bluuebunny/crossref_metadata_2025_split huggingface dataset:
7. Celestial Mechanics
Authors: Eckert W. J. , Duboshin G. N. , Chebotarev G. A. , Hagihara Y. , Kovalevsky J. , Kozai Y. , Message P. J. , Stumpff K. , Szebehely V. G. , Zagar F. 
Published: July 2016

The most exciting feature of contemporary celestial mechanics is the close interaction with three of the most dramatic engineering achievements of our time: the electronic computer, artificial celestial objects, and the precise measurement of distances in the solar system. The last two provide new information for and make new demands on celestial mechanics and the former provides an effective means of response. These developments have also stimulated people with backgrounds other than celestial mechanics to make contributions in the field.Since the last meeting of the Union, the use of the computer for literal theoretical developments has become effective and widespread.The creation of artificial celestial objects not only requires the services of celestial mechanics but provides the means of obtaining new measurements that may throw light on the physical laws that govern the motion of celestial objects. In other words, we can now perform experiments as well as observe.
30. Radial Velocities
Authors: Evans David S. , Abt H. A. , Batten A. H. , Blaauw A. , Bouige R. , Thackeray A. D. 
Published: July 2016

Les mesures de vitesse radiale (VR) ont été continuées par les trois techniques: prisme objectif, spectrographie à fente, interférométrie, avec des instruments en fonction à l’Observatoire de Haute Provence ainsi qu’à celui de l’ESO.Grand Nuage de Magellan: Le travail de 13 champs est pratiquement achevé et sera publié dès que les mesures de spectres de fente pris au Chili seront complètement dépouillés.Un catalogue comprenant 1765 étoiles galactiques et 469 étoiles du Grand Nuage de Magellan est achevé. Un supplément comprend environ 200 étoiles particulières de cette région.
Report of the IAU Working Group on ICRS
Authors: Mignard F. 
Published: July 2016

AbstractAfter the adoption of the ICRS and its primary materialization by the ICRF in January 1998, the last three years have witnessed a burst of interest in stellar astrometry stimulated by the availability of the ICRF and its optical counterpart. This paper reports on the activities carried out by the members of the IAU appointed working group on reference frames as well on other works directly related to the main goals of this working group.
Determination of Optical Positions for Extragalactic Radio Sources under the Collaboration Between SHAO and NAO
Authors: Tang Z.H. , Jin W.J. , Wang S.H. , Pinigin G. , Shulga A. , Maigurova N. , Protsyuk Yu. 
Published: July 2016

AbstractThe optical positions of 9 compact extragalactic radio sources have been determined by using the 1.56m, 1m and 60/90cm telescopes with CCDs in China and the Axial Meridian Circle at Nikolaev Astronomical Observatory since Jan. 1996 in a cooperative project between the two observatories. The instrumentation, observations and reduction are briefly described, and the preliminary results are presented. The comparison between the optical and radio positions for 9 sources are also given. More optical positions of radio sources are being processed.
Dynamical Reference Frame — Current Relevance and Future Prospects
Authors: Standish E.M. 
Published: July 2016

AbstractPlanetary and lunar ephemerides are no longer used for the determination of inertial space. Instead, the new fundamental reference frame, the ICRF, is inherently less susceptible to extraneous, non-inertial rotations than would be a dynamical reference frame determined by the ephemerides. Consequently, the ephemerides are now adjusted onto the ICRF, and they are fit to two modern, accurate observational data types: ranging (radar, lunar laser, spacecraft) and VLBI (of spacecraft near planets).The uncertainties remaining in the inner planet ephemerides are on the order of 1 kilometer, both in relative positions between the bodies and in the orientation of the inner system as a whole. The predictive capabilities of the inner planet ephemerides are limited by the uncertainties in the masses of many asteroids. For this reason, future improvements to the ephemerides must await determinations of many asteroid masses. Until then, it will be necessary to constantly update the ephemerides with a continuous supply of observational data.
Definition of the Celestial Ephemeris Pole and the Celestial Ephemeris Origin
Authors: Capitaine Nicole 
Published: July 2016

