Eight new radial velocity variables are found (HR 2786, R Pup, HR 3291, HR 4451, HD 114520, HR 5667, HR 7014, and Nu1 Sgr). Improved orbits are determined for 15 known spectroscopic binaries, and provisional orbits are obtained for seven new spectroscopic binaries.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 53; 553-571
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  • 4
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    Infrared observations of RS CVn stars (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper presents infrared photometry of the RS CVn binary stars AR Lac (1.2-10 microns) and MM Her (1.2-3.5 microns) as they egressed from their primary and secondary eclipses; of the eclipsing systems RS CVn and Z Her at maximum light (1.2-10 microns) and of the non-eclipsing systems UX Ari and HR 1099 (1.2-10 microns). An analysis of these and published V data based on flux ratio diagrams (linear analogues of color-color diagrams) shows that G and K stars supply the infrared light of these systems. In AR Lac, the combined light of a G5-K0 subgiant and either a late F dwarf or an early F subgiant can account for the observed visual and infrared light curves. None of these systems shows infrared emission from circumstellar matter. This result is simply understood: dust grains would not be expected to form in the physical conditions surrounding the subgiant, and the corona and chromosphere (whose properties have been deduced from spectroscopic X-ray observations) should not produce appreciable infrared emission.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 205; 859-873
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  • 5
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    Ultraviolet high-resolution spectroscopy from the Space Telescope (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The High Resolution Spectrograph is one of five scientific instruments which will be part of the Space Telescope observatory. The spectrograph was designed to take advantage of the imaging and pointing capabilities of the telescope to obtain ultraviolet spectra with spectral resolution comparable to large, ground-based coudeinstruments. Some of the results of the ground-based testing program will be described, along with applications of these properties to future science programs.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 543-549
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  • 6
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    Theoretical studies of the effects of grain noise on photographic stellar astrometry and photometry (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method of incorporating the effects of photographic emulsion grain noise into digital image centering algorithms is presented which improves the accuracy of the derived stellar positions and magnitudes. Theoretical formulae are then derived for the limiting error of the center, and the photometric parameters. For IIIa-J, this error is 0.2-0.3 mu for bright unsaturated images, which agrees quite well with measurements made with the Yale PDS microdensitometer. It is expected that, with further improvements in the positional accuracy of the PDS, it should be possible to reach the emulsion grain noise limit, providing that emulsion shifts or other large scale errors do not dominate. It is also shown that, with appropriate trimming, marginal distribution image centering algorithms can yield an accuracy only slightly poorer than that obtained with two-dimensional distributions.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; 1683-168
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  • 7
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    An improved celestial radio reference frame: JPL 1982-4 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In the development of a celestial radio reference frame, there are now over 100 sources whose relative positions are known with an average uncertainty less than 5 milliarcseconds. These sources are fairly uniformly distributed over the celestial sphere north of -40 deg declination. Their positions are expressed in the new IAU system. This presentation describes the analysis involved in obtaining these results, as well as future plans for linking this system to the JPL planetary ephemerides.
    Keywords: ASTRONOMY
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  • 8
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    Comet Halley ephemeris uncertainties in 1985-1986 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: For the planned flyby missions to Comet Halley in March 1986, the comet's ephemeris uncertainties completely dominate the spacecraft-comet miss distance. In an effort to determine realistic Comet Halley ephemeris uncertainties, a statistical covariance analysis was conducted using the actual data in 1909-1910-1911 and simulated data in 1984-1985-1986. In 1985-1986, Comet Halley's ephemeris uncertainties are very sensitive to the comet's orbital position, the optical data noise, data schedule, and whether or not the old data is included in the orbital solutions. The comet's ephemeris uncertainties in March 1986 are relatively insensitive to reasonable center of light/center of mass offsets and also to possible radar data taken in late November 1985. Accurate Space Telescope observations made in early March 1986 might significantly improve upon the comet's position uncertainties for the various intercepting spacecraft.
    Keywords: ASTRONOMY
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  • 9
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    Dust particles in the anomalous tail of Comet Kohoutek (1973 XII) (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Intermediate results from theoretical models of the anomalous spikelike dust distribution observed in the tail of Comet Kohoutek using the Skylab white-light coronograph on December 28.996, 1973, are reported. The time evolution is studied using the model of Finson and Probstein (1968) and assuming power-law variation of the dust-production rate and the particle-size distribution. Brightness profiles are calculated and presented graphically for comparison with those derived from the observation photograph: the model predicts a longer duration of the spike phenomenon than was observed. It is shown qualitatively that this discrepancy can be removed by introducing a finite dust-emission velocity (e.g., 1 m/s) into the model.
    Keywords: ASTRONOMY
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  • 10
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    Cometary nucleus and active regions (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: On the basis of the icy-conglomerate model of cometary nuclei, various observations demonstrate the 'spotted' nature of many or most nuclei; i.e., regions of unusual activity, either high or low. Rotation periods, spin axes, and even precession of the axes have been determined. Narrow dust jets near the nuclei of some bright comets require that small sources be embedded in larger active areas. Certain evidence suggests that very dusty areas and very dusty comets may be less active, respectively, than surrounding areas or other comets.
    Keywords: ASTRONOMY
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  • 11
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    Regions of stability of asteroids (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Using Hill's modified stability criterion, regions of orbital elements are established for conditions of stability. The model of the three-dimensional restricted problem of three bodies is used with the sun and Jupiter as the primaries. Four different cases are studied: direct and retrograde, outside and inside asteroidal orbits. The directions of the asteroidal orbits refer to the synodical reference frame and the positions refer to Jupiter's orbit. The orbital parameters of the asteroids are the semi-major axis (a), the eccentricity (e), and the inclination from Jupiter's orbital plane (i). The argument of the perihelion and the longitude of the ascending node are fixed at Omega = omega = 90 deg and the time of perihelion passage is T = 0 for all orbits.
    Keywords: ASTRONOMY
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  • 12
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    The JPL 'long ephemeris', DE102/LE51 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A number of applications exist in astronomical research for planetary and lunar ephemerides covering an extended length of time. This paper discusses such a set of ephemerides, DE102/LE51, produced at JPL, covering the time 1411 B.C. to 3001 A.D. The ephemerides are dynamically self-consistent, in that the equations of motion were integrated simultaneously. They also represent the most accurately known positions covering such a time span. They have already been used by a number of different users in a variety of different applications.
    Keywords: ASTRONOMY
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  • 13
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    Dynamical evolution of the Oort cometary cloud (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The dynamical evolution of comets in the Oort cloud under the influence of stellar perturbations has been modeled using Monte Carlo techniques. It is shown that the cloud has been depleted over the history of the solar system. Comets are lost from the cloud by direct ejection due to close stellar encounters, diffusion of aphelia to distances beyond the sun's sphere of influence, or diffusion of perihelia into the planetary region where Jupiter and Saturn perturbations either eject them on hyperbolic trajectories or capture them to short-period orbits. The population of the cloud is estimated to be 1.0 - 1.5 x 10 to the 12th comets and the total mass is on the order of 1.9 earth masses. In addition to random passing stars, less frequent encounters with giant molecular clouds may play a significant role in randomizing the orbits of comets in the cloud and reducing the effective radius of the sun's sphere of influence.
