From erik Tue Mar 20 11:41:29 2001 Subject: final program for workshop To: erik (Erik Hoeg) Date: Tue, 20 Mar 2001 11:41:29 +0100 (MET) X-Mailer: ELM [version 2.5 PL2] Content-Length: 20657 Status: OR HANDOUT ======= Workshop on GAIA photometry - Copenhagen 21/22 March 2001 --------------------------------------------------------- Niels Bohr Institute for Astronomy, Geophysics and Physics Copenhagen University Observatory Juliane Maries Vej 30 Auditorium 071 Background for the workshop in Copenhagen in March 2001 Final programme: Instrument Photometric systems and data reduction Utilization of Hipparcos results Utilization of GAIA photometry and spectrometry GAIA and planetary systems List of presentations, with abstracts List of participants Diagram of sampling Overview of filter photometry systems Map to the dinner restaurant - Wednesday at 19:00 Background for the GAIA workshop in Copenhagen in March 2001 ============================================================ This is the second workshop in Copenhagen about GAIA photometry in the few months since the GAIA mission was approved. And a third workshop on the same subject will be held in Copenhagen in the autumn of this year. This strong engagement of Danish astronomers in the mission is natural after their involvement in the Hipparcos/Tycho mission during 25 years and in the development of the GAIA mission since 1990. It also expresses their wish to take part likewise in the GAIA mission, both in the preparation and operation phases. We hope that funding can be secured. To understand the interest of Danish astronomers we should go back more than 50 years, to the work of Bengt Stroemgren who was then a leading astronomer and astrophycisists. He was professor at Copenhagen University and for a long period also director of the Yerkes and McDonald Observatories. He was Secretary General and later President of the International Astronomical Union, and had many other high posts. Stroemgren and his collaborators developed photoelectric photometry and a photometric system of intermediate width bands in the spectrum suited for astrophysical characterisation of stars, the u v b y Hbeta system. Most Danish astronomers since then have, at one time or another, made use of the Stroemgren photometric system. Stroemgren was one of the few astrophysicists of that time who saw the importance of astrometry, and who did something for astrometry. Most other leading astrophysicists of that time may have seen the importance of astrometry in principle, but in practice they used every opportunity to replace astrometrists by astrophysicists in their institutes. Stroemgren emphasized already in 1932 in a correspondence with Arthur Eddington the importance of combining kinematic data of stars, obtained from proper motions, distances and radial velocities, with astrophysical characteristics of stars, obtained from photometry. He used this approach in his whole scientific career to study the structure of the Milky Way, as he has described in numerous reviews. It is precisely this combination that will be exceedingly fruitful with GAIA. Stroemgren had in 1953 a new meridian circle installed at the new observatory site at Brorfelde, 50 km from Copenhagen. The meridian circle was called the "main instrument" of the new observatory. It was in this positive atmosphere about astrometry that Erik Høg as a fourth-year student started to work on the study of the meridian circle. Høg soon went to the Hamburg Observatory for 15 years (1958-73) where he invented and implemented a slit detector with photon counting for the meridian circle for an expedition to Australia. Otto Heckmann was director in Hamburg and very positive about astrometry. The photon counting slit detector opened the path to a combination of astrometry and photometry. With such an instrument both kinds of information are obtained from the same data. Which is in fact what the Hipparcos satellite did, including the Tycho experiment. In GAIA the much more efficient CCD detectors are used as proposed in 1992 by Høg at a symposium in Shanghai, giving an overall improvement of the light efficiency by a factor of a million over Hipparcos, for astrometry and photometry. 8 March 2001 J. Knude, H.E. Jørgensen, E. Høg -------------------------------------------------------------------- About the GAIA workshop in Copenhagen March 2001 ================================================ GAIA-CUO-083 E. Hoeg, C. Fabricius, J. Knude 5 March 2001 Full text on http://www.astro.ku.dk/~erik/gaia/83.march.workshop ABSTRACT: Contents: Preliminary programme: Instrument Photometric systems and data reduction Utilization of Hipparcos results Utilization of GAIA photometry and spectrometry GAIA and planetary systems List of presentations, with abstracts List of participants --------------------------------------------------------------- Workshop on GAIA photometry - Copenhagen 21/22 March 2001 --------------------------------------------------------- Niels Bohr Institute for Astronomy, Geophysics and