bluuebunny/crossref_metadata_2025 huggingface dataset:
Main Characteristics and Achievements of Ancient Indian Astronomy in Historical Perspective
Authors: Shukla Kripa Shankar
Published: July 2016

Ancient Indian astronomy may be classified into two main categories: (1) the vedic astronomy and (2) the post vedic astronomy. The vedic astronomy is the astronomy of the vedic period i.e. the astronomy found in the vedic saṃhitas and brāhmanas and allied literature. The principal avocation of the people in the vedic times being the performance of the vedic sacrifices at the times prescribed by the śastras, it was necessary to have accurate knowledge of the science of time so that the times prescribed for performing the various vedic sacrifices could be correctly predicted well in advance. Astronomy in those times, therefore, was essentially the science of time-determination. It centred round the Sun and Moon and its aim was to study the natural divisions of time caused by the motion of the Sun and Moon, such as days, months, seasons and years, special attention being paid to the study of the times of occurrence of new moons, full moons, equinoxes and solstices.
Vedic Literature Vis-a-Vis Mathematical Astronomy
Authors: Sarkar Pamatosh
Published: July 2016

The present paper restricts to the analysis of some passages from the Vedic literature, viz. Śatapatha Brāhmaṇa and Vedāṅga Jyautiṣa, from the view point of mathematical astronomy.

The Śatapatha Brāhmaṇa in 2.1.2.1 to 2.1.2.5, refers to some ritual in which some fire has to be set up. It recommends Kṛttikā as the nakṣatra or the lunar asterism under which to set up the fire. For, there are some special features that Śatapatha-Brāhmana obviously considers as good points. According to the text, one good point about Kṛttikā is that it is ′the most numerous′; secondly, it rises ′in the east′.
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

The 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.
An Examination of Al-Bīrūnī’s Knowledge of Indian Astronomy
Authors: Khan M.S.
Published: July 2016

By the time al-Bīrūnī wrote the KH (see al-Bīrūnī’s books; see also Boilot 1960; Kennedy 1970; Khan, A.S. 1982; Khan M.S. 1975) in the first half of the eleventh century, Greek astronomy specially the Almagest of Ptolemy was fully diffused among the Arabs. They also had some knowledge of Persian astronomy (Pingree 1963)- But he was not the first Muslim scientist to write on Indian astronomy. Before he visited India (around 408/1017) he had some knowledge of this subject derived from Arabic translations of Sanskrit astronomical works. He records that the Brāhmasphuṭa-siddhānta of Brahmagupta (ca. A.D. 598) was translated by the order of Caliph Manṣūr of Baghdad (754-775 A.D.) in 154/771 or in 156/77_3(KH, p.351) and its Arabic translation was called Sindhind al-Kabīr or the Great Sindhind. He adds that he translated it into Arabic and wrote a treatise on it. He also studied its method of calculation in his treatise Tarjumah mā fī Brāhma Siddhānd min Ṭuruq al-Ḥisab (Khan, A.S.1982, p.20). Al-Bīrūnī states that he also retranslated the Khaṇḍakhādyaka by Brahmagupta, called in Arabic al-Arkand and published a new correct translation (KH, pp.346-383; Nalino 1911, p.83; Nadwi 1930, p. 139). He had written a treatise entitled Tahddhīb zīj al-Arkand in which he corrected its errors but this is not available at present (Khan, A.S. 1982, No.6, p.12). The Āryabhatīya of Āryabhata (b. A.D. 476) called Arjabhadh in Arabic was translated by Abu’l-Hasan al-Ahwāzī and it was perhaps available to al-Bīrūnī(KH, p.357; Pingree 1970, p.308; Nalino 1911, p.172-73).
Bibliographical Notes on Islamic Astronomy, The Results of a Study of the Exact Sciences Among the Jews of Yemen
Authors: Langermann Y. Tzvi
Published: July 2016

The people of Yemen as a whole, and the Jews of that country in particular, possess a very rich cultural heritage, including achievements in the field of astronomy. The medieval astronomical sources were the subject of an exhaustive study by David A. King (Mathematical Astronomy in Medieval Yemen, Malibu 1983). Some material concerning Jewish interest in the subject was collected by Bernard R. Goldstein (The Survival of Arabic Astronomy in Hebrew, J. for the Hist, of Arabic Science 3, 1979, 31-39, note 2c.) The author of this paper has recently completed a monograph on the exact sciences among the Jews of Yemen. In this paper we present some discrete items of mainly bibliographic interest which emerged from that study. Note that our sources are all Arabic manuscripts, written in Hebrew characters.
Astronomical Efforts of Sawai Jai Singh – A Review
Authors: Sharma Virendra Nath
Published: July 2016

