Messenger No. 42 (December 1985)
Automatic analysis of interferograms.
Pirenne, B.; Ponz, D.; Dekker, H.
AA(University of Namur, Belgium) AB(ESO) AC(ESO)
Interferometric techniques have been used in optical testing for a long time. The introduction of the laser made this method a routine procedure in the evaluation of the quality of optical components. The interpretation of interferograms is in principie very simple. The fringes represent lines of equal phase difference between two wavefronts, one of which is often flat or spherical. The height difference between two adjacent fringes is usually one wavelength of the radiation used. From the shape and relative order number of the fringes, the map representing the phase difference between the two wavefronts can be reconstructed. Using this phase map, one can then proceed to calculate the more meaningful physical quantities like refractive index variation, distance or stress. This modelling process is different for each application. At ESO, interferometry is used in the testing of optical components for instruments, and programs have been developed that fit the phase map to a set of orthogonal quasi-Zernike eigenfunctions, representing the well-known optical aberrations like spherical aberration or coma. A difficulty has always been to enter into the computer the positions and order numbers of the fringes; up to now this was done manually. This paper briefly describes a new method of fringe analysis that reduces the manual interaction to aminimum, a more detailed explanation will be given in a forthcoming article.
Two New ESO Publications
List of ESO Preprints (September-November 1985)
A photometric study of the bright cloud B in Sagittarius: IV. 17 new diffuse objects
AA(Lyon, Observatoire, Lyons, France)
In 1976, a photometric study of the bright cloud B in Sagittarius was initiated. The investigation included a systematic survey of a large number of U, B, V, and R plates obtained with the aid of a 1 m Schmidt telescope. In addition, photometric measurements were conducted of several hundred stars. Up to now, 24 diffuse objects have been detected, three of which are planetary nebulae, while two are possible globular clusters. One is a possible galactic open cluster. Forty-two proper-motion stars and 621 red variable stars were also discovered. Current research is mainly concerned with field No. 1, which is located northeast of 45 Oph. Seventeen new diffuse objects were found during an analysis of the two first pairs of R plates and one pair of B plates. Data regarding these new diffuse objects are presented in a table, taking into account galactic and equatorial coordinates and their X; Y positions on the Palomar Observatory Sky Survey.
Acker, A, 1985, Private Communication.
van den Bergh, S. and Hagen, L., 1975, Astronomical Journal, 80.
Johnston, M. D., Bradt, H. V., Doxsey, R. E., Margon, S., Marshall, F. E.
and Schwartz, D. A., 1981, Astrophysical Journal, 245.
Paturel, G., Private Communication.
Terzan, A, Bernard, A et Ju, K. H., 1978a, Comptes Rendus Acad.
Sciences, Paris, 287, serie B, 157.
Terzan, A., Bernard, A. et Ju, K. H., 1978 b, Comptes Rendus Acad.
Sciences, Paris, 287, serie, B, 235.
Terzan, A. and Bernard, A., 1978, The Messenger, 15.
Terzan, A, and Ju, K. H., 1980, The Messenger, 20.
Terzan, A., Bernard, A, Fresneau, A et Ju, H. K., 1980, Comptes
Rendus Acad. Sciences, Paris, 290, serie S, 321.
Terzan, A. and Sernard, A., 1981 ,AstronomyandAstrophysics, Suppl.
Terzan, A, Bijaoui, A, Ju, H. K. and Ounnas, Ch., 1982, Astronomy
and Astrophysics, Suppl. Series, 49.
A catalogue of dwarf galaxies south of δ = -17°.5.
Feitzinger, J. V.; Galinski, T.
AA(Astronomisches Institut, Ruhr-Universit
The first systematic search for dwarf galaxies was undertaken by van den Bergh (1959) and resulted in a catalogue which contained 222 objects north of delta = -23° (in 1966 the list was expanded to 243 dwarfs north of -33°). Nilson (1973) noted in his "Uppsala General Catalogue of Galaxies" 687 dwarf systems north of -2.5. Both catalogues were produced with the aid of the "Palomar Observatory Sky Survey". The publication of two photographic surveys of the southern hemisphere (
A galaxy halo with a radius of 65 KPC
AA(CNRS, Institut d'Astrophysique, Paris, France)
In the spectra of QSOs, a large number of absorption lines are observed, and many of these systems are only known on the basis of their absorption characteristics. Special questions arise in connection with the Ly-alpha forest systems. These questions are considered in the context of a discussion of the different types of extrinsic absorption systems. Attention is also given to the detection of a galaxy identified with the absorption system in PKS 2128-12, and the nature of the Mg II absorption system detected in PKS 2128-12. Questions regarding the association of the absorbing cloud on the line of sight to PKS 2128-12 are considered. It is concluded that an association with a very extended disk is more likely than an association with a halo around a spiral galaxy of absolute luminosity Mv = -20.8.
