bluuebunny/crossref_metadata_2025 huggingface dataset:
106-107 K Gas in the Magellanic Clouds
Authors: Snowden S. L.
Published: July 2016

The Large Magellanic Cloud contains an extensive distribution of hot plasma and is one of the brightest extragalactic regions in the diffuse 0.5–2.0 keV X-ray sky. The plasma is not isothermal but increases in color temperature from west to east from ~106.6 K to ~106.9 K. The total flux from this plasma is ~ 1038 ergs s−1. The average emission measure is ~ 0.014 cm−6 pc, which if the emitting plasma is distributed uniformly throughout the LMC, implies a space density of ne ~ 0.002 cm−3. There is an apparent ¼ keV enhancement in the southwest of the LMC, which if associated with the LMC implies a considerable emission measure of ~ 106 K plasma. (The foreground column density of Galactic neutral hydrogen is ~ 6 × 1020 cm−2, or several optical depths for ¼ keV emission.)

The Small Magellanic Cloud exhibits less diffuse X-ray emission in the 0.5–2.0 keV band than the LMC with a total flux of ~ 4 × 1036 ergs s−1. The average emission measure of ~ 0.006 cm−6 pc also implies a space density of ne ~ 0.002 cm−3. The optical depth of Galactic HI for ¼ keV X-rays from the SMC is considerably lower than that for the LMC. However, while there is a significant variation in the ¼ keV band intensity over the SMC field, it is in general not particularly well correlated with anything associated with the SMC, although there is an enhancement which may be related to the leading edge of the SMC. Considerably more work is needed to unravel the origin of the structure, which may be associated instead with either emission or absorption variations in either the disk or halo of the Milky Way.
Interstellar Phases in the Magellanic Clouds
Authors: Dickey John M. , Marx-Zimmer Monika , Düsterberg Christian , Mebold Ulrich , Stanimirović Snezana , Staveley-Smith Lister , Kobulnicky H. A.
Published: July 2016

Surveys of λ21-cm absorption in the Magellanic System show that the cool phase of the HI is less abundant in the SMC than in the Milky Way, and may be so also in the LMC. The typical cool cloud temperature is colder than in the Milky Way, 30 to 40 K rather than 60 to 75 K. The lower abundance of cool phase HI can be traced to the lower heavy element abundances in the Magellanic environment. The cooler cloud temperatures are somewhat mysterious.
New HI Features of the Magellanic System
Authors: Putman M. E. , Gibson B. K. , Staveley-Smith L.
Published: July 2016

The first results from the HI Parkes All-Sky Survey (HIPASS) provide a spectacular view of the global HI distribution in the vicinity of the Magellanic Clouds and the southern Milky Way. A 2400 square degree mosaic around the South Celestial Pole (SCP) reveals the existence of a narrow, continuous counter-stream which “leads” the direction of motion of the Clouds, i.e., opposite in direction to the Stream. This strongly supports the gravitational model for the Stream in which the leading and trailing streams are tidally torn from the body of the Magellanic Clouds. The data also reveal additional tidal features in the Bridge region which appear to emanate from the LMC, and a distinct spiral structure within the LMC itself.
Superbubbles in the Magellanic Clouds
Authors: Oey M. S.
Published: July 2016

Superbubbles that result from the stellar winds and supernovae of OB associations probably play a fundamental role in the structure and energetics of the ISM in star-forming galaxies. Their influence may also dominate the relationship between the different interstellar gas phases. How do superbubbles form and evolve? How do they affect the local and global ISM? The Magellanic Clouds provide a superior opportunity to study this shell-forming activity, since both stellar content and gaseous structure can be examined in detail. Here, the results of recent studies of superbubbles in the Magellanic Clouds are reviewed.
Modeling the ISM: Molecular Gas, Ionizing Radiation, and Numerical Simulations
Authors: Bregman Joel N.
Published: July 2016

Three different topics regarding the ISM in the Magellanic Clouds are discussed. First, we examine how the Magellanic Stream can be used as a tracer of the ionizing radiation leaking out of Galaxy and the Magellanic Clouds. We show that the radiation reaching the Magellanic Stream is less than 1% of the ionizing radiation produced by Galactic 0 and B stars. Since about 14% of the ionizing radiation from these stars is required to ionize the Reynolds layer, which is within 1 kpc of the disk, most of this radiation must be absorbed before reaching the Stream.

Second, we examine the reliability of using CO as a tracer of H2 in regions of low or modest column densities (not giant molecular cloud complexes). For our Galaxy, the usual CO to H2 conversion factor overlooks a considerable amount of H2 and the evidence suggests that this may be true in the LMC as well. Finally, we present numerical hydrodynamical calculations of the interstellar medium in disk galaxies for a region of size 2 kpc along the plane and 15 kpc out of the plane. The simulations reveal a rich structure of low density hot regions separated by cold dense material, with the resulting position velocity diagrams being qualitatively similar to the recent HI studies of the LMC. A number of other aspects of these simulations are discussed also.
Molecular Clouds in the Magellanic System
Authors: Chin Yi-nan
Published: July 2016

Several molecular cores in the Magellanic Clouds have been investigated. While previous works only concentrated on “warm” clouds, our study provides the first systematic study to cover different environments. Preliminary results are presented with brief discussions.
CO Emission toward HI Absorption Sources in the Large Magellanic Cloud
Authors: Marx-Zimmer M. , Zimmer F. , Herbstmeier U. , Dickey J. M.
Published: July 2016

