Digital Preservation and Web Access to the Konkoly Observatory Schmidt Telescope Plate Archive

ACM Computing Classification System (1998): J.2.The digital preservation of the Konkoly Observatory Schmidt telescope plates, as well as the web access to the plate previews, aim for the preservation of this scientific heritage and the re-use of the astronomical photographic plates in time domain astronomy. The photographic plates used as detectors and information storage at astronomical observations with the Konkoly Schmidt telescope had been obtained in the period 1962–1996. The work on the digital plate preservation and web access started in 2001 with creation of an electronic plate catalogue and the digitization of selected representative plates as well as with interlinking of the publishing in Konkoly Observatory Information Bulletin on Variable Stars (IBVS) with the Wide-Field Plate Database (WFPDB) developing in Sofia. We describe the process of the digitization of the Konkoly Schmidt telescope plates.This work is supported by the bilateral project between the Bulgarian Academy of Sciences and the Hungarian Academy of Sciences and partially by the grants BG NSF DO-02-273 and BG NSF DO-02-275

Digital Preservation and Web Access to the Konkoly Observatory Schmidt Telescope Plate Archive

ACM Computing Classification System (1998): J.2.The digital preservation of the Konkoly Observatory Schmidt telescope plates, as well as the web access to the plate previews, aim for the preservation of this scientific heritage and the re-use of the astronomical photographic plates in time domain astronomy. The photographic plates used as detectors and information storage at astronomical observations with the Konkoly Schmidt telescope had been obtained in the period 1962–1996. The work on the digital plate preservation and web access started in 2001 with creation of an electronic plate catalogue and the digitization of selected representative plates as well as with interlinking of the publishing in Konkoly Observatory Information Bulletin on Variable Stars (IBVS) with the Wide-Field Plate Database (WFPDB) developing in Sofia. We describe the process of the digitization of the Konkoly Schmidt telescope plates.This work is supported by the bilateral project between the Bulgarian Academy of Sciences and the Hungarian Academy of Sciences and partially by the grants BG NSF DO-02-273 and BG NSF DO-02-275

Astroinformatics

As President of Commission on Astroinformatics and Astrostatistics of the International Astronomical Union, I welcome you to the first IAU Symposium on astroinformatics. This is not the first meeting in the field: the 26th meeting on ADASS (Astronomical Data Analysis Software and Systems) was held last weak in Trieste (and members of that group are here today), and this symposium has a strong heritage in workshops held in recent years at Caltech, Seattle, and Sydney. But this is the first time that the broader community of astronomers, through the IAU in collaboration of the giant IEEE organization has recognized this new field of study devoted to the challenges of Big Data and advanced methodology in astronomical research. This is the first time experts from around the world have gathered to share experiences and plan for the future. I have a comment to make. The typical IAU Symposium treats some well-established field of stars or galaxies or cosmology where the leading groups know each other well. But astroinformatics is such a young field, that we do not know each other and we do not know what ideas will emerge from this meeting. So I encourage each of us to have a creative approach to this meeting, work hard to talk to strangers, and help generate a community of scholars who can lead this field into the future

The most metal-poor galaxies

Metallicity is a key parameter that controls many aspects in the formation and evolution of stars and galaxies. In this review we focus on the metal deficient galaxies, in particular the most metal-poor ones, because they play a crucial role in the cosmic scenery. We first set the stage by discussing the difficult problem of defining a global metallicity and how this quantity can be measured for a given galaxy. The mechanisms that control the metallicity in a galaxy are reviewed in detail and involve many aspects of modern astrophysics: galaxy formation and evolution, massive star formation, stellar winds, chemical yields, outflows and inflows etc. Because metallicity roughly scales as the galactic mass, it is among the dwarfs that the most metal-poor galaxies are found. The core of our paper reviews the considerable progress made in our understanding of the properties and the physical processes that are at work in these objects. The question on how they are related and may evolve from one class of objects to another is discussed. While discussing metal-poor galaxies in general, we present a more detailed discussion of a few very metal-poor blue compact dwarf galaxies like IZw18. Although most of what is known relates to our local universe, we show that it pertains to our quest for primeval galaxies and is connected to the question of the origin of structure in the universe. We discuss what QSO absorption lines and known distant galaxies tell us already? We illustrate the importance of star-forming metal-poor galaxies for the determination of the primordial helium abundance, their use as distance indicator and discuss the possibility to detect nearly metal-free galaxies at high redshift from Ly$\alpha$ emission.Comment: 96 pages, 12 figures. To appear in the A&A Review. Version including proof correction

