bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Intercomparison of Connected-Element Interferometer and Lunar Laser Earth Rotation Parameters
Authors: McCarthy Dennis D. 
Published: July 2016

AbstractThe determination of Earth orientation parameters using techniques which promise an improvement in the precision of their measurements requires a careful evaluation of the systematic errors present in each series of observations. It is now possible to begin to inter-compare two of these sets of observations of the rotation of the Earth (UT1-UTC) obtained routinely and independently. These are the data obtained from laser ranging to the Moon and those derived from the connected-element interferometer information of the U. S. Naval Observatory. Although these data are available for a relatively short time span, it is possible to begin to inter-compare the observations in an effort to derive possible systematic errors existing in the data. This has been done using data from July 1979 to March 1980 in comparison with Bureau International de l’Heure (BIH) data. Using this information, the hypothesis that there is no correlation between the differences of the interferometer and laser ranging data with respect to the BIH must be rejected. This indicates that both sets of observations show that systematic errors do exist in the BIH data. The nature of the correlation of the two series is examined to establish possible models of the systematic errors. A much longer series of data from both techniques is necessary to improve the estimates, and the results will depend critically on adopted models used in the reductions and the degree of smoothing to which the raw data are subjected.
Dependence of the Lunisolar Perturbations in the Earth Rotation on the Adopted Earth Model
Authors: Capitaine Nicole 
Published: July 2016

If no perturbation exists, the motion of the Earth around its center of mass would be a rigid rotation around a fixed axis in space with constant angular velocity.In fact, many perturbations disturb this ideal motion and produce variations in both the celestial orientation of the rotation axis and the Earth’s angular velocity.The mechanisms responsible for these perturbations are the changes in the total angular momentum due to external torques and also the changes in the inertia tensor of the Earth (due to deformations or motions of matter) or in the relative angular momentum in the terrestrial frame (due for instance to winds or to turbulent flow inside the core).
Modelling the Effect of Earth Tides in the Lunar Orbital Motion
Authors: Mulholland J. Derral , Calame Odile 
Published: July 2016

AbstractThe effect of tidal friction in the lunar orbit is one of the classic examples of ad hoc modelling of an unknown physical phenomenon. The two basic calculational approaches in current use are developed in some detail, and numerical tests and comparisons are presented. Although attention is normally concentrated on the acceleration in orbital longitude produced as a result of terrestrial dissipation, it is shown that the variation in Earth-Moon distance due to Earth tides is far from negligible. A significant, though minor, fraction of this variation is supplied by the radial component of the acceleration, which would exist even in the absence of tidal friction. In fact, this represents almost all the difference in the predictions of the two models.
Comparison of ELP-2000 to a JPL Numerical Integration
Authors: Chapront Jean , Chapront-Touzé Michelle 
Published: July 2016

This contribution is an outline of the main results obtained by the authors in comparing their solution ELP-2000, to a JPL numerical integration, LE-51. A full paper containing discussions and comments on the results will be proposed to Astronomy ’ Astrophysics.A solution for the orbital motion of the Moon has been built by the authors. It is named ELP-2000, the epoch of reference being J2000. It is a semi-analytical solution, its structure being quite similar to Brown-Eckert’s one, as it appears in the Improved Lunar Ephemeris, ILE, j=2, (Eckert et al., 1954). The main purpose of this work is to present the results of a comparison of a provisional but complete solution, to an external numerical integration, LE-51, built at JPL (Williams, 1980), and fitted to lunar laser rangings. The JPL numerical integration is regarded as an “observational model”. It is a first attempt to compare as a whole, a new lunar ephemeris, derived from a semi-analytical theory, to observations, via a numerical integration.
The Union list of Astronomy Serials
Authors: Bausch Judith Lola 
Published: July 2016