    Keywords: ASTRONOMY
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  • 14
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    Properties of young clusters near reflection nebulae (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Near infrared observations in the reflection nebulae NGC 703, 2023, and 2068 are used to study clusters of young stars found associated with these nebulae. At least 30 percent to 60 percent of these stars are pre-main sequence objects, as indicated by their infrared excesses, hydrogen line emission, or irregular variability. The spatial distributions and observed luminosity functions of these young open clusters are derived, and the inferred mass function and star formation efficiencies are discussed. Previously announced in STAR as N83-25628
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; July 198
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  • 15
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    Cometary impacts with the sun - Physical and dynamical considerations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Michels et al. (1982) observed the apparent impacting of the sun by a comet, and Sekanina (1982) showed that the comet, 1979XI, was probably a member of the Kreutz group of sun-grazing comets, although its perihelion of 0.35 solar radii was much smaller than the 1.2-1.9 solar radii common for this comet class. The perihelion change cannot be explained by planetary, stellar, or nongravitational perturbations. The most plausible explanation is collision with another body, probably a comet, at large heliocentric distance. The probability of such an event is, however, extremely small. The sublimation of the comet's nucleus before impact is discussed, and it is suggested that its ultimate destruction probably resulted from the shock of entry into the denser regions of the solar atmosphere, just above the photosphere.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 55; Sept
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  • 16
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    An infrared study of the eclipsing dwarf nova U Geminorum (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: One series of data comprising the present J, H, K broadband IR photometry of the cataclysmic binary system U Geminorum over the course of two orbital cycles was obtained several days before an outburst, while a second was gathered when the system had almost completely returned to quiescence from that outburst. In quiescence, the M4-M5.5 red dwarf star supplies most of the IR luminosity of the system, while the light curves at this time are tidally induced ellipsoidal variations of the red dwarf which exhibit an amplitude such that the red dwarf must fill, or nearly fill, its Roche lobe. This shows directly that Roche lobe overflow is important in cataclysmic variable stars. The range of the disk IR colors after outbursts suggest that cool and optically thick gas, together with optically thin gas, supply most of the IR light of the disk.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 204; Sept
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  • 17
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    Very large spiral galaxies (1983)
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    Publication Date: 2011-08-18
    Description: As a first step in the systematic study of large spirals, which may be useful in cosmological tests and studies of galaxy evolution, a catalog of the 107 largest known spiral galaxies is presented. Catalog galaxies have isophotal diameters greater than 90 kpc, assuming an H(zero) value of 50 km/sec per Mpc. UBVR photoelectric photometry is presented for 20 of these galaxies, and absolute magnitudes are derived for all galaxies in the catalog by transforming Zwicky magnitudes to the B(T) system.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 204; Sept
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  • 18
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    Further studies on criteria for the onset of dynamical instability in general three-body systems (1983)
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    Publication Date: 2011-08-18
    Description: Numerical experiments designed for the elucidation of the conditions under which self-gravitating, three-body systems become dynamically unstable are examined of the cases of four orbital configuration types: circular, prograde, and coplanar; circular, retrograde, and coplanar; circular, direct, and inclined; and eccentric, direct, and coplanar. Results indicate that orbital inclination does not significantly affect stability in 'outer planet' configurations, while the stability of 'inner planet' configurations, where the tertiary is in close orbit about one member of the binary, is markedly less affected, once the relative orbital inclination is greater than 50 deg. It is found that the onset of dynamical instability is only weakly dependent on the eccentricity of either the binary or tertiary orbit, as long as the mass of the tertiary is comparable to the reduced mass of the binary.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; Sept
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  • 19
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    DE 102 - A numerically integrated ephemeris of the moon and planets spanning forty-four centuries (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: It is pointed out that the 1960's were the turning point for the generation of lunar and planetary ephemerides. All previous measurements of the positions of solar system bodies were optical angular measurements. New technological improvements leading to immense changes in observational accuracy are related to developments concerning radar, Viking landers on Mars, and laser ranges to lunar corner cube retroreflectors. Suitable numerical integration techniques and more comprehensive physical models were developed to match the accuracy of the modern data types. The present investigation is concerned with the first integrated ephemeris, DE 102, which covers the entire span of the historical astronomical observations of usable accuracy which are known. The fit is made to modern data. The integration spans the time period from 1411 BC to 3002 AD.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 125; 1, Au; Aug. 198
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  • 20
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    The IRAS telescope (1983)
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    Publication Date: 2011-08-18
    Description: The IRAS telescope is described in terms of its system configuration and physical characteristics, subsystem functions and descriptions, and performance characteristics. The mission and the configuration are reviewed briefly, and the major functional components of the telescope are described, including the focal plane assembly, the optics, the electronics, the cryogenics, and the thermal control. Exploded and cross-sectional views and block diagrams are presented for the telescope system configuration, focal plane assembly, infrared subarray module, optical subsystem, infrared channel data flow, and main cryogen dewar. The telescope physical characteristics are listed. The performance characteristics are listed and discussed, including the spectral response, sensitivity, optical quality, and photometric accuracy. Relative system spectral response curves for the infrared bands are shown.
    Keywords: ASTRONOMY
    Type: vol. 36; Jan. 198
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  • 21
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    Coordinate systems (1983)
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    Publication Date: 2011-08-18
    Description: Jovian coordinate systems are different from those employed in the case of the earth. Latitude and longitude coordinates are usually established relative to some solid surface. Because Jupiter does not have a solid surface (at least none which is visible through the clouds), arbitrary, but convenient, coordinate grids have been prescribed. A spin equator is made out from observations of cloud motion, and the direction of the planetary spin axis is, therefore, determined with relatively good accuracy. The problem in establishing a Jupiter longitude system is that the mean rotation period of the clouds is a function of latitude. The solution selected was to define two separate longitude grids. A third longitude system became necessary with the detection of radio signals which gave evidence for a rotating planetary magnetic field. Attention is also given to orbital phase angle and longitude conventions for satellites, and two latitude systems for Jupiter
    Keywords: ASTRONOMY
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  • 22
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    Transformations of the perturbed two-body problem to unperturbed harmonic oscillators (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Singular, nonlinear, and Liapunov unstable equations are made regular and linear through transformations that change the perturbed planar problem of two bodies into unperturbed and undamped harmonic oscillators with constant coefficients, so that the stable solution may be immediately written in terms of the new variables. The use of arbitrary and special functions for the transformations allows the systematic discussion of previously introduced and novel anomalies. For the case of the unperturbed two-body problem, it is proved that if transformations are power functions of the radial variable, only the eccentric and the true anomalies (with the corresponding transformations of the radial variable) will result in harmonic oscillators. The present method significantly reduces computation requirements in autonomous space operations.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics (ISSN 0008-8714); 30; May 1983
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  • 23
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    Revised orbits for 105 Herculis and Pi Cephei A and a model for the Pi Cephei system (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New orbital elements for the giant primary components of 105 Herculis and Pi Cephei A are derived using radial velocities from Dominion Astrophysical Observatory coude plates. These data are combined with those of Harper (1925) in order to estimate the velocity amplitude of Pi Cephei A in the visual orbit of this triple system. Two models of this system are developed. In the first model, the unseen spectroscopic secondary component is a single main-sequence star, although this seems unlikely, while in the alternative model the unseen secondary component is itself double.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society; vol. 203
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  • 24
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    Lunar luminescence measurements (1983)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Spectra of lunar sites obtained in June 1983 have been analyzed for residual luminescence using the spectral line depth technique. The results or three sites each at three wavelengths are presented. The sites observed were Mare Crisium, Kepler, and Aristarchus. In each case, the value quoted was based not only on the strong Fraunhofer line in the spectral range covered but also on from 11 to 21 weaker lines within 80 A of the strongest feature. These data do not support previous observations. The values given do not indicate a greatly reddened spectrum, and the luminescence spectrum of the mare site is not significantly different from the two young crater sites. These observations cannot be adequately explained by thermal luminescence, theories of direct excitation are also unable to explain the strength of the flux.
    Keywords: ASTRONOMY
    Type: NASA. Johnson (Lyndon B.) Space Center The 1983 NASA/ASEE Summer Faculty Fellowship Research Program Research Reports; NASA. Johnson (Lynd
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  • 25
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    Radio Astronomy (1983)
    In:  CASI
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    Publication Date: 2014-09-12
    Description: Deep Space Network (DSN) 26- and 64-meter antenna stations were utilized in support of Radio Astronomy Experiment Selection Panel experiments. Within a time span of 10 days, in May 1983 (267.75 hours total), nine RAES experiments were supported. Most of these experiments involved multifacility interferometry using Mark 3 data recording terminals and as many as six non-DSN observatories. Investigations of black holes, quasars, galaxies, and radio sources are discussed.
    Keywords: ASTRONOMY
    Type: The Telecommun. and Data Acquisition Rept.; p 112-113
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  • 26
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    Upper Limits to the Annihilation Radiation Luminosity of Centaurus a (1983)
    In:  CASI
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    Publication Date: 2014-09-10
    Description: A high resolution observation of the active nucleus galaxy Centaurus A (NGC 5128) was made by the GSFC low energy gamma-ray spectrometer (LEGS) during a balloon flight on 1981 November 19. The measured spectrum between 70 and 500 keV is well represented by a power law of the form 1.05 x 10 (-4) (E/100 keV) (-1.59) ph/sq cm /s with no breaks or line features observed. The 98% confidence (2 sigma) flux upper limit for a narrow ( 3 keV) 511-keV positron annihilation line is 9.9 x 10 (-4) ph/ sq cm /s. Using this upper limit, the ratio of the narrow-line annihilation radiation luminosity to the integral or = 511 keV luminosity is estimated to be 0.09 (2 sigma upper limit). This is compared with the measured value for our galactic center in the Fall of 1979 of 0.10 to 0.13, indicating a difference in he emission regions in the nuclei of the two galaxies.
