bluuebunny/crossref_metadata_2025 huggingface dataset:
The Interstellar Medium in the Magellanic Bridge
Authors: Lehner N. , Keenan F. P. , Smoker J. V. , Dufton P. L. , Rolleston W.R.J. , Mckenna F.C. , Sembach K. R. , Tohline J. E. , White G. , Stanimirović S.
Published: July 2016

HST ultra-violet and ground-based optical spectroscopy are presented for DI 1388, an early-type star in the Magellanic Bridge. These data have been supplemented with H I radio mapping of its environment. The spectroscopy shows interstellar components at LSR velocities of 0, 90 and 200 km s−1 – corresponding to the local ISM, a high velocity cloud and the Magellanic Bridge ISM, respectively. The last is the first absorption line detection of this material and shows the presence of both low (e.g., N I) and high (Si IV) ionization material. Further optical and HST UV observations of DI 1338 and another Bridge star, DGIK 975, are scheduled to investigate the chemical homogeneity and star formation history of the Bridge.
New Particle Simulation of the Magellanic Clouds
Authors: Li P. S. , Thronson H. A.
Published: July 2016

We use a modified TreeSPH code to simulate the MilkyWay-LMC-SMC system using the latest observational results from Hipparcos on the proper motion of the Clouds. More than 120,000 particles are used for the simulation. Gravitational and hydrodynamic interactions among gaseous and stellar components in the system have been considered. The Magellanic Stream, some high velocity clouds, and the barred structure of LMC are reproduced. A leading gas arm from the SMC is predicted. From the simulation, the long term binary status of LMC-SMC is questioned as frequent encounters between the LMC and the SMC will have difficulty in explaining the survival of the SMC.
The Metallicity and Dust Content of HVC287+22+240: Evidence for a Magellanic Clouds Origin
Authors: Wakker Bart , Savage Blair D. , Lu Limin , Sargent Wallace L.W. , Sembach Kenneth R. , Oosterloo Tom A.
Published: July 2016

We present evidence that the properties of the high-velocity cloud catalogued as #187 by Wakker & van Woerden (1991) (HVC287+22+240) can be explained if it is part of a leading arm counterpart of the Magellanic Stream, and we use this to argue that the HVC originated in the Magellanic Clouds after a tidal interaction.
Recent Results on Cepheids in the Magellanic Clouds from the EROS Survey
Authors: Marquette J.B.
Published: July 2016

Between October 1996 and February 1997 a specific campaign of the EROS experiment was devoted to Cepheids in central regions of the LMC and the SMC. The Period–Luminosity (PL) relations were determined in the EROS photometric system, and a significant slope change of the period–luminosity relation has been observed for the SMC fundamental mode Cepheids with periods shorter than 2 days.
The effect of step-size on the numerical integration of satellite orbits
Authors: Hadjifotinou K.G. , Harper D.
Published: July 2016

This work is a continuation of our study of the efficiency of two well-known methods for the numerical integration of the equations of motion of planetary satellites together with the variational equations of the system. The methods are the 10th-order Gauss-Jackson backward-difference method described in [4, 6] and the Runge-Kutta-Nyström RKN12(10)17M [1].
Model of the comet outbursts based on a fragmentation of ice grains in its atmosphere
Authors: Andrienko D.A. , Mischishina I.I.
Published: July 2016

Outbursts of the comet's brightness play a significant role in the study of the physical nature and evolution of comets. The causes of cometary outbursts are still not properly understood. It is known, however, that there is correlation between the outbursts and the high-velocity flux of solar wind. The evidences of such causal relationship are the following: the existence of the correlation between the geomagnetic perturbations and the outburst activity of the comets [1]; two-peaks distribution of the comet's outbursts, which depends on the 11-year solar cycle phase with maxima at phases 0.2–0.3 and 0.7–0.8, in coincidence with the distribution of physical characteristics of high-velocity fluxes [2]; the repeated character of the outbursts with main intervals of 7–8, 14–15, 22–24 and 30 days, this corresponds to the four-sector structure of the interplanetary magnetic field [3].
New series of rigid and non rigid Earth nutation. Comparison with observations
Authors: Souchay J.
Published: July 2016

After analysing the recent developments of the theory of the nutation for a simplified rigid Earth model (Kinoshita and Souchay, 1990) with new corrections and new contributions (Williams, 1994; Souchay and Kinoshita, 1996), we will study the effect of these developments on the calculation of the coefficients of nutation for a non rigid Earth model, based on the transfer function given by Wahr (1979). The relative improvements characterized by the residuals with the observations are explained in the following.
On the measure of the structure around an invariant KAM torus
Authors: Froeschlé C. , Giorgilli A. , Lega E. , Morbidelli A.
Published: July 2016

In a recent paper, Morbidelli and Giorgilli (1995) proved the superexponential stability of invariant tori. As usual in the theory of dynamical systems, the results are rigorously proved assuming that the perturbation is small enough. The numerical experiments show, however, that invariant tori persist up to much larger perturbation magnitudes. Therefore, it is interesting to check numerically if the superexponential stability and the other properties outlined in Morbidelli and Giorgilli's theorem persist up to the value of the perturbation for which the torus actually breaks up. Moreover, one would like to have a numerical indication about the size of the super-exponentially stable region existing around a torus. Is the superexponential stability just an asymptotic result, or does it concern a macroscopic region of physical interest?
Relativistic rotational effects: application to the Earth-Moon system
Authors: Vokrouhlický David
Published: July 2016

