bluuebunny/crossref_metadata_2025 huggingface dataset:
L'arc Geodesique le Plus Long: Delisle, Les Struve et L'observatoire de Pulkovo
Authors: Debarbat Suzanne
Published: July 2016

The longest geodetic arc ever mesured by classical goedesy is long of 25° from the Baltic to the Black Sea through the Dorprat meridian. This arc is based upon measurements made, from 1816 to 1855, by a russian general, a norvegian, a Swedish and F.G.W. Struve, the founder of the Pulkovo Observatory; its lenght is 2° more than the arc Delisle, then at the Petersburg Observatory, intended to determine along the meridian of this observatory in the year 1737. Russia, at that time, became part of the european triangulation, a prelude to circumterrestrial modern campaigns.
On the Use of Statistical Parallaxes for the Proper Motion Reductions
Authors: Bronnikova N.M. , Shakht N.A.
Published: July 2016

The Pulkovo program of determination of proper motions with respect to galaxies approaches completion. It consists of 157 fields from +90° to −4° of declination. The proper motions and reductions with use of galaxies were derived for all areas. The errors of reductions are equal to ± 0.″006. In addition the statistical reductions Rx, Ry were computed for the control and for the zones of avoidance. The following formulae were used:

where is the secular parallax according to Binnendijk [1]; P and P′ are parallactic factors; Q and Q′ are members dependent on the galactic rotation.
A Proposal for Astrometric Observations From Space
Authors: Chubey M.S. , Makarov V.V. , Yershov V.N. , Kanayev I.I. , Fomin V.A. , Streletsky Yu.S. , Schumacher A.V.
Published: July 2016

Some aspects of the realisation of a celestial reference frame using a space astrometry facility are considered. An observational program is described, consisting of observing stars up to magnitude 14, radiostars and bright QSO's, planets, asteroids and of laser signals from the Earth. A scheme of an astrometric facility consisting of two telescopes on board the satellite is proposed. The overview strategy with“inita”is estimated, and the estimates of the accuracy of a single observation (0.″02-0.″05) and of the output catalogues (0.″001-0.″007) are made.
Circle-Reading Device of the Meridian Instrument with Self-Installed Zero-Point
Authors: Pinigin G. I. , Bubnov Y. A. , Shumacher A. W.
Published: July 2016

A circle-reading device of the meridian circle with a constant link to the vertical line and the method of using the device are proposed. The accuracy of a circle reading is expected to be 0.″02.
General Relativistic Description of Celestial Reference Frames
Authors: Voinov A. V.
Published: July 2016

The astonomical consequences of recently developed theoretical methods of relativistic astrometry are discussed. The set of practically important reference systems is described. These reference systems generalize the locally inertial frames of general relativistic test observer, the hierarchy of Jacoby coordinates for dynamical problems and the dynamically inertial reference systems of fundamental astrometry. In practical application of this formalism much attention is paid for relativistic transformation functions relating the ∗∗ecliptical coordinates corresponding to the baryecnters of the Solar system, the Earth-Moon subsystem and the Earth. Solutions to several kinds of relativistic precession are also presented.
Transformation of the Mean Place from FK4 to FK5
Authors: Sôma Mitsuru , Aoki Shinko
Published: July 2016

Transformation procedures from the FK4 reference system of B1950.0 to the FK5 reference system of J2000.0 have been developed by Standish (1982) and by Aoki et al. (1983). We review here these procedures and discuss the differences between them. Especially we note that among researchers of this field a misunderstanding still exists in the problem at which stage the equinox correction should be applied. We show that the equinox correction should be applied in the precessing frame as Aoki et al. did. We also show that the epoch of the transfer from the FK4 to the FK5 in the transformation procedure is related to the systematic and individual corrections to the FK4.
Nutation Theory for a Non-Rigid Earth: Present Status and Future Prospects
Authors: Wahr J.
Published: July 2016

The 1980 IAU nutation series includes effects of the Earth's non-rigidity. Certain simplifying assumptions were made in the model, including that the Earth is elastic and hydrostatically pre-stressed. The rationale was that geophysicists didn't understand the Earth well enough to justify a relaxation of those assumptions, and that the nutation observations were not accurate enough to detect the difference, anyway. Geophysicists are still not able to construct a more accurate model that is independent of the nutation observations, themselves. But, the observations have improved enormously. Recent results obtained from VLBI data show discrepancies with the IAU model of close to 2 milliseconds of arc: many times the observational uncertainty. Thus, the nutation observations are beginning to tell us things about the Earth that cannot presently be inferred as accurately from other techniques. I will discuss some of these possible geophysical applications. Among them are the shape and internal structure of the core, and the Earth's anelasticity.
Proposals for an Improved Nutation Formula
Authors: Groten E. , Zhu S. Y.
Published: July 2016