I would first like to present a little history of this project. I started working at Yerkes Observatory in March of 1972 and found out about the informal meeting in June of that year of observatory and astronomy librarians meeting at Harvard-Smithsonian after the Special Libraries Association meeting in Boston. I arranged to go to that one-day meeting to meet some of the people working in the field; especially in order to know who to call for some good advice once in a while.My notes from the business meeting that day tell me that “a Union List of Observatory Publications/Astronomy Journals was discussed; no decision.” So I first heard about a union list of astronomy journals in 1972, but it may have been discussed many years before that. The Union List was further discussed at meetings in Pittsburgh in 1973, Toronto in 1974, Chicago in 1975, Denver in 1976, etc., etc.,
Library Collections of Machine-Readable Astronomical Catalogs
Authors: Warren Wayne H. 
Published: July 2016

AbstractMajor astronomical facilities generally use a large number of machine-readable catalogs and data sets. These are requested over a long period of time, usually by individual staff members who seldom request data through their library services. An important drawback of this procedure is that the same catalogs are often requested by different persons at the same institute, thus requiring a duplicate effort on the part of the service organization (usually the data centers) and longer than necessary delays for the persons requesting data. It is suggested that libraries at major facilities build collections of important data sets and maintain library catalogs of these collections for use by staff astronomers. This paper discusses simplified and efficient methods of building such collections and details possible ways of storing and retrieving particular catalogs easily when they are required by staff members.
The On-line IUE Uniform Low Dispersion Archive
Authors: Barylak M. , Wamsteker W. , Driessen C. , Munoz J.R. , Talavera A. 
Published: July 2016

AbstractAfter a decade of IUE observations, the dearchiving rate for IUE data in the public domain is more than 1000 images per month, which is more than twice the number of images taken monthly at both groundstations (ie. Goddard Space Flight Center and the ESA Villafrance Satellite Tracking Station). Considering this high interest in IUE data, an effort was made to improve the accessibility of the IUE archive taking into account the availibility of current intercomputer networks.
Care and Handling of Bound Library Materials
Authors: Roosa Mark , Smith Merrily 
Published: July 2016

AbstractThe care and handling of library and archival materials has become a much - discussed topic in recent years. Considerable time, effort, and money are being invested by many libraries and archives in protective housing, rebinding, conservation, and preservation microfilming programs. These activities are expensive. Therefore it makes good fiscal sense to delay the need for these costly activities by making an effort to preserve library materials in good condition for as long as possible.
Sky Brightness at the Kitt Peak National Observatory
Authors: Pilachowski C.A. , Africano J.L. , Goodrich B.D. , Binkert W.S. 
Published: July 2016

ABSTRACTWe report on the results of a program to measure the brightness of the night sky at the Kitt Peak National Observatory during the recent minimum in the solar cycle, a time noted for the darkest nighttime skies. We have measured sky brightness using a 0.9-meter telescope with a photoelectric photometer on seven nights in 1986 and the first half of 1987. During this period, the average sky brightness in the V (yellow) band is 21.92 magnitudes per square arc-sec. This corresponds to an increase of only 6.5 percent over the natural sky illumination, as compared to an increase of over 10 percent predicted by R. Garstang from the presence of cities and towns in southern Arizona. The continued dark skies over Kitt Peak, despite the rapid growth of Tucson’s population, can only be attributed to the effectiveness of light pollution control programs in place since 1972.
Past and Present Studies Relating to the Illumination of the Night Sky
Authors: Walker Merle F. 
Published: July 2016

During the period from 1965-1977, I was engaged in a program of selecting and acquiring a new dark sky site in California for the Lick Observatory. Even though the effort was, in the end, unsuccessful, this work did lead to several important advances in our understanding of the general problem of optimizing optical-region astronomical observing conditions. These included:
1)The development of the polar star trail method of seeing measurement (Harlan and Walker 1965; Walker 1971).2)Definition of the conditions required to optimize the seeing through the use of the polar star trail method of measurement at a number of potential and established observing sites around the world (Walker 1970, 1971, 1983, 1984; McInnes and Walker 1974).3)Demonstration of the widespread effects of atmospheric pollution in reducing photometric quality at potential sites in California (Walker 1970).4)The first extensive study of the effects of light pollution on astronomical observations.
Publicizing Light Pollution and Its Cures
Authors: Schaaf Fred , Kurczewski Rick 
Published: July 2016

