bluuebunny/crossref_metadata_2025_split huggingface dataset:
Work of Art of the Han Dynasty Unearthed in China and Observations of Solar Phenomena
Authors: Zhen-tao Xu 
Published: July 2016

In Chinese ancient times the Sun worship was in vogue. Mainly there were two sorts of the worship rites: 1) for rising and setting Sun; 2) for solar eclipses. Many evidences for Sun worship have been found in Chinese ancient books and bone inscriptions (Xu Zhentao et al.1985).The everyday worship to the Sun certainly caused spontaneous observations for solar phenomena. Since the ancients only had a limited knowledge they could not understand what were these phenomena and they, however, created many wonderful myths to describe them. These myths about Solar phenomena have vividly been expressed in the works of art of the Han Dynasty recently unearthed. So analysing the works of art we may trace the original phenomena of solar activity.
Research on Scale and Precision of the Water Clock in Ancient China
Authors: Hejun Quan 
Published: July 2016

The instruments of measuring time have been closely related to astronomy, especially to astrometry. In ancient China, before mechanical clocks were imported from European countries, accurate Water Clocks, main tools for measuring time, had been developed two thousand years ago.In this paper the sizes (mainly the height) of five single vessel-type Clocks of Western Han Dynasty (206 B.C.-25 A.D.), which were either unearthed in recent years or recorded in some historical documents, are taken as a sample for studying the scaling of indicator-rods and precision of Clock.
The Meridians of Reference of Indian Astronomical Canons
Authors: Mercier Raymond 
Published: July 2016

AbstractThe canons of Sanskrit astronomy depend on mean motions which are normally postulated to refer to the central meridian of Ujjain. The present work is a statistical analysis of these mean motions designed to discover the optimum position of the meridian, by comparison with modern mean motions. This follows earlier work done by Billard in determining the optimum year. The results confirm that from the time of Aryabhata all the canons were referred to meridians lying well within India, and in many cases clearly identifiable with Ujjain within the statistical bounds.
Astronomical Efforts of Sawai Jai Singh – A Review
Authors: Sharma Virendra Nath 
Published: July 2016

AbstractSawai Jai Singh, the statesman astronomer of 18th century India, designed instruments, built observatories, prepared Zīj, and sent a fact-finding scientific mission to Europe. His high-precision instruments were designed to measure time and angles with accuracies of ± 2 second, and ±1’ of arc respectively. The Ṣaṣṭhāmsa, a meridian dial with aperture, can still measure angles with precision of ± 1’ of arc. In the age of Newton and Flamsteed, Jai Singh and his associates remained medieval, in the tradition of Ulugh Beg, and did not initiate the new age of astronomy in the country. A complex interaction of poor communications, religious taboos, theological beliefs, national rivalries and plain simple human shortcomings are to be blamed for the failing.
The Case Low-Dispersion Northern Sky Survey
Authors: Pesch Peter , Sanduleak N. 
Published: July 2016

AbstractThe Burrell Schmidt-type telescope of the Warner and Swasey Observatory in its new location on Kitt Peak in Arizona is being used for a spectroscopic survey of the region b > +30°. and δ > +30°. The plates, which cover 5° x 5° are taken with the 1.8 prism which provides a dispersion of 1350 Å mm-1 at Hγ. Eastman Kodak IIIa-J plates, baked in forming gas, are used without filter to cover the spectral range 3300 to 5350 Å. The exposure times of 75 minutes reach a limiting blue magnitude of ~ 18.0 for threshold detection of an unwidened stellar continuum. The categories of objects which are being catalogued are blue and/or emission-line galaxies, probable HII regions, blue and/or mission-line stellar objects, known and probable blue stars, main-sequence late B and A-type stars, suspected field horizontal-branch stars of types A and F including RR Lyrae variables, suspected F and G-type subdwarfs showing a UV excess, faint carbon and late M suspected halo giants, and peculiar objects.
A Faint Galaxy Survey from Cosmos Measures on Deep UKST Plates
Authors: MacGillivray H.T. , Dodd R.J. 
Published: July 2016

AbstractDeep photographs taken with the UK 1.2m Schmidt Telescope are being scanned with the COSMOS automatic plate-measuring machine in order to carry out a survey of galaxies over large areas of sky down to faint limits (B ~ 21.5). Several fields have been examined, and the data are being used to investigate the properties and largescale projected distribution of galaxies.
Automatic Analysis of Objective Prism Spectra
Authors: Hewett P. , Irwin M. , Bunclark P. , Bridgeland M. , Kibblewhite E. , McMahon R. 
Published: July 2016