There are a variety of reasons why in geodesy an improved formula for nutation is needed; related topics of interest are the determination of time-dependences in low degree zonals of the earth gravity field, ocean tide modeling, determination of odd harmonics of gravity field etc. in satellite geodesy. A combined model of deterministic and stochastic components is used in order to evaluate two new nutation series where, in an adjustment, mainly VLBI data (IRIS, GSFC, IERS) have been applied. Contrary to earlier revisions of the present nutation formula, not only the five significantly affected waves (annual, semi-annual, FCN etc.) are corrected but rather all constituents are revised in such a way that white noise residuals result from the adjusted observations, based on the new formula. Still remaining problems (such as the separation of long-period terms from precession etc.) are outlined.
The Results of the Reconstruction of the Coefficients of the Nutation for the Rigid Earth Model and Their Comparison With Numerical Integration
Authors: Souchay J. , Kinoshita H.
Published: July 2016

In view of the present accuracy of the astrometric observations and of the development of the theory of the nutation, it became necessary to make a complete revision of this theory for a rigid Earth model. We present the results of our recent one (Kinoshita and Souchay, 1989), which includes planetary effects and second order effects no considered in the previous tables (Kinoshita, 1977). We analyze the difference between these tables and the new ones providing from the revision above and the comparison between the theory and numerical integrations recently performed (Kubo and Fukushima, 1987; Shastok et al., 1987; Shastok et al., 1989). The results of this comparison are much better after revision than before.
Can the Core-Mantle Boundary Topography Influence the Earth's Nutation?
Authors: Bykova V. V.
Published: July 2016

The nutation of the Earth with slightly nonelliptical liquid core is investigated by the perturbation theory method. It is shown that first-order terms affect the core ellipticity and its triaxiality. The most sensitive nutation terms in the second approximation were found to be retrograde 18.6-year term and retrograde annual term. The observed nutation amplitude values can be satisfied by special core-mantle boundary form.
Possible Contributions of Classical Astrometric Instrument to the Study of Geoscience and Requirements on Star Catalogues
Authors: Yanben Han , Zhisen Li
Published: July 2016

In this paper possible contributions of classical instrument of time and latitude determinations in the study of geoscience is discussed. Some research results indicate that the observations of the classical instruments contain rich information on geoscience study. They can play a certain role in research of crust structure, plate motion, vertical variation, topography of core-mantle boundary, and in study of seismicity and major earthquake forecasting. It is important that a stable reference system is established and maintained and a relevant observed programme is formulated upon a star catalogue with good quality for geoscience and astro-geodynamics. Some instruments with high precision, especially located in seismic regions, would be continuously operated after the end of their task in ERP determination.
The Possibility to Link Radio and Optical Reference Frames With Artificial Satellites
Authors: Fu Tong
Published: July 2016

Based on extragalactic radio sources, a new high precision extragalactic radio reference frame can be established from radio interferometric measurements. To link the optical fundamental reference frame presently represented by the FK4/5 to the extragalactic radio frame, the optical counterparts of extragalactic radio sources (quasars, BL Lac objects etc.) and radio stars are the most important classes of objects. Besides these two classes of objects, are there any other objects which can be used to link the optical and radio frames? A posible answer is that artificial satellites could be a candidate class of objects contributing to this subject.
Improved Method for Orbital Elements Differential Correction
Authors: García A. López , Ortí J. A. López , Machí R. López
Published: July 2016

As was pointed out by IAU in 1976, an important problem in fundamental astronomy is the improvement of the vernal equinox and equator positions. To this aim, it is necessary to know the accurate values of minor planets orbital elements. The classical methods of orbital elements differential corrections are based on linking the observations at different epochs considering equal derivatives respect to the initial and osculating elements.

In this paper we present an improved method in which the least squares matrix coefficients is calculated from the integration of the Lagrange planetary equations and its derivatives.
Systematic Astrometric Errors in Pulsar Timing
Authors: Fairhead L.
Published: July 2016

A new analysis of the timing data acquired on the fast pulsar PSR1937+214 is presented. Parameters are evaluated with various models based on two ephemerides, two atomic time scales and two TT—TB time transformations. Comparisons are carried out with results from other programs. We provide evidence that systematic errors induced by the model adopted are 5 to 10 times larger than the formal uncertainties calculated by the fitting procedure. Great care must thus be taken when using results from different millisecond pulsars timing programs for accurate astrometric purposes.
Points: A Global Reference Frame Opportunity
Authors: Chandler J.F. , Reasenberg R.D.
Published: July 2016

POINTS is a space-based optical astrometric interferometer, capable of measuring the angular separation of two stars about 90° apart with 5-microarcsec (μas) nominal accuracy. During the intended ten-year mission, a repeated survey of a few hundred targets over the whole sky, including a few bright quasars, will establish a “rigid” reference grid with 0.5 μas position uncertainties. At that level, the grid will be free of regional biases and tied to the extra-Galactic frame that is our present best candidate for an inertial frame. POINTS will also determine parallaxes and annual proper motions at about the same level. Further, the planetary ephemeris frame will be tied through stellar aberration to the grid at about 300 μas. Additional targets of interest, to a limiting magnitude of greater than 20, will be observed relative to the grid, yielding determinations with uncertainties depending on the observing schedule. Measurement at the microarcsec/year level of the apparent relative velocities of quasars that are widely separated on the sky will severely test the assumption of cosmological quasar distances and may also constrain models of the early Universe.
Realization of an Inertial Reference Frame From Mark III VLBI
Authors: Ma C.
Published: July 2016