In the Large Magellanic Cloud (LMC) a large number of cool HI clouds have been detected with temperatures much lower than those found for atomic clouds in the Milky Way (Dickey et al. 1994; Mebold et al. 1997; Marx-Zimmer et al. 1998). Apparently, the population of cool HI clouds reaches kinetic gas temperatures down to as low as 10 or 20 K. These clouds may play an important role in the formation of stars in the LMC. We studied the association between the cool atomic gas and molecular gas in the LMC by 12CO(1–0) line observations in directions of cool HI clouds using the 15-m Swedish-ESO Submillimetre Telescope (SEST).
Molecular Clouds in the LMC Observed with NANTEN: III. Comparison with HII Regions
Authors: Abe R. , Hara A. , Hayakawa T. , Kato S. , Kawamura A. , Mizuno A. , Mizuno N. , Ogawa H. , Onishi T. , Saito H. , Tachihara K. , Xiao K. C. , Yamaguchi N. , Yamaguchi R. , Fukui Y. , Yonekura Y.
Published: July 2016

We have made 12CO(J=1-0) observations in the LMC with NANTEN, and compared the detected giant molecular clouds (GMCs) with HII regions and stellar clusters. It is found that ~ 80% of the GMCs are associated with HII regions. The results of comparisons of the GMCs with the HII regions and the stellar clusters are presented.
The Compact HII Regions N11A and N88A in the LMC and SMC
Authors: Testor G. , Rola C. S. , Whiting A. B.
Published: July 2016

Several spectra have been obtained in the 3600–10000 Å range, for the HII regions N11A and N88A in the LMC and SMC, respectively. The spectral type of their exciting star was determined and from the emission-line intensities we have derived the gas electron density and temperature, and computed the chemical abundances of He, O, N, Ne, S, and Ar. These abundances are then compared with the ones found for other HII regions in the Magellanic Clouds.
Abundances in Magellanic Cloud Young Populous Clusters
Authors: Hill V.
Published: July 2016

Detailed abundances are measured in cool supergiants in Magellanic Cloud young populous clusters (NGC 330 in the SMC, NGC 2004, NGC 2100 and NGC 1818 in the LMC) and compared to those recently observed in samples of field supergiants in each Cloud. The analysis of the field supergiants shows no evidence of any abundance dispersion among the stars, compatible with a well mixed gas in these galaxies. However, previous determinations of the metallicity of NGC 330 and NGC 1818 give values well below the respective field values. This difference is investigated using a homogeneous method for the field and cluster samples, and the abundance ratios of various elements are examined.
The Star Formation History and IMF in the LMC and SMC from Deep HST Imaging
Authors: Holtzman J. , Mould J. R. , Gallagher J. S.
Published: July 2016

We present deep photometry to V ~ 27.5 obtained with the HST in several fields in the LMC and the SMC. We derive luminosity functions for the faintest stars which are consistent with an initial mass function similar to that of the solar neighborhood, although moderate variations are not excluded. We discuss implications of these observations for the star formation history in these regions of the LMC and SMC.
The Centre of the LMC Bar – Analysis of HST Data
Authors: Linde P. , Ardeberg A. , Gustafsson B.
Published: July 2016

We used the HST to obtain high resolution images of the LMC Bar centre. Through careful data analysis, taking into account cleaning, dithering and crowded field decomposition, we show that accurate uvby photometry can be achieved for F dwarfs, reaching stars around the lower turn-off region, as faint as V=22.
Strömgren Photometry of Field Red Giants in the LMC
Authors: Cole Andrew A. , Gallagher John S. , Smecker-Hane Tammy A.
Published: July 2016

We present here preliminary results of our program to obtain rough abundance estimates for > 104 red giant branch and red clump stars in four fields of the LMC. The derived abundance distributions will be a strong constraint on models of the LMC's star-formation history based on field star color-magnitude diagrams.
The Carbon Star Luminosity Functions in the Magellanic Clouds
Authors: Marigo Paola , Girardi Léo
Published: July 2016

We address the question of reproducing the observed luminosity functions of carbon stars (CSLF) in both the LMC and SMC, characterized by quite different features (i.e., faint end and peak location), using a new formalism for the third dredge-up in TP-AGB models.
The Oldest Star Clusters in the Small Magellanic Cloud
Authors: Mighell Kenneth J. , Sarajedini Ata , French Rica S.
Published: July 2016

We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F450W (~B) and F555W (~V) of the intermediate-age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Lindsay 113, to investigate the age sequence of these seven star clusters in order to improve our understanding of the formation chronology of the SMC. We analyzed the V vs B–V and MV vs (B–V)o color-magnitude diagrams of these populous Small Magellanic Cloud star clusters using a variety of techniques and determined their ages, metallicities, and reddenings. These new data enable us to improve the age-metallicity relation of star clusters in the Small Magellanic Cloud. In particular, we find that a closed-box continuous star-formation model does not reproduce the age-metallicity relation adequately. However, a theoretical model punctuated by bursts of star formation is in better agreement with the observational data. The full details of this analysis are reported in Mighell, Sarajedini, & French (1998, AJ, 116, 2395).
The Formation and Evolution of LMC Globular Clusters: The Database
Authors: Beaulieu S. F. , Elson R. , Gilmore G. , Johnson R. A. , Tanvir N. , Santiago B.
Published: July 2016