Radial velocities of faint galaxies from objective prism spectra

Since Hubble's discovery of the correlation between galaxy radial velocity and distance, velocities of galaxies have been obtained using slit spectra to establish the value of the Hubble constant. More recently, with the acceptance of a general Hubble flow, velocities have also been used to examine the distribution of galaxies in space. Velocities within clusters of galaxies have also been used to establish cluster velocity dispersions, and hence uirial masses. Large numbers of galaxy velocities obtained over a small area of sky to a faint limiting magnitude would help to construct a clearer picture of the medium scale (supercluster-sized) structure of the Universe.In this thesis the basis for a method of obtaining radial velocities of faint galaxies from their objective prism spectra is described. Measurement techniques, both manual and computer -based, using digitised data from several measuring machines, are discussed. The parameters able to affect the velocity measurement are examined, and checks are made to compare velocities obtained from objective prism spectra with velocities of the same objects obtained from slit spectra. The method is shown to be easily applied to measurements of individual known galaxies, but quite difficult to apply to large numbers of objects using computer techniques. In particular the signal to noise ratio in galaxy spectra has a very important effect on automated velocity measurements.elocity measurements. The application of the method to clusters of galaxies is demonstrated, and preliminary results presented for several Abell clusters. The application of the method to the general field is discussed, and the problems encountered with this application described. It is concluded that the technique described has great potential for both the study of clusters of galaxies, and if certain measurement problems can be overcome, for the study of the distribution of galaxies in large volumes of space

Full-disc Ca II K observations -- a window to past solar magnetism

First such observations were made in 1892 and since then various sites around the world have carried out regular observations, with Kodaikanal, Meudon, Mt Wilson, and Coimbra being some of the most prominent ones. By now, Ca II K observations from over 40 different sites allow an almost complete daily coverage of the last century. Ca II K images provide direct information on plage and network regions on the Sun and, through their connection to solar surface magnetic field, offer an excellent opportunity to study solar magnetism over more than a century. This makes them also extremely important, among others, for solar irradiance reconstructions and studies of the solar influence on Earth's climate. However, these data also suffer from numerous issues, which for a long time have hampered their analysis. Without properly addressing these issues, Ca II K data cannot be used to their full potential. Here, we first provide an overview of the currently known Ca II K data archives and sources of the inhomogeneities in the data, before discussing existing processing techniques, followed by a recap of the main results derived with such data so far

Das Digitale "Gedächtnis der Menschheit" : eine Untersuchung dokumentarischer Praktiken im Zeitalter der digitalen Technologie