AbstractThe adoption of the International Celestial Reference System (ICRS) by the IAU in use since 1 January 1998, and the accuracy achieved by the most recent models and observations of Earth rotation call for a redefinition of the Earth Orientation Parameters (EOP). First, the precession-nutation parameters and Greenwich sidereal time, which are currently defined in the FK5 System, have to be re-defined to be consistent with the ICRS. Second, the current definition of the Celestial Ephemeris Pole (CEP) has to be extended in order to be consistent with the most recent models for nutation and polar motion at a microarsecond accuracy including diurnal and sub-diurnal components, as well as with new strategies of observations. Such issues have been under consideration by the subgroup T5 named “Computational Consequences” of the IAU Working Group “ICRS”. This paper gives, as the basis for future recommendations, the preliminary proposals of the subgroup T5 for a modern definition of the CEP, for the definition of more basic EOP in the ICRS and for the choice of a new origin on the equator of the CEP in place of the equinox. Then, the paper emphasizes the use of the Celestial Ephemeris Origin (CEO) which is defined as the “non-rotating origin” in the celestial frame on the equator of the CEP.
Improved Models for Precession and Nutation
Authors: Mathews P.M. 
Published: July 2016

AbstractThe modeling of nutations and precession has advanced to the point where the rms of residuals between theory and the observational estimates from the VLBI data of the past decade is only 0.16 mas in Δψ sin є0 as well as in Δє. Such a fit is provided by the MHB2000 nutation series (Mathews et al., 2000) based on geophysical theory with a few basic Earth parameters estimated by a fit to nutation-precession data, and its accompanying precession rate. A brief account of the series is presented, along with an outline of the theoretical background and of the geophysical information of interest obtained in the process of constructing the series. A series due to Shirai and Fukushima (2000) also gives a somewhat comparable fit to data, improving on the IERS 1996 series, but it is essentially empirical and provides no geophysical insights.
Precession-Nutation Estimates from Optical Astrometry 1899.7–1992.0 and Comparison with VLBI Results
Authors: Vondrák Jan , Ron Cyril 
Published: July 2016

AbstractThe most recent solution of Earth orientation parameters from the observations made by optical astrometry in 1899.7-1992.0 at 33 observatories is used to estimate the corrections of the present IAU model of precession-nutation. Since the resolution of the solution is about five days, only the terms with periods of 14 days and longer are considered. The results are compared with VLBI-based corrections of the standard precession-nutation model, and the differences are discussed.
Sub-Microarcsecond Astrometry and New Horizons in Relativistic Gravitational Physics
Authors: Kopeikin Sergei M. , Gwinn Carl R. 
Published: July 2016

AbstractAttaining the limit of sub-microarcsecond optical resolution will completely revolutionize fundamental astrometry by merging it with relativistic gravitational physics. Beyond the sub-microarcsecond threshold, one will meet in the sky a new population of physical phenomena caused by primordial gravitational waves from the early universe and/or different localized astronomical sources, space-time topological defects, moving gravitational lenses, time variability of gravitational fields of the solar system and binary stars, and many others. Adequate physical interpretation of these yet undetectable sub-microarcsecond phenomena cannot be achieved on the ground of the “standard” post-Newtonian approach (PNA), which is valid only in the near-zone of astronomical objects having a time-dependent gravitational field. We describe a new, post-Minkowskian relativistic approach for modeling astrometric observations having sub-microarcsecond precision and briefly discuss the light-propagation effects caused by gravitational waves and other phenomena related to time-dependent gravitational fields. The domain of applicability of the PNA in relativistic space astrometry is outlined explicitly.
Numerical Data-Processing Simulations of Microarcsecond Classical and Relativistic Effects in Space Astrometry
Authors: Kopeikin Sergei M. , Shuygina N.V. , Vasilyev M.V. , Yagudina E.I. , Yagudin L.I. 
Published: July 2016