We present details of the database from a large Cycle 7 HST project to study the formation and evolution of rich star clusters in the LMC (see Elson et al., this volume). Our data set, which includes NICMOS, WFPC2 and STIS images of 8 clusters, will enable us to derive deep luminosity functions for the clusters and to investigate the universality of the stellar IMF. We will look for age spreads in the youngest clusters, quantify the population of binary stars in the cores of the clusters and at the half-mass radii, and follow the development of mass segregation.
On the Period-Luminosity-Color Relation of Classical Cepheids
Authors: Bono G. , Marconi M.
Published: July 2016

We compare the theoretical and empirical PL relations in V and I bands for Cepheids in the LMC. We found that, within the current intrinsic dispersions, the theoretical predictions are in remarkable agreement with observational data. We also discuss the PLC relations in (V,B-V) and (V,V-I) as well as the dependence of distance determinations on uncertainties in colors, in reddening corrections and in metal content.
Calibration of the Cepheid Distance Scale with the Infrared Surface Brightness Technique
Authors: Gieren Wolfgang , Fouqué Pascal
Published: July 2016

We review the process of determining the distances to Cepheid variables with the infrared surface brightness technique. We show that both versions of this technique (working with theV, V–Kand the pure infraredK, J–Kmagnitude/color combinations) yield consistent distances to Cepheid variables. For a Cepheid with average-quality photometric and radial velocity data, the typical total uncertainty in the distance is ±5%. We use the distances of 34 Galactic variables to calibrate period-luminosity relations in theV, I, J, H, Kbands and demonstrate that these relations lead to distance moduli of the LMC which agree to ±0.02 mag. The infrared surface brightness technique yields a best LMC distance modulus of 18.46 ±0.02. We discuss possible metallicity corrections, such as the ones determined by Sasselov et al. from EROS Cepheids comparison in the LMC and SMC, and conclude that our distance modulus is negligibly affected by these corrections. Finally, we present a program to obtain reddening- and metallicity-independent infrared surface brightness distances of Cepheid variables in LMC clusters which will yield an even more accurate mean LMC distance independent of any metallicity correction to Cepheid absolute magnitudes.
The Theoretical PLC Relations of Classical Cepheids
Authors: Marconi Marcella
Published: July 2016

On the basis of an extensive grid of Cepheid, nonlinear, nonlocal, time-dependent convective models by Bono et al., analytical Period-Color-Luminosity (PLC) relations as a function of chemical composition were evaluated and compared with observations in LMC and SMC. I provide an analysis of PL and PLC residuals and suggestions for disentangling the effects of reddening and metallicity on the Cepheid distance scale.
Surface Brightness Scale of Galactic Cepheids
Authors: Di Benedetto G. P.
Published: July 2016

An accurate calibration of the surface brightness scale SV as a function of the near-IR color (V – K) has been recently measured for non-variable Galactic dwarf and giant stars. It can be shown that this correlation can be applied to the SV scale of Galactic Cepheid variable stars, which are of major cosmological interest.
The Magellanic Clouds, Past, Present and Future - A Summary of IAU Symposium No. 190
Authors: van den Bergh Sidney
Published: July 2016

Important problems to which we would like to find answers are:

•

What are the distances to the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC)?

•

What is the present distribution of stars, gas and dark matter in the Clouds, and how did it evolve?

•

How, and where, did the Magellanic Clouds form, and how have their orbits evolved?

•

Finally the recent discovery of numerous microlensing events in the Clouds provides answers to questions that we have only recently started to ask.
Analytical solution of the motion of the planets over several thousands of years
Authors: Bretagnon P.
Published: July 2016

The results of a planetary theory built by an iterative method are given here in order to show the relation with the secular variation theories and the meaning of the mean elements in these latter theories. The general theories have a validity span of several millions years but a weak precision; on the contrary, the secular variation theories reach a great precision over several thousand years. Two applications of the analytical planetary theories are presented: the relation between the barycentric coordinates and the geocentric ones; the determination of the terms of precession and nutation for the rigid Earth.
Numerical efficiency of the elliptic function expansions of the first-order intermediary for general planetary theory
Authors: Brumberg Victor A. , Klioner Sergei A.
Published: July 2016

We compare numerical efficiency of the two kinds of series for the first-order intermediate orbit for general planetary theory: (1) the classical expansion involving mean longitudes of the planets; (2) an expansion resulting from the theory of elliptic functions. We conclude that mutual perturbations of close couples of planets (the ratio of major semi-axes ∼ 1) can be represented in more compact form with the aid of the second kind of series.
New constants for Sampson-Lieske theory of the Galilean satellites of Jupiter from mutual occultation data
Authors: Vasundhara R. , Arlot J.E. , Descamps P.
Published: July 2016

New constants for Sampson-Lieske theory of the Galilean Satellites have been derived using 6360 individual photographic positions (1891–1990) and 438 pseudo astrometric positions from mutual occultations during 1973, 1979, 1985 and 1991. Using these new sets of constants, significant improvement is noticed in the O-C values of the sky plane coordinates of the mutual event data set and residuals in longitude for Io and Europa are found to improve. Problems concerning the inclusion of mutual event data in attempting evaluation of secular variations of the mean motions of the satellites are discussed.
From telescope to MPC: Organizing the minor planets
Authors: Marsden B.G.
Published: July 2016

