Download or read book Developments in Astrometry and Their Impact on Astrophysics and Geodynamics written by Ivan I. Mueller and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this review talk, I would like to report on the proper motion analysis, which has been recently carried out together with M. Soma and M. Yoshizawa: There has been a persistent demand in astronomy for accurate stellar positions and proper motions, which are represented by an inertial reference system constructed on the basis of a set of consistent astronomical constants. In the reference system the precessional constant plays a primary role. In a series of papers Fricke (1967a,b, 1977a,b) has deter mined the luni-solar precessional correction to Newcomb's value and the fictitious motion of the equinox, which have been adopted in the "IAU (1976) System of Astronomical Con stants". Based on the precessional correction and the equinoctial motion thus established, the fundamental reference system, the FK5 system (Fricke et al. 1988) for positions and proper motions, has been constructed. However, for several years geodetic VLBI (McCarthy & Luzum 1991) and LLR (Williams et at. 1991) observations have been suggesting an additional correction to the luni-solar precessional constant of the IAU (1976) System. That is, these observations indicate the precessional correction of 6. p ~ -0:'30/cent to the FK5 system. But, the observational period ofthe earth orientation is considered to be still insufficient to separate unambiguously the precessional change of the earth orientation from the nutation with the longest period of 18. 6 years.
Download or read book Literature 1988 Part 1 written by U. Esser and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1266 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ...The abstracts are classified under more than a hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews#1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine#2
Download or read book Very Long Baseline Interferometry written by Marcello Felli and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: The quest for high resolution has preoccupied radio astronomers ever since radio waves were first detected from space fifty years ago. This venture was par ticularly stimulated by the discovery of quasars, and led to the development of interferometer techniques using baselines of transglobal dimensions. These meth ods have become known as Very Long Baseline Interferometry (VLBI). Arrays of radio telescopes situated all over the Earth (or even in space) are regularly used for researches in radio astronomy, reaching resolutions as small as a fraction of a milli arcsecond. The technique also allows the measurement of the positions of the radio telescopes to a few millimeters and so VLBI has become a major tool in geodesy and the study of the rotation of the Earth. VLBI has now passed the pioneer stage and is becoming a standard facility available to astronomers and geodesists, requiring the coordination of the operations of indpendently owned radio telescopes around the world. In Europe observatories from England, Federal Republic of Germany, France, Italy, Poland, Sweden and The Netherlands are coordinated in their VLBI activity by the European VLBI Network Consortium (EVN). The Programme Committee of the EVN allocates time to scientific projects on a routine basis three times a year. The Unites States has a similar arrangement of a network of independent radio observatories, and joint experiments using 'Global Network' are often made.
Download or read book Beams and Jets in Astrophysics written by Philip A. Hughes and published by Cambridge University Press. This book was released on 1991-01-25 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first to provide students and researchers in the field of astrophysical jets with a comprehensive and up-to-date account of current research. An important feature of the book is that it combines discussions of both extragalactic and Galactic jets. There are ten chapters, authored by fourteen active researchers, each of whom is an expert on their chosen topic, and the book has been edited to provide a cohesive account of this field of study. This is the first volume to integrate studies of jets on all length scales. It will be an important textbook for graduate students, and a valuable reference source for researchers in many areas of extragalactic and Galactic astronomy. It will also be of interest to plasma physicists and space scientists.
Download or read book Very High Angular Resolution Imaging written by J.G. Robertson and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 1990s are proving to be a very exciting p&iod for high angular resolution astronomy. At radio wavelengths a combination of new array instruments and pow erful imaging algorithms have generated images of unprecedented resolution and quality. In the optical and infrared, the great technical difficulties associated with constructing separated-aperture interferometers have been largely overcome, and many new instruments are now operating or are being developed. As these pro grams start to produce observational results they will be able to draw extensively on the experience gained by the radio-interferometry community. Thus it seemed that the time was ripe for a meeting which would bring together workers from all wavelength ranges to discuss the details of the science and art of "Very High Angular Resolution Imaging" . While the main emphasis of Symposium No. 158 was on high resolution tech niques from the radio, mm-wave, infrared and optical bands, it also provided an opportunity for presentation of astronomical results from these techniques. As well as giving our colleagues from the Northern Hemisphere a break from midwinter, the location of the Symposium in Australia recognised the continuing development of astronomical interferometry in this country, especially the recent completion of the Australia Telescope radio array, and the progress toward com missioning of the Sydney University Stellar Interferometer. A number of the par ticipants visited these instruments during the post-symposium tour.
Download or read book Third International Symposium on Space Mission Operations and Ground Data Systems Part 1 written by and published by . This book was released on 1994 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parsec Scale Radio Jets written by J. Anton Zensus and published by Cambridge University Press. This book was released on 1990-08-16 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quasars and active galaxies are the most powerful emitters of radiation in the universe. Modern radio telescope arrays have shown that the ultimate energy source resides in the central few parsecs of the galactic nucleus, and powers the emitting regions by way of two oppositely-directed relativistic jets of energy. This volume presents the latest observations and theories of these remarkable objects. Topics discussed include superluminal motions, the physics of jets and shock fronts in jets, related optical observations, and cosmic evolution. Particular attention is given to the "unified theories," which attempt to show that many of the phenomena in powerful extragalactic objects are different aspects of a single, basic mechanism; the main difference in their appearance is a result of their different orientation with respect to the observer.