AbstractThe accuracy of astrometric observations conducted via a space-borne optical interferometer orbiting the Earth is expected to approach a few microarcseconds. Data processing of such extremely high-precision measurements requires access to a rigorous relativistic model of light ray propagation developed in the framework of General Relativity. The data-processing of the space interferometric observations must rely upon the theory of general-relativistic transformations between the spacecraft, geocentric, and solar barycentric reference systems allowing unique and unambiguous interpretation of the stellar aberration and parallax effects. On the other hand, the algorithm must also include physically adequate treatment of the relativistic effect of light deflection caused by the spherically-symmetric (monopole-dependent) part of the gravitational field of the Sun and planets as well as the quadrupole- and spin-dependent counterparts of it. In some particular cases the gravitomagnetic field induced by the translational motion of the Sun and planets should be also taken into account for unambigious prediction of the light-ray deflection angle. In the present paper we describe the corresponding software program to take into account all classical (proper motion, parallax, etc.) and relativistic (aberration, deflection of light) effects up to the microarcsecond threshold and demonstrate, using numerical simulations, how observations of stars and/or quasars conducted on board a space optical interferometer orbiting the Earth can be processed and disentangled. For numerical simulations the spacecraft orbital parameters and the telescope optical-system-characteristics have been taken to be similar to those in the Hipparcos mission. The performed numerical data analysis verifies that the relativistic algorithm chosen for data processing is convergent and can be used in practice to determine astronomical coordinates and proper motions of stars (quasars) with the required microarcsecond precision. Results shown in the paper have been obtained with a rather small number of stars (a few thousand). Simulations based on a much larger number of stars, e.g., from the Guide Star Catalogue used to model original observations will give more complete information about potential abilities of the space astrometric missions.
Pulsar Scintillation: Overview and Some Recent Results
Authors: Gupta Yashwant 
Published: July 2016

AbstractRadio signals from pulsars are significantly affected by scattering in the interstellar medium. A review of this phenomenon of pulsar scintillation forms the main objective of this paper. The basic concepts are described and some new results related to the following aspects are presented: (i) understanding of refractive scintillation effects and (ii) constraining the spectrum of electron density fluctuations in the interstellar medium.
Frequency Structure of Radio Scintillations for Several Pulsars
Authors: Kondratiev V.I. , Popov M.V. , Soglasnov V.A. , Kostyuk S.V. 
Published: July 2016

AbstractScintillation times and decorrelation bandwidths for the pulsars B0329+54, B1641-15, B1508+55 and B1919+21 are determined. The results are based on observations made with different instruments and at different radio frequencies. All objects but the pulsar B1508+55 were detected to have more than one frequency scale. The obtained values of scattering parameters are not contrary in general to the Kkolmogorov form of density fluctuation spectrum.
Scintillation Observations of Strong Northern Pulsars
Authors: Wang Na , Manchester R.N. , Yusup Aili , Wu Xinji , Zhang Jin , Chen Maozheng 
Published: July 2016

AbstractScintillation of pulsar radio emission provides information about the interstellar medium along the path to the pulsar and the velocities of pulsars. It also affects the precision of pulse timing observations. Using a pulsar timing system developed at the Urumqi Astronomical Observatory 25 m telescope, we observed diffractive scintillation dynamic spectra for several strong northern pulsars. This paper introduces the observing system and discusses the observational results.
Pulsar Investigation Using Interstellar Scintillation
Authors: Smirnova T.V. , Shishov V.I. 
Published: July 2016

AbstractWe discuss the resolution of pulsar magnetospheres using interstellar scintillation. The two-dimensional spatial structure of pulsar emission zones can be obtained from analysis of diffractive scintillations at low frequencies. Based on refractive and diffractive scintillation of pulsars we can also reconstruct the distribution of turbulent plasma along the line of sight, and using this analysis a new approach to pulsar distance estimation can be made.
VSOP Observations of the BL Lac Object 2007+777
Authors: Jin C. , Krichbaum T.P. , Witzel A. , Nan R. , Peng B. , Kraus A. , Lobanov A. , Qian S. , Zensus J.A. 
Published: July 2016

AbstractWe present three epochs of VSOP observations of the BL Lac object 2007+777 at 5 GHz. Compared with the ground-based VLBA data, the space baselines with HALCA clearly reveal a more detailed and finer source structure. Mainly based on the quite uniform and circular UV-coverages of the VLBA, and using a new cross-selfcalibration method, we have found evidence for weak structural changes on a timescale of two weeks in the core region of this intraday variable source. The physical causes for these variations are discussed.
Interpretation of Extreme Scattering Events
Authors: Walker Mark A. 
Published: July 2016