Physics Copenhagen University Observatory Juliane Maries Vej 30 Auditorium 071 Final programme 19 March 2001 =============== 9:00 21 March *** Welcome by Director of the Niels Bohr Institute, professor Nils O. Andersen *** Instrument: Point-spread function of the Spectro instrument C. Fabricius, L. Lindegren Calibration of GAIA photometry by means of the spikes Erik Høg *** Photometric systems and data reduction: Evaluation of the GAIA Photometric Systems V. Vansevicius, A. Bridzius, V. Deveikis, and R. Drazdys 10:30-11:00 Coffee break Accuracy of the GAIA Photometric System A. Kazlauskas, A. Bridzius, R. Drazdys, R. Kalytis, and V. Vansevicius Some consequences of the differences of the ultraviolet and violet bands in the Vilnius and Stroemgren systems Jens Knude, Nadia Kalcheva Photometric abundances for red giants Chris Flynn Photometric data reduction for GAIA Anthony Brown 12:45-14:30 Lunch, Coffee *** Utilization of Hipparcos results: Hipparcos and the distribution of interstellar matter near the sun Francoise Crifo *** Utilization of GAIA photometry and spectrometry: Multi-colour photometry of the diffuse sky background with GAIA Erik Høg Review of Diffuse Sky Background Photometry -- and Scientific Motivations and Challenges for GAIA K. Mattila The impact of GAIA on investigation of the Magellanic Clouds evolution A. Kucinskas, A. Bridzius, and V. Vansevicius QSO colors in the GAIA photometric system Jean-Francois Claeskens 16:30 Coffee 19:00 Dinner at a Copenhagen Restaurant --------------------------------------------------------------- 22 March 9:00 *** GAIA and planetary systems: Multi-colour photometry of minor planets with GAIA Claes-Ingvar Lagerkvist and Rene Michelsen Activity in solar-type stars from GAIA observations of the Ca triplet. Uffe Gråe Jørgensen Census of exoplanets based on GAIA photometry Erik Høg, Anders Johansen, Britt R. Hansen Detection of dangerous asteroids with GAIA E. Høg, J. Knude 10:30 Coffee break Informal discussions 12:45 Lunch ---------------------------------------------------------------- Workshop on GAIA photometry - Copenhagen 21/22 March 2001 List of presentations, with abstracts 5 March 2001 ===================================== Sequence: surname of first author Photometric data reduction for GAIA Anthony Brown ABSTRACT : Starting from simulated GAIA data we are investigating how to proceeed with the reduction of the photometric data. Preliminary results will be discussed. QSO colors in the GAIA photometric system Jean-Francois Claeskens ABSTRACT : Depending on their redshift, QSOs have colours different from the stars and can be identified in colour-colour diagrams. The QSOs colours in the GAIA photometric system are explored. Hipparcos and the distribution of interstellar matter near the sun Francoise Crifo ABSTRACT : Using the Hipparcos distances and individual high-resolution spectra showing the interstellar absorption along the line of sight in the NaI doublet, it has been possible to construct equal-absorption contours for the interstellar matter around the sun. The so-called "Local Bubble", filled with very tenous, hot gas, is well defined and surrounded by "walls" of colder and denser matter. It is rather squeezed in the galactic plane, and is more elongated towards north and south. Due to Hipparcos accuracy, the distances are limited to 300 pc. With GAIA, a much larger sample of target stars in specific directions will be available , and the possible interaction with other more distant "loops" will become visible. Point-spread function of the Spectro instrument C. Fabricius, L. Lindegren ABSTRACT : Examples of PSFs for the Spectro instrument have been derived. The wave front errors are assumemed to be similar to the Astro WFEs, but eventually realistic values should be computed for the Spectro design. We also discuss the possibility of using the image wings for photometry of bright stars. Photometric abundances for red giants Chris Flynn ABSTRACT : We examine existing photometric abundance indicators for red giants and clump giants, as a means of checking if the proposed GAIA filter system can reasonably be expected to recover abundances and luminosities for such stars. These will be of particular use in the outer Galactic halo. Calibration of GAIA photometry by means of the spikes Erik Høg ABSTRACT : Due to the rectangular apertures of the GAIA telescopes the diffraction images show spikes, two along and two perpendicular to the scan direction. The spikes perpendicular to scan are readily measured by the long samples of GAIA since they are as narrow as the central part of the image. These spikes can therefore be used for astrometry and photometry of bright stars. Their fall-off in brightness is a known function of the wavelength thus providing a magnitude scale which can be used for photometric calibration. Multi-colour photometry of the diffuse sky background with GAIA Erik Høg Full text on http://www.astro.ku.dk/~erik/gaia/82.background ABSTRACT : The report discusses the possible multi-colour