Over 350 000 dual frequency Mark III VLBI observations from several geodetic and astrometric observing programs have been used to realize an inertial reference frame through the positions of 325 compact extragalactic radio sources uniformly distributed over the sky with standard errors typically under 1 milliarcsecond (mas). Internal and external tests indicate that the reference frame defined by the relative positions of these radio sources should be accurate and stable at the 1-2 mas level. Because the conventional precession and nutation models are adjusted in the estimation of the source positions, the positions and relative angles are not degraded over the interval of observations or at epochs away from the reference epoch.
A Progress Report on the Establishment of the Radio / Optical Reference Frame
Authors: Russell J. L. , Johnston K. J. , de Vegt C. , Zacharias N. , Ma C. , Shaffer D. , Jauncey D. L. , White G. L. , Nicolson G. , Kemball A. , Hindsley R. , Hughes J. , Reynolds J. E.
Published: July 2016

In 1987 we began a 5-year program to establish a reference system of at least 400 extragalactic sources which are compact and flat spectrum in the radio and which also display optical emission. This reference frame is to be global with about one source per 100 sq deg (Johnston, et al., 1988). The program incorporates some data which had been obtained previously for other purposes. Altogether, in one or another aspect of the program, 489 sources have been considered so far.
Expectations for Astrometry With the Hubble Space Telescope
Authors: Duncombe R.L. , Jefferys W. H. , Benedict G. F. , Hemenway P. D. , Shelus P. J.
Published: July 2016

The Hubble Space Telescope, a large optical instrument having an aperture of 2.4 meters and a length of 8.8 meters has been developed by the U.S. National Aeronautics and Space Administration in cooperation with the European Space Agency. The Space Shuttle will be used to place the telescope in orbit. The primary astrometric instrument will be one of the three Fine Guidance Sensors which have the capability of measuring the position of one object with respect to another to an accuracy of ±0.″002. To facilitate use of the Hubble Space Telescope, observers will be provided with the Astrometric Data Reduction Software package. The variety of astrometric problems and the several modes of operation are mentioned as well as the cooperative program with the European astrometric satellite project HIPPARCOS.
Optical Reference Frame Defined by Carlsberg Meridian Catalogue La Palma Number 4
Authors: Morrison LV , Argyle RW , Helmer L , Fabricius C , Einicke OH , Quijano L , Muiños JL
Published: July 2016

The contribution of the Carlsberg Meridian Catalogue La Palma Number 4 to the determination of the optical reference frame is discussed. This catalogue of almost 51000 stars provides one of the most accurate optical reference frames at the present epoch, having a density of 1 star per square degree, and an average accuracy of 0.″12 in position and 0.″003 per year in proper motion for stars with V<9. The catalogue also contains positions of reference stars with V>11 in the fields of benchmark extragalactic radio sources which can be used in linking the optical reference frame defined by the FK5 to the extragalactic frame.
Physical Data of the Fundamental Stars
Authors: Dingjiang Luo , Baocai Zhang
Published: July 2016

The precise positions and proper motions (J2000.0) of 1535 Basic FK5 stars in the FK5 system have been used in the reduction of the local vertical monitoring and the catalog observations at Beijing Astronomical Observatory. In addition, similar data for 1987 FK4 Sup stars, in which 980 stars indicated by “F” will be included in the FK5, were made available recently by Heidelberg via Prof. Tong Fu, director of Purple Mountain Observatory. The positions and proper motions of the other 1007 FK4 Sup stars in the FK5 system are provided by the Astronomisches Rechen-Institut with relatively low accuracies. However, the physical data, such as the visual magnitudes and the spectral types of these rs with rather large uncertainties have their origin in the Henry Draper Catalogue since the compilation of the FK4 and the FK4 Sup. More accurate visual magnitudes available in the well-defined photoelectric system and the spectrum types in the MK-system may be found, for example in the Bright Star Catalogue and its supplement.

For the convenience of users of astrometric observations and for geodetic purposes, visual magnitudes (V), color indices (V-B), spectral types (Sp), tritonometric parallaxes (p in mas), and radial velocities (RV in km/sec) for the 1535 FK4 stars and 1987 FK4 Sup stars are available.

These data are available from the authors in machine-readable form which includes the mean positions and proper motions of J2000.0 in the FK5 system and the cross-references to the GC of FK4 stars and FK4 Sup stars. Printed or magnetic versions of the data may be requested from the authors.
The Machine-Readable Durchmusterungen: Classical Catalogs in Contemporary Form
Authors: Warren Wayne H. , Ochsenbein François , Rappaport Barry N.
Published: July 2016

The entire series of Durchmusterung (DM) catalogs (Bonner, Southern, Córdoba, Cape Photographic) has been computerized through a collaborative effort among institutions and individuals in France and the United States of America. Complete verification of the data, both manually and by computer, the inclusion of all supplemental stars (represented by lower case letters), complete representation of all numerical data, and a consistent format for all catalogs, should make this collection of machine-readable data a valuable addition to digitized astronomical archives.
The Establishment of an Astrometric Standard Region in the NGP: Star Catalogue
Authors: Pakulyak L.K.
Published: July 2016

The positions and proper motions catalogue in the area near the NGP is presented.
The Plasma Universe
Authors: Fälthammar Carl-Gunne
Published: July 2016

The term “Plasma Universe”, coined by Hannes Alfvén, emphasizes the fact that plasma phenomena discovered in the laboratory and in accessible regions of space, must be important also in the rest of the universe, which consists almost entirely of matter in the plasma state.