Sawai 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 ESO Sky Surveys
Authors: West Richard M.
Published: July 2016

Technical aspects of the production of photographic Sky Surveys and Atlasses are discussed. The need to optimize all factors, e.g. telescope site, telescope optics, mechanics and control system, hypersensitization, calibration, processing and reproduction is illustrated by the ESO 1m Schmidt telescope and the ESO Sky Surveys.
The Case Low-Dispersion Northern Sky Survey
Authors: Pesch Peter , Sanduleak N.
Published: July 2016

The 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.
The Automated Detection of Variable Objects on Schmidt Plates
Authors: Hawkins M.R.S.
Published: July 2016

This paper will review progress on the automated detection of variable objects on Schmidt plates, describe the various populations of variables which have been discovered, and summarise some of the most interesting results to date. So far, the searches have been based on sequences of a dozen or more sky limited UK 1.2m Schmidt plates taken on timescales from one day to several years. The plates were measured on the COSMOS measuring machine at the Royal Observatory, Edinburgh which typically detects between 100,000 and 200,000 images in the central 16 deg2 of each plate. The measures for each field are combined, and calibrated using deep electronographic sequences, to give data sets of some 100,000 objects, complete in the magnitude range B = 13–21. The procedure is described in some detail by Hawkins (1983a) and results in a sequence of magnitudes accurate to about 0.1m for each object in the measured area. Field effects across the plates are allowed for, and an extensive set of diagnostics allows the distribution of errors as a function of magnitude, and on each plate, to be monitored.
A Faint Galaxy Survey from Cosmos Measures on Deep UKST Plates
Authors: MacGillivray H.T. , Dodd R.J.
Published: July 2016

Deep 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

An 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.
A New Wide Field Electrographic Camera as an Optimum Detector for Schmidt-Type Telescopes
Authors: Griboval P.J. , Jia X.Z.
Published: July 2016

The electrographic (E.G.) camera is one of the most powerful modern detectors having high sensitivity, extended spectral response, extreme spatial resolution, low background, no threshold, good linearity and large dynamic image. A combination of highly uniform electric and magnetic fields produces distortion-free and extremely sharp images which are recorded by electron sensitive emulsions (Figure 1).
Japanese Orbiting Ultraviolet Telescope Project: UVSAT Working Group Report
Authors: lye Masanori
Published: July 2016

The ultraviolet-telescope satellite (UVSAT) project has been proposed to the Institute of Space and Astronautical Science (ISAS/Japan) by the UVSAT Working Group. The main telescope will be an F/4 Cassegrain with a 60cm primary mirror. A design study and some preliminary experiments of an intensified CCD camera with an objective spectroscopic capability are under way.
Compilation of the Hipparcos Input Cataloguean Extensive Use of Schmidt Sky Surveys
Authors: Turon-Lacarrieu C.
Published: July 2016

The ESA Astrometry satellite Hipparcos is due to be launched in early 1988. It will measure very precise positions, parallaxes and proper motions for about 100 000 stars. However, in order to be included in the Input Catalogue, the programme stars should have positions and magnitudes known in advance with respective accuracies of about 1" and 0.5 magnitude. This will require new astrometric and photometric measurements and observations. Sky Survey Schmidt plates will be extensively used, especially for astrometric measurements in the Southern hemisphere.
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

Photographic 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.
Missing Matter in the Vicinity of the Sun
Authors: Bahcall John N.
Published: July 2016

The combined Poisson-Boltzman equation for the gravitational potential is solved numerically for a detailed Galaxy model. The main result - obtained by comparing the calculated densities with observations of F dwarfs and K giants - is that about half of the mass density in the vicinity of the Sun has not yet been observed.
The Young Open Cluster NGC 2384
Authors: Hassan S.M.
Published: July 2016

Combined 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.
An Automated Method of General Star Counts For Dark Clouds
Authors: Ohtani H.
Published: July 2016