ABSTRACTPublicity is the first and most important tool in efforts to achieve control and reduction of light pollution. It should identify the ways in which light pollution is detrimental to vital human concerns, such as esthetic enjoyment of the heavens, scientific research, and the operation of cost efficient lighting, and take into account the relative importance of the various concerns for each prospective audience or readership.
Big Island Cities at Night
Authors: Westpfahl David 
Published: July 2016

ABSTRACTPhotographs taken during a clear, moonless night from the walkway of the dome of the Canada-France-Hawaii Telescope on Mauna Kea show light trespass from street lighting in Hilo and in Waimea and the sky glow from the growing area around Kona. More full cut-off fixtures would help to prevent deterioration of the quality of the Mauna Kea site.
Radio Spectrum Management and RFI in the United States
Authors: Price R. Marcus 
Published: July 2016

ABSTRACTIn the United States, civil common carrier telecommunications are provided by private companies, not by any agency of the government. Regulation of these services and spectrum management oversight is provided by the Federal Communications Commission (FCC), an agency of the government. Government telecommunications are operated by individual agencies, e.g. the Department of Defense, under the overall regulation of the Office of Spectrum Management of the National Telecommunications and Information Administration (NTIA), a government body separate from the FCC. In bands shared by the civil and government sectors, liaison and coordination is effected between the FCC and the NTIA.
Effects of RFI on Solar Microwave Bursts Observed with Hightime Resolution
Authors: Luo Xianhan 
Published: July 2016

ABSTRACTSolar microwave burst observations with high time resolution (~ 1 ms) are important but difficult to make. It is shown by the experiments of radiometer at wavelength 21 cm on 1 ms time scale that some ultrafast time structures in microwaves, which includes spike impulses, switch-on and switch-off structures, etc., may not be from solar emission but from RFI (radio-frequency interference) or from radiometer itself. Because of the uncertainty at 21 cm and other several wavelengths, we suggest that joint observations of the solar microwave bursts on 1 ms time scale should be carried out on the peak years of the 22nd solar activity cycle.
As Bad as Things are for Radio Astronomy in the Protected Bands -- They are Worse for SETI!
Authors: Tarter Jill 
Published: July 2016

ABSTRACTIf the funding that has been requested in NASA’s FY89 budget is forthcoming, the Search for Extraterrestrial Intelligence (SETI) will inaugurate its microwave search program on Columbus Day, 1992. This systematic search for evidence of narrowband microwave signals generated by another technology will continue at several sites around the world until at least 1998. The search will be conducted in two modes: a sensitive targeted search of selected solar type stars covering 1 to 3 GHz, and an all sky survey that covers 1 to 10 GHz. This region of the spectrum is the quietest in terms of natural background noise from astrophysical sources and/or the terrestrial atmosphere, which is why it was chosen. Unfortunately, at the same time that terrestrial technology has enabled this systematic search, it also threatens to render the search all but impossible from the surface of the Earth. Terrestrial transmissions generated for an enormous number of different purposes will be the signals most frequently detected by the SETI systems! This paper describes the design decisions and observing plans that the SETI Program is now making in order to have a chance of successfully “listening” throujgh this heavily utilized portion of the spectrum. We do not yet know precisely how heroic our efforts to discriminate against and identify RFI may have to be, but we have been accumulating observational experience and data that demonstrate convincingly that the situation is rapidly growing worse. Because of the real-time nature of the signal processing being planned, SETI systems will provide an excellent opportunity to monitor, and perhaps identify, sources of narrowband interference within the radio astronomy bands at each site where observations are being conducted.
What are LBV’s? — Their characteristics and role in the upper H-R diagram
Authors: Humphreys Roberta M. 
Published: July 2016