Relativistic spin effects involved in the Earth-Moon dynamics are reviewed. They enclose: (i) the coordinate system effects, and (ii) the relativistic physical librations. The geodetic precession is the only relativistic spin phenomenon which has been firmly detected so far. The best candidates of the effects which might be detected in the forthcoming period are the lunar physical librations and coordinate nutations. As for the latter, however, a fine cancellation between the geodetic and the Lense-Thirring coordinate effects results in decreasing their amplitude just below the possibility of the Lunar Laser Ranging technology.
Evolution of Ephemerides Representation and Diffusion
Authors: Seidelmann P.K.
Published: July 2016

There has been, and continues to be, a close interaction between celestial mechanics used for the generation of ephemerides, mathematical techniques, and computer technology. As the computer capabilities of the ephemerides offices and the users of ephemerides have improved, the methods of determining and the accuracies of ephemerides have changed and the medium and representation of the ephemerides provided to the user have evolved.

Ephemerides have been provided in the form of theories, tables, tabulations, polynomials, graphics, and subroutines by means of the printed page, punched cards, magnetic tape, floppy disks, CD/ROMs, and electronic mail. As mathematical techniques and computer technology continue to develop and the requirements for ephemerides evolve, the methods of representing and diffusing ephemerides will continue to improve.
Experience of numerical integration and approximation with applying Chebyshev polynomials for constructing ephemerides of the solar system natural and artificial bodies
Authors: Trubitsina A.A.
Published: July 2016

Successful experience of applying the Chebyshev polynomials as a power “mathematical tool” for numerical integration and approximation techniques in celestial mechanics is presented. Detailed analysis of approximation function behavior inside an integration step allows to elaborate a special technique for high accuracy and rapid integration of piece-wise continuous functions, modeling the Earth's shadow effect for artificial satellite orbits. Original software is elaborated for creating the ephemeris file simultaneously with the process of numerical integration. This technique is applied for the construction of ephemerides of natural and artificial celestial bodies as well as for the compact polynomial representation of different geodynamic parameters.
Long-focus CCD astrometry of planetary satellites
Authors: Pascu D.
Published: July 2016

CCD detectors are rapidly replacing the photographic plate and photomultiplier in satellite observations used for orbital improvement. This includes both phenomena timings as well as tangent plane astrometry. In most cases this change has been for the better, but in some areas there has been no gain – even a loss. We will review this change in terms of the recent history of satellite observations. The impact of the CCD will be discussed in terms of its applications, and the increase in precision it affords. Finally, a few things will be said about future directions, especially about spin-off applications.
Observation of solar system bodies on board the future russian astrometric satellite
Authors: Yershov V.N.
Published: July 2016

A future Russian astrometric satellite (Struve) is aimed at an extension of the fundamental coordinate system down to 18-th magnitude stars. The positional accuracy of observations is planned to be about 0.6 mas. Many of the Solar System objects will be observed by the Struve satellite. Problems of registration and reduction of these observations are discussed.
Astrometric observations of faint satellites
Authors: Martins R. Vieira , Veiga C. H. , Assafin M.
Published: July 2016

We present a method to obtain the reference system for isolated observations of faint satellites made with CCD1. The method consists in the construction of a secondary catalogue of faint stars using ‘The Digitized Sky Survey’ and ‘The Guide Star Catalogue’ corrected by modern astrometric catalogues.
The PHESAT95 campaign of observations of the phenomena of the saturnian satellites
Authors: Arlot J.-E. , Thuillot W. , Colas F. , Descamps P. , Berthier J. , Morando B. , Veiga C.H. , Vu D.T. , Ruatti Ch. , Lecacheux J. , Laques P.
Published: July 2016

This paper reports on the international PHESAT95 campaign of observations of the Saturnian events coordinated by Bureau des longitudes. Thanks to CCD or photometric receptors, accurate astrometric data can be get from the observation of the eclipses by Saturn and mutual events of the Saturnian satellites. These events occur from 1994 to 1996 and we give our first results.
The “black drop” phenomenon and reduction of the mercury transits observations
Authors: Sveshnikov A.M. , Sveshnikov M.L.
Published: July 2016

Mercury transits are important for the investigation of long-term variations in the Earth rotation. They have been observed for more than 300 years. The basic array of this set is the visual observation of contacts (as a rule the second and third ones). The detection of the instant corresponding to the geometrical contact of the solar and Mercury limbs is a difficult task, since during 10s to 60s, the set of phases is observed transforming continuously from one to another. One of the encumbering factors, is the so-called “black drop” phenomenon, i.e., the dark cross-bar formed between the limbs (Struve, 1882; Kuhl, 1929; Wittman, 1974; Morrison et al., 1975). The influence of this factor could be negleted if the observations were distributed uniformly with regard to contacts, observers and observational conditions. In fact, it is far from that and the necessity of reduction corrections arises.
Reference Frames
Authors: Kovalevsky Jean , Feissel Martine
Published: July 2016

After a short introduction on the definition and the construction of a reference frame, the presentation concentrates on the actual construction of the new IAU conventional reference frame. The 1991 IAU resolutions on reference systems is reviewed and the present state of the implementation of these resolutions is discussed. The IERS extragalactic reference frame is described and we show that it fulfills the IAU requirements. The Hipparcos catalogue will be linked to this frame before the end of this year. The state of advancement of this job is presented.
IAU standards – its future
Authors: Fukushima Toshio
Published: July 2016