Bergeron, J., Kunth, 0.: 1983, Monthly Notices Roy. Astron. Soc. 205,
Guiderdoni, B., Rocca-Volmerange, B.: 1985, Erice workshop, Spectral
evolution 0f galaxies, in press and pre-publication N° 110,
Institut d'Astrophysique, Paris.
Tytler, D., Boksenberg, A., Sargent, W. L. W., Young, P., Kunth, D.:
Weymann, R. J., Boroson, T.A., Peterson, B. N., Butcher, H. R.: 1978,
Astrophys. J. 226, 603.
Young, P., Sargent, W. L. W., Boksenberg, A.: 1982, Astrophys. J.
Suppl. 48, 455.
Comet Halley's plasma tail photographed from Germany with a focal reducer to be used at ESO's 1 m telescope.
Jockers, K.; Geyer, E. H.
AA(Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, FRG) AB(Observatorium Hoher List, Oaun, FRG)
A picture of the plasma tail of Comet Halley was obtained at the 1 m telescope of Hoher List Observatory on November 12, 21 UT. A focal reducer, combining instrumentation built at Hoher List Observatory and the Max-Planck-Institute for Aeronomy, was used. At a 1 m telescope the plate scale ofthe focal reducer very nearly equals the scale of the ESO Schmidt telescope but the field has only 25 mm diameter, corresponding to about in the sky. The exposure ofComet Halley was taken through an interference filter of a bandpass of 425 +/ -3nm, which transmits the 0-2 band of the CO+ comet tail band system. A two-stage proximity focus image intensifier was employed and 103 a- F film was pressed against its exit window. Exposure time was 15 minutes.
Discovery of Neptune's ring at La Silla
Haefner, R.; Manfroid, J.; Bouchet, P.
AA(Universitaets-Sternwarte, Munich, West Germany), AB(Liege, Universite, Cointe-Ougree, Belgium), AC(European Southern Observatory, Garching, West Germany)
The unexpected rediscovery of the Uranian rings in 1977 and the discovery of the faint Jovian rings in 1979 led to an intensified search for rings around Neptune. A description is given of observing programs at the European Southern Observatory (ESO) in Chile, which led to a discovery of such a ring, taking into account the utilization of the ESO 0.5 m and 1 m telescopes. The discovery is based on observations made on the night of July 22, 1984, in connection with a stellar occultation by the planet. Explanations for the observed differences in shape and timing of the occultation event, as recorded by both telescopes, are discussed. The obtained conclusions could be confirmed by a study of the results of a group of American astronomers working at the Cerro Tololo observatory. The observations strongly favor the existence of, at least, a part of a ring which has a width of roughly 10-15 km over a length of at least 100 km.
Gutierrez, F., Haefner, R., Manfroid, J., Vega, R.: 1984, IAU Circular
Haefner, R., Manfroid, J.: 1984, IAU Circular No. 3968.
Hubbard, W.B.: 1984, lAU Circular No. 4022.
Rawal, J.J.: 1981, The Moon and the Planets 24,407.
Reitsema, H.J., Hubbard, W.B., Lebofsky, L.A., Tholen, D.J.: 1982,
Science 215, 289.
Schmeidler, F.: 1985, private communication.
A second GEC CCD with UV sensitive coating tested on the CASPEC spectrograph.
The ESO Messenger No. 41 contained a short summary of the properties of the CCOs in operation at the La Silla telescopes, among them a GEC CCO (ESO # 6) coated in the ESO lab to enhance the UV-blue sensitivity. A detailed description of the coating technique, the spectral response curve and the first spectroscopic results have been given elsewhere (1). A second GEC CCO was coated and tested successfully in August of this year in the ESO detector lab by Sebastian Deiries and Roland Rei
(1) Cullum, M., Deiries, S., D'Odorico, S., Rei
ESO Image Processing Group: MIDAS Memo
Spectrophotometry of globular cluster stars with the CASPEC system - A comparison with results from other spectrographs
Spite, F.; Francois, P.; Spite, M.