Somewhat more than a century after its introduction for the purpose of discovering minor planets, photography is now rapidly giving way to the CCD as the technology of choice for observing these bodies. A CCD has been used in scanning mode in the University of Arizona's ‘Spacewatch’ program for the discovery of minor planets since as long ago as 1984 (Gehrels 1984, Gehrels et al. 1986), while a CCD in stare mode was first applied as a matter of routine to an established observing program for astrometric follow-up in 1989—that at the Oak Ridge Observatory in Massachusetts (McCrosky 1990). After its initial 1984–1986 success, Spacewatch was modified with the help of a larger CCD and improved computer software and with the adoption of the particular mission of searching for NEOs, or minor planets (and comets) that pass close to the earth (Rabinowitz 1991, Scotti 1994). The Oak Ridge program utilizes a 1.5-m reflector, and the first CCD observations were reduced using the Astrographic Catalogue, the mainstay of the Oak Ridge photographic program back to its inauguration in 1972, as well as of other older photographic programs in which the fields observed were significantly less than 1° across. Within months, the availability, on CD-ROMs, of the STScI Guide Star Catalogue (Villard 1989) effectively consigned the venerable AC to the scrap-heap, and the rapid development of ready-made and relatively inexpensive CCD systems (e.g., di Cicco 1992) has recently increased the volume of CCD astrometry considerably, allowing it to be conveniently and reliably carried out, even by amateur astronomers. At the present time, very nearly 50 percent of the astrometric observations, typically 6000, published each month in the Minor Planet Center's Minor Planet Circulars are obtained by means of a CCD.
On the Hecuba gap
Authors: Ferraz-Mello S.
Published: July 2016

An asteroid captured in the Hecuba gap (2/1 resonance with Jupiter) may remain there for a long time before escaping. However, the study of the diffusion of orbits in the gap indicates an escape timescale in the range 107–109 years. The short-period perturbations of Jupiter's orbit play a determinant role in the creation of the stochasticity responsible for the escape.
Chaotic asteroidal trajectories exhibiting multiple bursts of eccentricity: A statistical analysis
Authors: Shevchenko Ivan I. , Scholl Hans
Published: July 2016

For chaotic asteroidal trajectories exhibiting multiple bursts of eccentricity in the 3/1 Jovian resonance, we derive the distribution function of time intervals between such bursts. At the onset, the resulting distribution decays exponentially. In the tail, an algebraic decay is observed, with the power-law index for the integral distribution in the range −2 to −1.
Orbital stability of high inclination asteroids
Authors: Solovaya N. A. , Pittich E. M.
Published: July 2016

The orbital evolutions of fictitious asteroids with high inclinations have been investigated. The selected initial orbits represent asteroids with movement, which corresponds to the conditions of the Tisserand invariant for C = C (L1) in the restricted three body problem. Initial eccentricities of the orbits cover the interval 0.0–0.4, inclinations the interval 40–80°, and arguments of perihelion the interval 0–360°. The equations of motion of the asteroids were numerically integrated from the epoch March 25, 1991 forward within the interval of 20,000 years, using a dynamical model of the solar system consisting of all planets. The orbits of the model asteroids are stable at least during the investigated period.
A numerical analysis of the process of capture into resonance
Authors: Gomes Rodney S. , Miguelote Alexandre Y.
Published: July 2016

The process of capture into a mean motion resonance induced by a non conservative force has been studied by many authors (Henrard, 1982); Peale, 1986). Capture probabilities have been established through the use of an analytical model based on averaged Hamiltonian systems, with an adiabatic varying parameter (Henrard, 1982; Lemaitre, 1984). For each resonance, these probabilities are basically function of the orbital element involved (eccentricity and/or orbital inclination) far from the resonance and the perturber's mass, there being no dependence on the dissipation rate. However when the process is not adiabatic, the dissipation rate has a fundamental importance for capture probabilities (Gomes, 1995). For these processes, an analytical association of orbital elements far from the resonance with capture probabilities is still an open question. Association of orbital elements just before resonance with the process of capture is presented in (Marzari and Vanzani, 1994) and (Lazzaro et al, 1994). In these works the eccentricity and longitude of the perihelion are checked for in respect with capture into resonance. Here we aim at verifying how the trapping process changes with orbital elements just before resonance, but not restricting ourselves to the pair eccentricity-perihelion.
About the application of angle–action variables to the rotation of deformable celestial bodies
Authors: Barkin Yuri V. , Ferrandiz Jose M. , Getino Juan
Published: July 2016

We begin with the development of a new analytical theory for the rotational motion of deformable celestial bodies. In this work we present a new unperturbed Hamiltonian which includes the main term affecting the Chandler period.
A numerical scheme to integrate the rotational motion of a rigid body
Authors: Fukushima Toshio
Published: July 2016

Once, we numerically integrated the precession and nutation of a spheroidal rigid Earth (Kubo and Fukushima 1987). As a natural extension, we tried to integrate the rotation of a triaxial rigid Earth numerically and faced a problem: a loss of precision in long-term integration. This is due to the smallness of the characteristic period of the problem: 1 day. Of course, one can integrate the rotational motion in higher precision arithmetics with a smaller stepsize. However, the quadruple precision integration is roughly 30 times more time-consuming than the double precision integration. See Table 1. Therefore, it is desirable if there is a formulation 1) reducing the overall integration error, 2) being independent on the choice of the integrator and 3) requiring no extra computations. The key points to achieve this goal will be to find a set of variables which 1) are efficiently convertible to the physical quantities required finally, say, the orientation matrix in the case of the rotational dynamics, and 2) vary with time as smoothly as possible. In this note, we report a discovery of such an example.
Symplectic mappings
Authors: Hadjidemetriou John D.
Published: July 2016