An automated method of general star counts has been developed for the purpose of deriving the distributions of extinction of large dark clouds. The result of the application to the Southern Coalsack is given.
Narrow Spectral Range Objective-Prism Technique Applied to A Search For Small Magellanic Cloud Members
Authors: Azzopardi Marc
Published: July 2016

The Magellanic Clouds are exceptional galaxies for the study of massive stars and other luminous objects, because they are close and seen in directions where the galactic interstellar extinction is relatively low. In addition the Small Magellanic Cloud (SMC) is of special interest because of the possible peculiar effects that its low metal abundance, compared to the Solar neighbourhood, may have on the evolution of its stellar population. Consequently, a search for the most luminous SMC members has been the subject of many studies. Among the different means used to detect SMC members, the wide field cameras equipped with objective prisms, Grisms or Grenses have played a prominent part. The method consists of selecting stellar objects showing high luminosity or typical spectral features. Such surveys have been especially successful in detecting SMC Ha emission-line objects (Henize, 1956; Lindsay, 1961), OB and blue supergiant stars (Sanduleak, 1968, 1969), planetary nebulae (Sanduleak et al., 1978; Sanduleak and Pesch, 1981) or carbon and late M-type stars (Blanco et al., 1980).
Luminosity Function of Old Globular Clusters in the SMC
Authors: Kontizas M. , Kontizas E.
Published: July 2016

Luminosity Functions (LFs) provide useful information on the stellar content of a star cluster. One of the problems of studying the colour-magnitude (c-m) diagrams in remote clusters is the contamination of cluster members with field stars. If all the stars of a cluster are measured in concentric rings one can reach the field and compare the c-m diagram of the field with that of the central areas. For the SMC where the field and cluster areas seem to have similar c-m diagrams, this method is not always useful and then the LF becomes an important tool of overcoming this obstacle.
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

The 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

The 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.
Microcalorimeters for X-Ray Spectroscopy
Authors: Silver E. , Hailey C. , Labov S. , Madden N. , Landis D. , Goulding F. , Chanan B. , Rutledge J. , Bernstein G. , Richards P. , Kahn S. , Becker R.
Published: July 2016

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.
A New AID for Interpolating and Assessing Collision Strengths and Rate Coefficients
Authors: Burgess A. , Mason H.E. , Tully J.A.
Published: July 2016

A 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 < T < ∞. 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

Spectra 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

We 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

The spectra of heavy elements (Z > 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

We 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

Superthermal 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

Multicharged 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

Ti, 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

The 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 Interpretation of Solar Spectral Intensities
Authors: McWhirter R.W.P.
Published: July 2016

The intensity of a specrtal line from an optically thin plasma such as the outer atmosphere of the sun depends on both the atomic properties of the atomic ion responsible for the line and the physical nature of the plasma. In this paper we discuss the various ways in which the measured spectral intensities from the sun are used to discover something about the nature of the sun’s atmosphere. The technique has been referred to as the emission measure method. It has important limitations in terms of the accuracy of the specrtal data as well as the atomic data. We discuss some of these and suggest methods by which they may be assessed. The technique is illustrated by application to real observations from a number of authors.
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

Electron 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:

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the type of material, i.e. pure aluminium or some alloy

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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.
Mirror Compensator for Testing Convex Secondary
Authors: Junhua Pan
Published: July 2016

The testing of convex secondary mirror of large telescope is known as a difficault thing, because it needs for a large mirror or lens. In USA, they used to use Hindle sphere for testing convex hyperboloids, and in West Germany as I know, they often use concave matrix probe for testing convex mirrors. In the case of Hindle method, the diameter of testing sphere always is about 2 or 3 times as the convex mirror under testing, in the later case, the matrix probe must has the same size as the convex mirror, further more, the probe itself needs another testing facilities. Some other methods had been suggested by R. Wilson, E, Gaviola and others but they have rarely been used in practice.
Measuring Atmospheric Seeing
Authors: Roddier F.
Published: July 2016

Since a lot of efforts and money are being put in building larger telescopes, astronomers are becoming more concern with the effects of “atmospheric seeing” on astronomical observations. Observers need to correct their observations for image degradation and put more and more emphasis on the importance of good seeing conditions. Both observers and optical engineers try to compare the image quality between different telescopes and sites. In addition, engineers are interested in locating the origin of image degradation. What are the relative contributions of the dome and of the free atmosphere to image degradation ? As engineers become able to reduce dome seeing, the selection of a good astronomical site becomes more crucial and reliable methods for site testing become necessary.
Progress of the Large Interferometer at CERGA
Authors: Labeyrie A. , Schumacher G. , Thom C. , Dugué M. , Foy F. , Foy R. , Cormier P. , Vakili F.
Published: July 2016

The coude beams from a pair of 1.5 meter telescopes are recombined to achieve coherent aperture synthesis. The spherical telescopes move along a 70-meter baseline, expandable to 300 meters. For the VLT, a grid of railway tracks with 2-D carriages meets the requirements for incoherent and coherent observing.