Relevant aspects of this concept will be discussed. They include the response of the plasma to electric currents, the support of magnetic-field aligned electric fields, violation of the frozen-field condition, rapid release of magnetically stored energy, acceleration of charged particles, chemical separation, filamentary and cellular structures, and critical velocity interaction.
Problems of Solar Convection
Authors: Unno Wasaburo
Published: July 2016

Kinetic energy of convection is transported inwards in the main body of convection zone. The temperature gradient becomes super-radiative at the top of the overshooting zone. These two effects make the solar equilibrium model much less sensitive to the assumed mixing length in Xiong's eddy diffusion theory. Observed brightening of downflow at high level in the surface region over intergranular lanes seems to be consistent with the overshooting model. Momentum transport by convective motion is shown to be crucial in pushing down magnetic flux tubes against buoyancy. Also, subadiabatic layers are possibly formed temporarily in the middle of the convection zone, exciting oscillations and generating chaotic motions.
Effect of Turbulence on Emerging Magnetic Flux Tubes in the Convection Zone
Authors: D'Silva Sydney , Choudhuri Arnab Rai
Published: July 2016

Working under the hypothesis that magnetic flux in the sun is generated at the bottom of the convection zone, Choudhuri and Gilman (1987; Astrophys. J. 316, 788) found that a magnetic flux tube symmetric around the rotation axis, when released at the bottom of the convection zone, gets deflected by the Coriolis force and tends to move parallel to the rotation axis as it rises in the convection zone. As a result, all the flux emerges at rather high latitudes and the flux observed at the typical sunspot latitudes remains unexplained. Choudhuri(1989; Solar Physics, in press) finds that non-axisymmetric perturbations too cannot subdue the Coriolis force. In this paper, we no longer treat the convection zone to be passive as in the previous papers, but we consider the role of turbulence in the convection zone in inhibiting the Coriolis force. The interaction of the flux tubes with the turbulence is treated in a phenomenological way as follows: (1) Large scale turbulence on the scale of giant cells can physically drag the tubes outwards, thus pulling the flux towards lower latitudes by dominating over the Coriolis force. (2) Small scale turbulence of the size of the tubes can exchange angular momentum with the tube, thus suppressing the growth of the Coriolis force and making the tubes emerge at lower latitudes. Numerical simulations show that the giant cells can drag the tubes and make them emerge at lower latitudes only if the velocities within the giant cells are unrealistically large or if the radii of the flux tubes are as small as 10 km. However, small scale turbulence can successfully suppress the growth of the Coriolis force if the tubes have radii smaller than about 300 km which may not be unreasonable. Such flux tubes can then emerge at low latitudes where sunspots are seen.
On the Location of the foot-points of Sub-Arc-Second Magnetic Structures in the Quiet Sun Photosphere
Authors: Sivaraman K.R. , Bagare S.P. , November Laurence J.
Published: July 2016

We present the results of our study of a long sequence of high spatial resolution filtergrams obtained with the Universal Birefringent filter (UBF) at the Vacuum Tower Telescope of the National Solar Observatory, Sacramento Peak on July 14, 1987. The UBF has a band pass of 0.25A and was set sequentially in the following wavelengths, and filtergrams were obtained at each of the settings.
The Heating of the Quiet Solar Chromosphere
Authors: Kalkofen Wolfgang
Published: July 2016

The quiet solar chromosphere shows three distinct regions. Ordered according to the strength of the emission from the low and middle chromosphere they are (1) the magnetic elements on the boundary of supergranulation cells, (2) the bright points in the cell interior, and (3) the truly quiet chromosphere, also in the cell interior. The magnetic elements on the cell boundary are associated with intense magnetic fields and are heated by waves with very long periods, ranging from six to twelve minutes; the bright points are associated with magnetic elements of low field strength and are heated by (long-period) waves with periods near the acoustic cutoff period of three minutes; and the quiet cell interior, which is free of magnetic field, may be heated by short-period acoustic waves, with periods below one minute. This paper reviews mainly the heating of the bright points and concludes that the large-amplitude, long-period waves heating the bright points dissipate enough energy to account for their chromospheric temperature structure.
Interaction of Flux Tubes with Sound Waves
Authors: Uberoi C
Published: July 2016

The Landau damping of sound waves in a plasma consisting of ensemble of magnetic flux tubes is discussed. It is shown that sound waves cannot be Landau damped in general but under certain restricted conditions on plasma parameters the possibility of absorption of these waves can exist. The possibility of radiative damping of the acoustic waves along the magnetic filaments is also discussed. It appears that the most plausible mechanism of damping of sound waves in a plasma consisting of magnetic filaments can be due to scattering of a sound wave by the filaments.
Cosmic Ray Signatures of Different Types of Solar Wind Streams
Authors: Shrivastava P.K. , Agrawal S.P.
Published: July 2016