The ongoing movement of standardization in Fundamental Astronomy was reviewed. Its history was briefly presented with an emphasis on the problems which triggered its creation. The achievements of the first term of the IAU WG on Astronomical Standards were given. The major goals of a second term were presented with the author's view to resolve them.
The FK5 equinox and equator from combined radar and optical data of the near-earth asteroids
Authors: Shuygina N.V. , Yagudina E.I.
Published: July 2016

Minor planets optical observations have long been used for the purpose of establishing a Celestial reference frame. Being in existence since the early 1960s modern high-accuracy radar measurements of the so-called near-Earth asteroids (NEAs) have been widely extended to the orbit determination process and predicting of the next apparition of the asteroid. Even few radar measurements, when added to optical ones, significantly improve asteroid's ephemeris and reduce standard deviations of the orbital elements (Yeomans et al., 1987). The idea to connect optical and radar data in the problem of the catalogue zero-point determination has been stated by several scientists (Boiko, 1975). And even the first attempt of the authors (Krivova et al., 1994) with actual optical and radar observations of two NEAs: (4179) Toutatis and (1862) Apollo appears to have considerable promise. It was demonstrated the possibility of obtaining standard deviations of catalogue orientation parameters 1.5–2 times better with radar data included.
Effects of precession uncertainties on planetary ephemerides
Authors: Walter H.G.
Published: July 2016

Several methods of data analysis applied recently to precise astrometric observations give evidence for a correction of the luni-solar precession (ψ) of the order of Δψ = −3 milliarcseconds per year (Williams et al., 1994). When studying the motion of bodies of the planetary system from photographic observations, an inertial stellar reference frame is required. Thus, any imperfection of the luni-solar precession would have repercussions on the determination of the orbit dynamics of the celestial body under investigation.
Photographic Sky Surveys
Authors: Reid I.N.
Published: July 2016

Photographic surveys have played a vital role in virtually every area of astronomical research over the last 50 years. Indeed, one can make a strong case that Schmidt telescopes in general, and the Palomar 48-inch Schmidt in particular, have made the most substantial contribution to our understanding of the Universe—at least at optical wavelengths. The all-sky atlases compiled since the initiation of the POSS I O/E survey in 1949 will continue to provide fundamental reference catalogues and potent research tools for many years to come (for our children's children's children), particularly when combined with the second epoch surveys currently under way. However, as far as undertaking new, large-scale sky surveys are concerned, it is clear that we have reached the end of an era. Alternative detector technology and new instrumentation (i.e., CCD mosaics) can now match and, indeed, exceed the capabilities of the photographic Schmidt telescopes in undertaking effective wide-field photometric surveys.

In this review, I report on the progress being made in completing the all-hemisphere photographic surveys currently being undertaken from Siding Spring with the UK Schmidt and from Palomar with the Oschin Schmidt. I also provide a summary of the availability of machine scans and/or object catalogues derived from the various surveys. Photographic survey work is not confined to these atlases, however, and section 3 provides discussion of other more specialised projects currently being undertaken. Finally, I consider the future possibilities for photographic Schmidt surveys.
Prospects for Future Astrometric Missions
Authors: Seidelmann P.K.
Published: July 2016

Hipparcos and the Hubble Space Telescope have demonstrated the astrometric capabilities in space. SIM and GAIA are being studied for future missions. There have been many proposals for new astrometry missions from many different countries, but most of them have not been funded.

The best possibility for a mission within the next five years would be through a collaborative effort for a small, fast, cheap spacecraft which could be a precursor for future, larger, more accurate missions, which are under study.
The Ratan Galactic Plane Survey
Authors: Trushkin S.A.
Published: July 2016

Now in radio continuum surveys more than 10,000 radio sources have discovered in the Milky Way plane but the Galactic origin only of a small part of them has been determined. The problem comes from the absence of estimates of source distance and the optical identification even for bright radio sources, and the most of sources have not spectral data at 2-3 frequencies. As followed some hundreds of sources have not classified as thermal or non-thermal. Now we don't know the full number of supernova remnants (SNRs) in the Galaxy. The simple estimates show that a sample of Galactic SNRs is not full as for weak and extended (> 15′) as for bright and compact (< 3′) SNRs (Trushkin 1993).
Denis: A Deep Near Infrared Southern Sky Survey
Authors: Epchtein N.
Published: July 2016

The aim of DENIS is to map the southern sky in three near-infrared photometric bands (I, J, Ks) at the 1mJy sensitivity level (14th magnitude in Ks) and arcsecond resolution using the ESO 1 meter telescope at La Silla, Chile. The DENIS operations have started in December 1995 after a protosurvey period of one year mainly dedicated to technical tests and pilot surveys of selected regions of high astronomical interest. In September 1996, approximately 3000 square degrees of the sky have been covered, and the survey should be completed in 1999.
The European Large Area ISO Survey: Elais
Authors: Oliver S. , Rowan-Robinson M. , Cesarsky C. , Danese L. , Franceschini A. , Genzel R. , Lawrence A. , Lemke D. , McMahon R. , Miley G. , Puget J.-L. , Rocca-Volmerange B.
Published: July 2016