    Keywords: ASTRONOMY
    Type: NASA(Goddard Space Flight Center Contrib. to the Workshop on Positron-Electron Pairs in Astrophys.; p 39-44
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  • 27
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    HD 207739 - A strange composite star (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This star, classified F8 IIe + B:, has a very unusual ultraviolet spectrum, with abnormally strong and numerous absorption features in the far-UV and exceptionally strong Mg II emission. There is some resemblance to shell and pre-main-sequence B stars, but it more closely matches the strange spectra of the eclipsing systems VV Cep and SX Cas, and it probably has considerable circumstellar material at fairly high temperature. HD 207739 is probably an interacting binary and needs to be monitored for light and velocity variations.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 264
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  • 28
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    U.S. data processing for the IRAS project (1983)
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    Publication Date: 2011-08-18
    Description: The JPL's Scientific Data Analysis System (SDAS), which will process IRAS data and produce a catalogue of perhaps a million infrared sources in the sky, as well as other information for astronomical records, is described. The purposes of SDAS are discussed, and the major SDAS processors are shown in block diagram. The catalogue processing is addressed, mentioning the basic processing steps which will be applied to raw detector data. Signal reconstruction and conversion to astrophysical units, source detection, source confirmation, data management, and survey data products are considered in detail.
    Keywords: ASTRONOMY
    Type: vol. 36; Jan. 198
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  • 29
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    Experimental test of the variability of G using Viking lander ranging data (1983)
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    Publication Date: 2011-08-18
    Description: Results are presented from the analysis of solar-system astrometric data, notably the range data to the Viking landers on Mars. A least-squares fit of the parameters of the solar system model to these data limits a simple time variation in the effective Newtonian gravitational constant to (2 + or - 4) x 10 to the -12th/yr and a rate of drift of atomic clocks relative to the implicit clock of relativistic dynamics to (1 + or - 8) x 10 to the -12th/yr. The error limits quoted are the result of uncertainties in the masses of the asteroids.
    Keywords: ASTRONOMY
    Type: Physical Review Letters (ISSN 0031-9007); 51; 1609-161
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  • 30
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    Astrometry (1983)
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    Publication Date: 2011-08-18
    Description: Progress in astrometry is reviewed. Aspects of photographic astrometry are addressed, including the use and optimization of emulsions as detectors and the application of side-field and long-focus photographic astrometry to the determination of stellar positions, to proper motion surveys, the determination of more accurate parallaxes, the study of binaries, and the examination of the membership and internal motions of star clusters. The advantages and disadvantages of photoelectric astrometry are summarized, and the instruments used in this field is discussed, including scanners, detector arrays, stellar interferometers, space telescopes, and satellites. Promising observational methods for studying binary stars are addressed. Astrometry derived from meridian circle observations is considered, emphasizing the FK4 system. The use of radio astrometry is briefly discussed.
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    Photoelectric photometry of selected SAO stars. III (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photometric observations of 131 SAO stars for use in calibrating data obtained from the Near Infrared Photographic Sky Survey (NIPSS) are reported. The serial numbers of the primary NIPSS program fields in which the photometry was done are shown along with the approximate position of each field and the number of stars observed in each field. The observations are listed, showing the SAO numbers of the program stars, their 1950 equatorial coordinates, the V magnitudes, and the (V-R) and (V-I) color indices. The mean errors in magnitudes and color indices obtained by averaging deviations from the mean for each star are on the order of 0.02 mag.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 876
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  • 32
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    The unique cometary nebula Parsamian 13 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Parsamian 13 is found to be a cometary nebula, with a deeply embedded star suffering strong absorption by silicate grains. A feature near 2.7 microns, attributed to absorption by terminal OH groups, may represent the first detection in an astrophysical environment of water ice grains diluted by another molecule, for example by CO. The bolometric luminosity suggests that this star is either an extremely young T Tauri star or an evolved low-mass star, now a red giant, high on its convective track. Most unusual is the presence of cold (50 K) TiO gas in sufficient abundance to show in absorption in the optical and very near-infrared regions; this material probably represents very recently expelled photospheric layers.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 624-632
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  • 33
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    The future of VLBI observatories in space (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The angular resolution of radio maps made by earth-based VLBI observations can be exceeded by placing at least one element of a VLBI array into earth orbit. A VLBI observatory in space can offer the additional advantages of increased sky coverage, higher density sampling of Fourier components, and rapid mapping of objects whose structure changes in less than a day. This paper explores the future of this technique.
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  • 34
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    Radio stars - A possible link between the Hipparcos optical reference frame and an extra-galactic very long baseline interferometry reference frame (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The concept of typing the Hipparcos optical and the JPL VLBI frames of reference by means of VLBI measurements of the positions and proper motions of the radio components of some bright stars is considered. The properties of the thermal and non-thermal radio-stars are discussed and 22 candidate stars are selected to achieve this tie. A description is given of the first VLBI attempt to detect these stars on the intercontinental baselines of the Deep Space Network with the Mark II recording system.
    Keywords: ASTRONOMY
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  • 35
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    Earth rotation from lunar laser ranging (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The rotational orientation (Universal Time and the variation of latitude at McDonald Observatory, Texas) of the earth has been determined between mid 1970 and mid 1982 from McDonald Observatory lunar laser ranging (LLR) data. Universal Time, UT1, is calculated and supplied in three forms, the raw daily decomposition values, the Gaussian filtered values and the Fourier smoothed values. Formal error estimates are available for all three types. LLR can calculate corrections to one component of polar motion, the variation of latitude at McDonald Observatory. Modelling improvements have been applied here and a significant drop is seen in the residuals. The rms weighted residual for the entire thirteen year data span (3,326 'normal' points acquired between August 1969 and May 1982) is 18.7 cm.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics Supplement Series (ISSN 0365-0138); 54; 519-540
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  • 36
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    A large aperture balloon-borne telescope for a submillimeter wavelength survey of the galactic plane (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A balloon-borne, 1.2 meter Cassegrain telescope with a servo-controlled chopping secondary mirror has been developed and used to survey the Galactic Plane at submillimeter wavelengths. The telescope pointing system uses a gyroscope as the primary stabilization reference and makes use of microprocessors for pointing control, on-board data collection, and telemetry formatting. A description of the telescope, multi-channel liquid-helium-cooled focal plane and the aspect and orientation subsystems are presented.
    Keywords: ASTRONOMY
    Type: (ISSN 0273-1177)
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  • 37
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    Experimental limits of the extreme ultraviolet background (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Photometric observations of the diffuse extreme ultraviolet background with two photometers having bandpasses of 750-940 A and 1040-1080 A are reported. The payload, which was flown aboard an ARIES sounding rocket in June 1982, is described, including the electron detectors, filters, and calibration. The operation of the probe during the experiment, including its motions, are described. The primary experiment involved spectroscopic observation of the hot white dwarf HZ43. The photometer count rate is shown and the measurements of the diffuse background are compared with theoretical predictions. Despite the lower limits obtained using a narrowband detector, the measurements are not sensitive enough to draw any relevant astrophysical conclusions.
    Keywords: ASTRONOMY
    Type: (ISSN 0374-1958)
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  • 38
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    Five years of photometry of Sigma Geminorum (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Thirteen observatories have collaborated in obtaining five years of photoelectric photometry for the bright, K1 III RS CVn binary Sigma Geminorum. Except for one year, the light curve has exhibited two minima which are separated by approximately half a cycle. At the 1977.2 epoch of discovery one minimum was shallower, but as of 1982.2 they have become comparable in depth. During the 1979-80 season, the light curve changed shape rapidly, with the shallower minimum becoming as deep as the other within a period of no more than 80 days. The overall brightness range during the five years in V has been 4.13-4.29 mag, and it is found that the times of both minima can be fit with a photometric period of 19.423 days.