Steps in the design and construction of a coherent telescope array have been described previously (Labeyrie, 1982, 1984). In 1975, it was first verified that stellar light from two telescopes could be recombined coherently. In 1978, it was decided to develop spherical mounts for 1.5-meter telescopes. Among the expected features were: 1. coude focus with only one flat mirror; 2. wheels for mobility along railway tracks; 3. structural stiffness for interferometric stability, also implying vibration amplitudes inferior to 0.1 micrometer at each reflective surface. This last and most critical requirement implies materials which have to be stiff and also damped.
A Modular Structural Design for a Spectrographical MMT
Authors: Freire Ferrero Rubens , Chevreton Michel , Felenbok Paul
Published: July 2016

With the aim to propose alternative solutions for Multi Mirror Telescopes, we present some ideas about a MMT for High Resolution Spectroscopy purposes. The alternative solution is intended both in technical conception and in economical costs.

This possible project consider the use of a system of 36 mirrors about 1.5 meter in diameter, collecting light independently each other and transmitting the light down to the slit spectrograph by optical fibers.

To reduce mirror costs and structural weight, we propose to develop the “replique” technique over light-weighted supports modelled and adjusted over a master convex mirror.

Different project design for a modular hive structure are considered.
Some Possible VLT Sites in Chile
Authors: Ardeberg A. , Lindgren H.
Published: July 2016

A report is given on the site-testing programme for a Very Large Telescope in Chile. Data are now available from seven months of investigations. Comments are made on the places which have so far seemed most attractive. Meteorological data from constant monitoring of a coastal mountain, Paranal, are presented and discussed. These data indicate an average percentage of photometric nights of around 85. Atmospheric integrated water-vapour content seems very low in the winter but relatively high in the summer. Other meteorological parameters seem favourable for astronomical observations.
Fabry-Perot Spectrographs for VLT's
Authors: Monnet Guy
Published: July 2016

Four Reasons are advocated to stress the interest of Fabry-Perot Spec-trographs (F.P.S.) as potentially useful instruments for the future Very Large Telescopes :

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Reasonably wide spectrum of Astronomical uses

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Good use of Telescope area

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Relative cheapness

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Versatility
Considerations in Photographic Detection for Very Large Telescopes
Authors: Millikan Allan G.
Published: July 2016

Current practice with four-meter reflectors is reviewed and the good match with fine-grained photographic plates of high DQE is examined. The present designs of 15-meter-class telescopes appear to point to instruments with a large flat focal plane and an image scale in the 5 arc sec/mm range. This requires an emulsion of considerably larger microcrystal size than currently used. Extension of the present emulsion type to the required grain size is not likely to be efficient; however, the use of new emulsion technologies should offer the opportunity to devise appropriate photographic detectors for use with an f/6, 5 arc sec/mm telescope. A gain in detective quantum efficiency appears possible.
Emploi de la caméra électronique grand champ avec les très grands télescopes - Extrapolation des résultats obtenus avec le télescope C.F.H.
Authors: Wlérick G. , Renard L. , Horville D. , Gex F. , Munier J.M. , Lelièvre G. , Llebaria A. , Bijaoui A. , Dubout R. , Petit M.
Published: July 2016

the large field Lallemand electronographic camera has proved to be an ideal receptor for bidimensional photometry with the C.F.H. 3.6 m. Telescope. It permits to measure faint stars up to about B = 25. Plates of a large variety of objects have been obtained ; for example : crowded fields such as the nearby galaxy Messier 33 ; fields where one must recognize faint galaxies from stars; objects for which a high spatial resolution is needed, such as the optical jet of Messier 87 or gravitational lenses. It is possible to predict the limits of the receptor with a very large telescope.
Star Formation
Authors: Moorwood A.F.M.
Published: July 2016