I describe a project to survey ∼ 13 square degrees of the sky at 15μm and 90μm with the Infrared Space Observatory (ISO). The European Large Area ISO Survey (ELAIS) is a collaboration involving 19 European institutes (in addition to the authors and others at their institutes the following people and others their institutes are involved I. Gonzalez-Serrano, E. Kontizas, K. Mandolesi, J. Masegosa, K. Mattila, H. Norgaard-Nielsen, I. Perez-Fournon, M. Ward) and is the largest open time project being undertaken by ISO. We expect to detect at least 1000 extra-galactic objects and a similar number of Galactic sources.
The Wide-Field Infrared Explorer (Wire) Mission
Authors: Shupe D.L. , Hacking P.B. , Herter T. , Gautier T.N. , Graf P. , Lonsdale C.J. , Stacey G.J. , Moseley S.H. , Soifer B.T. , Werner M.W. , Houck J.R.
Published: July 2016

The Wide-Field Infrared Explorer (WIRE) (Schember et al. 1996 and references within) is a small spaceborne telescope specifically designed to study the evolution of starburst galaxies. This powerful astronomical instrument will be capable of detecting typical starburst galaxies at z ∼ 0.5, ultraluminous infrared galaxies beyond a z ∼ 2, and luminous protogalaxies beyond z ∼ 5. The WIRE survey, to be conducted during a four month period in 1998, will cover over 100 deg2 of high Galactic latitude sky at 25 μm and 12 μm.
Some Results of the BATC CCD Color Survey
Authors: Chen J.-S.
Published: July 2016

The BATC (Beijing-Arizona-Taiwan-Connecticut) CCD color survey started 2 years ago. It is based on observations with the 60/90cm f/3 Schmidt Telescope of the Beijing Astronomical Observatory using a 2k×2k CCD and 15 intermediate band filters covering from 300nm to 1000nm to obtain the spectral energy distribution (SED) of all objects in 500 selected fields down to mV = 20 (Chen 1994). The basic framework of the survey including instrumentation, data acquisition system, archive data system, and the various steps of data reduction has been established. About 60 fields have been observed. Most fields are still short of observations in UV band. We are waiting for a new thinned CCD to improve the quantum efficiency.
The Aist-Struve Space Project Sky Survey
Authors: Chubey M.S. , Kopylov I.M. , Gorshanov D.L. , Kanayev I.I. , Yershov V.N. , Il'In A.E. , Kirian T.R. , Vydrevich M.G.
Published: July 2016

The Struve space astrometric project (Yershov et al. 1995) is being developed by a consortium of Russian space instrumentation institutes in order to extend the Hipparcos satellite reference system (the project initially named AIST, owes its current name to the first director of the Pulkovo Observatory).
Simultaneous Spectra of a Complete Sample of Sources from the PMN Survey
Authors: Mingaliev M.G. , Botashev A.M. , Stolyarov V.A.
Published: July 2016

The broad spectral coverage of radio sources including high frequency data are desirable for a number of reasons. Over the last decade, researchers have identified a new class of very high-redshift objects that are more closely related to normal galaxies than to quasars. Surveys with radio telescopes have been instrumental in finding these extremely distant galaxies, which are barely visible at optical wavelengths. The selection of candidates with steep radio spectra has proven a particularly effective means for finding galaxies with redshifts greater than z = 2. Secondly, they uncover flat spectrum sources which are likely to be compact and useful as radio astrometric standards and as well as candidates for further interferometric observations. Third, they provide information about physics and, in particular, about the high-energy particles responsible for radio emission. And last but not least, simultaneous observations at several wavelengths will exclude variability of sources in interpretation of their spectra. Here we present the preliminary results of an ongoing investigation of a complete sample of radio sources from the PMN Survey.
A Denis Survey of Star Forming Regions
Authors: Copet E.
Published: July 2016

A complete census of embedded stellar population can be made by exploring in the infrared large areas of the sky in which giant molecular clouds extend. Very recently, thanks to the of large format IR array detectors, studies of young stellar population in GMCs, have been undertaken by different authors (i.e., Lada et al. 1991) but all these observations were limited to relatively small regions of the whole GMCs, the DENIS project (Epchtein, this volume, p. 106) surveys the south hemisphere at I, J and Ks bands, including most of these clouds.
An Hα Survey of the Galactic Plane
Authors: Parker Q.A. , Phillipps S.
Published: July 2016

We describe a major new Anglo-Australian proposal for a U.K. Schmidt Telescope (UKST) Hα survey of the Southern Galactic plane, Magellanic clouds and selected regions. The agreed survey will use a new 12 × 12 inch monolithic Hα interference filter of very high specification in combination with Tech Pan film. Tech Pan offers significant advantages for this work due to an inherent sensitivity at Hα and its extremely fine grain, high resolution, exceptional DQE, excellent imaging and low noise (e.g., Parker et al. 1994). The combination of Tech Pan and a narrow band Hα filter will provide a survey of unprecendented area coverage, depth and resolution, superior to any previous optical survey of ionized gas in the galaxy. It should to lead to exciting new discoveries and avenues of research.
Kinematics and the Galactic Potential
Authors: Bienaymé O.
Published: July 2016

The analysis of stellar kinematics and the Galactic potential is linked to the study of the spatial distribution of stars in the Galaxy since they are related through the Boltzmann and Poisson equations. Measuring all the visible density and mass distribution from general star counts and the gas cloud density gives only a small fraction of the total amount of the dynamical mass that is deduced from the kinematics of the galactic constituents. As in many spiral galaxies, most of the Galactic mass is unseen and unknown.
Proper Motions in the Bulge: Looking Through Plaut's Low Extinction Window
Authors: Méndez R.A. , Rich R.M. , Van Altena W.F. , Girard T.M. , Van Den Bergh S. , Majewski S.R.
Published: July 2016