    Keywords: ASTRONOMY
    Type: Astrophysics and Space Science (ISSN 0004-640X); 93; 2, Ju; June 198
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  • 39
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    Infrared (JHK) photometry of asteroids. II (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: JHK (1.2, 1.6, and 2.2 micron) photometry for 38 asteroids of various spectral classifications is reported. M asteroids tend to have infrared colors intermediate between the color domains of E and P asteroids. A few D asteroids have redder J - H colors than most C asteroids. The unusually red J - H color of 246 Asporina indicates it is a member of the A class.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; July 198
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  • 40
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    Massive eclipsing binary candidates (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New UBV data are provided for 63 southern OB stars which are either identified in the survey by Garrison, Hiltner, and Schild as having double lines or are known from Wood et al. to be eclipsing binaries. Twenty of the stars are known eclipsing variables. Four stars, not previously known as eclipsing, have both spectroscopic evidence of duplicity and significant photometric variations. Several additional stars have a marginally significant spread in V magnitude.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 52; May 1983
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  • 41
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    Worldwide photometry and lightcurve observations of 16 Psyche during the 1975-1976 apparition (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Twenty-six lightcurves of Psyche are presented together with UBV photometry and phase functions from 1975 and 1976. Combining photometric data from this opposition with those from previous apparitions resulted in a mean phase coefficient in V of 0.026 + or - 0.002 mag/deg. No significant phase-dependent variation in the U-B color could be determined from the data; the B-V color, however, displayed a reddening with phase of 0.0010 + or - 0.0004 mag/deg. It is concluded that compositional variations over Psyche's surface are minor, and that Psyche's opposition effect is typical of that for other well-observed asteroids. Psyche's behavior is accounted for if, to the first order, its shape is that of a triaxial ellipsoid with axial ratios near 5:4:3.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 54; April 19
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  • 42
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    Worldwide photometry and lightcurve observations of 1 Ceres during the 1975-1976 apparition (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Lightcurves and UBV photometry of Ceres from the 1975-1976 apparition are presented. The synodic period is 0.37812 + or 0.00004 day, the mean absolute V magnitude is 3.61 + or 0.03, and the phase coefficient is 0.040 + or - 0.001 mag/deg. The U-B and B-V phase coefficients are +0.0015 + or - 0.0007 and +0.0006 + or - 0.0003 mag/deg, respectively. The colors at zero phase are B-V = +0.70 + or - 0.01 and U-B = +0.41 + or 0.01.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 54; April 19
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  • 43
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    Pole orientation of asteroid 44 Nysa via photometric astrometry, including a discussion of the method's application and its limitations (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The results of photometric astrometry, a method of determining the orientation of a rotation axis, as applied to asteroid 44 Nysa, are presented. The pole orientation of Nysa was found to be lambda(zero) = 100 deg, beta(zero) = +60 deg with an uncertainty of 10 deg. The sidereal period is 0.26755902 days + or - 0.00000006, and the rotation prograde. Refinements to, and limitations of, the application of the method of photometric astrometry are discussed. In light of the results presented herein, it is believed that all photometric astrometry pole determinations of the past should be redone.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 54; April 19
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  • 44
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    Lightcurves and phase function of asteroid 44 Nysa during its 1979 apparition (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Lightcurves of asteroid 44 Nysa obtained during 20 nights in 1979 as part of a global compaign are presented. The synodic period was 6 hours and 25.3 minutes. The phase coefficient of the primary maximum was 0.026 mag/deg and the absolute V magnitude 7.05. The phase function is linear from 2 to 25 deg, no opposition effect is present.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 54; April 19
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  • 45
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    Aperture synthesis observations of Orion B at 2.695 and 8.085 GHz (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Interferometer observations of Orion B at 2.695 and 8.085 GHz are presented. Orion B appears to be a double source: one H II region associated with the star NGC 2024 No. 2 and an extended H II region surrounding the star NGC 2024 No. 1. This structure gives support to the model that the stars NGC 2024 No. 2 and No. 1 (of spectral type O 9.5 and B 0.5, respectively) ionize the nebula.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 120; 2, Ap; April 19
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  • 46
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    Speckle imaging for planetary research (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present study of speckle imaging technique effectiveness encompasses image reconstruction by means of a division algorithm for Fourier amplitudes, and the Knox-Thompson (1974) algorithm for Fourier phases. Results which have been obtained for Io, Titan, Pallas, Jupiter and Uranus indicate that spatial resolutions lower than the seeing limit by a factor of four are obtainable for objects brighter than Uranus. The resolutions obtained are well above the diffraction limit, due to inadequacies of the video camera employed. A photon-counting camera has been developed to overcome these difficulties, making possible the diffraction-limited resolution of objects as faint as Charon.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 53; March 19
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  • 47
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    Theory of motion of Saturn's coorbiting satellites (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A simple analytic theory describing the 1:1 orbital resonance is presented and applied to Saturn's coorbiting pair, 1980S1 and 1980S3. These satellites are very small and can approach to within 15,000 km, but are prevented from passing each other by their mutual gravitational interaction. The long-term stability of the S1-S3 orbital configuration is discussed in this paper, and a tie between the 1966 and 1980 observations is established.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 53; March 19
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  • 48
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    Report of the IAU working group on cartographic coordinates and rotational elements of the planets and satellites - 1982 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: ASTRONOMY
    Type: Celestial Mechanics (ISSN 0008-8714); 29; April 19
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  • 49
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    Two-dimensional photometry of planetary nebulae (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In connection with the study of planetary nebulae, problems still exist in understanding such basic properties as three-dimensional structure, optical opacity to the central star's ionizing flux, and electron temperature and electron density variations within the nebular gas. To study these properties, two-dimensional images taken in many spectral lines are required. However, such a study presents a formidable problem in data analysis. In the present investigation, an attempt has been made to overcome the difficulties by using an imaging system which encodes the data digitally. Calibrated intensity maps could be constructed to test models of ionization structure and to produce two-dimensional maps of electron temperature and density. Both the results of a uniform-shell test and the nature of the solutions for the volume emissivity were found to support a nebular model in which the bright ring is part of a closed shell of variable density that resembles the torus proposed by Minkowski and Osterbrock (1960).
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
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  • 50
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    Local circumstances in Java during the total solar eclipse of 1983 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A total solar eclipse of unusually long duration will occur on 11 June 1983. The path of totality begins in the Indian Ocean, passes over many of the islands of Indonesia and ends in the Coral Sea. The duration of totality is maximum near Java where weather prospects are also quite favourable. Local circumstances are examined in detail, presenting predictions for 34 cities on the island. A consideration of lunar-shadow geometry is given to clarify some of the confusion concerning the advantages of observing from the centre line. A comparison of the present predictions with those of the U.S. Naval Observatory reveals some differences which could have important implications for observers.
    Keywords: ASTRONOMY
    Type: Royal Astronomical Society of Canada; vol. 77
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  • 51
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    10 micron polarimetry of Ceres (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Linear polarimetry of Ceres at 10 micron is presented. These data represent the first published polarization measurements of an asteroid in the thermal infrared. It is found that Ceres is polarized at the 0.2-0.6 percent level. This data set is compared with theoretical models of the linear polarization of emitted radiation from a spherical plane. These models are used to derive the pole position and thermal inertia of Ceres. Ceres is best fit with a thermal inertia of 0.0010 + or 0.0003 cal (sq cm K) per square root of second and a pole orientation of beta(p) = 36 deg + or - 5 deg + or -5, lambda(p) = 270 deg + or - 3. It is concluded that 10 micron polarimetry is a potentially powerful technique for remotely sensing the pole orientation and thermal inertia of asteroids.
    Keywords: ASTRONOMY
    Type: Icarus (ISSN 0019-1035); 56; 381-392
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  • 52
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    Celestial mechanics with geometric algebra (1983)
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    Publication Date: 2011-08-18
    Description: Geometric algebra is introduced as a general tool for Celestial Mechanics. A general method for handling finite rotations and rotational kinematics is presented. The constants of Kepler motion are derived and manipulated in a new way. A new spinor formulation of perturbation theory is developed.
    Keywords: ASTRONOMY
    Type: Celestial Mechanics (ISSN 0008-8714); 30; 151-170
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  • 53
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    High resolution X-ray images of Puppis A and IC 443 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Soft X-ray photomosaic images of two supernova remnants, Puppis A and IC 443, constructed from a series of exposures by the Einstein imaging instruments, are presented. The complex morphologies displayed in these images reflect the interaction between 'middle-aged' supernova remnants and various components of the interstellar medium. Surface brightness variations across Puppis A suggest that inhomogeneities on scales from 0.2 to 30 pc are present in the interstellar medium, while the structure of IC 443 is apparently dominated by the interaction between the remnant and a giant molecular cloud.
    Keywords: ASTRONOMY
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  • 54
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    Observations of spectroscopic binaries at ultraviolet and red wavelengths (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of IUE-satellite and ground-based-Reticon observations for the study of spectroscopic binaries is examined, and sample data from the Reticon are presented. IUE radial-velocity determinations with uncertainties as low as 2-5 km/sec should be possible for binaries with early-type secondary components, using UV spectral lines where contamination by the later-type primary is reduced. The Reticon solid-state photodiode-array detector has been used at the coudefocus of the 2.7-m telescope at McDonald Observatory for observation of complex multiple systems in the 400-950-nm range with a quantum efficiency of 40-80 percent and resolution of 20-30 pm at 440 pm/mm. The fundamental parameters of 15 systems observed with this apparatus are listed in a table, and two sample spectra are shown.
    Keywords: ASTRONOMY
    Type: Lowell Observatory Bulletin (ISSN 0024-7057); 167,
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  • 55
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    Evaluation of a 32 x 32 InSb CCD for use in astronomy (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: We have been fortunate to receive several infrared CCD array detectors on loan from Santa Barbara Research Center. The devices are evaluation samples, not commercially available at this time. Dr. Alan Hoffman of SBRC has made the arrangements for this loan and provided considerable technical support to this project. One aim of this project has been to evaluate the performance potential of this array technology, using astronomical objects. A quick summary of our findings is given. In short, we have found the imaging properties to be excellent under both low and high background conditions and the sensitivity to be quite good (each pixel is competitive with current InSb single-detector systems in use for astronomy). We anticipate improved low-background performance when we run these detectors at a lower and more stable temperature. The device characteristics are described, laboratory testing is summarized, and the first astronomical imaging is presented. Various circuits developed (clocks, clock drivers, DC supplies, clamp-amplifier, and a real time display system) are given.