Only ten years ago a symposium on the special class of stars we now call Luminous Blue Variables (LBV’s) would not have been possible. At that time we were only just beginning to recognize the similarities among the stars we call S Doradus variables, P Cygni stars, and Hubble-Sandage variables, and their importance in the evolution of the most massive stars.About a decade ago it became clear that the observed H-R diagram has an upper luminosity limit and thatηCar, P Cyg, and S Dor are all near the temperature-dependent boundary for hot stars. With hindsight the luminosity boundary can be seen in an H-R diagram for hot stars published by Hutchings (1976), but the full temperature range is necessary to show that it really exists. When more data became available in 1977—1978, including the evolved and cool supergiants, the upper luminosity limit became obvious; and we proposed that an instability causingrapidandunsteadymass loss (i.e., LBV’s) is the basic reason for this boundary (Humphreys and Davidson 1979). We emphasized the temperature-dependence of the boundary for the most luminous hot stars, the lack of cooler counterparts at similar luminosities, the nearly temperature-independent limit to the luminosities of cool hypergiants, and the critical role that objects likeηCar, P Cyg, and S Dor may play in the evolution of the most massive stars.
The H-R diagrams of the LMC and SMC
Authors: Garmany C. D. , Fitzpatrick E. L. 
Published: July 2016

AbstractWe present new determinations of the H-R diagrams for luminous, hot stars in the LMC and the SMC. Using all available photometric and spectroscopic data, we discuss the conversion of the observed measurements to temperature and luminosity. The resulting H-R diagrams for normal stars confirm the upper luminosity limit, and also show an interesting “ridge” not noted before.
“Normal” LBV eruptions à la S Doradus
Authors: Wolf B. 
Published: July 2016

AbstractThe main characteristics of the LBVs with “normal” S Dor-type outbursts are reviewed. At quiescence they are luminous (MBol≈ −9 to −10) OB supergiants (14 000 K ≲ Teff≲ 30 000 K) occupying an inclined instability strip in the HRD. The most luminous S Dor variables are the hottest ones. During outburst dense envelopes are expelled of equivalent spectral type middle A to early F. S Dor variables occupy at maximum a vertical strip in the HRD at T≈8000 K. The observed amplitudes in the visual range increase from 1 mag (e.g. R71; Teff= 14500 K at quiescence) to 2.5 mag (e.g. R127; Teff= 33000 K at quiescence). The existence of an amplitude-luminosity relation is suggested which can be used to derive extragalactic distances.
The formation of shells in the wind from P Cygni
Authors: Kahn F. D. 
Published: July 2016

AbstractA mechanism is proposed for the formation of shells around P Cygni. These shells seem to arise at approximately two monthly intervals and each appears to undergo a steady acceleration of some 0.6 cm s-2during the six months that it is present. In the process to be described the formation of the shells takes place in a stellar wind that moves outwards ballistically from the photosphere. Small fluctuations in wind speed are introduced there and eventually lead to the condensation of shells at a radial distance of the order of 1014cm. The density in the shells is large enough to account for their acceleration by the Lyman continuum emitted by the star. It is also proposed here that the observed time scale of two months is set by the dynamics of the flow field in interaction with the random fluctuations imposed on it at the photosphere.
Stellar Kinematics of Elliptical Galaxies in Pairs
Authors: Madejsky Rainer , Bender Ralf 
Published: July 2016

Observations of elliptical galaxy pairs allow the study of different states of tidal interaction between galaxies. The comparison with normal elliptical galaxies directly reveals the disturbed morphological and kinematical properties. Numerical simulations have shown that with the known initial luminosity profile, the time elapsed since closest approach between two galaxies can be estimated from the radial position of the disturbances (Aguilar and White, 1986).The two galaxy pairs Arp 166 (NGC 750/1) and 3C 278 (NGC 4782/3) considered here exhibit distorted and nonconcentric isophotes (cf. Madejsky, 1989). In Arp 166 the major relative shift of the centers of the isophotes occurs in the outer parts while in 3C 278 the nonconcentric isophotes are more pronounced in the inner parts of the galaxies, suggesting that more time ha&elapsed since the moment of closest approach in Arp 166 than in 3C 278. Furthermore, in Arp 166, both galaxies have the same radial velocity, implying that their orbital plane is perpendicular to the line of sight. In turn, the galaxies NGC 4782 and NGC 4783 are moving with a very high radial velocity difference of 680kms-1. Taking into account the location of both galaxies, which are the dominant members of a small group of about 25 galaxies (De Souza and Quintana, 1990), the true velocity difference probably is not much higher than the observed radial velocity difference. Therefore it is very likely that we are viewing at high inclination onto (i.e. nearly parallel to) the orbital plane of the galaxies NGC 4782 and 4783.
An Atlas of Mixed-Morphology Pairs
Authors: Sharp N. A. 
Published: July 2016