AbstractAn automated system to measure and analyse large numbers of objective prism spectra from photographic plates using the Automated Plate Measuring (APM) facility at Cambridge is described. The system is being applied in a number of ways including automated quasar detection and subsequent clustering analyses, galaxy redshift surveys, and wide field searches for rare objects, such as carbon stars.
Wide-Field Imaging of Halley’s Comet During 1985-1986 Using Schmidt-Type Telescopes
Authors: Brandt J.C. , Klinglesmith D.A. , Niedner M.B. , Rahe J. 
Published: July 2016

AbstractPhotographic imaging of the plasma- and dust-tails of bright comets requires fast (f<4.0), wide-field (F0V>5°) optics for the proper recording of these large, low surface brightness features. Schmidts and astrographs are well-suited to this task and a large number of these instruments around the world will be turned toward Halley's Comet in 1985-1986 in support of the Large-Scale Phenomena Discipline of the International Halley Watch (IHW). This “worldwide network” should provide imagery with a time resolution never before realized in the study of a comet, and major breakthroughs in the understanding of highly-variable, elusive plasma processes in comets are expected. The imagery will also provide support for the GIOTTO, VEGA, AND PLANET-A deep space probes to the comet.
The Young Open Cluster NGC 2384
Authors: Hassan S.M. 
Published: July 2016

AbstractCombined photoelectric – photographic UBV-photometry for NGC 2384 is discussed. The results achieved so far are summarized and indicate that this cluster is young enough to be used as spiral arm tracer out to a distance of 3.27 kpc. The colour excess E(B-V) is 0.31, the apparent distance modulus is 13m.50 and its earliest spectral type is BO.
UV Galaxies and Superassociations
Authors: Khachikian E.Ye. 
Published: July 2016

I will talk about the UV galaxies discovered on plates of the 1-m Schmidt telescope of the Byurakan Observatory by Markarian and his collaborators and by Kazarian. Up to now the number of UV galaxies is more than 2000.It is well known that more than 85% of UV galaxies show emission spectra. Among them there have been discovered OSO's, Seyfert galaxies and galaxies with active nuclei with narrow emission lines. It turns out also that some UV galaxies show spectra typical of superassociations (SA). Some of them really turn out to be SA, connected with nearby galaxies, for example, Markarian 94 (Arp & Khachikian 1974), Markarian 5, 59, 71, 256 (Khachikian & Sahakian 1975). Altogether, in the first six lists of Markarian it has been found about 40 of these types of objects. Contrary to OSO's, Seyferts and narrow emission line galaxies, which have starlike nuclei, the central regions of some other UV galaxies entirely consist of several SA: Markarian 7 (Casini, Heidmann and Tarenghi 1979), Markarian 8 (Khachikian 1972), Markarian 325 (Coupinot, Hecquet and Heidmann 1982), Kazarian 5 (Kazarian & Khachikian 1977). In many cases UV galaxies themselves contain one or more SA: Markarian 12, 38, 307, 848, 984 (Khachikian, Petrossian & Sahakian 1983a). There are case when one or both components of double nucleus UV galaxies have the characteristics of SA: Markarian 104, 306, 111, 710, 739 (Khachikian, Petrossian & Sahakian 1979, 1980a,b; Khachikian, Korovyakovskiy,Petrossian & Sahakian 1981). It is necessary to note just one more type of SA often called ‘isolated giant HII regions’: Markarian 116=IZwl8 (Searle & Sargent 1972). Apparently, among UV galaxies there are quite a number of isolated SA. Actually, they are a particular type of compact galaxies which mainly consist of hot stars and diffuse matter.
Detection of Qsos Near Large Galaxies
Authors: Pocock A.S. , Blades J.C. , Penston M.V. , Pettini M. 
Published: July 2016

We have presented here some results of our search for quasars near large galaxies. Papers on these results are to be published shortly in Monthly Notices of the Royal Astronomical Society (Mon. Not. R. astr. Soc.)The aim of our programme is to use the absorption spectra of QSOs and related objects (BL Lacs, Seyfert galaxies) as probes of the interstellar media of intervening galaxies. For such a study it is necessary to find new suitably bright QSOs and related objects lying close on the sky to large galaxies because very few are known at present.
Implementation and Use of Wide Fields in Future Very Large Telescopes
Authors: Angel J.R.P. 
Published: July 2016