    Keywords: ASTRONOMY
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 69 p
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  • 56
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    The morphology and kinematics of the Cep IV star formation region (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Rossano et al. (1980) have discussed the morphology and kinematics of Cep IV star formation region. The present investigation is concerned with H2CO observations which have been conducted to examine the relationship between the neutral and ionized gas in the Cep IV star formation region and to study the origin of the unusual kinematics and morphology of the stars, gas, and dust in this region. Six-cm H2CO observations were undertaken throughout a one half degree square area centered on the H II region W1. In addition, VLA observations of the Cep IV region at 6 and 20 cm were also performed. The neutral gas in the vicinity of W1 is found to be located in clouds having velocities of -13, -7, and 1 km/s. The gas at - 7 km/s appears to be undisturbed gas from the original dark cloud complex.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; 1835-184
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  • 57
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    Einstein X-ray observations of optical-radio selected areas (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Einstein Observatory Imaging Proportional Counter X-ray observations of fields in SA 57, SA 68, and U Mi that possess deep optical and radio coverage have been conducted with a sensitivity comparable to that of the Einstein Observatory's medium sensitivity survey of serendipitous X-ray sources. The number of X-ray sources detected is consistent with a log N(greater than S) - log S slope of about -1.5. The fraction of active galactic nuclei in the X-ray sample is less than about 50 percent, with the rest being composed of clusters and normal galaxies, consistent with the medium sensitivity survey.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 1-7
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  • 58
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    Determination of the Io heat flow. 1: Eclipse observations (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The thermal emission from Io during eclipse by Jupiter yields data from which the total thermal flux from the volcanoes on the satellite surface can be estimated. Thermal infrared observations in spectral bands between 3.5 and 30 microns of five Io eclipse reappearances and one eclipse disappearance are reported and discussed. The thermal emission of the volcanoes which occurs almost all of the time was determined from the Io heat flux data. The thermal observations of Io are discussed with respect to previous thermophysical theories.
    Keywords: ASTRONOMY
    Type: NASA-CR-173631 , NAS 1.26:173631
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  • 59
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    International Ultraviolet Explorer Observations of Wolf-Rayet Binaries: Wind Structures (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Spectra of six WN + OB Wolf-Rayet systems obtained with the IUE are analyzed for phase-dependent variations. Periodic variability at emission-line frequencies is detected in V444 Cyg, HD 90657, HD 211853, HD 186943 and HD 94546 on low dispersion SWP images. No changes in the low dispersion spectra of HD 193077 are apparent. We find the variations in the UV to be similar in nature to those observed in optical spectra of various WR sources. That is, there is a strengthening of absorption components in P Cygni-type features at orbital phases in which the O-star is behind the WR wind. With the aid of a computer code which models this type of variations, and through a comparison with HD 193077, the dominant mechanism producing the variations is shown to be selective atmospheric eclipses of the O-star by the WR wind. Based on this interpretation, a straightforward technique is applied to the line of N IV 1718, by which an optical depth distribution in the WN winds of the form tau varies as r(-1) is derived for 16 r 66 solar radii. Phase-dependent variations in the width of the C IV 1550 absorption component in V444 Cyg, HD 90657 and HD 211853 are interpretated as wind-wind collision effects.
    Keywords: ASTRONOMY
    Type: NASA-CR-175235 , NAS 1.26:175235
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  • 60
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    Rocket and laboratory studies in aeronomy and astronomy (1983)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Data extracted from semi-annual status reports presented include: a list of all sounding rocket launches performed under NASA sponsorship; a list of Ph.D. and M.A. degrees awarded to students who worked in these programs; a summary bibliography of all publications through 1983; the most recent list of the publications from the IUE program; a summary of instrument development supported by the Johns Hopkins sounding rocket program; and a list of faculty and post-doctoral research associates whose work was supported by this grant.
    Keywords: ASTRONOMY
    Type: NASA-CR-177887 , NAS 1.26:177887
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  • 61
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    Space telescope (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Space telescope drawings, mockup drawings, space support equipment, and Spacelab experiment hardware are discussed.
    Keywords: ASTRONOMY
    Type: NASA-CR-170948 , NAS 1.26:170948 , H-83-06
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    The dynamics of elliptical rings (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The paper investigates the evolution of eccentric rings under the influence of (1) differential precession due to the planetary quadrupole moment; (2) self-gravity; (3) viscous forces due to interparticle collisions; and (4) eccentricity excitation by shepherd satellites. The principal conclusions are that: (1) uniform precession can be enforced by self-gravity; the resulting configuration is both dynamically and secularly stable. (2) due to viscous forces the line of apsides at the inner ring edge is not exactly aligned with the line of apsides at the outer edge; the apse shift may be detectable in the alpha and beta rings of Uranus; (3) the mean eccentricity is determined by a balance between viscous damping and excitation by shepherds; (4) and the dimensionless eccentricity gradient is expected to be positive and of order unity in most eccentric rings, as observed.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; Oct. 198
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  • 63
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    Ultraviolet photometry of dwarf novae in outburst (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Broad-band photometry from the Astronomical Netherlands Satellite of five dwarf novae at 1550, 1800, 2200, 2500, and 3300 A is presented. EM Cyg in standstill exhibits a flux excess at 3300 A. The lack of a strong extinction feature at 2200 A is seen as suggesting that the reddening is small toward all five systems. Using an independent estimate of the distances, mass flux rates are derived by fitting steady-state, optically thick accretion disk models to the observed UV luminosity. The rate is found to be 3 x 10 to the 17th g/s for Z Cam and EM Cyg in outburst and a factor of 3 smaller of Z Cam in standstill. The models, however, do not reproduce the slope of the Balmer continuum. Of special interest are the observations of outburst rises of SS Aur, SU UMa, and EM Cyg. SS Aur exhibits an exponential increase at a rate of 3.5 mag in 0.5 d. The outburst in EM Cyg also reveals an exponential rise, but at a rate of only 1.2 mag per day.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 15
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  • 64
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    VLA observations of a complete sample of extragalactic X-ray sources. II (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A complete sample of 35 X-ray selected sources found with the Einstein Observatory has been observed with the Very Large Array at 6 cm to investigate the relationship between radio and X-ray emission in extragalactic objects. Detections include three active galactic nuclei (AGNs), two clusters or groups of galaxies, two individual galaxies, and two BL Lac objects. The frequency of radio emission in X-ray selected AGNs is compared with that of optically selected quasars using the integral radio-optical luminosity function. The result suggests that the probability for X-ray selected quasars to be radio sources is higher than for those optically selected. No obvious correlation is found in the sample between the richness of X-ray luminosity of the cluster and the presence of a galaxy with radio luminosity at 5 GHz larger than 10 to the 30th ergs/s/Hz.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 15
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  • 65
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    CCD photometry of the BL Lacertae object 1400+162 and the associated group of galaxies (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Surface photometry of the BL Lacertae object 1400+162 and an apparently associated group of galaxies has been obtained using a CCD camera. Observations were made in V, broad bandpasses centered on 0.75 micron and 1.0 micron and with no filter. The colors of all but two of the galaxies suggest they are ellipticals, with the colors of the remaining two considerably bluer. Analysis using a method described by Schechter and Press (1976) suggests the group is a small one. The group may be similar to the one associated with the quasar 3C 273. The spectral index of the BL Lac object is 1.49 + or 0.21. This value allows, but does not require, the presence of an underlying elliptical galaxy. The radio-optical and optical-X-ray indices for 1400+162 are similar to values found for quasars.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 15
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  • 66
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    Remarkable modification of light curves for shadowing effects on irregular surfaces - The case of the asteroid 37 Fides (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Photometric observations of the asteroid 37 Fides carried out at four observatories are reported. The data were taken at phase angles ranging from approximately 2-23 deg. A composite of the light curves obtained revealed that, considering a period of 7.33 hr, the full cycle light curve exhibits one maximum and one minimum. An increase in brightness was observed following a primary minimum, a factor that indicated the cyclical appearance and disappearance of a large topographical feature. It is concluded that the 7.33 hr period is the rotational speed of the asteroid, in contrast with a previously held 14.66 hr rotational period. The method is concluded useful for identifying rotational periods of asteroids when only partial light curve data from different sources is available, and when the projections can be checked observationally.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 123; 2 Ju; July 198
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  • 67
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    A directional gamma-ray telescope using coded aperture techniques (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A directional detector for gamma-ray astronomy has been developed to image sources in the energy range 0.1 to 5 MeV. An array of 35 gain stabilized bismuth germanate detectors, together with a coded aperture mask based on a uniformly redundant array allows imaging in 4 deg square sky bins over a 16 x 24 deg field-of-view. The position of a strong point source, such as the Crab Nebula, can be determined to within not more than about 1 deg. A complementary 'anti-mask' greatly reduces systematic effects arising from nonuniform background rates amongst the detectors. The telescope has an effective area of 190 sq cm and an energy resolution of 19.5 percent FWHM at 662 keV. Results of laboratory tests of the imaging system, including the ability to image multiple sources, uniformity of response over the field-of-view, and the effect of the 'anti-mask', are in good agreement with computer simulations. Features of the flight detector system are described and results of laboratory tests and computer simulations are reviewed. A balloon flight of the telescope is planned for the fall of 1982.