This research is a study of the UNESCO “Memory of the World” Programme established with the purpose to increase awareness of the existence and relevance of documentary heritage, and to achieve its universal and permanent accessibility. In this context, digital technology is increasingly used to provide access to documentary heritage but this activity also leads to a series of changes in how documents are understood and handled. Starting from the observation that the conceptual and practical changes triggered by digital technology in the “Memory of the World” do not seem to accurately reflect its stated philosophy, this research pursues the aim to critically analyze the possibilities and limits it offers. This analysis is facilitated by a conceptual framework anchored in the medium theory of Harold Innis and his concepts of medium, bias, space and time, and balance, which serve as analytical lenses to closely study selected aspects of digital technology and their influence. Despite popular beliefs that digital technology is most suitable for universal access, the findings of this present research lead to the observation that this cannot really be the case, and it reveals that an over-emphasis on the technical possibilities of digital access is not supportive of the overall purpose of the “Memory of the World”, leading to the narrowing down of its potential relevance. At first glance, this may suggest not recommending at all the use of digital technology. However, acknowledging that each medium has both limits and possibilities, instead of rejecting digital technology the study searches for solutions that may assist with integrating it in the “Memory of the World” in accordance with its overall purpose and philosophy. To this end, three recommendations are elaborated, the same conceptual framework that revealed the limits of digital technology being applied to construct on their possibilities. In order to motivate why following the recommendations of this analysis would be necessary, the study concludes by shifting attention from the relevance of digital technology in the “Memory of the World” Programme to the relevance of the Programme in a world changed by digital technology.Diese Forschung befasst sich mit dem UNESCO-Programm „Memory of the World“, das eingeführt wurde, um Achtsamkeit über die Existenz und Bedeutung von Dokumentenerbe zu schaffen, und um ihre universale und permanente Zugänglichkeit zu erreichen. In diesem Zusammenhang benutzt man zunehmend die digitale Technologie, um Zugang zu Dokumentenerbe zu ermöglichen, aber dies führt auch zu einer Reihe von Veränderungen wie Dokumente verstanden und behandelt werden. Angefangen von der Beobachtung, dass die konzeptionellen und praktischen Veränderungen, die durch die digitale Technologie im Memory of the World Programm ausgelöst werden, scheinbar nicht genau die festgelegte Philosophie reflektieren, verfolgt diese Forschung den Zweck, deren Möglichkeiten und Grenzen kritisch zu analysieren. Diese Analyse wird von einem konzeptionellen Rahmen gestützt, welcher in der Medium Theorie von Harold Innis und seinen Konzepten über das Medium, Bias, Space and Time, und Balance verankert ist. Diese Theorie dient als analytisches Objektiv, um ausgesuchte Aspekte der digitalen Technologie und ihren Einfluss näher zu untersuchen. Entgegen der allgemeinen Meinung, dass die digitale Technologie am besten geeignet ist für den universellen Zugang, führen die Resultate dieser aktuellen Forschung zu der Beobachtung, dass dieses nicht wirklich der Fall sein kann, und sie beweisen, das eine Überbewertung der technischen Möglichkeiten des digitalen Zugangs nicht hilfreich für die allumfassenden Absichten des Memory of the World Programms sind, und zu einer Einschränkung seiner potenziellen Bedeutung führt. Auf den ersten Blick könnte dieses heißen, den Gebrauch der digitalen Technologie überhaupt nicht zu empfehlen. Allerdings anerkennend, dass jedes Medium sowohl Grenzen wie auch Möglichkeiten hat, lehnt diese Forschung die digitale Technologie nicht ab, sondern sucht nach Lösungen die helfen könnten, diese in das Memory of the World Programm zu integrieren, und zwar im Einklang mit den allumfassenden Absichten und ihrer Philosophie. Um zu motivieren warum es notwendig wäre den Empfehlungen dieser Analyse zu folgen, beendet diese Forschung ihre Schlussfolgerung durch das Verlagern der Aufmerksamkeit von der Bedeutung der digitalen Technologie im Memory of the World Programm, zu der Bedeutung des Programms in einer durch digitale Technologie veränderten Welt