AbstractThe full potential of the next generation of larger telescopes will be realized only if they have well instrumented large fields of view. Scientific problems for which very large ground-based optical telescopes will be of most value often will need surveys to very deep limits with imaging and slitless spectroscopy, followed by spectroscopy of faint objects taken many at once over the field. Improved instruments and detectors for this purpose are being developed. Remotely positioned fibers allow the coupling of light from many objects in the field to the spectrograph slit. CCD arrays, operated in the TDI or drift scan mode, will make large area detectors of high efficiency that may supercede photographic plates. An ideal telescope optical design should be based on a fast parabolic primary, have a field of at least 1° with achromatic images < 0.25 arcseconds and have provision for dispersive elements to be used for slitless spectroscopy and compensation of atmospheric dispersion over the full field. A good solution for a general purpose telescope that can satisfy these needs is given by a three element refractive corrector at a fast Cassegrain focus. A specialized telescope dedicated to sky surveys, with better image quality and higher throughput than presently available, might be built as a scaled up Schmidt with very large photographic plates. Better performance in most areas should be obtained with a large CCD mosaic detector operated in the drift scan mode at a telescope with a 2-mirror reflecting corrector.
Spectroscopic Techniques for Determining Electron Densities in the Solar Atmosphere
Authors: Mason H.E. 
Published: July 2016

AbstractThe determination of electron density in the solar atmosphere using diagnostic line ratios has been a field of intense activity over the past ten years. These spectroscopic techniques have given us an insight into the physical conditions of such diverse phenomena as flares, active regions, sunspots, coronal holes and the quiet Sun. In this paper, an overview will be given of the methods used for determining electron densities in the solar atmosphere. This will include a discussion of the accuracy of the atomic parameters required in such analyses. Several different approximations are used to calculate electron scattering cross-sections. These will be outlined and their accuracy for individual ions will be assessed.The use of these techniques have led to some fundamental discoveries about the nature of the solar atmosphere. The transition region was conventionally envisaged as a homogeneous layer between the low temperature chromosphere and the high temperature corona. We now know that the transition region has unresolved filamentary structures with very small “filling factors” at low temperatures. In contrast, the coronal emission seems to be more homogeneously distributed. A lot of effort has gone into the determination of the electron densites in solar flares, particularily during the impulsive phase. Such studies are crucial to distinguish between various theoretical flare models. These problems will be discussed in relation to analyses of spectral data from SKYLAB, HRTS, SMM, SOLEX and XSST and with a view to future projects such as SOHO.
A New AID for Interpolating and Assessing Collision Strengths and Rate Coefficients
Authors: Burgess A. , Mason H.E. , Tully J.A. 
Published: July 2016

AbstractA new way of critically assessing and compacting data for electron impact excitation of positive ions is proposed. This method allows one (i) to detect possible printing and computational errors in the published tables, (ii) to interpolate and extrapolate the existing data as a function of energy or temperature, and (iii) to simplify considerably the storage and transfer of data without significant loss of information. Theoretical or experimental collision strengths Ω(E) are scaled and then plotted as functions of the colliding electron energy, the entire range of which is conveniently mapped onto the interval (0,1). For a given transition the scaled Ω can be accurately represented - usually to within a fraction of a percent - by a 5 point least squares spline. Further details are given in (2). Similar techniques enable thermally averaged collision strengths upsilon (T) to be obtained at arbitrary temperatures in the interval 0 &lt; T &lt; ∞. Application of the method is possible by means of an interactive program with graphical display (2). To illustrate this practical procedure we use the program to treat Ω for the optically allowed transition 2s → 2p in ArXVI.
Nickellike Gadolinium Spectra from the PLT Tokamak
Authors: von Goeler S. , Beiersdorfer P. , Bitter M. , Bell R. , Hill K. , LaSalle P. , Ratzan L. , Stevens J. , Timberlake J. , Maxon S. , Scofield J. 
Published: July 2016