The earlier concept of average solar wind speed has changed with time. Besides quiet periods of low/average solar wind speeds, two different kinds of solar sources (solar flares and coronal holes) have been identified to produce high speed solar wind streams. In an earlier investigation, it was reported that the high speed streams associated to these sources produce distinctly different effects on the cosmic ray intensity (Venkatesan, et. al., 1982).
Slight Disappearance of Prominence Plasma to the Solar Corona
Authors: Rusin V. , Dermendjiev V. , Rybansky M. , Buyukliev G.
Published: July 2016

The problem of prominences-corona relationship is relativelly old. Already in 1931 Lockyer [1] showed that there is a close relation between prominences distribution and the form of white-light corona. However, this problem is still debatable and poses a number of controversial questions. One of them is the question of the energy and mass exchange between prominences and the ambient corona. It is generally assumed that the mass balance exists between the corona and prominences, but unambiguous observational proofs for prominences-corona plasma exchange are very rare. There are little data [2-4], as well, that could be used to address the problem of slight plasma flows from prominences to the corona.
Diagnosing Solar Plasmas From EUV and X-Ray Emission Lines
Authors: Dwivedi Bhola N.
Published: July 2016

The electron density and temperature measurement of solar plasmas from EUV and X-ray emission lines have been briefly discussed. Diagnostic EUV line ratios from MgVI ion and X-ray line ratios from MgVIII and SiX ions have been presented. A brief account of the general methodology for diagnostics of inhomogeneous structures has also been given.
Modelling a Solar Flare from X-UV and Radio Observations
Authors: Chiuderi Drago F. , Monsignori Fossi B.C.
Published: July 2016

A slow evolving flaring loop has been observed by the UVSP, XRP and HXIS instruments on board SMM on June 10, 1980. Simultaneous radio observations from Toyokawa (Japan) are also available. The former instruments have an angular resolution ranging from 3“ to 30“ which allows the determination of the loop structure. The XRP:FCS rasters permit to analyze the flare only during three time intervals of about 10 minutes each.
Rate of Enrichment of the Galactic Disc With Metals From Data on Open Clusters
Authors: Dluzhnevaskaya O. B. , Piskunov A. E. , Vereshchagin S. V.
Published: July 2016

Recent investigations of stellar chemical composition made it possible to estimate some parameters of the galactic disc chemical evolution: the abundance gradient, d[Fe/H]/dR, and rate of enrichment, d[Fe/H]/dt. Practically all the conclusions of these investigations were based on data on chemical composition of single stars, for which the error in age determination is considerable.
The Dynamics of Open Clusters
Authors: King Ivan R.
Published: July 2016

This is a review of a subject that turns out to be rather dismal. Both in theory and in observation we know and understand open clusters poorly – either in comparison with globular clusters or on an absolute basis.
Dynamical History of the Solar Neighbourhood
Authors: Vader J. P.
Published: July 2016

The dynamical evolution of the solar neighbourhood is described by an accretion model in which the gas accretion rate decays exponentially with time. Stars form at a rate proportional to the local gas volume density and their velocity dispersion is increased after birth by star-cloud collisions. The present mass density distribution of stars and of gas perpendicular to the galactic plane (Oort 1965) and the observed increase of stellar velocity dispersion with age (Mayor 1974; Mayor and Martinet 1977) are reproduced for an e-folding time of 3 × 109 y of the gas accretion rate and a characteristic star formation time scale of 2.8 × 109 y.
Open Clusters as Tests of Stellar Evolution
Authors: Maeder A. , Mermilliod J. C.
Published: July 2016

The HR diagram (HRD) of clusters constitutes an especially sensitive test of physical processes in stellar interiors. Let us remember that the picture of inhomogeneous stellar evolution imposed itself by the fact that the cluster sequences turn to the right in the HRD (cf. Schwarzschild, 1958).
Flare Stars in Evolved Clusters
Authors: Parsamian E. S.
Published: July 2016

A new method of determination of the ages of aggregates based on flare star observations is proposed. The method is specially useful in the case of young clusters and associations, for which the usual method involving their H-R diagrams encounters difficulties. The method can be used also for particular flare stars.
Ages and Abundances of Globular Clusters and the Oldest Open Clusters
Authors: Demarque Pierre
Published: July 2016

It used to be that interest in the ages of the globular clusters was primarily motivated by cosmological considerations. In recent years, remarkable progress in the quality and quantity of observations and advances in the understanding of stellar atmospheres and in the construction of theoretical isochrones make possible the use of globular clusters as probes of galactic evolution. A new picture, still tentative at this point, is emerging of the formation and chemical enrichment of the halo, in its nucleus and in its outer reaches through observations of globular clusters, dwarf spheroidal galaxies and the Magellanic Clouds.
Globular Clusters in the LMC
Authors: Hartwick F.D.A. , Cowley A. P.
Published: July 2016

Because globular clusters are the oldest stellar systems, they should be sensitive probes of the early dynamical and chemical evolution of galaxies. Since some success has been achieved in understanding these problems in our own galaxy, it seems appropriate to see what can be learned from the clusters in the Large Magellanic Cloud (LMC).
The SMC Cluster NGC330
Authors: Janes Kenneth A. , Carney Bruce W.
Published: July 2016