Download or read book The Westerbork Observatory Continuing Adventure in Radio Astronomy written by Ernst Raimond and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: A small country builds a world-class telescope in its backyard and lives happily ever after (or at least for a quarter century). That in a nutshell is the story told in this collection of essays. The country of course is the Netherlands, and the telescope is the Westerbork Synthesis Radio Tele scope (WSRT), brainchild of Jan Oort. Living happily in this context is a continuing record of discovery and as such also a continuing basis for se curing observing time on facilities in other countries and operating at other frequencies. As our community celebrates the Silver Anniversary of the radio tele scope at Westerbork, it is fitting that we pause to take account of the scientific discoveries and insights it made possible. Initially the instrument represented the very significant step away from university-run, specialist facilities to a well-supported, common-user radio imager also having spec tral and polarization capabilities. It pioneered the mode of operation now common for satellite observatories, in which data is taken and calibrated by technicians and provided to researchers ready for analysis. It has been a major source of discovery in, among other areas, research on neutral hy drogen and studies of dark matter in galaxies.
Download or read book Plate Tectonics written by Naomi Oreskes and published by CRC Press. This book was released on 2018-10-08 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of the history of plate tectonics, including in-context definitions of the key terms. It explains how the forerunners of the theory and how scientists working at the key academic institutions competed and collaborated until the theory coalesced.
Download or read book Variability of Blazars written by E. VALTAOJA (Ed) and published by Cambridge University Press. This book was released on 1992 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blazars (also known as BL Lac objects), first discovered in 1978, are unusually energetic objects in the extragalactic universe. About 200 are known or suspected. They are radio sources with highly variable optical and radio emission, as well as high polarisation, and their optical spectra normally have no distinguishable features. It is generally accepted that they belong to that class of galaxies with active galactic nuclei, which are presumed to be driven by infall of matter to a supermassive black hole. In this book researchers give a complete summary of the observations of blazars and the theoretical interpretation. A comprehensive listing of confirmed and candidate objects is included. Mechanisms in which the variability can arise from shocks and relativistic jets are discussed. There are at least four different answers given to the question: what is a blazar? This book is a complete overview of the violent activity observed in these extreme active galactic nuclei.
Download or read book Reports on Astronomy written by Derek McNally and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: IAU Transactions are published as a volume corresponding to each General Assembly. Volume A is produced prior to the Assembly and contains Reports on Astronomy, prepared by each Commission President. The intention is to summarize the astronomical results that have affected the work of the Commission since the production of the previous Reports up to a time which is about one year prior to the General Assembly. Volume B is produced after the Assembly and contains accounts of Commission Meetings which were held, together with other material. The reports included in the present volume range from outline summaries to lengthy compilations and references.
Download or read book Earth Resources written by and published by . This book was released on 1988 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earth Resources A Continuing Bibliography with Indexes issue 61 written by and published by . This book was released on 1989 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supernovae written by Stanford E. Woosley and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 791 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supernova explosions are not only important to the ecology of the universe, seeding it, among other things, with the heavy elements necessary for the existence of life, but they are also a natural laboratory in which a host of unique physical phenomena occur. While still far from a complete understanding, scientists have made great advances during the last twenty-five years in understanding the nature and conse- quences of supernovae. This book presents the state of supernova studies at the beginning of the 1990's, as reported at a two-week meeting on the Santa Cruz campus of the University of California in July 1989 in- volving 177 astronomers and astrophysicists from 17 nations. The 110 papers contained in this volume report all aspects of the field - observations at all wavelengths from radio through gamma-rays, bolometric light curves and spectra, neutrino observations, the theory of stellar explosions, multidimensional models for mixing, nucleosynthesis calculations, synthetic spectral modeling, presupernova evolution, supernova remnants, supernova rates, supernovae as standard candles, the interaction of supernovae with their surroundings - and constitute the most comprehensive and up-to-date treatment of SN 1987A currently available. Astronomers and astronomy graduate students will find this an in valuable summary of the current state of supernova research. The informed layperson or undergraduate astronomy student will also find it a useful introduction and guide to the literature in the subject.
Download or read book Precise Geodetic Infrastructure written by National Research Council and published by National Academies Press. This book was released on 2010-10-25 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geodesy is the science of accurately measuring and understanding three fundamental properties of Earth: its geometric shape, its orientation in space, and its gravity field, as well as the changes of these properties with time. Over the past half century, the United States, in cooperation with international partners, has led the development of geodetic techniques and instrumentation. Geodetic observing systems provide a significant benefit to society in a wide array of military, research, civil, and commercial areas, including sea level change monitoring, autonomous navigation, tighter low flying routes for strategic aircraft, precision agriculture, civil surveying, earthquake monitoring, forest structural mapping and biomass estimation, and improved floodplain mapping. Recognizing the growing reliance of a wide range of scientific and societal endeavors on infrastructure for precise geodesy, and recognizing geodetic infrastructure as a shared national resource, this book provides an independent assessment of the benefits provided by geodetic observations and networks, as well as a plan for the future development and support of the infrastructure needed to meet the demand for increasingly greater precision. Precise Geodetic Infrastructure makes a series of focused recommendations for upgrading and improving specific elements of the infrastructure, for enhancing the role of the United States in international geodetic services, for evaluating the requirements for a geodetic workforce for the coming decades, and for providing national coordination and advocacy for the various agencies and organizations that contribute to the geodetic infrastructure.
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1991 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Geodynamics Program written by and published by . This book was released on 1990 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