We are conducting the deepest and largest photographic proper-motion survey ever undertaken of the Galactic bulge. Our first-epoch plate material (from 1972-3) goes deep enough (Vlim ∼ 22) to reach below the bulge main-sequence turnoff. These plates cover an area of approximately 25′ × 25′ of the bulge in the low-extinction (Av ∼ 0.8 mag) Plaut field at l= 0°, b= −8°, approximately 1 kpc south of the nucleus. This is the point at which the transition between bulge and halo populations likely occurs and is, therefore, an excellent location to study the interface between the dense metal-rich bulge and the metal-poor halo.
Muti-Color Imaging of Clusters of Galaxies with Mosaic CCD Cameras
Authors: Okamura S. , Doi M. , Kashikawa N. , Kawasaki W. , Komiyama Y. , Sekiguchi M. , Shimasaku K. , Yagi M. , Yasuda N.
Published: July 2016

At present, the photometric data for clusters at z ≲ 0.2 mainly come from photographic photometry. The lack of CCD data for such clusters is simply due to the fact that no CCD camera had been available until recently that covers the wide extension of clusters within a reasonable amount of observing time. We have developed a large mosaic CCD camera and conducted multicolor imaging observations of z ≲ 0.2 clusters using the 40-inch Swope telescope at Las Campanas Observatory.
The Calar Alto Deep Imaging Survey
Authors: Hippelein H. , Beckwith S. , Fockenbrock R. , Fried J. , Hopp U. , Leinert C. , Meisenheimer K. , Röser H.-J. , Thommes E. , Wolf C.
Published: July 2016

The Calar Alto Deep Imaging Survey (CADIS) combines deep multicolor imaging in broad and narrow band filters with deep probing in several selected wavelength intervals through a Fabry-Pérot (FP) interferometer with a spectral resolution of ∼450.
Large Scale Structure in the LYα Forest
Authors: Williger G. , Smette A. , Hazard C. , Baldwin J. , McMahon R.
Published: July 2016

We have conducted a survey of the Lyα forest in the redshift domain 2.15 < z < 3.37 in front of nine QSOs within a 1o field to probe spatial structure along planes perpendicular to the line-of-sight. We find evidence for correlations of the Lyα absorption line wavelengths in the whole redshift range, and, at z > 2.8, of their equivalent widths. Such a correlation is consistent with the emerging picture that Lyα lines arise in filaments or large, flattened structures.
A Rich Cluster Redshift Survey for Large-Scale Structure Studies
Authors: Batuski D. , Slinglend K. , Hill J. M. , Haase S. , Miller C. , Michaud K.
Published: July 2016

We have used the MX multifiber spectrometer on the Steward 2.3m measuring redshifts of up to 25 galaxies in each of about 90 Abell cluster fields with richness class R ≥ 1 and mag10 ≤ 16.8 (estimated z ≤ 0.12) and no more than one previously-measured redshift. This work has resulted in a deeper, more complete sample for two-point correlation and other studies of large-scale structure. To date, we have collected such data for 110 clusters (a few not in our sample). For most, we have seven or more cluster members with redshifts, enough to add significantly to the available sample of cluster velocity dispersions for other studies of cluster properties.
Input Catalogue for the 2DF QSO Redshift Survey
Authors: Smith R.J. , Boyle B.J. , Shanks T. , Croom S.M. , Miller L. , Read M.
Published: July 2016

Observations that radio-quiet QSOs exist in average galaxy cluster environments (Smith et al. 1995 and references therein) demonstrate that QSOs can be used to derive important information on the structure of the Universe at the largest scales. Previous studies of QSO clustering have been frustrated by the lack of large QSO redshift surveys. Although QSO clustering is detected in the largest existing QSO catalogues (see Shanks & Boyle 1994), it is difficult to place strong limits on the cosmological evolution of QSO clustering or the level of clustering at large scales (> 10h–1 Mpc) with current QSO catalogues.
Redshift Survey of 951 IRAS Galaxies in the Southern Milky Way
Authors: Visvanathan N. , Yamada T.
Published: July 2016

In this paper we present the results of a redshift survey of IRAS galaxies behind the whole southern Milky Way region 210° < l < 360° at |b| < 15°. The galaxy candidates in the southern Milky Way were selected from IRAS Point Source Catalogue (IPSC) by applying flux density and infrared colour criteria (Strauss et al. 1990; Rowan-Robinson et al. 1991). The selected sample is flux limited with f60 > 0.6Jy. A visual search for galaxy-like objects have been carried out in UK-Schmidt Infrared and IIIaJ films in the selected IRAS positions. In spite of the large Galactic extinction in this region, 966 galaxy candidates have been identified (Yamada et al. 1993).
A Deep 20 CM Radio Mosaic of the ESP Galaxy Redshift Survey
Authors: Prandoni I. , Gregorini L. , Parma P. , Vettolani G. , de Ruiter H.R. , Wieringa M.H. , Ekers R.D.
Published: July 2016

In two strips of 22° × 1° and 5° × 1° near the SGP Vettolani et al. have made a deep redshift survey as an ESO Key Project (the ESO Slice Project galaxy redshift survey). All the galaxies down to bJ ∼ 19.4 were observed with the OPTOPUS multi-fibre spectrograph on the 3.6 m telescope in La Silla, yielding 3348 redshifts.
Radio Emission from High Redshift Galaxies: VLA Observations of the Hubble Deep Field
Authors: Richards E.A.
Published: July 2016