AbstractSpectra in the 7 to 9 Å region of gadolinium were measured on the PLT tokamak with a vacuum curved crystal spectrometer. The wavelength are compared with theoretical predictions from the RAC code for iron, cobalt, nickel, copper, and zinclike chargestates.
Broadband (1-25Å) X-ray Crystal Spectroscopy of Impurity Ions in the Dite Tokamak
Authors: Barnsley R. , Evans K.D. , Hawkes N.C. , Peacock N.J. 
Published: July 2016

AbstractWe present results from a Bragg rotor spectrometer and refer to wide–ranging studies of intrinsic and injected impurity ions in the DITE Tokamak. The instrument has absolute calibration for flux and wavelength and can detect impurities at the part per million level in the band from 1 to 24Å. Monochromator and fast spectral survey modes, combined with a spatial scan facility, result in a versatile and powerful diagnostic tool.
Analysis of Quasi-Continuum Bands and Line Spectra of Highly Ionized W and Au
Authors: Mandelbaum P. , Schwob J.L. , Finkenthal M. , Klapisch M. 
Published: July 2016

AbstractThe spectra of heavy elements (Z &gt; 50) observed in laser-produced plasmas, vacuum sparks and Tokamaks are characterized by a strong quasi-continuum band emitted in the 40–100Å range. This band originates from the blending of a great number of lines emitted in the Δn=0, n=4 transitions. Indeed, the Unresolved Transition Array (UTA) computations show that for about twenty adjacent ionization states, the mean wavelength of the main resonance transitions remains in a very small wavelength range. The results of these computations are given here for tungsten and gold. The computations rely on new UTA formulae which include the effect of configuration mixing. This work extends the previous results obtained for the rare-earths spectra.
The Soft X-Ray Laser Program at Livermore
Authors: London R.A. , Ceglio N.M. , Eder D.C. , Hazi A.U. , Keane C.J. , Macgowan B.J. , Matthews D.L. , Maxon M.S. , Phillips T.W. , Rosen M.D. , Scofield J.H. , Stearns D.G. , Trebes J.E. , Whelan D.A. , Whitten B.L. 
Published: July 2016

AbstractWe describe the experiments and supporting theoretical modelling to develop and characterize soft x-ray lasers. The x-ray lasers are created in dense plasmas produced by optical laser irradiation of solid targets with line focussed beams. We use mainly thin foil targets, which upon appropriate illumination, produce rather uniform plasmas. We consider laser schemes pumped by electron collisional excitation and dielectronic recombination in Ne-like and Ni-like ions, and schemes pumped by collisional and radiative recombination following rapid cooling for H-like and Li-like ions.Experimental measurements of the time and space resolved spectra taken both along the lasing axis and at other viewing angles, in addition to data on the angular pattern of x-ray laser radiation and on the absorption and scattering of the optical laser light are presented. These data allow us the determine the characteristics of the plasmas which have been created, as well as the properties of the x-ray lasers, such as the gain coefficients for the inverted transitions, and their spatial and temporal distributions. The modelling includes calculations of the absorption of the optical laser light, the hearing and hydrodynamics of the targets and the evolution of the atomic level populations within the plasma. Transfer of the emitted radiation is calculated, including resonance line trapping, amplification for inverted transitions, and refraction of the x-ray laser beam due to electron density gradients. Results are used to optimize x-ray laser designs before the experiments and to interpret the measured spectra.The latest experimental results from the NOVA laser facility on the performance of several laser schemes and on the use of multilayer mirrors to produce x-ray laser cavities are reported. These results arc compared to the models to test and improve our understanding of the complex physics involved in making x-ray lasers. Based on current experiments, we show how the modelling can be use to design shorter wavelength and more efficient schemes for use in applications such as x-ray holography.
Angular Distribution and Polarization of the Continuum Emission in Plasmas with Toroidal Symmetry
Authors: Lamoureux M. , Jacquet J. , Pratt R.H. 
Published: July 2016

AbstractSuperthermal electrons in plasmas are usually strongly directional, and this confers angular dependence and polarization to the X-ray continuum radiation emitted. Here, we give the relations between the anisotropic distribution functions f(v,θ) and the degree of polarization of the emission due to direct radiative recombination and bremsstrahlung. An application is then made to a tokamak plasma whose f(v,θ) we obtained from a Monte Carlo code.
A Theoretical Survey of 4s–4p and 4p–4d Transitions in Nickel-Like Ions
Authors: Wyart J.-F. 
Published: July 2016