This paper reviews the main methods for constructing mapping models for Hamiltonian systems, for the study of motion in the Solar System. The emphasis is given to the relation between the various mapping techniques, the methods to check how close is a mapping model to the original system and the effects of an incomplete model on the evolution of the system.
L'algèbre symbolique en mécanique céleste
Authors: Deprit André
Published: July 2016

Que dire de l'algèbre symbolique en mécanique céleste si ce n'est que les astronomes furent les premiers sur le chantier. Rien là qui doive surprendre.
PSP: A new Poisson series processor
Authors: Ivanova T.V.
Published: July 2016

A specialized Poisson Series Processor (PSP) is proposed. It is designed for manipulating long Poisson series. The Keplerian Processor and analytical generator of special celestial mechanics functions based on the PSP are proposed as well.
Analytic-numerical solutions of restricted non-resonance planar three-body problem
Authors: Ryabov Y. A.
Published: July 2016

We consider a restricted planar circular three-body problem (Sun-Jupiter-asteroid) in a non-resonance case. There are two new algorithms developed for construction of a quasi-periodic solution in a trigonometric form by means of computer algebra. The first corresponds to classical method of simple iterations leading to series in powers of small mass mJ, the second, to iterations with rapid (quadratic) convergence, but having ordinary type and not involving a successive coordinate transformations. All these iterations require a realization of algebraic operations on trigonometric polynomials with the help of computers of high capacity. It would be interesting to compare the solutions obtained with the two algorithms and to estimate the domain of their practical convergence.
Carlsberg optical astrometry of the outer solar system
Authors: Morrison L.V. , Buontempo M.E.
Published: July 2016

The Carlsberg astrometric telescope has made about 17000 observations of outer Solar System objects since it began operation in 1984. The observed positions of the major planets are compared with JPL DE200 and DE403. The agreement with DE403 is good in general, but unresolved discrepancies of the order 0″.1 are found in Jupiter and Saturn. The run-off between the observations and DE200 which was fitted to observations before 1980 emphasize the need to continue optical observations of the outer planets.
Accuracy estimation of new sets of the Sun and Planets observations
Authors: Kharin A. S. , Kolesnik Yu. B. , Chuichenko O. E.
Published: July 2016

The PLANETS database has been conceived and firstly compiled at the Golosiiv Observatory in 1984, Kiev (Kharin et al. 1987). Since 1988, it is updated, maintained and analysed in cooperation with the Institute of Astronomy, Moscow. By this time the database comprises most of the published optical observations of the Sun and 7 major planets made from 1960 onwards with 21 meridian instruments, 15 astrographs and 11 astrolabes at 29 observatories.
McDonald observatory lunar laser ranging: Beginning the second 25 years
Authors: Shelus P.J. , Ricklefs R.L. , Ries J.G. , Whipple A.L. , Wiant J.R.
Published: July 2016

Lunar laser ranging (LLR) (Dickey et al., 1994) consists of measuring changes in the round-trip travel time for a laser pulse traveling between a transmitter on the Earth and a reflector on the Moon. The lunar surface reflectors are still operating normally after almost three decades of use. The ranging data exhibit a rich spectrum of change due to many effects.
An updated GSC as the astrometric reference for minor planet observations
Authors: Röser Siegfried
Published: July 2016

Minor planet observers generally use the Guide Star Catalog (GSC) as the astrometric reference for the reductions of their CCD frames. Two problems are related with GSC. First, it contains no proper motions, and second, it shows severe systematic errors near the plate edges.

I report on the status of a new reduction of GSC and present a first version of STARNET, a catalogue of 4.3 million positions and proper motions using GSC as second, and a new reduction of the Astrographic Catalogue (AC) as first epoch. In STARNET the average rms-accuracy of the proper motions is 5 milliarcsec/year, that of the present-day positions 0.3″.
Analysis of the Sun's observations with prismatic Astrolabe
Authors: Leister N.V. , Poppe P.C.R. , Emilio M. , Laclare F.
Published: July 2016

A regular program of observations of the Sun with prismatic astrolabes is under way since 1974 in both, the “Abrahão de Moraes” (φ = −23°0.1′) and “Caussols” (φ = +43°44.9′) observatories. The zenith distance of 2968 transits of the solar limbs observed during the period from 1988 January to 1994 April, in both centers, are analysed. The primary goal of this programme is to determine corrections ΔE and ΔA to the FK5 equinox and equator, as well as to the Earth's orbital constants. Secondly, we present here possible variations of the solar radius, which are of interest because of their astrophysical significance. The results of the analysis of the observations made with these instruments depend on both the prism angles used during the observation and the latitude of the site (Leister 1989, Poppe 1994). With the use of the different reflector prisms, instead of the refracting equilateral, it was possible to observe at differents zenith distances, allowing to sweep, at the brazilian observatory, the apparent orbit of the Sun during a period of about 10 months per year, with two prisms. The instrument of the french observatory works with 11 differents zenith distances, permitting an increase of about 10 months per year in the observational period either.
Radio Surveys
Authors: Condon J.J.
Published: July 2016