Multi-object astronomical spectroscopy with optial fibres

A full account is given of the relatively new astronomical technique of multi- object spectroscopy with optical fibre lightguides. The thesis begins with a survey of the number densities of a wide range of astronomi- cal object classes, and, after comparing the merits of the various techniques for multi- object spectroscopy, shows (by defining the "effective aperture" of a multiple fibre - coupled telescope) that the multi -fibre tech- nique is very well- suited to the real distribution of celestial objects.A review of the properties of optical fibres is given, together with an exposition of the important considerations in the design of fibre feeds for astronomy. This is followed by a description of the requirements in the design of telescopes, spectrographs and detectors to render them suitable for the multi -fibre technique. Equations are derived for the performance of these systems in terms of signal -to -noise ratio, and an example is given.A survey of the equipment that has been built for multi -fibre spectroscopy at observatories throughout the world is presented, and special attention is paid to the FOCAP fibre system at the 3.9 -metre Anglo- Australian tele- scope. The thesis gives an example of the use of FOCAP in work carried out by the writer to investigate the kinematics of RR Lyrae variables in the nuclear bulge of the Galaxy. Evidence is found in the preliminary results for the existence of non -circular motions along the galactic centre line -of- sight.A description is then given of the FLAIR wide -field fibre -coupled multi- object spectroscopy system built by the writer for the 1.2 -metre UK Schmidt Telescope. Reports are presented on a series of observational pro- grammes designed to test the system, including the classification of stars in the Chamaeleon dark cloud, spectroscopy of Orion cluster flare stars, spectroscopy of objects in the Large Magellanic Cloud, the measurement of galaxy redshifts, and the observation of quasar candidates. An experiment in time -resolved multi- object photometry is also described. It is shown that for spectroscopy, the prototype system will perform well on stellar targets to V "16 -17, but, although galaxy redshifts have been obtained, its usefulness for the systematic measurement of redshifts is hampered by its low sensitivity in the blue region of the spectrum. An account is then given of the relatively simple steps needed to rectify this, together with a brief description of a proposed, fully- optimised FLAIR system.Finally, the future prospects for multi -fibre astronomical spectroscopy are briefly reviewed, from the point of view of the new instrumentation becoming available, and the astronomical results that will be produced

Nebular metallicities in isolated dwarf irregular galaxies

The motive for this work was to investigate whether small, isolated gas-rich galaxies show evidence of chemical evolution, by studying their nebular metallicities. I have identified a sample of 83 objects chosen for low luminosity and mass, the presence of active star formation, and isolation from other galaxies and galaxy clusters that might generate tidal effects or enrich the intergalactic medium. From these I have measured the spectra of 35 objects, using theWiFeS IFU spectrograph on the ANU 2.3m telescope at Siding Spring. In analysing spectra extracted from the WiFeS data cubes, I found that standard ‘strong line’ methods using emission line ratios to measure atomic abundances, gave either erratic or no results. I found that for those galaxies showing the [O iii] 4363Å auroral line, the metallicities determined using the standard ‘electron temperature’ methodwere inconsistent with previous published work. This led me to investigate the conventional assumption that electrons in Hii regions are in thermal equilibrium. I show that the non-equilibrium ‘ ’ electron energy distribution, found almost universally in solar system plasmas, can explain the long recognised ‘abundance discrepancy’ between recombination line and collisional line abundance calculations in nebular metallicity measurements. This has added an important new dimension to the analysis of nebular spectra. Using the extensively revised Mappings photoionisation modelling code and new atomic data to analyse the spectra of two exceptionally isolated dwarf galaxies, I find that they exhibit metallicities similar to galaxies in more crowded environments, and appear to have evolved quite normally, through periodic star formation and subsequent enrichment of their interstellar media. I present a new approach for calculating total oxygen abundance using electron temperatures that appears to give more consistent results than earlier methods. I apply this to my measured spectra, together with the revised Mappings photoionisation modelling code, to explore the physical parameters affecting the measurement of nebular metallicities. In particular, I find strong evidence for several of the observed nebulae being—in part—optically thin. I use the models to show that nebular optical depth affects measured abundances and temperatures, and that electron densities also have an important role. I develop models that give a very good match to the observations. I conclude that the measurement of abundances and temperatures in Hii regions is a more complex question than had generally been assumed, and important physical parameters affecting the measurement processes have in the past not been taken fully into account