The cluster NGC330 is compact, populous, and one of the brightest objects in the Small Magellanic Cloud. Because of its size and its large number of blue supergiants, it has been referred to as a “blue globular”, as have several other clusters in the Clouds. To learn whether this appellation is more than superficial, we have undertaken a general study of the cluster. We have obtained DDO photometry, photoelectric and photographic UBV photometry, and low-dispersion spectroscopy of stars in and near the cluster. We report here our preliminary analyses of the data.
Recent Results on the Turn-Off of ω Centauri
Authors: Cannon R. D.
Published: July 2016

It is now well established that there is a wide range of surface chemical composition among the evolved stars of ω Centauri, and that this causes exceptional scatter on the red giant branch in the V, (B-V) C-M diagram. However, different atomic and molecular species vary in different ways and it is not clear how much of the variation should be attributed to mixing during evolution and how much if any is primordial.
Evidence for Primordial Inhomogeneities From Abundance of Giants in M5, M13, and M22
Authors: Peterson Ruth C.
Published: July 2016

There is spectroscopic evidence for initial abundance inhomogeneities from star to star within M13 and M22. Among three stars in M13, there is an order-of-magnitude range in the sodium-to-iron ratio, which lies well beyond all known random and systematic errors; details will be given in a paper in preparation. In M22, the spread discussed below in logarithmic iron-to-hydrogen ratios, [Fe/H], is 0.6 dex, which is far larger than that found here for any other globular cluster.
Chemical Compositions of Southern Globular Clusters: 47 Tucanae, NGC3201, and NGC6752
Authors: Pilachowski Catherine A. , Sneden Christopher , Canterna R.
Published: July 2016

The metallicities of the globular clusters 47 Tucanae, NGC3201, and NGC6752 have been determined from high dispersion spectra obtained with the echelle spectrograph at CTIO. The mean iron deficiencies of NGC3201 and NGC6752 are −1.0 and −1.3, respectively. Oxygen is enriched by a factor of two in NGC3201; no oxygen data are available in NGC6752 due to the small radial velocity of this cluster. The atmospheric parameters and the abundances, relative to the Sun, of individual elements for two stars in 47 Tuc are tabulated below. Star identifications are taken from Hesser and Hartwick (1977). The stellar effective temperatures were established from the spectroscopic data; the data do not permit temperatures much in excess of those quoted. Surface gravities were calculated from the cluster's distance modulus and other reasonably well-known quantities, with the assumption that the mass of a cluster giant is 0.8 M⊙.
The Integrated Photometry of Globular Clusters in the Vilnius Photometric System
Authors: Zdanavičius K. , Straižys V.
Published: July 2016

Thirty-three globular clusters of our Galaxy were observed with the filters of the Vilnius photometric system UPXYZVS with 3450, 3740, 4050, 4660, 5160, 5440, 6550 å filters (Straižys 1977). For the classification of clusters in metallicities the reddening-free parameters QUYV QPYV and QXYV can be used. In Figure 1 these Q parameters, having a range of variation of the order of 0.4, are plotted against metallicity values from Kukarkin (1974). The parameter QPYZ has an even larger range of variation (of the order of 0.6). For determination of color excesses of clusters every color index can be used if its intrinsic values for a given metallicity defined by quantities Q are known (Figure 2). Average color excesses determined from the diagrams QUYV, (Y-V)o; QPYV, (Y-V)o and QXYV (Y-V)o and transformed to EB-V in Figure 3 are compared with color excesses from Kukarkin (1974). To summarize, the Vilnius system presents a number of metallicity sensitive, reddening-free parameters which can be used for [Fe/H] and color-excess determinations of globular clusters.
Propagation of Large Amplitude Pulsar Waves
Authors: Asséo E. , Llobet X. , Pellat R.
Published: July 2016

Large amplitude waves (hereafter l.a.w.) have been studied mainly in connection with pulsars. A rotating neutron star, with an intense non-aligned magnetic dipole field, surrounded by a vacuum, radiates beyond the light cylinder distance, large amplitude electromagnetic vacuum waves of very low frequency (Ostriker and Gunn, 1969). In such a rotating configuration electromagnetic effects completely dominate and imply the existence of a relativistic plasma in the pulsar magnetosphere (Goldreich and Julian, 1969). Because the oblique vacuum model predicts a value of 3 for the braking index of the pulsar whereas the observed or computed values are different, a realistic model has to include both the relativistic plasma outflow and the electromagnetic wave emission. The vacuum wave model has been changed to include self-consistent plasma effects (Asséo et al., 1975; Asséo et al., 1978) in plane geometry and inhomogeneities linked to spherical geometry (Asséo et al., 1981). This results in very restrictive conditions for the possibility of propagation of the l.a.w.
Pulse Emission from the Light Cylinder
Authors: Ferguson Dale C.
Published: July 2016

The light cylinder is the second most popular location for pulsar emission. The fact that it has a sizable following, and yet is not the most popular location, is due to many aspects of light cylinder models. They have several advantages in explaining the pulsar phenomenon, but they have been little developed. This is mainly because they deal with the light cylinder, where our general ignorance of magnetospheric structure is greatest. Although light cylinder models have had considerable success in explaining the optical radiation from the Crab and Vela pulsars, I will restrict this paper to a discussion of radio pulsars.
Macroscopic and Microscopic Behavior Following Four Large Jumps in the Vela Pulsar (PSR 0833-45)
Authors: Downs G. S.
Published: July 2016