Radio surveys have an important role in astronomy, one that has changed with technology and scientific requirements. Most objects studied by radio astronomers today are the unexpected discoveries of early surveys. The survey “discovery” phase began with Jansky's detection of Galactic radio emission and Reber's 160 MHz maps showing that this emission is non-thermal. Surveys made just after World War II revealed strong discrete sources which were later identified with supernova remnants, radio galaxies, and quasars. Pulsars were discovered during a sky survey for scintillating sources. BL Lac objects were recognized in early high-frequency surveys. The first gravitationally lensed quasar appeared in the extensive Jodrell Bank 960 MHz survey, and the first measurement of gravitational radiation came from the binary pulsar serendipidously found in a pulsar survey.
Infrared Surveys: A Golden Age of Exploration
Authors: Beichman C.A.
Published: July 2016

The next decade promises an explosion of information about the infrared sky from wavelengths from 1 μm to 1,000 μm, in the continuum and in spectral lines. Measurements of objects ranging from comets in the Kuiper Belt to newly-forming galaxies will be useful for almost every branch of astrophysics. The number of catalogued infrared sources will increase a thousand-fold from the 600,000 presently known from IRAS. This talk addresses the compelling scientific interest of the infrared and describes why, years from now, astronomers will view this decade as a golden era for the exploration of the infrared sky.
Astronomy on the Midcourse Space Experiment
Authors: Price S.D. , Tedesco E.F. , Cohen M. , Walker R.G. , Henry R.C. , Moshir M. , Paxton L.J. , Witteborn F.C.
Published: July 2016

The Midcourse Space Experiment (MSX) carries a varied suite of sensors for imaging in the ultraviolet to the mid-infrared, hyperspectral imaging in the ultraviolet through visible and infrared spectroscopy with a Michelson interferometer. At comparable sensitivity to the Infrared Astronomical Satellite (IRAS) but with a 40 times smaller point response function, the MSX infrared radiometer is ideal for surveying specific large areas such as those in which IRAS was degraded by confusion or not covered at all. This experiment obtains simultaneous observations over a very wide spectral range, from 0.11 to 25 μm, thus providing unique information on the energetics of such diverse objects as comets and H II regions. Initial observations indicate that the astronomy objectives on this experiment will be achieved.
Interstellar Cirrus Observed in Balmer Hα
Authors: McCullough P.R.
Published: July 2016

We present Hα images with 0.1° resolution and fields of view larger than 10°. In some regions of the sky, the Balmer Hα emission is correlated positively with IRAS 100 μm emission. Observations of such sensitivity and angular scale as these provide a new view of the interstellar medium of our Galaxy (see also Dennison et al., this volume, p. 182) and may allow us to distinguish between Galactic foreground and cosmic background for both the free-free emission and the thermal dust emission associated with the warm ionized medium of the Milky Way.
Structure and Kinematical Properties of the Galaxy at Intermediate Galactic Latitudes
Authors: Ojha D. K. , Bienaymé O. , Robin A. C.
Published: July 2016

We have carried out a sample survey in UBVR photometry and proper motions in various directions in the Galaxy. Three fields in the direction of galactic anticentre, centre, and antirotation have been surveyed. Using our new data together with wide-area surveys in other fields available to date, we discuss the radial and vertical structure of the Galaxy. Our results confirm that the thick disk population is distinct from other populations based on their kinematical and spatial distribution. The most probable value of scale height for the thick disk component is determined to be hz≃760±50 pc and a local density of ≃7.4+2.5−1.5% relative to the thin disk. The ratio of the number of thick disk stars in our galactic centre region to that in anticentre region yield hR≃3±1 kpc for the scale length of thick disk. These values are in perfect agreement with the recent determination given by Robin et al. (1996).
The K-Band Wide Field Survey: Understanding the Local Galaxies
Authors: Huang J.
Published: July 2016

We have conducted a wide-field K-selected galaxy survey with complementary optical I- and B-band imaging in six fields with a total coverage of 9.8 square degrees (Huang et al. 1997). The observations were carried out on the UH 0.6m and the UH 2.2m telescopes. The purpose of this survey is to study the properties of the local galaxies and explore the evolution of K-selected galaxies at low redshifts. Star-galaxy discrimination is performed using both galaxy color properties and object morphologies, and 6264 galaxies are found. This survey establishes the bright-end K-band galaxy number counts in the magnitude range 13 < K < 16 with high precision. We find that our bright-end counts have a significantly steeper slope than the prediction of a no-evolution model, which cannot be accounted for by observational or theoretical error. Since it is very unlikely that there is sufficient evolution at such low redshifts to account for this effect, we argue that there is a local deficiency of galaxies by a factor of 2 on scale sizes of around 300 Mpc. This would imply that local measurements of Ω0 underestimate the true value of the cosmological mass density by this factor and that local measurements of H0 could be high by as much as 33%.
A Search for Large Voids from Combined Samples of Galaxy Clusters and Galaxies
Authors: Stavrev K.Y.
Published: July 2016

This paper is part of a more extensive study of the large voids in spatial volumes both wide and deep. Three samples of optical tracers with spectroscopically measured redshifts in a volume with b≥30° and z≤0.14 have been extracted from the catalogue of Lebedev and Lebedeva (1986) and the NASA/IPAC Extragalactic Database (NED):

(1)

a homogeneous sample of 277 rich Abell clusters

(2)

an inhomogeneous sample of 969 objects: rich and poor Abell clusters, Zwicky clusters, other clusters, and groups