photometry of the sky surface with the Astro and Spectro telescopes of GAIA. This photometry makes use of the data in the star patches for stars, thus no extra telemetry is required, only a proper data reduction on the ground. The ordinary photometry of faint stars will give good results for at least 500 million spots on the sky. The precision per spot for the mission average values are given. At a surface brightness of e.g. uV=21.0 mag/arcsec^2 a precision of 0.001 mag in G and about 0.01 mag is obtained in all medium width photometric bands for spots of 7 arcsec diameter. We conclude that GAIA photometry is suited to tackle the whole range of astrophysically interesting diffuse sky components. The required accuracy and low level of straylight can be realised by proper design of the photometric data reduction and by introduction of a conical baffle in the Spectro telescope. Census of exoplanets based on GAIA photometry Erik Høg, Anders Johansen, Britt R. Hansen ABSTRACT : The transit of exoplanets across a stellar disk will occur ten thousands of times in GAIA observations. A safe detection of the slight dimming of the star can be made if the star is sufficiently constant in intensity, and the photometry is very precise. The constancy can be be verified by analysis of all photometric measurements of the star. The possible stellar atmospheric activity will be monitored with the Ca-triplet observed in the high-dispersion spectrograph of GAIA, and with filter photometry of Halpha. An orbit of the planet may be obtained from the simultaneous GAIA astrometry or from ground-based radial velocities. The scientific harvest is orbit, mass and mass density for thousands of exoplanets. The GAIA sample will comprise exoplanets of all spectral type stars, the sample covers all sky, and stars are closer to us than in other large surveys, the sample will have very well known selection functions. These features are important for the theoretical interpretation in terms of planetary systems formation. Detection of dangerous asteroids with GAIA E. Høg, J. Knude ABSTRACT: We proposed in June 2000 in the report CUO-77 a modification of GAIA suited for efficient detection of NEOs. With this modification GAIA will be able to detect a large number of NEOs closer to the sun than with any other method: 35 degrees or 0.6 AU. This has recently been shown in realistic simulations by F. Mignard. We discuss the possibility for ground-based followup of such detections. Activity in solar-type stars from GAIA observations of the Ca triplet. Uffe Gråe Jørgensen ABSTRACT : The variation in the EW of the Ca lines (mainly the visual Ca H&K lines) of the Sun has been studied systematically through several decades. It is now well established that the EW of the Ca lines is a good measure of the solar magnetic activity (i.e., the sunspot number, the flare activity, etc). Research mainly through the 1990'ies have indicated that the variations in the magnetic activity may have a major influence on the climate of the Earth. Some researchers even believe that the increase in the Earth's mean temperature through the 20th century is caused by the increased solar magnetic activity through the century rather than by the increased atmospheric content of greenhouse gases. Historically, long cold periods on Earth have been associated with periods of low solar activity, and periods of warm global weather have been associated with periods of high solar activity. However, it is not known how often the Sun is in general active periods (like in the Viking age and through the 20'th century), and how often it is in long quiet periods (like the Maunder minimum in the 17'th century). By studying the Ca EW of solar type stars observed with GAIA, we will get the best ever statistical sample of activity measurements of solar type stars, and hence knowledge of how often we shall expect the Sun to be in various of its activity levels. Accuracy of the GAIA Photometric System A. Kazlauskas, A. Bridzius, R. Drazdys, R. Kalytis, and V. Vansevicius ABSTRACT : We investigate the effects of filter and CCD chip ageing and inhomogeneity of spectral characteristics across the filter/chip. For this purpose we have used a numerical GAIA machine to simulate realistic observations in the medium-band photometric system 3G. We estimate the accuracy of photometric transformations and discuss the precision of the determined physical parameters for different types of stars. Some consequences of the differences of the ultraviolet and violet bands in the Vilnius and Stroemgren systems Jens Knude and Nadia Kaltcheva ABSTRACT : In a comparison of all published Vilnius and Stromgren photometry we noticed significant differences in similar indices, apparently due to small deviations of central wavelength and band width. Deviations are most pronounced for the differently defined ultraviolet (u and U) and violet (v and X) bands. We suggest that the shift and widening of the Vilnius bands introduce a metal and luminosity sensitivity not present