AA(Paris, Observatoire, Meudon, France), AB(Paris, Observatoire, Meudon, France), AC(Paris, Observatoire, Meudon, France)
It is pointed out that the analysis of globular cluster stars provides a unique opportunity to understand the early history of the Galaxy. Questions regarding the aim of abundance determination in globular cluster stars are discussed along with the Caspec spectrograph and the precision of the obtained data. A comparison is conducted of the results obtained with the Caspec and the results provided by the 1.5 coude spectrograph, taking into account spectra of the field halo giant HD 184711. Attention is also given to M22-IV97, a star already observed at Kitt Peak. Questions regarding the chemical composition of M22-IV97 and Omega Cen 65 are explored, and data obtained on the basis of preliminary abundance determinations in the atmospheres of the stars are presented in a table.
Aller, L. H.: 1963, The Atmosphere of the Sun and Stars, 2nd edition,
Ronald Press, New York, p. 320.
Carney, B. W.: 1979, Astrophys. J., 233, 877.
Cayrel, R., Jugaku, J.: 1963, Ann. Astrophys. 26, 495.
Oelbouille, L., Roland, G., Neven. L.: 1973, Photometrie Atlas of the
Solar Speetrum from). 3000 to 10000 A, Liege: Institut d'Astrophysique
de Liege (presently available tram ),,3600 to 8000 A).
O'Odorico, S., Gratton, R. G., Ponz, 0.: 1985, Astron. Astrophys., 142,
Gratton, R. G., Pilachowski, C. A., and Sneden, C.: 1984, Astron.
Astrophys. 132, 11.
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Gustatsson, B .: 1977 (private communication).
Holweger, H., Müller, E.A.: 1974, Solar Phys., 39, 19.
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Suppl. 52, 241.
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Astrophys. J., 263, 187.
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High resolution monitoring of the emission lines in SS 433
Angebault, P.; Dodorico, S.; Miley, G.
AA(European Southern Observatory, Garching, West Germany), AB(European Southern Observatory, Garching, West Germany), AC(Space Telescope Science Institute, Baltimore, MD; ESA, Astrophysics Div., Noordwijk, Netherlands)
The star 433 of the Stephenson Sanduleak catalog of emission-line objects has now become one of the most intensively observed sources in the Galaxy. There is evidence that SS 433 is an X-ray binary whose compact component is either a neutron star or a black hole. An investigation has been conducted with the objective to relate the changing details in the H-alpha profile to the moving blobs in the radio jet, taking into account an employment of the Caspec echelle spectrograph on a 3.6 m telescope to monitor the spectrum of SS 433 simultaneously with VLBI measurements of the radio structure. Attention is given to the purpose of the high spectral resolution, preliminary results from the Caspec data, and the results which can be expected from a comparison of optical and VLBI data.
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T Tauri stars through the looking-glass
Finkenzeller, U.; Basri, G.
AA(California, University, Berkeley), AB(California, University, Berkeley)
It is pointed out that the Caspec on the 3.6 m telescope is a very powerful new instrument for high dispersion spectroscopy. It has been used to obtain optical information on a number of T Tauri stars, taking into account calibrated resolved full spectral coverage. Seven low to intermediately active T Tauri stars from the spectral catalog of Appenzeller et al. (1983) have been selected. Two different spectrographs have been used concurrently, including the ESO echelle spectrograph with CCD (Caspec) at the 3.6 m telescope and the IDS at the 1.5 m telescope. It was attempted to cover the most important lines of Ca II and hydrogen along with photospheric lines of all strengths. Attention is also given to details of data processing, line ratios, absolute line and continuum fluxes, the study of chromospheric structure, and a schematic representation of the Eddington-Barbier relation in a spectral line.
Appenzeller, I., Jankovics, I., Krautter, J. 1983, Astron. Astrophys.
Suppl. 53, 291.
Baldwin, J. A., Stone, R.P.S. 1984, M.N.R.A.S. 206,241.
Bouvier, J., Bertout, C. 1985, The Messenger 39, 33.
Carroll, L. MDCCCL.XXI, Through the Looking-Glass and What Alice
Found There, Macmillan.
Gray, D.F. 1976, The Observation and Analysis 01 Stellar Photospheres,
LaBonte, B.J. 1985, Astrophys. J., preprint.
Schwartz, R.D. 1977, Astrophys. J. Suppl. 35, 161.
Strom, S.E. 1983, Revista Mex. Astron. Astrof. 7, 201.
List of ESO Publications
First IRSPEC Spectra
Comet Halley Observed at ESO
El cometa Halley observado en la ESO
Frank Middelburg (1936-1985)
La noticia de la desaparicion de Frank Middelburg, en el dia 15 de Noviembre de 1985, conmovio a tode el mundo astronomico con un sentimiento especial de tristeza. Frank no solo era un experto reconocido en el campo de procesamiento de imagen y un ingeniero de sistemas altamente respetado, tambien era un preciado amigo y colega.