    Keywords: ASTRONOMY
    Type: Advances in Space Research (ISSN 0273-1177); 3; 4 19; 1983
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  • 68
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    The probable association of SN 1957d in NGC 5236 (M83) with an unresolved radio source (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Astrometric measurements of the position of SN 1957d in the spiral galaxy NGC 5236 using archival plates indicate that it is within 2 arcsec of the position of a point radio source of approximately Cas A strength on a VLA map made by Cowan and Branch (1982). This coincidence strongly suggests that the radio source originated from the supernova. If further investigation shows this point source to indeed be a supernova remnant, then this would be the first reported detection of an intermediate-age supernova remnant.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 270; July 1
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  • 69
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    IUE observations of the perplexing bipolar planetary nebula NGC 2346 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A preliminary analysis of International Ultraviolet Explorer (IUE) low-dispersion spectrograms of NGC 2346, obtained at various phases of the eclipsing nucleus, shows features typical of a high-excitation planetary nebula. Variations in line profiles, intensities, and stellar continuum are observed as a function of time. An orbital period of 16.0 days was determined from 1.8m(v) variations measured by the IUE Fine Error Sensor (FES) and agrees with the period derived from radial velocity measurements by Mendez.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 270; July 1
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  • 70
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    The dynamics of rich clusters of galaxies. II - The Perseus cluster (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The dynamics of the Perseus cluster are analyzed using self-consistent equilibrium analytical models. Using existing data in the literature plus new radial velocities reported here, composite surface density and velocity dispersion profiles are derived. These profiles have been compared with dynamical models described by Kent and Gunn (1982). The best fit suggest the presence of a significant degree of anisotropy in the velocity distribution: galaxy orbits are constrained to pass within a radius of seven cluster radii, or 1.3 deg of the cluster center. For Hubble constant = 50, a core radius of 340 kpc 11 arcmin and a mass to visual light ratio M/L = 300 are found. Using these results, X-ray observations of the intracluster medium in Perseus are reanalyzed. A previously noted discrepancy between the observed temperature of the hot gas and the cluster velocity dispersion is reduced but not eliminated. A cooling accretion flow previously deduced to exist in this cluster is shown to extend to only about one-third of the cluster radius.
    Keywords: ASTRONOMY
    Type: Astronomical Journal (ISSN 0004-6256); 88; June 198
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  • 71
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    The binary central star of the planetary nebula LT-5 (1983)
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    Publication Date: 2019-06-28
    Description: Data from the IUE shows that the true central star of the giant planetary Longmore-Tritton 5 (339+88.1 deg) is a binary companion to the G5 star SAO 82570. The slope of the energy distribution curve indicates that the star may be one of the hottest known. The Mg II doublet associated with the G star is very strong, consistent with the existence of a close binary companion.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 15
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  • 72
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    A statistical VLBI study of milli-arcsecond cores in extragalactic radio sources (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: VLBI observations at 2.3 GHz with a baseline of approximately 8 x 10 to the 7th wavelengths were performed on a complete sample of 103 sources from the Parkes + or - 4 deg catalog. Compact milli-arcsec cores were found in 35 percent of all sources: in 80 percent of quasars, in 10 percent of galaxies, and in 20 percent of empty field sources. It is shown that for quasars the percentage of the source flux density coming from milli-arcsec cores increased with increasing radio spectral index, radio variability, and optical redness. It is noted that quasars with extended radio structure (not less than approximately 10 arcsec) seem more likely to have a detectable milli-arcsec core than do extended radio galaxies. The absence of a strong correlation between quasar milli-arcsec structure and redshift is found to be evidence for a lack of strong physical evolution in quasars.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 15
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  • 73
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    The optical identification content of the Einstein Observatory deep X-ray survey of a region in Pavo (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Results are presented from the Einstein deep X-ray survey in Pavo, with correlated optical and radio observations of a complete sample of candidate identifications. There are 16 X-ray sources detected with positional accuracy better than 10 arcsec, of which five are identified, with a further seven (and a maximum nine) probable identifications. Of the identified sources, four are QSOs with J-magnitude about 20 (one is an inverted spectrum radio source) and one is associated with extended emission from a pair or cluster of galaxies. Of the probable identifications, one is a galaxy and the rest are a subset of a yellow stellar object population which may also be QSOs. Identifications with QSOs and QSO candidates with J less than 24 account for 60-80 percent of the detected sources.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 15
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  • 74
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    X-ray emission from the Pleiades cluster (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The detection and identification of H0344+24, a new X-ray source located in the Pleiades cluster, is reported, based on observations made with HEAO A-2 low-energy detector 1 in the 0.15-3.0-keV energy band in August, 1977. The 90-percent-confidence error box for the new source is centered at 03 h 44.1 min right ascension (1950), near the center star of the 500-star Pleiades cluster, 25-eta-Tau. Since no likely galactic or extragalactic source of X-rays was found in a catalog search of the error-box region, identification of the source with the Pleiades cluster is considered secure. X-ray luminosity of the source is calculated to be about 10 to the 32nd ergs/sec, based on a distance of 125 pc. The X-ray characteristics of the Pleiades stars are discussed, and it is concluded that H0344+24 can best be explained as the integrated X-ray emission of all the B and F stars in the cluster.
    Keywords: ASTRONOMY
    Type: Astrophysics and Space Science (ISSN 0004-640X); 92; 1 Ma; May 1983
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  • 75
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    Optical and X-ray observations of faint quasars in an optically selected sample (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The confirmation of six quasars from spectrographic observations made in 1981 using the Multiple Mirror Telescope, and the characterization of 10 quasars from 1980 Einstein-Observatory X-ray observations (using both imaging proportional counter and high-resolution imager), are reported. The candidates had been selected by Formiggini et al. (1980) in a 1.72-sq-deg region centered on 13h 6 deg, on the basis of ultraviolet excess and a limiting B magnitude of 19.20. A total sample of 10 UV-excess quasars of this magnitude has now been confirmed, for an integral surface density of 5.8 + or - 1.8 per sq deg. Confirmation of three objects from another sample with B less than 18.25 as quasars yielded a surface density of 0./59 + or - 0.13 per sq deg at that magnitude. Data from the complete samples were used to compute the number-flux relation, found to be described by a power law with a 2.25 index for quasars with B between 17.0 and 19.2. From the X-ray observations it was determined that quasars with z less than 2.2 and B less than 19.20 contribute about 15 percent to the cosmic 2-keV background.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 269; June 1
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  • 76
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    Optical photometry with the Kuiper Airborne Observatory (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The properties of optical photometric data obtainable with the 0.9-meter telescope of the Kuiper Airborne Observatory are described. The major differences between airborne and ground-based data are the absence of scintillation and the increased cosmic-ray background in the airborne data and the large size and vibration of the airborne images. The underlying cause of the large airborne images in not known although refraction in the turbulent boundary layer of the aircraft is suspected to be the major factor.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; May 1983
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    An example of the performance of the space telescope planetary camera (1983)
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    Publication Date: 2019-06-28
    Description: A ground-based CCD picture of the relatively local dwarf irregular galaxy Sextans B is used to simulate a Space Telescope Planetary Camera image of a similar galaxy at the distance of the Virgo cluster. The gains to be had with the Space Telescope are discussed graphically.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; May 1983
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  • 78
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    ANS spectrophotometry - Delta Pictoris as an upper-main-sequence algol system (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The early-type eclipsing binary Delta Pictoris has been studied with 260 observations in each of five UV bands. These are the most accurate observations to date, and no strong evidence for light-curve complications produced by circumstellar material has been found. Combined light curves from four epochs separated by intervals of six months do not show any strong dips or shoulders as seen in earlier investigations. The strength of th C IV wavelength 1550 line is independent of phase to better than 0.01 m. The root-mean-square scatterer shown by the light curves ranges from 0.006 m to 0.014 and may be evidence that either or both of the components are intrinsically variable. The integrated colors of the system are consistent with a B1 V spectral type and very little interstellar extinction. A detached solution of the light curves for a Roche model well with the spectroscopic mass ratio, but a semidetached solution cannot be ruled out.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; May 1983
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  • 79
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    Orbital motion and mass flow in the interacting binary Be star HR 2142 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The discovery of an unusual, periodic, two-component shell phase of short duration in the 'classical' Be star HR2142 (HD41335, MWC133) offered convincing evidence that this object is a mass-transfer binary system. A model based solely on the phase-dependent behavior of the hydrogen shell lines in this 80(d).860 binary was developed by Peters and Polidan (1973) and by Peters (1976). The present investigation is concerned with a refinement to the earlier model, taking into account the utilization of an orbital solution obtained from measurements of the wings of the broad photospheric features observed in the rapidly rotating primary. Velocities and equivalent widths from the sharp 'shell' lines, presumably formed in or near the gas stream, provide additional information on the mass flow in the Balmer-line-formation region.