Star formation is an extremely active area of current research with studies ranging from the detailed properties of forming stars in the Galaxy to the evolution of galaxies at cosmological distances. Some of the problems being tackled are of long standing but many are related to unexpected discoveries which have followed from the application of new and improved observing capabilities throughout the electromagnetic spectrum during the last few years. Amongst others, these include the nature of y and X-ray sources in molecular clouds, the origin of the molecular mass outflows and various related phenomena (e.g. H2O masers, hot H2 emission...) observed in the vicinity of forming massive stars, the mechanism responsible for generating bursts of star formation in galaxy nuclei and the nature of star formation in cooling flows of intracluster gas. At the present time therefore there would be no shortage of good optical/infrared observing proposals which could take full advantage of the order of magnitude gain in sensitivity and, at least in the infrared, the improved angular resolution promised by most of the proposed VLT projects. The need for improved capabilities in the near and mid-infrared is also being pressed by developments in related observational techniques. In particular, sub-mm and mm wave molecular astronomy is set to advance rapidly during the next few years with the completion of several dedicated large dishes. Far infrared astronomy has also recently come of age with the completion of the IRAS all sky satellite survey and the adoption by ESA of ISO (infrared Space Observatory) as its next major astronomy mission.
The 15-Meter National New Technology Telescope: an Update
Authors: Barr L.D.
Published: July 2016

The 15-Meter National New Technology Telescope (NNTT) Program, growing out of the earlier "Next Generation Telescope" studies at Kitt Peak National Observatory, is now responding to the recently published recommendation of the Astronomy Survey Committee of the American National Academy of Sciences:

"...the construction of a New Technology Telescope (NTT) [NNTT] in the 15-m class on the ground for observations in the optical and in the near- and mid-infrared regions of the spectrum (0.3-to 20µm wavelength). The design studies needed before the NNT can be constructed are of the highest priority and should be undertaken immediately."
The Penn State Spectroscopic Survey Telescope
Authors: Ramsey L.W. , Weedman D.W.
Published: July 2016

To map the distribution of galaxies and quasars in the universe, we desire a telescope large enough to obtain spectra to about 20th magnitude in under 20 minutes integration and which is devoted entirely to such spectroscopic survey projects in dark time. We also desire extensive bright time observing to monitor large numbers of G-M stars with high-resolution spectroscopy for many years in search of solar-like activity. These projects are suited to a telescope with a large fixed primary, assembled from many spherically figured segments. We present a design for such a telescope that consists of 73 segments, each of 0.9-m diameter and 26-m radius of curvature. Mirror blanks of this size can be cut from standard Pyrex sheets. Effective aperture of the telescope exceeds 7-m; the focal plane system can track objects for 40 minutes, and sky coverage of 48 degrees is obtained by using a fixed tilt for the primary and making the entire telescope and dome rotatable. The focal plane system is lightweight and precisely pointable because spectrographs are coupled to the focus by fiber optic cables. Off-the-shelf components and existing technology are used to keep engineering and development costs low; we must remain within a budget feasible for a university. Because the telescope will be equipped with standard, minimal instrumentation and is intended for very routine observing programs, operating costs will also be low. Hardware components are now being assembled in a laboratory to develop the focal plane control system and the mirror support system.
Radius Determination for Nine Short Period Cepheids
Authors: Burki G.
Published: July 2016

From November, 1981 to March, 1982, nine Pop I and Pop II cepheids of periods between 1.5 and 4.2 days have been monitored, in Geneva photometry from La Silla Observatory (Chile) and in radial velocities from the Haute-Provence Observatory (France). These cepheids are listed in Table 1. Figure 1 shows an example of the light, colour and velocity curves for EU Tau, a small amplitude cepheid with a period of 2.10 days.
Cepheid Radii from Infrared Photometry
Authors: Welch D. L. , Evans Nancy Remage , Drukier G.
Published: July 2016

We have determined radii for Cepheids using nearinfrared K(2.2 µm) photometry and Balona’s approach to the Baade-Wesselink method of radius determination. The lower sensitivity of the K flux to temperature variations results in improved sensitivity to radius changes. We present the results of maximum-likelihood radius solutions for Cepheids with modern radial velocity curves. We point out limitations of the Balona technique as it is currently applied in the optical and suggest improvements.