To study galaxy populations and their evolution at the highest possible redshifts, a small area of the sky, the Hubble Deep Field (HDF) was imaged to an unprecedented sensitivity of R = 29.5 (Williams et al. 1996). As a complement to the HST observations, we have used the VLA at 8 GHz to image an area 5.′4 in diameter (FWHM) centered on the HDF to an rms sensitivity of 2 μJy. With a radio resolution of about 3″, we have 33 sources above 9.5 μJy, seven in the 4 arcmin2 HDF field of which six have clear optical IDs. There are an additional 12 IDs in the HST flanking fields. The optical counterparts of the radio sources are a mixture of ellipticals, spirals, and irregulars, consistent with earlier surveys of comparable depth (Windhorst et al. 1995). With a median redshift  ∼ 1, the radio galaxies we are sampling are somewhat more distant than the classical starbursting galaxies which dominate less sensitive radio surveys. Our HDF identifications are predominately with post-starburst galaxies, moderate power AGN, and blue irregulars (Fomalont et al. 1996).
Cataloging of the Digitized Poss-II: Initial Scientific Results
Authors: Djorgovski S.G. , de Carvalho R.R. , Gal R.R. , Pahre M.A. , Scaramella R. , Longo G.
Published: July 2016

The Second Palomar Sky Survey (POSS-II) is now nearing completion. It will cover the entire northern sky with 894 fields (6.5° square) at 5° spacings, with no gaps in the coverage. Plates are taken in three bands: IIIa-J + GG395, λeff ∼ 480 nm; IIIa-F + RG610, λeff ∼ 650 nm; and IV-N + RG9, λeff ∼ 850 nm. Typical limiting magnitudes reached are BJ ∼ 22.5, RF ∼ 20.8, and IN ∼ 19.5, i.e., ∼ 1m −1.5m deeper than the POSS-I. The image quality is improved relative to the POSS-I, and is comparable to the southern photographic sky surveys. For more details, see Reid et al. (1987), and Reid & Djorgovski (1993).
The Hamburg Identification Program of Rosat All-Sky Survey Sources
Authors: Bade N. , Cordis L. , Engels D. , Reimers D. , Voges W.
Published: July 2016

The ROSAT All Sky Survey (RASS), performed between July 1990 and February 1991, provided about 60,000 X-ray sources in a soft X-ray band (0.1–2.4keV) with a flux limit of approximately 5 × 10–13 ergs cm–2 s–1 for exposure times of 400 sec (a typical value in low ecliptic latitudes). A wealth of information can be extracted from the RASS source content and many objects deserve (or have already deserved) extensive follow-up studies. However, this possibility is limited by the fact that the nature of most of the RASS sources is unknown i.e., they are unclassified. A correlation with the SIMBAD data base yields only identifications for about one third of the RASS sources.
Exploring Terabyte Archives in Astronomy
Authors: Szalay A.S. , Brunner R.J.
Published: July 2016

Astronomy is about to undergo a major paradigm shift, with data sets becoming larger, and more homogeneous, for the first time designed in the top-down fashion. In a few years it may be much easier to “dial-up” a part of the sky, when we need a rapid observation than wait for several months to access a (sometimes quite small) telescope. With several projects in multiple wavelengths under way, like the SDSS, 2MASS, GSC-2, POSS2, ROSAT, FIRST and DENIS projects, each surveying a large fraction of the sky, the concept of having a “Digital Sky,” with multiple, TB size databases interoperating in a seamless fashion is no longer an outlandish idea. More and more catalogs will be added and linked to the existing ones, query engines will become more sophisticated, and astronomers will have to be just as familiar with mining data as with observing on telescopes.
Skyview: The Multi-Wavelength Sky on the Interne
Authors: McGlynn T. , Scollick K. , White N.
Published: July 2016

The SkyView virtual observatory provides a single, simple interface where users can retrieve images of the sky at all wavelengths from the radio through gamma rays. Below we discuss how SkyView works and how it represents a new paradigm in astronomical data archives. Users get to SkyView over the WorldWideWeb at http://skyview.gsfc.nasa.gov. Within a few moments they can have high-quality images from ground- or satellite-based surveys.
The SDSS Science Archive
Authors: Brunner R. J.
Published: July 2016

Designing and implementing the Science Archive for the Sloan Digital Sky Survey (Gunn et. al 1992) has presented several unique architectural obstacles. First, the final archive will be large; the cumulative data products will exceed tens of Terabytes. Second, the data will be complex; extracted parameter catalogs will contain links to images, spectra, and objects in other wavelength catalogs. Third, the archive will be widely distributed allowing transparent world-wide access to the available data. Finally, the archive is expected to remain viable well into the next century.
Summary Talk : Multi-Wavelength Sky Surveys
Authors: Lahav O.
Published: July 2016

An astronomer's career can be viewed in a 3-dimensional space where the (nearly orthogonal) axes are :

– the objects of interest (from planets to the Universe),

– techniques (from instrument design to analytic calculations),

– the wavelength (from the radio to gamma rays).
Search and preliminary analysis of new Galactic PNe
Authors: Zanin C. , Cappellaro E. , Sabbadin E , Turatto M.
Published: July 2016