AbstractMulticharged ions in the isoelectronic sequence of nickel have a current interest, due to possible population inversions occuring between excited levels. The identification of 4s-4p and 4p-4d transitions was recently extended up to Mo XV, owing to new experiments performed at I.S.A.N., Troitsk (USSR), and to the subsequent interpretation of the first excited configurations by means of the Slater-Condon method and generalized least squares fit of energy parameters along a sequence. For predicting transitions in higher charge states, the same configurations have been studied ab initio by using the relativistic parametric potential method and selected transitions involving short-lived lower levels are given for 14 ions in the sequence from Sr XI to Eu XXXVI.
The Use of Ti, Si, C, Be and LiF in Soft X-Ray Optics
Authors: Vinogradov A.V. 
Published: July 2016

SummaryTi, Si, C, Be and LiF have been studied as coatings for normal incidence (multilayers) and grazing incidence (steering many-fold reflection mirrors) optical elements. The multilayers have been tested with soft (130+250 Å and hard (1.54 Å) X-rays. From these measurements the multilayer parameters have been deduced.The carbon and lithium fluorine steering mirrors showed the reflection of 10+60% for the turning angles of 30 and 45 degrees and two wavelengths of 44.7 Å and 67.6 Å. The perspectives of other materials are also discussed.
High-Resolution Detectors for Imaging and Spectroscopy at Ultraviolet and Soft X-Ray Wavelengths
Authors: Timothy J.G. , Morgan J.S. , Slater D.C. 
Published: July 2016

AbstractThe Multi-Anode Microchannel Arrays (MAMAs) are a family of pulse-counting imaging array detectors designed specifically for astrophysical investigations in space. The MAMAs have a number of unique performance characteristics which make them particularly suitable for imaging and spectroscopy at ultraviolet and soft x-ray wavelengths. First, they employ “solar blind” photocathodes eliminating the “red leak” problem associated with solid state arrays such as the CCDs. Second, they operate with zero readout noise, yielding photon-statistics limited signals. Third, they utilize a random readout technique and can determine both the location of a detected photon and also its arrival time to an accuracy of the order of 100 ns. This paper will give an overview of the construction, mode-of-operation and performance characteristics of the MAMA detectors and will describe the current status of the development program.
The Comparison of Helium-Like Ion Emission Line Ratios with Solar X-Ray Spectral Data
Authors: McCann S.M. , Keenan F.P. 
Published: July 2016

AbstractElectron impact excitation rates recently calculated by Keenan, McCann and Kingston for transitions in the He-like ions Al XII, Si XIII and S XV are used to derive the electron temperature sensitive emission line ratio G and the density sensitive ratio R in its low density limit (Ro). These ratios are compared with those calculated by other authors and with the values obtained for solar flares using instruments on board the P78-1 and Solar Maximum Mission satellites. In general it is found that our results resolve discrepancies which currently exist between observation and theory, which provides experimental support for the methods and atonic data adopted in the present analysis.
Optical Wavefront Analysis of Thermally Cycled 500 mm Metallic Mirrors
Authors: Noethe L. , Franza F. , Giordano P. , Wilson R. 
Published: July 2016

Warping is a major concern in the use of aluminium as a material for large mirrors. The warping characteristics are influenced by:*the type of material, i.e. pure aluminium or some alloy*the type of fabrication, i.e. cast, rolled or forged.So far there is little data available on the warping characteristics of aluminium mirrors. Therefore ESO has tested the warping behaviour of 18 aluminium mirrors under thermal cycling conditions with a glass ceramic mirror, which has not been cycled, as a reference mirror. The set of 500 mm mirrors selected for this experiment is described in [1].
A Finite Element Approach to the Design of the Support System for the ESO 1 M. Active Optics Experiment
Authors: Ballio G. , Contro R. , Poggi C. , Citterio O. 
Published: July 2016

A way to follow in order to reduce the weight of the primary mirror is to accept an higher ratio diameter-thickness and to find a remedy to the consequent greater deformability of the mirror by an active control system of it. A technique using closed loop active optics control has been proposed in references.In these papers, a coherent scheme of active optics control for the ESO New Technology Telescope (NTT) was presented, based on analysis of the image errors in terms of an appropriate polynomial (the ESO off-line telescope test polynomial) and the production of equivalent correction terms by force modulation of the primary axial support.