to the same degree of the Stroemgren bands. The impact of GAIA on investigation of the Magellanic Clouds evolution A. Kucinskas, A. Bridzius, and V. Vansevicius ABSTRACT : The aim of this study is to estimate the scientific output which can be expected from GAIA's observations of stellar populations in the Large Magellanic Cloud (LMC). For this purpose we simulate the conditions of real observations of stars in the globular clusters of the LMC, and derive their basic parameters using our new 4-D stellar classification engine. The obtained stellar parameters are used further to simulate age derivation procedure which employs the isochrone fitting. We derive the limits where such procedure can be applied successfully to obtain reliable population ages. These results are used further to discuss the expected impact of GAIA on the study of star formation histories in the LMC. Multi-colour photometry of minor planets with GAIA Claes-Ingvar Lagerkvist and Rene Michelsen ABSTRACT : Taxonomic types of asteroids are closely related to the distance from the Sun. There are also compositional differences between different asteroid families as well as within some subgroups such as the Hildas. A classification into different taxonomic types is possible from broadband photometry. The multi-colour photometry as proposed for GAIA will be a very efficient tool for classifying a large number of asteroids, covering not only the main belt asteroids, but also NEAs, Hildas and Trojans. Review of Diffuse Sky Background Photometry -- and Scientific Motivations and Challenges for GAIA K. Mattila ABSTRACT : I will review our current knowledge of the Diffuse Sky Background in the optical, frequently also called the Light of the Night Sky, as seen from above the Earth's atmosphere. These components are the Zodiacal Light, the Diffuse Galactic Light which at high latitudes is called Galactic Cirrus, the line emission by ionised gas, and finally the Extragalactic Background Light. I will discuss what GAIA could potentially contribute to our understanding of these components and how the selection of the GAIA filter bands might be optimised for this purpose. Evaluation of the GAIA Photometric Systems V. Vansevicius, A. Bridzius, V. Deveikis, and R. Drazdys ABSTRACT : We compare photometric systems proposed for GAIA (1F, 2A, and 3G) in terms of their power to derive main stellar parameters. The same straightforward minimum distance method for simultaneous determination of Teff, log g, [Fe/H], and E(B-V) was applied for all systems. Advantages and disadvantages of the photometric systems to reveal Galactic structure are discussed basing on star distributions modeled in several directions up to the distance of 5 kpc. ----------------------------------------------------------------- Workshop on GAIA photometry - Copenhagen 21/22 March 2001 List of Participants 2 March 2001 ==================== with updates 16 March Audrius Bridzius Institute of Physics, Gostauto 12, Vilnius LT-2600, Lithuania bridzius@astro.lt Anthony Brown European Southern Observatory Munich abrown@eso.org Jean-Francois Claeskens Liege (BELGIUM) claesken@astro.ulg.ac.be Francoise Crifo MEUDON francoise.crifo@obspm.fr Dafydd Wyn Evans Cambridge dwe@ast.cam.ac.uk Claus Fabricius Copenhagen cf@astro.ku.dk Chris Flynn Piikavuorentie 6, Masku, Finland cflynn@astro.utu.fi Britt R. Hansen Copenhagen Bodil Helt Copenhagen bodil@astro.ku.dk Erik Høg Copenhagen University Observatory erik@astro.ku.dk Anders Johansen Copenhagen A. Jorissen Institut d'Astronomie - Universite Libre de Bruxelles ajorisse@astro.ulb.ac.be Henning E. Jørgensen Copenhagen Uffe Gråe Jørgensen Copenhagen uffegj@nbi.dk Algirdas Kazlauskas Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius LT-2600, Lithuania, Finland algisk@mserv.itpa.lt Jens Knude NBIfAFG Copenhagen indus@astro.ku.dk Arunas Kucinskas Institute of Theoretical Physics and Astronomy, Gostauto 12, Vilnius LT-2600, Lithuania ak@mserv.itpa.lt Claes-Ingvar Lagerkvist Astronomiska observatoriet, Box 515 751 20 Uppsala classe@astro.uu.se Lennart Lindegren Lund Observatory Lund, Sweden lennart@astro.lu.se Søren Madsen Lund soren@astro.lu.se Kalevi Mattila Observatory, University of Helsinki FIN-00014 Helsinki mattila@cc.helsinki.fi Rene Michelsen Copenhagen Birgitta Nordstrom Copenhagen birgitta@astro.ku.dk D. Pourbaix Institut d'Astronomie - Universite Libre de Bruxelles pourbaix@astro.ulb.ac.be Fredrik Quist AIP Potsdam, Germany fquist@aip.de Vladas Vansevicius Institute of Physics, Gostauto 12, Vilnius LT-2600, Lithuania wladas@astro.lt *** Late registrations Rene' Michelsen Copenhagen Astronomical Observatory / Uppsala Astronomical Observatory Copenhagen rene@astro.ku.dk Poul Erik Nissen Institut for Fysik og Astronomi, Aarhus Universitet 8000 Aarhus C pen@ifa.au.dk Poul G. Hjorth Department of Mathematics, B-303, DTU Kgs. Lyngby p.g.hjorth@mat.dtu.k Ole H. Einicke Copenhagen University Observatory Copenhagen ohe@astro.ku.dk -------------------------------------------------------------------