Current theories of galaxy formation imply that environment is the most important factor in deciding whether a collapsing region becomes a spiral galaxy or an elliptical galaxy. If this is the case, then isolated pairs comprising a galaxy of each morphology provide an especially interesting test, since, strictly speaking, they should not exist.The first phase of studying E-S pairs is to define a sample which is genuinely isolated and genuinely E-S. The catalog compiled by Karachentsev is the most useful northern hemisphere starting point, containing 603 pairs which obeyed certain well-defined angular isolation criteria. All of these pairs now have velocities, enabling further removal of at least some of the non-physical binaries. The conventional cutoff at 500 km s−1 was used for this purpose.
Dumb-Bell Galaxies in Southern Clusters: Catalog and Preliminary Statistical Results
Authors: Vettolani G. , Gregorini L. , Parma P. , de Ruiter H.R. 
Published: July 2016

The dominant galaxy of a rich cluster is often an object whose formation and evolution is closely connected to the dynamics of the cluster itself. Hoessel (1980) and Schneider et al. (1983) estimate that 50 % of the dominant galaxies are either of the dumb-bell type or have companions at projected distances less than 20 kpc, which is far in excess of the number expected from chance projection (see also Rood and Leir 1979).Presently there is no complete sample of these objects, with the exception of the listing of dumb-bell galaxies in BM type I and I-II clusters in the Abell statistical sample of Rood and Leir (1979).
Observational Effects of Interaction in the Seyfert galaxy NGC 7469
Authors: Pronik I. , Metik L. 
Published: July 2016

AbstractSome pecularities of the circummucleus of the Seyfert galaxy NGC 7469 were revealed, plausibly caused by interaction with the satellite IC 5283 and a starlike detail, situated on the edge of the west spiral branch 14” from the nucleus. Shock excited HII regions were noted in the part of NGC 7469 turned toward the satellite IC 5283. The galaxy’s central radio structure (λ ~ 6 cm) stretches in the direction toward the satellite IC 5283 and the starlike detail. The spectum and color index of the starlike detail suggest that it is a cluster of early type stars (Mv = -19m) and dust clouds (Av = 3m), in NGC 7469.
Dust and Ionized Gas in Active Radio Elliptical Galaxies
Authors: Forbes D.A. , Sparks W.B. , Macchetto F.D. 
Published: July 2016

AbstractWe present broad and narrow bandwidth imaging of three southern elliptical galaxies which have flat-spectrum active radio cores (NGC 1052, IC 1459 and NGC 6958). All three contain dust and extended low excitation optical line emission, particularly extensive in the case of NGC 1052 which has a large Hα + [Nil] luminosity. Both NGC 1052 and IC 1459 have a spiral morphology in emission-line images. All three display independent strong evidence that a merger or infall event has recently occurred, i.e., extensive and infalling HI gas in NGC 1052, a counter-rotating core in IC 1459 and Malin-Carter shells in NGC 6958. This infall event is the most likely origin for the emission-line gas and dust, and we a currently investigating possible excitation mechanisms (Sparks et al. 1990).
Correlations between Environmental Parameters and Nuclear Activity
Authors: Kollatschny W. , Fricke K.J. 
Published: July 2016

The occurrence and quantitative properties of Seyfert 1 and Seyfert 2 galaxies as a function of the galaxy environment have been studied in a systematic way. For this investigation we have selected from the Catalogue of Quasars and Active Nuclei (Veron & Veron, 1989) all Seyfert galaxies with the following properties:(i) mV ≤ 15,(ii) listed classification as Sey 1, Sey 2, or Sey 3,(iii) vrad ≤ 20000 km s-1.This results in a sample size of 242 Seyfert galaxies. For all these objects their galaxy environment has been inspected on POSS and ESO/SRC plates.The vicinity of each sample Seyfert galaxy was searched for companion galaxies out to at least 0.5 Mpc. Lacking redshift information we adopted as a companion galaxy any galaxy in this area having a size between 20 and 200 percent of the Seyfert galaxy size.