AbstractExtreme Scattering Events are sometimes manifest in the light-curves of compact radio-quasars at frequencies of a few GHz. These events are not understood. The model which appears to offer the best explanation requires a new population of AU-sized, neutral gas clouds; these clouds would then make up a large fraction of the Galaxy’s dark matter. Independent of the question of which theoretical model is correct, if we extrapolate the observed behaviour to low radio-frequencies, we expect that the sky should be criss-crossed by a network of narrow caustics, at frequencies below about 700 MHz. Consequently at these frequencies sources should typically manifest additional, faint images which are substantially delayed with respect to the primary image. Although some examples of this type of behaviour are already known, it is expected that these are just the tip of the iceberg, with strong selection biases having been imposed by the instrumentation employed to date.
Magnetic Fields in our Galaxy: How much do we Know? I. Disk fields within a few kpc of the Sun
Authors: Han J.L. 
Published: July 2016

AbstractThe large scale magnetic fields of our Galaxy have been mostly revealed by rotation measures (RMs) of pulsars and extragalactic radio sources. In the disk of our Galaxy, the average field strength over a few kpc scale is about 1.8 μG, while the total field, including the random fields on smaller scales, has a strength of about 5 μG. The local regular field, if it is part of the large scale field of a bisymmetric form, has a pitch angle of about −8°. There are at least three, and perhaps five, field reversals from the Norma arm to the outer skirt of our Galaxy.
Active Adaptive Arrays: The Astron Approach to SKA
Authors: Strom Richard G. , Smolders Bart , van Ardenne Arnold 
Published: July 2016

AbstractIt has been argued, for a number of reasons, that the next generation radio telescope should be a multi-element interferometer with a collecting area of about 1 km2. The remaining parameters of such an instrument – frequency range, angular resolution, instantaneous bandwidth, etc. – will be science driven. The requirements for propagation studies are briefly discussed, and it is pointed out how variable-source confusion may differ from the normal variety. Finally, the Dutch project to achieve a large collecting area using adaptive arrays of active antennas is described. A systematic approach has been adopted, with the construction of arrays of increasing complexity to test design features at each state. Recently, development of a low frequency array (LOFAR) has become an additional option. It would facilitate tests of some of the larger instrument’s features, and provide real data on the influence of the ionosphere and interfering sources.
Spectroscopic Spin Variability in new IP Candidates
Authors: de Martino Domitilla , Haberl Frank , Alcalá Juan M. , Grado Aniello 
Published: July 2016

AbstractWe present fast spectroscopy of RX J1548-45 and BT Mon acquired with EFOSC-ESO 3.6 m in March & April 2002, with the aim to detect for the first time spectral variability at the white dwarf rotation.
Stream Eclipse Mapping with ‘Fire-Flies’
Authors: Bridge C. M. , Hakala Pasi , Cropper Mark , Ramsay Gavin 
Published: July 2016

AbstractWe apply a new method of eclipse mapping to the light curves of eclipsing polars. The technique aims to locate the bright emission associated with the accretion stream, using a technique that makes the fewest prior assumptions about the location of the accretion stream material. We have obtained data of EP Dra and HU Aqr with the S-Cam 2 superconducting tunnel junction camera using the William Herschel Telescope. The location of emission regions in both systems show that previously assumed trajectories are consistent with those found using our technique. Most of the emission is located in a region where we expect material to be confined to magnetic field lines, particularly for HU Aqr, while there appears to be a lack of emission from where we conventionally expect material to follow a ballistic trajectory from the L1 point.
Can the propeller outflow from AE Aquarii be imaged directly?
Authors: Still Martin , Horne Keith , Knigge Christian 
Published: July 2016

AbstractWe calculate the Hα luminosity of an outflow nebula resulting from propeller action in AE Aqr. While the outflow is bright enough to be detected as an extended source, 1 arcsec across, it is dominated by the point-spread function (PSF) wings of the central object. By subtracting a PSF model from HST PC data we rule out the extreme models of high mass-loss rate combined with narrow-angle outflow, but more precise measurements are required to explore the propeller parameter space further.
Earth Rotation Information Derived from Merit and Polaris VLBI Observations
Authors: Robertson D. S. , Carter W. E. 
Published: July 2016