    Keywords: ASTRONOMY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; May 1983
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  • 80
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    The galaxy's 157 micron (C II) emission - Observations by means of a spectroscopic lunar occultation technique (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Galactic (C II) 157 micron, fine-structure emission was estimated. At a Galactic longitude of 8 deg, the peak power observed in a 7' x 7' field is approx. 5 x 10 to the -9 Watt. The method used to detect this radiation involved chopping against the cold side of the Moon. Previously announced in STAR as N83-24437
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 268; May 15
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  • 81
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    VLBI observations of a radio flare of Circinus X-1 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: VLBI 2.3 GHz observations of a strong radio flare of the binary star system Circinus X-1 indicate a radio source flaring component angular size of 0.0015-0.015 arcsec. This is equivalent to a linear size of 15-150 AU at the 10 kpc distance of Circinus X-1, although interstellar medium scattering may have enlarged the apparent angular source size. Since the radio source quiescent component, observed prior to the flare, had an angular size greater than 0.2 arcsec (equivalent to more than 2000 AU at 10 kpc), the quiescent radio emission comes from a region much larger than that proposed in recent models for Circinus X-1. The quiescent component appears to be variable on a time scale of years, and is probably fueled by the Circinus X-1 binary system.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 268; May 1
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  • 82
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    Extragalactic 1 millimeter sources - Simultaneous observations at centimeter, millimeter, and visual wavelengths (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Observations simultaneously made at visual (B, V, and R) wavelengths, at 1, 1.4, and 3.4 mm and at 1.3, 2, 6, and 20 cm of 9 QSOs and BL Lac objects are reported. The range of the millimeter-visual spectral index alpha sub mv was only 0.65-0.82, typical of optically thin synchrotron emission. This may indicate that the electrons radiating synchrotron emission in this portion of the spectrum are not subjected to large radiation losses, and therefore relativistic bulk motion with Doppler factors of about 10 are required. The visual spectral index is much more broadly distributed and typically larger than alpha sub mv. The spectral energy distributions have not changed much in the last two to five years except for 2251+15 and perhaps 0235+164. Only 1749+09 shows a sharp spectral break shortward of 1 mm. Sixteen other sources were observed at 1 mm, of which seven were detected.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 268; May 1
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  • 83
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    The Cancer Cluster - An unbound collection of groups (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A surface density contour map of the Cancer Cluster derived from galaxy counts in the Zwicky catalog is presented. The contour map shows that the galaxy distribution is clumpy. When this spatial distribution is combined with nearly complete velocity information, the clumps stand out more clearly; there are significant differences in the mean velocities of the clumps which exceed their internal velocity dispersions. The Cancer Cluster is not a proper 'cluster' but is a collection of discrete groups, each with a velocity dispersion of approximately 300 km/s, separating from one another with the cosmological flow. The mass-to-light ratio for galaxies in the main concentration is approximately 320 solar masses/solar luminosities (H sub 0 = 100 km/s Mpc).
    Keywords: ASTRONOMY
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 268; May 1
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  • 84
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    X-rays from supernovae remnants 3C400.2 (= G53.7 - 2.2) and MSH 15 - 56 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Keywords: ASTRONOMY
    Type: Astrophysics and Space Science (ISSN 0004-640X); 89; 2 Ja; Jan. 198
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  • 85
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    Supernova remnants in the Magellanic Clouds (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The present updated catalog of SNRs in the Large and Small Magellanic Clouds (LMC and SMC) incorporates remnants recently discovered as a result of coordinated X-ray, optical, and radio surveys, and contains 25 confirmed SNRs in the LMC and six in the SMC. Optical images are included for all of the new SNRs, together with X-ray isophotes for 24 of the SNRs in the LMC which have been obtained with the high resolution imager and imaging proportional counter of the Einstein Observatory. The cumulative number-diameter relation for Type II SNRs with D smaller than 50 pc in the LMC is N(D)= 0.36 D exp 1.0 + or 0.2, suggesting that the SNRs have evolved much faster than expected from Sedov theory and that the free expansion phase dominates their evolution up to diameters of 30-40 pc. SNR production frequencies in the LMC and SMC are calculated to be 1/275 and 1/800 years, respectively, or nearly equal to the galaxies' luminosity ratios.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal Supplement Series (ISSN 0067-0049); 51; April 19
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  • 86
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    Five years of photometry of Lambda Andromedae (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Photoelectric photometry of the bright variable RS CVn-type binary Lambda And obtained in 1977-78 and 1980-81 is presented and used, together with earlier photometry, to derive the photometric period and discuss the changing shape of the light curve. The best ephemeris for times of minimum light is 2443829.2 + 53.95 d E. Because times of minimum and maximum extending back to those of Calder in 1933-37 can be phased together properly, the principal dark region must have maintained its identity for almost 50 yr. Over the last five years the brightness range has been between 3.70 and 4.05 m. During 1980-81 shallow secondary minima developed at phases where maxima occurred in previous years. Lambda And remains the only well-established case of nonsynchronous rotation among the known RS CVn variables.
    Keywords: ASTRONOMY
    Type: Astrophysics and Space Science (ISSN 0004-640X); 90; 1 Fe; Feb. 198
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  • 87
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    Analysis of optical imagery for Seyfert's Sextet and VV 172 (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Seyfert's Sextet and VV 172, 5-m photographs have been subjected to image processing to yield field-galaxy density analysis, redshift-scaled imagery, interaction morphology display and enhancement, color difference imagery,modeling of the VV 172 halo, and image texture analysis of the spiral galaxy components of Seyfert's Sextet. An effort is made to evaluate the evidence for physical association of the discordant redshift components of these groups. An especially noteworthy characteristic of the groups is their extended luminous halos. The halo of VV 172 cannot be explained by the overlapping envelopes of galaxies with normal luminosity profiles, and the high redshift spiral galaxy in the Sextet is found to have an asymmetric internal structure and associated filament which suggest gravitational perturbation by the other members of the group.
    Keywords: ASTRONOMY
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 120; 1 Ap; April 19
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  • 88
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    A search for weak H-alpha emission line pre-main-sequence stars (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A spectroscopic survey of 177 stars brighter than about 12.5 in R near four dark clouds in an effort to find pre-main-sequence (PMS) stars with weak H-alpha emission is reported. A number of such stars have been found previously in X-ray images of star formation clouds. Six new candidate PMS stars with EW (H-alpha) between 0.4 and 4.2 A, in addition to four X-ray discovered stars, are found in the L1551 and L1529 clouds in the Taurus-Auriga complex. The total number of pre-main-sequence stars in these clouds appears to be about two times the number of strong emission line T Tauri stars.