In general, the methods for searching new PNe exploit one of their characteristics and typically introduce a bias in the sample extracted. It is therefore important to perform PN searches based on different selection criteria. Some years ago we started a new search for PN candidates on the plates of the Palomar Near Infrared Photographic Survey of the Galactic Plane. The selection criterion is based on the consideration that PNe have I(R) > I(NIR) up to AV ∼ 10, whereas normal field stars have I(R) < I(NIR). First the plates are examined directly using a binocular, with a medium magnification, searching for faint diffuse nebulosity. Hereafter the comparison between R and NIR images is used both to detect new compact PN candidate and to discard, among diffuse objects, reflection nebulae. Spectra and imaging of the new objects were obtained in dedicated program both at the ESO and Asiago Observatories. From a preliminary analysis of the data for the new PNe it appears that the sample contains objects with very different characteristics. They have different morphologies and spectral features, but in general only few of the new PNe have an IRAS counterpart and these show a small flux in the IR. In particular, in the IRAS color-color plot they do not seem confined to the area of the bona-fide PNe; this still preliminary evidence may indicate that our selection criteria is pointing to PNe which remain undiscovered using other methods.
Distances of Galactic PN from the population segregation of the Peimbert types
Authors: Maciel W. J.
Published: July 2016

Recent work on the PN classification scheme initially proposed by Peimbert has shown that objects of types I, II, and III have markedly different properties such as central star mass, height distribution relative to the galactic plane, and kinematic behaviour. This fact can be used in order to determine distances, especially for the younger disk objects.
Family links between Planetary Nebulae nuclei and cataclysmic variables, binary white dwarfs, R CrB stars, and SNe IA
Authors: Yungelson L.R. , Tutukov A.V.
Published: July 2016

We analyse the population of PNe and links between binary PNNi and stars which are in the later evolutionary stages. In a model which assumes that all stars are born in binaries, about 16% of PN result from ejection of common envelopes in close binaries, 85% of single PNNi are formed by merger of components of binaries. In the model, 5% of PNNi may be precataclysmic binaries, 5% may be precursors of symbiotic stars, 0.4% may be pre-SN Ia, 0.1% - precursors of hydrogen-deficient giants. About 0.1% of all PNe may be hydrogen-deficient.
Quantitative spectral analyses of CSPNs of early [WC]-type
Authors: Koesterke L. , Hamann W.-R
Published: July 2016

Among the Central Stars of Planetary Nebulae (CSPN) there are several stars which show Wolf-Rayet-type spectra resembling those of Pop. I Wolf-Rayet (WR) stars of the carbon sequence (WC). Due to progress in computer technology and new solution techniques it became possible ten years ago to calculate models which account for the very complex physical conditions in Wolf-Rayet atmospheres (Hillier 1989, Hamann et al. 1992). These models have been successfully applied to the vast majority of Pop. IWR stars in the Galaxy and the Magellanic Clouds (Hamann et al. 1995) and, in the last three years, to an increasing sample of CSPNs of [WC] type (Koesterke & Hamann 1996, Leuenhagen & Hamann 1996, Leuenhagen this meeting). Here we present the analyses of ten CSPNs of early [WC] type, i.e. from [WC 2] to [WC 4].
Fading and variations in the spectrum of the central star of the young Planetary Nebula SAO 244567 (Hen 1357)
Authors: Parthasarathy M. , Garcia-Lario P. , de Martino D. , Pottasch S. R. , de Cordoba S.F.
Published: July 2016

SAO 244567 (= Hen 1357) is a very young planetary nebula. It was discovered by Parthasarathy et al. (1993, A and A 267, L19). Based on the spectrum obtained around 1950 Henize (1976, ApJ Suppl 30, 491) classified it as a B or A type H-alpha emission line star. The optical spectrum of SAO 244567 obtained in 1971 shows that it was a post-AGB B1 supergiant at that time. It has turned into a planetary nebula within the last 20 years (Parthasarathy et al. 1995, A and A 300, L25).
HST spectrophotometric data of the central star of the Planetary Nebula LMC-N66
Authors: Peña M. , Hamann W.-R. , Koesterke L. , Maza J. , Méndez R.H. , Peimbert M. , Ruiz M.T. , Torres-Peimbert S.
Published: July 2016

N66 (WS 35, SMP 83) is a Type I (He-N rich) PN in the LMC with a high ionization degree. It shows a bipolar morphology with a filamentary structure (Dopita et al. 1993). Its central star has shown very impressive changes, in short time scale, that have been investigated. Here we describe the history of these changes:
NLTE analysis of central stars of highly excited Planetary Nebulae
Authors: Rauch T. , Köppen J. , Napiwotzki R. , Werner K.
Published: July 2016

Very hot central stars (CSPN) of highly excited planetary nebulae (PN) display directly the formation of white dwarfs. Only a few of these CSPN have been analyzed so far due to their low brightness and thus, the interpretation of their evolutionary status is hampered by statistical incompleteness. In the last decade many spectral analyses of very hot post-AGB stars by means of state-of-the-art NLTE model atmospheres have been performed (e.g. Rauch et al. 1996; Werner & Rauch 1994; Rauch & Werner 1995) and our picture of post-AGB evolution has been improved.
Spectroscopy of the central stars of three old Planetary Nebulae
Authors: Saurer W. , Werner K. , Weinberger R.
Published: July 2016

The knowledge of the planetary nebula central star - white dwarf transition region has dramatically increased during the most recent years and dozens of stars now populate this former gap in the HRD. Each addition to the limited sample of central stars that has been studied spectroscopically in detail is, however, of value.
Molecular envelopes of young and proto PNe
Authors: Deguchi S.
Published: July 2016