Eleven years of arrival time data for PSR 0833–45 collected at Goldstone, CA were analysed by fitting a simple model of the pulse period to the data in a least-squares sense. Four large jumps δP in period P of δP/P ~ −2 × 10−6 have occurred in which P increases up to 2% of its pre-jump value. Then P decays nearly exponentially with a time scale of 40 to 80 days to (1.2471 ±5) x 10−13 ss−1, regardless of the size of the jump. Q values for the jumps are about 6.5%. Further decay of P is at the constant rate (within an interjump era) of −5 × 10−24 < P < −9 × 10−24 ss−2. The observable effects of random fluctuations in P or P are an order of magnitude smaller than the systematic effects evident in P.
Thermal Properties of Neutron Stars
Authors: Tsuruta S.
Published: July 2016

The problem of neutron star thermodynamics has become a rather hot issue during the last one to two years, mainly because the enormous technological improvements brought by the Einstein Observatory (HEAO-B) and the exciting data which have become available to us through this satellite have given us a better hope of testing some of neutron star theories, which may eventually give us invaluable insight into various fields of physics. A somewhat extensive review of the pre-Einstein (Observatory) days was given in Tsuruta (1979a). Since then, many papers, both observational and theoretical, have come out. Most of the observational papers are reports from the Einstein Observatory. Stimulated by such progress on the observational side, various authors of recent theoretical papers attempted to reinvestigate and (or) improve the cooling and heating theories. Dave Helfand (1981) has already given a comprehensive summary of the most recent developments in heating theories. Therefore, in our present report, we shall restrict ourselves to the most recent developments in cooling theories and the comparison with the latest observations. The reader is referred to the earlier reviews (e.g. Tsuruta 1979a, b, 1980a) for the earlier work and the details.
The Galactic Distribution of Pulsars
Authors: Lyne A. G.
Published: July 2016

The galactic distribution of pulsars follows the general form of many population I objects in galactocentric radius, but has a wide distribution above and below the galactic plane due to high space velocities imparted to the pulsars at birth. The evidence for this model is described and the various factors involved in estimating the total galactic population and the galactic birthrate of pulsars are discussed. The various estimates of the galactic population which cluster around 5 × 105 are seen to be critically dependent upon the cut-off at low luminosities and upon the value of the mean electron density within 500 pc of the Earth. Estimates of the lifetimes of pulsars are available from both the characteristic ages and proper motion measurements and both give values of about 5 million years. The implied birthrate of one in every 10 years is barely compatible with most estimates of the galactic supernova rate.
Galactic Distribution and Genesis of Pulsars
Authors: Guseinov O. H. , Kasumov F. K.
Published: July 2016

At the end of 1978 the results of the second pulsar survey at the Molonglo Observatory (Manchester et al., 1978) and of a new survey of the northern hemisphere made at Green Bank (Damashek et al., 1978) were published. More than 80% of the celestial sphere were thus searched for pulsars in a careful and homogeneous manner. As a result of these surveys 172 new pulsars were discovered and parameters of 95 previously known pulsars were improved. Recently two new pulsars were discovered in the Pushino Observatory (Alekseyev et al., 1979), bringing the grand total of known pulsars to 325.
22. Projections into the Future
Authors: Zwicky F.
Published: July 2016

Science owes much of its success to the specialized approach, which endeavours to isolate objects and phenomena and to study them under elimination of the disturbing influences of the surroundings and internal contaminations. Thus, for instance, physicists grow pure single crystals of various chemical elements and compounds and study their mechanical, thermal, electrical, magnetic and optical properties under strictly controlled conditions of pressure, temperature and other parameters.
Creep in the Earth and Planets (Invited Lecture)
Authors: Jeffreys Harold
Published: July 2016

An outstanding problem is to reconcile the Moon's rotation with the persistence of its non-hydrostatic dynamical ellipticities. The first requires imperfection of elasticity under strains of order 10−7; the second apparently little under larger ones.

Lomnitz gave experimental evidence that creep is linear at elastic shears from 10−5to 10−4, indicating that a linear rule could be right at still smaller values. Positive evidence for the Earth comes from the damping of the 14-monthly nutation, which has a relaxation time of the order of 30 yr. Most work on imperfect elasticity has assumed that under constant shear stress the strain increases with time either liket(elasticoviscosity) or like logt.If the result from the 14-monthly nutation, with elasticoviscosity, is applied to the Moon, the dynamical ellipticities would have subsided considerably in the last 200 yr. With the logarithmic rule anSpulse at 80° would have its beginning spread out over about 70 s and be unreadable. These contradictions are avoided if the increase under constant stress is about liket0.2. The resulting law involves two constants. Without change of these, applications are made to other phenomena. The rotations of the Moon and of other satellites whose rotations are known are explained; so is the persistence of the Moon's dynamical ellipticities; also the failure to detect three free oscillations that might theoretically exist. Elasticoviscosity would imply rapid disappearance of the non-hydrostatic second and third harmonics in the Earth's gravitational field; this is avoided with the new law. Study of damping of free vibrations of the Earth (including surface waves) has usually assumed the logarithmic law, but it appears that the new law fits the data at least as well, and that it may also explain those that have been interpreted in favour of layers of low velocity. It appears that the damping at depths up to 400 km or so is much more severe than the average for the Earth's shell, and more evidence for shorter periods is much needed.