(3)

a sample of 18 623 NED galaxies.
Low Luminosity Galaxy Distribution in Low Density Regions
Authors: Hopp U.
Published: July 2016

We performed two surveys at the Calar Alto Observatory to identify low luminosity galaxies (LLG) in 4 fields towards nearby voids. While the central parts of the voids remain empty, we found about 20 very isolated (nearest neighbour distances of DNN ≥ 4Mpc) galaxies along the rims of some (but not all) voids (Hopp et al. 1995, Hopp & Kuhn 1995, Kuhn et al. 1996, Popescu et al. 1996). Many of them are dwarfs, a few are giants. CCD surface photometry revealed normal properties (Vennik et al. 1996), HI-observations show a tendency that the isolated dwarfs are overabundant in neutral gas compared to sheet and cluster galaxies of the same luminosity (Huchtmeier et al. 1996).
Multiwavelength Study of the Shapley Concentration
Authors: Bardelli S. , Zucca E. , Zamorani G. , Vettolani G. , Scaramella R.
Published: July 2016

The Shapley Concentration is a prominent supercluster in the southern sky. It is interesting not only for its relevance in the peculiar motion problem (it seems to be responsible of ∼ 30% of the acceleration acting on the Local Group of galaxies), but also because it is the most remarkable feature which appears studying the distribution of the Abell-ACO clusters of galaxies: Zucca et al. (1993) found that at every density contrast the Shapley Concentration stands out as the richest supercluster in the sky. In particular, the central part of this supercluster is dominated by a complex containing the three ACO clusters A3556, A3558 and A3562 and the poor cluster SC1329-314, which form a structure elongated ∼ 3° along the East-West direction. We are carrying on a long term study of the Shapley Concentration in order to describe its dynamical state and to determine its mass. The project consists of redshift determinations (with the ESO telescopes at La Silla) for galaxies both in the clusters (Bardelli et al. 1994) and in the inter-cluster field of this supercluster, X-ray observations (ROSAT) of the hot gas in the clusters (Bardelli et al. 1996) and radio observations (ATCA, MOST and VLA, Venturi et al. 1996) of the radiogalaxies.
Gspc-II: A Catalog of Photometric Calibrators for the Second Generation Guide Star Catalog
Authors: Postman M. , Bucciarelli B. , Sturch C. , Borgman T. , Casalegno R. , Doggett J. , Costa E.
Published: July 2016

The Guide Star photometric Catalog (GSPC-I; Lasker et al. 1988) is an all-sky set of photoelectrically determined BV sequences created to provide photometric calibrators for the Guide Star Catalog (Paper-I: Lasker et al. 1990, Paper-II: Russell et al. 1990, Paper-III: Jenkner et al. 1990). Although the GSPC-I has been the basis of preliminary photometric calibrations for the Digitized Sky Survey (DSS; Doggett et al. 1995), its relatively bright cutoff at about 15th magnitude limits its capability to support calibration of sky surveys, e.g., the new GSC-II (McLean et al. 1996, this volume, p. 431).
Techniques for Schmidt Plate Reductions with Application to GSC1.2
Authors: Morrison J. E. , Röser S.
Published: July 2016

Over the last few years there has been considerable progress in developing successful algorithms for obtaining astrometric quality positions from Schmidt plates which compensate for deficiencies of the polynomial approach; the sub-plate method (Taff 1989), the mask method (Taff et al. 1990), the collocation method (Bucciarelli et al. 1993) the filter method (Röser et al. 1995) and a filter weighting according to the method of infinitely overlapping circles (Morrison et al. 1996b.) However, none of these nor any other studies have investigated the magnitude dependence of the position estimates outside the magnitude range of standard reference catalogs. Often Schmidt plates cover the magnitude range from 6m to 19m (for the GSC it is 6m to 15m). Presently available reference catalogs, however, have a limiting magnitude of V ≈ 10m. Therefore, no magnitude dependent term for fainter stars can be reliably found by reducing the measurements based only on comparisons with reference stars.
Overview of the Tycho Catalogue
Authors: Høg E. , Fabricius C. , Makarov V.V. , Egret D. , Halbwachs J.L. , Bässgen G. , Großmann V. , Wagner K. , Wicenec A. , Bastian U. , Schwekendiek P.
Published: July 2016

The final Tycho Catalogue (ESA 1997b) has been derived from 37 months of observations with the star mapper of the astrometric satellite Hipparcos. The Hipparcos Catalogue (ESA 1997a) with about 120,000 stars is the result of the main Hipparcos mission and has, e.g., been described by Kovalevsky et al. (1995). Both catalogues will be published in 1997.
The Second Guide Star Catalogue
Authors: McLean B. , Hawkins G. , Spagna A. , Lattanzi M. , Lasker B. , Jenkner H. , White R.
Published: July 2016

Although the HST GSC–I (Paper-I: Lasker et al. 1990, Paper-II: Russell et al. 1990, Paper-III: Jenkner et al. 1990) has been used with great success operationally, it was always known that it was possible to improve the scientific and operational usefulness by an increase in scope to include multi-color and multi-epoch data. Once the GSC-II concept was established, it was evident that, even beyond the original motivations in HST operations, it would address a number of other astronomical needs such as increasing demands for fainter catalogues to support remote or queue scheduling capabilities and adaptive optics on the next generation of large-aperture, new-technology telescopes. In addition, the all sky nature of the GSC–II makes it a natural data source for research in galactic structure.
Cross Wavelength Comparison of Images and Catalogs
Authors: Bartlett J.G. , Egret D.
Published: July 2016