I review recent results of mm-wave interferometric observations of molecular envelopes of young and proto planetary nebulae. Spatial resolutions of mm-wave interferometers now reach from one to a few arcseconds; together with line observations reveale very small structures in molecular envelopes of planetary nebulae. These small scale structures are probably caused by an instability of the radiation-driven, gas-dust outflow. Implications of these observations and theories are discussed.
On the morphology and internal kinematics of PNe
Authors: Manchado A.
Published: July 2016

The study of the morphology of planetary nebula (PN) is fundamental for addressing several questions in the context of stellar evolution. An AGB star can loose most of its mass due to strong stellar winds. Kwok et al. (1978) proposed that the interaction of a low-density fast wind with a high-density slow wind, will form the PN. This model can account for the round observed PNe with a great degree of symmetry. However as we will see later, round PNe are not the most common ones. Therefore a mechanism for causing asymmetry has to be invoked. Several processes have been proposed by different authors.
Astrophysical applications of the Iron Project: Ionization structure and spectra of iron in nebulae
Authors: Bautista Manuel A. , Pradhan Anil K.
Published: July 2016

We study the physical structure of H II regions, including Planetary Nebulae (PNe), through detailed analysis of the ionization structure and spectra of iron in relevant ionization stages. This results from our work in the Ohio State group on: (i) calculation of new and improved atomic data for Fe I-VI (photoionization cross sections, recombination rates, collision strengths, and transition probabilities); (ii) detailed study of ionization, recombination, and excitation mechanisms and radiative transfer effects under nebular conditions; (iii) study of the physical structure and kinematics of nebulae and their ionization fronts. This includes further examination of high density regions deduced from the spectroscopic analysis of optical [Fe II], [Ni II], and [O I] emission (Bautista etal 1996; and references therein). The study also addresses the issue of chemical abundances in fully ionized and partially ionized zones of nebulae.
A 3D kinematic model of NGC 3242
Authors: Dudziak G. , Walsh J. R. , Walton N.
Published: July 2016

TAURUS-II imaging Fabry-Perot data in the emission lines of Ha, He II, [O I], [O III] and [N II] have been obtained to study the kinematics of NGC 3242. By studying the kinematic structure in lines of a range of ionization, the expansion of the nebula from close to the central star to the low ionization outer regions can be explored.
Effect of ambient wind velocity on Planetary Nebula morphology
Authors: Dwarkadas Vikram V. , Chevalier Roger A. , Blondin John M.
Published: July 2016

Planetary Nebulae (PNe) are formed by the interaction of the fast wind from a post-Asymptotic Giant Branch Star with the slow ambient wind from a previous epoch. If the two interacting winds have constant properties, the velocity of the PN shell tends towards a constant with time and the shape becomes self-similar. Additionally, if the velocity of the fast wind is much higher than the expansion velocity of the shell, the interior of the hot shocked bubble becomes isobaric. Using semi-analytical methods, complemented by hydrodynamic simulations, we have calculated the shapes of PNe in the self-similar stage (Dwarkadas et al. 1996). We have investigated the contribution of the ambient wind velocity to PN morphology, which has hitherto not received much attention since the work of Kahn & West (1985). We find that the nebular morphology is a consequence of the density contrast between pole and equator in the ambient medium, the steepness of the density profile and the velocity of the ambient wind; classification of PNe purely on the basis of the first two factors may be misleading. In particular, the ratio of ambient wind velocity to PN velocity is important in determining whether the nebula shows a bulge or a cusp at the equator. A high density contrast coupled with a low velocity for the external medium gives rise to extremely bipolar nebulae. For large density contrasts and a significant value of the slow wind velocity, the surface density maximum of the shell shifts away from the equator, giving rise to peanut-shaped structures with pronounced equatorial bulges. As long as the external wind velocity is small compared to the expansion velocity of the nebula, the PNe tend to be more bipolar, even with a moderate density contrast. If the PN velocity is close to that of the external wind, the shape is relatively spherical. However, inclusion of an asymmetric velocity profile in the slow wind, with the velocity increasing towards the pole, can lead to a bipolar nebula if the equatorial velocity is sufficiently low. Preliminary results with a slow wind velocity increasing towards the equator (as is found in calculations of common envelope evolution) show that the nebulae tend to be more oblate, which is not often observed in nature. Representative results for shapes of PNe using various values of the relevant parameters are presented.
A mechanism for the production of jets and Ansae in Planetary Nebulae
Authors: Frank Adam , Balick Bruce , Livio Mario
Published: July 2016

The general properties of elliptical planetary nebulae have been very successfully explained by a class of hydrodynamic models known as interacting stellar winds (ISW). PNs also contain a variety of microstructures (Anase,“FLIERs”) whose origins have remained puzzling. We (Frank, Balick, & Livio 1996) have shown that such flows will naturally occur in the ISW model in momentum-conserving PPN bubbles, and that they can naturally account for the formation of jets and ansae in a way consistent with extant observations.
How to analyze 2-D nebular spectra
Authors: Gesicki K. , Acker A. , Zijlstra A.
Published: July 2016

For a nebula we construct a model, which is a spherical shell defined by inner and outer radii, density distribution and velocity field. The Teff and the luminosity of the central star are assumed to agree with observations. Then the photoionization structure is calculated and the emission lines are integrated. Having found the density from analysis of images the deduction of velocity field in order to fit the observed shapes of spectral lines is relatively easy. A detailed description of computer codes applied for the analysis of nebular spectra is presented in our earlier paper: Gesicki et al. (1996). See also Górny et al. in this volume.