    Keywords: ASTRONOMY
    Type: Astronomical Journal; 88; Mar. 198
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  • 89
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    VLBI observations of the nucleus of Centaurus A (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: VLBI observations of the nucleus of Centaurus A made at 2.3 GHz on baselines with minimum fringe spacings of 0.15 and 0.0027 arcsec are presented. Results show that the nuclear component is elongated with a maximum extent of approximately 0.05 arcsec which is equivalent to a size of approximately 1 pc at the 5 Mpc distance of Centaurus A. The position angle of the nucleus is found to be 30 + or - 20 degrees, while the ratio of nuclear jet length to width is less than or approximately equal to 20. The nuclear flux density is determined to be 6.8 Jy, while no core component is found with an extent less than or approximately equal to 0.001 (less than or approximately equal to 0.02 pc) with a flux density of greater than or approximately equal to 20 mJy. A model of the Centaurus A nucleus composed of at least two components is developed on the basis of these results in conjunction with earlier VLBI and spectral data. The first component is an elongated source of approximately 0.05 arcsec (approximately 1 pc) size which contains most of the 2.3 GHz nuclear flux, while the second component is a source of approximately 0.0005 arcsec (approximately 0.01 pc) size which is nearly completely self-absorbed at 2.3 GHz but strengthens at higher frequencies.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
    Format: text
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  • 90
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    Secondary standard stars for absolute spectrophotometry (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Based on an adopted absolute spectral energy distribution for the primary standard star Alpha Lyrae, absolute fluxes are given for the four very metal-deficient F type subdwarfs HD 19445, HD 84937, BD + 26.2606 deg, and BD + 17.4703 deg. Somewhat inferior data are also given for HD 140283. The data are given for 40-A bands and cover the wavelength range from 3080 A to 12,000 A. The four stars, all near magnitude 9 and distributed around the sky, are intended as secondary standards for absolute spectrophotometry.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
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  • 91
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    High-resolution radio and X-ray observations of the supernova remnant W28 (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present study has the objective to report the first high resolution radio and X-ray observations of the central part of the galactic supernova remnant, W28, taking into account the possible association of the remnant with the unidentified gamma-ray source, 2CG 006-00. This gamma-ray source is approximately two-thirds as bright as the Crab pulsar above 100 MeV, and has a somewhat flatter spectrum. Both the radio and X-ray observations reveal previously unknown aspects of W28 which support the possibility of W28 being a gamma-ray source. The radio data show a flat-spectrum, nonthermal component reminiscent of the Crab Nebula and Vela, both of which are confirmed gamma-ray sources. The X-ray observations reveal a compact source within W28, again suggestive of both the Crab and Vela. If the similarities among W28, the Crab Nebula, and the Vela remnant are valid, the gamma-ray source 2CG 00-00 should be studied for periodicity, the conclusive signature of a compact source of emission.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
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  • 92
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    A survey by HEAO 1 of clusters of galaxies. III - The complete Abell catalog (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A catalog of 128 X-ray emitting clusters, including the Virgo Cluster, is presented. Ninety-one of these are new identifications. The catalog was obtained by searching the HEAO 1 survey observations for coincidences of X-ray sources with Abell clusters. The distribution of these sources in the sky has been examined in search of associations with other Abell clusters, with a null result. The X-ray luminosity has been correlated with cluster richness, but no association with Bautz-Morgan class has been found. The cluster luminosity function has been evaluated, and using this function the contribution of clusters to the diffuse X-ray background radiation has been estimated. It amounts to less than 15% at 2 keV and 3% at 6 keV.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 266
    Format: text
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  • 93
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    Numerical simulations of the decay of satellite galaxy orbits (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A multiple three-body technique is used to study the orbital evolution of satellite galaxies which is similar to the N-body method but neglects two-body forces between stars in the halo of the parent galaxy. It is found that, for satellites orbiting within the halo, Chandrasekhar's (1960) dynamical friction formula accurately describes the orbital decay rate, including its variation with satellite mass and size and with the number density and mass of halo stars. Significant frictional forces are present even outside the halo, and the orbital decay rate, instead of depending on the procedure used to place the satellite in its orbit, is determined only by the current orbital parameters. This semirestricted N-body method is sufficiently fast to have permitted the running of 200 simulations to date, many more than would have been possible by means of the conventional N-body technique.
    Keywords: ASTRONOMY
    Type: Astrophysical Journal; vol. 264
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  • 94
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    Seeing Halley's Comet: A guide for observers in the Northern Hemisphere (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A guide for the observation of Halley's comet is presented. The path of the comet is described for the fly by dates and charts are provided for location of the comet in the morning or evening skies. Suggestions for visual observation and photography of Halley's comet are included.
    Keywords: ASTRONOMY
    Type: NASA-CR-173604 , JPL-400-189 , NAS 1.26:173604
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  • 95
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    Documentation for the machine-readable version of the Survey of the Astrographic Catalogue From 1 to 31 Degrees of Northern Declination (Fresneau 1983) (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A description of the machine readable catalog, including detailed format and tape file characteristics, is given. The machine file is a computation of mean values for position and magnitude at a mean epoch of observation for each unique star in the Oxford, Paris, Bordeaux, Toulouse and Northern Hemisphere Algiers zone. The format was changed to effect more efficient data searching by position and additional duplicate entries were removed. The final catalog contains data for 997311 stars.
    Keywords: ASTRONOMY
    Type: NASA-TM-85569 , NAS 1.15:85569 , NSSDC/WDC-A-R/S-83-16
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  • 96
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    Documentation for the machine-readable version of the SAO-HD-GC-DM cross index version 1983 (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An updated and extended machine readable version of the Smithsonian Astrophysical Observatory star catalog (SAO) is described. A correction of all errors which were found since preparation of the original catalog which resulted from misidentifications and omissions of components in multiple star systems and missing Durchmusterung numbers (the common identifier) in the SAO Catalog are included and component identifications from the Index of Visual Double Stars (IDS) are appended to all multiple SAO entries with the same DM numbers, and lower case letter identifiers for supplemental BD stars are added. A total of 11,398 individual corrections and data additions is incorporated into the present version of the cross index.
    Keywords: ASTRONOMY
    Type: NASA-TM-85570 , NSSDC/WDC-A-R/S-83-17 , NAS 1.15:85570
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  • 97
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    Far-IR spectroscopy of the galactic center: Neutral and ionized gas in the central 10 pc of the galaxy (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The 3P1 - 3P2 fine structure line emission from neutral atomic oxygen at 63 microns in the vicinity of the galactic center was mapped. The emission is extended over more than 4' (12 pc) along the galactic plane, centered on the position of Sgr A West. The line center velocities show that the O I gas is rotating around the galactic center with an axis close to that of the general galactic rotation, but there appear also to be noncircular motions. The rotational velocity at R is approximately 1 pc corresponds to a mass within the central pc of about 3 x 10(6) solar mass. Between 1 and 6 pc from the center the mass is approximately proportional to radius. The (O I) line probability arises in a predominantly neutral, atomic region immediately outside of the ionized central parsec of out galaxy. Hydrogen densities in the (O I) emitting region are 10(3) to 10(6) cm(-3) and gas temperatures are or = 100 K. The total integrated luminosity radiated in the line is about 10(5) solar luminosity, and is a substantial contribution to the cooling of the gas. Photoelectric heating or heating by ultraviolet excitation of H2 at high densities (10(5) cm(-3)) are promising mechanisms for heating of the gas, but heating due to dissipation of noncircular motions of the gas may be an alternative possibility. The 3P1 - 3P0 fine structure line of (O III) at 88 microns toward Sgr A West was also detected. The (O III) emission comes from high density ionized gas (n 10(4) cm(-3)), and there is no evidence for a medium density region (n 10(3) cm(-3)), such as the ionized halo in Sgr A West deduced from radio observations. This radio halo may be nonthermal, or may consist of many compact, dense clumps of filaments on the inner edges of neutral condensations at R or = 2 pc.
    Keywords: ASTRONOMY
    Type: NASA-CR-166510 , NAS 1.26:166510
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  • 98
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    Astronomical and statistical algorithms used in the Space Telescope guide star selection system (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The construction of the Space Telescope Guide Star Catalog from digitized Schmidt survey plates covering the entire sky is described. In order to provide sufficient pointing information, the Guide Star Selection System has to contain a catalog of 20 million guide star candidates in the range of 9.0 to 14.5 visual magnitudes. An image inventory process extracts the relevant object data; after photometric and astrometric calibration the data are screened to arrive at suitable guide star candidates. The selection process for a given target takes into account geometric and photometric parameters of the field, scheduling information, and acquisition probabilities for each guide star pair.
    Keywords: ASTRONOMY
    Type: ESA Statist. Methods in Astron.; p 65-68
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  • 99
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    Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Phenomenological fits to the hard X-ray spectrum of AM Herculis left unexplained the high equivalent width (0.8 + or - 0.1 keV) of Fe K alpha emission. A purely thermal origin implies a much steeper spectrum than was observed. With Monte Carlo calculations, scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base were investigated. The strength of the iron emission and the flat spectral continuum can be explained by the effects of fluorescence and absorption within the accretion column and the surface of the white dwarf on a thermal X-ray spectrum. Thomson optical depths across the column in the range 0.2 to 0.7 are acceptable. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values. Estimates of the column size differ by a factor of 40. Small spot sizes and low luminosities would be consistent with the soft component being the expected reprocessed bremsstrahlung and cyclotron radiation, although the constraint of matching the spectrum confines one to solutions with fluxes exceeding 20% the Eddington limits.
    Keywords: ASTRONOMY
    Type: NASA-TM-86045 , NAS 1.15:86045
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  • 100
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    Observations of emission in bright, low redshift quasars (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Ultraviolet, infrared, and optical spectra were combined to obtain a data set sample as broad as possible in the range of hydrogen lines in individual quasars. From the measured Lyman fluxes, coupled with Balmer and Paschen line fluxes measured in these same objects, an effort was made to establish observational constraints that would guide models of the broad emission line regions of quasars. It was found that IUE spectra were generally of sufficiently high quality to derive line profiles of the ultraviolet lines Lyman alpha and CIV 1550 A, which were compared to the Balmer line profiles. The objects observed and the line fluxes are tabulated. Plots of line profiles are included.
    Keywords: ASTRONOMY
    Type: NASA-CR-175376 , NAS 1.26:175376
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