We would like to start this discussion by attempting to make a useful, working distinction between catalogs and databases of astronomical objects. It seems to us that such a distinction could be made based upon the mode of access to the information: A catalog may be considered as a list of objects, almost invariably ordered by coordinates; a database, on the other hand, may be distinguished by its ability to extract a set of objects based on user-given criteria, such as all objects within a certain sky region with magnitudes brighter than m in the blue. Catalogs form the basis of the database, which adds the means of multi-criteria access to the information. In concrete terms, one usually thinks of SIMBAD, NED and LEDA as databases, while an ftp site containing electronic lists of objects may be thought of as a catalog storage warehouse.
Spectroscopy of new faint Planetary Nebulae
Authors: Kerber F. , Gröbner H. , Weinberger R. , Roth M.
Published: July 2016

Our department has a long–standing tradition of discovery of planetary nebulae (PN), see e.g. Tamura & Weinberger (A&A 298, 204 (1995)) and Kerber et al. (A&AS in press (1996)) for the latest contributions.
The IAC morphological catalog of Northern Galactic Planetary Nebulae
Authors: Manchado A. , Guerrero M. A. , Stanghellini L. , Serra-Ricart M.
Published: July 2016

Planetary Nebulae (PNs) are highly representative of the late stages of intermediate mass stellar evolution. However, there are still many unresolved questions in their evolutionary scheme. Mass loss processes during the Asymptotic Giant Branch (AGB) are not fully understood. Binarity, rotation and magnetic fields may play an important role in PNs formation. The morphological study of PNs will help us to address those questions, and therefore a meaningful homogeneous database is needed.
Expansion distances of Planetary Nebulae
Authors: Terzian Yervant
Published: July 2016

The distances of planetary nebulae are discussed as derived from their angular expansions and radial expansion velocities. An assessment is given of distances derived by this method both at optical and radio wavelengths. The recent VLA radio data show promise in establishing a more accurate distance scale for planetary nebulae.
Correlation between N/O nebular ratio and central star mass: distances to Galactic PN
Authors: Cazetta J. O. , Maciel W. J.
Published: July 2016

In the planetary nebulae (PNe) studies, their distance determination remains a confusing issue. The statistical distance scales cannot be regarded as reliable, and there are few PNe with individual distance determinations. In this work, we present a distance scale based on the method of individual distance determination by Méndez et al. (1988, A&A 190, 113).
O++ relative abundance in IC 418 from permitted lines
Authors: Echevarría J. , Costero R.
Published: July 2016

Two multisite campaigns devoted to HD 35914, the variable central star of IC 418, have been performed (Handler et al., 1996). In the second one, many spectra of the star were obtained during five nights on November 1994. The Echelle REOSC spectrograph and a 1024 × 1024 Tektronix CCD detector, attached to the 2.1m telescope at the Observatorio Astronómico Nacional in San Pedro Mártir, México, was used then. The north-south diameter of the nebula was included in the 20 spectra taken the night of November 18 (184–minute total exposure). The spectral coverage and reciprocal resolution was 4300 å to 7350 å and about 0.16å/pix, respectively. The projected slit size was 1″ × 26″, approximately.
Variable central stars of young Planetary Nebulae
Authors: Handler G.
Published: July 2016

Three different kinds of variable stars can be found among central stars of Planetary Nebulae. Close binary central stars change their light level because of eclipses and due to the reflection effect; some hot variables have been identified as multiperiodic pulsators (e.g. see Ciardullo & Bond 1996).
NLTE analysis of Keck HIRES spectra of K648: Central star of the Planetary Nebula Ps1 in M15
Authors: McCarthy James K. , Méndez Roberto H. , Becker Sylvia , Butler Keith , Kudritzki Rolf-Peter
Published: July 2016

Küstner (1921) catalogued K648 in his photographic survey of M15, but it was not recognized as a PN central star until Pease (1928) discovered the nebula, denoted Ps1. As one of very few PN known in globular clusters — it was the only known until Gillet et al. (1989) reported the discovery of a second in M22 and Jacoby et al. (this meeting) announced two new but very faint objects — K648 offers one of the better opportunities to study the post-AGB evolution of extreme Pop. II stars. Previous investigations of the nebula and star (Adams et al. 1984; Peña, Torres-Peimbert, & Ruiz 1992; Heber, Dreizler, & Werner 1993) all concluded that the stellar temperature is slightly less than 40000 K. Heber et al. also concluded the photospheric He and C abundances were 3 × and 5 × higher than solar.
IR Fabry-Perot imaging of NGC 3132
Authors: Allen L. E. , Ashley M.C.B. , Ryder S. D. , Storey J.W.V. , Sun Y-S. , Burton M. G.
Published: July 2016

Near-infrared (1-3μm) emission lines of molecular and ionized hydrogen are excellent tools for investigating the morphology, energetics and kinematics of planetary nebulae, especially those PNe which contain large amounts of dust and are thus obscured at shorter wavelengths. The southern planetary nebula NGC 3132 was imaged with UNSWIRF (University of New South Wales Infrared Fabry-Perot) and IRIS on the 3.9m AAT Images in the H2 v=1-0 S(1) and H2 v=2-1 S(1) lines at 2.12μm and 2.25μm, and in Hii Brγ at 2.16μm are presented.