AbstractIn September and October 1980, the National Geodetic Survey, jointly with the National Aeronautics and Space Administration and several other agencies and institutions, conducted a series of astronomical radio interferometry (VLBI) observing sessions to support the IAU/IUGG MERIT short campaign. A total of 14 days of observations, organized into two 7-day sessions, was collected by three observatories in the United States (Harvard Radio Astronomy Station (HRAS), Haystack Observatory, and Owens Valley Radio Observatory) and the Onsala Space Observatory in Sweden. Chilbolton Observatory, England, and Effelsberg Observatory, West Germany, also participated on some days. Immediately following the MERIT campaign, NGS initiated a series of 24-hour observing sessions, spaced at approximately 2-week intervals, as a pilot program to project POLARIS. All of these sessions included two observatories, HRAS and Haystack, and Onsala participated in about half of the sessions. The MERIT and POLARIS observations were made with the third generation MARK III VLBI system using procedures and schedules designed to yield high quality geodetic information, including Earth rotation values. This paper briefly traces the planning, observing, and data processing activities, and presents the Earth rotation information thus far derived from the data.
Results from Lunar Laser Ranging Data Analysis
Authors: Dickey J. O. , Williams J. G. , Yoder C. F. 
Published: July 2016

AbstractThe lunar laser range data taken at McDonald Observatory between August 1969 and May 1980 has been analyzed. The simple rms residual for the 2954 ranges is 31 cm. Results of the analysis include GMearth = 398600.45±0.02 km3/sec2 and a secular acceleration of the lunar orbital mean longitude of ṅ = −23.8±1.5“/century2 which yields a Q of 12.3 at semidiurnal frequencies. The lunar harmonic C30 is (−8.7 ± 1.1) × 10−6 and the lunar rotational dissipation k2mT = (4.7 ± 0.5) × 10−3 day. Also resulting from the solution are geocentric coordinates of McDonald accurate to 30 cm, including the first value for the longitude with the new IAU constants and a dynamical equinox.
Correspondence, Unpublished Papers and Data: Present making of Historical Records
Authors: Motais de Narbonne Anne-Marie 
Published: July 2016

Research process generates public and formal informations accessible through published documents or public data bases which libraries are used to deal with. It also generates informal, anachieved informations in format of correspondances, notes, calculus, reports, drawings... or other unpublished documents that libraries must not either leave aside.Since fundamental research, versus technological research for instance, implies great personal involvement, informal informations are mainly issued from individuals or small groups of individuals. It is probably the reason why this kind of informations and documents is often considered erronously as private by astronomers deciding by themselves to destroy, to move or leave behind their so-called personal papers. These documents and informations actually belong to the institutions. They must be preserved because they are part of the research production and also because they may be used for astronomical research as it is illustrated in S. Débarbat’s communication.
Outdoor Lighting in Tucson: A Photo Record
Authors: Robinson William T. 
Published: July 2016

ABSTRACTPhotographic documentation of outdoor lighting installations has been underway in Tucson and throughout Arizona for some time. Such photos show what can be done to minimize the problem of light pollution, illustrating examples of both good and bad lighting designs and installations. Copies of such photos (mostly in the form of slides) are available from the International Dark-Sky Association.
Evolutionary diagnostics of LBV spectra and systems in the LMC
Authors: Walborn Nolan R. 
Published: July 2016

AbstractThe characteristics of the Ofpe/WN9 class in the LMC, including two newly discovered members, are reviewed; a strong relationship between this class and the LBVs is established by HDE 269858 = Radcliffe 127, currently in outburst with a spectrum identical to that of S Doradus. The evidence for CNO-cycle products,i.e., enhanced N and He, on the surfaces and in the circumstellar nebulae of Ofpe/WN9 objects and LBVs is discussed, with emphasis on recent near-IR observations of He/H. Finally, the occurrence of several Ofpe/WN9 and LBV stars in compact multiple systems will enable valuable information about the evolutionary status of the peculiar objects to be derived. Strong threads unite these three topics: the same objects frequently recur in each.