Any law with an index less than 1 would forbid thermal instability (convection) and continental drift.
Spectral Analyses of the Chandler Wobble
Authors: Pedersen G. P. H. , Rochester M. G.
Published: July 2016

Spectral analyses of 70 yr of ILS-IPMS data on the variation of latitude are discussed from the point of view of the confidence limits that can be placed on statistical estimates. The available data cannot be used to support the existence of two resonant frequencies in the Chandler wobble, nor are the latter required to remove an anomaly in the value of Q for wobble as long as the oceans cannot be dismissed as an energy sink.
Analysis of the Chandler Period of Polar Coordinates Calculated by the Orlov Method
Authors: Proverbio E. , Carta F. , Mazzoleni F.
Published: July 2016

The coordinates x and y of the pole related to mean pole of the epoch in the period 1900–1962 for the ILS station were calculated utilising the method proposed by Orlov (1955). The values of the latitudes are those reduced in the homogeneous system of Carnera-Cecchini by Proverbio et al. (1969). The values of the amplitudes and periods of the polar motion were calculated. The comparison of the data seems to confirm a correlation between the amplitudes and periods of Chandler motion, that is the validity of the time-variable model suggested by Melchior (1949) and other authors.
On the Short Period Terms in the UT1 and Those in the Polar Motion
Authors: Iijima Shigetaka , Okazaki Sêichi
Published: July 2016

Short period terms ranging from 0.3 to 6.0 yr. are resolved from 13.5 yr data of UT1 and polar motion on periodograms, considering the mutual interference effects caused by truncation of data. Beside principal terms known well, 26 month term is reconfirmed but any Chandlerian term is not found in UT1. Minor amplitude terms are found around 0.48, 0.86, 1.36, 1.58, 3, and 4 yr in UT1, and 1.12, 1.26, and 1.43 yr in polar motion.
On the Regularity of Fluctuations in Annual and Secular Polar Motions
Authors: Abraham H. J.
Published: July 2016

It may become possible to explain much of the behaviour and remarkable regularity of fluctuations in reported annual and secular polar motions if the potential that causes an immediate excitation is also a factor in that excitation's rate of change afterwards.

The Chandler frequency, for example, being a function of the deformation excitation, should then vary with the librational and nutational displacements of the pole of rotation. It is found that the frequency does in fact do so.

The annual excitation would be affected as well. The steady and seasonal primary excitations are known to cause free and forced nutations that are accompanied by periodic secondary excitations. These would arise partly at once and partly in the course of time; they would modulate the primary annual excitation and also one another, according to the period of the beats between the annual and Chandler nutations. It is found that the reported annual excitation shows phase and amplitude fluctuations of this kind. (The data also show another large excitation that occurred briefly on two occasions).

Finally, the amplitude and phase of the secular librations appear to have followed an expression that is obtained by integrating the rates of change of excitation. This expression is a function of the amplitude of the annual excitation and the period of the beats between the annual and Chandler nutations.
Accuracy of Doppler Determinations of Station Positions
Authors: Anderle R. J.
Published: July 2016

Locations of Doppler satellite observing stations have been revised to obtain a set which is more self-consistent and more consistent with the CIO pole. Residuals of satellite observations for 1970 have been analyzed using the new coordinates to determine mean and standard errors for five days of observations of latitude versus station, time of day, and elevation angle. The accuracy of the determination of latitude is about 4 meters at moderate and high elevation angles. But since more satellite passes occur at lower elevation angles, the accuracy of determination of a component of position based on five days of observation of one satellite is only about 2 meters.
Corrections to Star Catalogues from Satellite Observations
Authors: Williams Carol A.
Published: July 2016

A theoretical investigation is made to explore the possibility of obtaining corrections to star catalogues from the observations of artificial satellites. A model is established to represent the system formed when such corrections are determined simultaneously with corrections to the geocentric position of the observer. The covariance matrix is established analytically for the two-dimensional case. The resulting correlations and weights are discussed. Since this method presents an independent way of obtaining the systematic errors in star catalogues, it is related to the measurement of all quantities which depend on star positions.
Polar Wandering and the Earth's Dynamical Evolution Cycle
Authors: Pan Cheh
Published: July 2016

With a triaxial deformable Earth model an attempt is made to integrate the dynamics of polar wandering with that of the tectonic movements of the Earth's upper layers. Polar wandering is interpreted as a mechanical response of the rotating Earth to the episodic energy perturbation in the upper layers, whereas the tectonic movements are the adjustments of the upper layers to the polar instability. The present analysis suggests that the attempt of the Earth to adjust itself for polar stability is the driving mechanisms of continental drift and sea-floor spreading, and also that the Earth's wobble is rather a quasi-permanent (slow damping) phenomenon and has two components. And that the Earth would not reach its rotational equilibrium as long as the excess heat-generation in its interior continues to supply energy for its cyclic dynamical evolution.