ADS BibCode:
1981Msngr..25....1H
Author(s)/Affiliation(s):
Hofstadt, D.
AA(ESO)
Abstract:
It is a major challenge for the technical statt at La Silla to handle experimental and unique type of equipments rather than welltested commercial machines. But it is an art to deal with a particular species which is just as unique and very peculiar indeed: the astronomer.

ADS BibCode:
1981Msngr..25....1.
Author(s)/Affiliation(s):
ESO
AA(ESO)
Abstract:
On 26 June, ESO was chosen by ESA to be the host institute for the Space Telescope European Coordinating Facility. There were three other candidates: the Royal ObseNatory at Edinburgh, the Institute of Space Astrophysics at Frascati (Italy) and the Institut d'Astrophysique and the ObseNatoirede Paris in a joint proposal.

ADS BibCode:
1981Msngr..25....2A
Author(s)/Affiliation(s):
Appenzeller, I.; Stahl, O.; Wolf, B.
AA(Landesstemwarte Heidelberg) AB(Landesstemwarte Heidelberg) AC(Landesstemwarte Heidelberg)
Abstract:
The class of bright blue variable stars, which we call "Hubble-Sandage" or "s Dor" variables, contains some of the most luminous stars known in the universe. At maximum light at least their visual brightness may surpass that of any known non-variable star. Because of their high luminosity and since these stars can be distinguished from faint galactic foreground stars by their particular light curves, the identification of such objects in extragalactic systems is relatively easy, and a considerable number of these stars has been discovered in nearby galaxies. Since they can be detected over so large distances, Hubble-Sandage variables could in principle provide a useful tool in the calibration of the extragalactic distance scale and in studies of the physical conditions in extragalactic systems. However, before such investigations can be considered, we first have to learn much more about the nature and structure of these stars. Since all these objects are blue and since as a rule Hubble-Sandage variables are surrounded by dense expanding circumstellar envelopes, spectroscopic observations at ultraviolet wavelengths (where the most common ions in these envelopes have their strongest spectral lines) are particularly important for clarifying the nature of these stars. Therefore, we used the International Ultraviolet Explorer (IUE) satellite to observe some of these objects.

ADS BibCode:
1981Msngr..25....3.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25....5.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25....6I
Author(s)/Affiliation(s):
Imbert, M.; Prevot, L.
AA(Observatoire de Marseille) AB(Observatoire de Marseille)
Abstract:
CORA VEL is a spectrometer specialized for the determination of stellar radial velocities with very high time resolution and high accuracy. The first instrument has been operational since 1977 on the 1 m Swiss telescope at the Haute-Provence Observatory where nearly 20,000 radial velocity measurements have been made by astronomers from the Geneva and Marseille Observatories. Although a preliminary report on the prototype has been given by M. Mayor (THE MESSENGER No. 8, March 1977) it seems interesting to give further information about the instrument's performance: they are exceptional both for accuracy (0.5 km S-1 or better) as weil as for highspeed acquisition (measurements in less than 5 min.) and for sensitivity (Iimiting magnitude B > 13). The efficiency of this technique was so impressive that observing programmes in the southern hemisphere far beyond the limit of classical radial velocity spectrographs could be considered. Therefore a second CORA VEL has been installed at the Cassegrain focus of the 1.54 m Danish telescope at La Silla, and observations took place in January-February 1981. The results obtained during this period are quite I remarkable.

ADS BibCode:
1981Msngr..25....7.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25....8H
Author(s)/Affiliation(s):
Huchtmeier, W. K.; Richter, O. G.; Materne, J.
AA(Max-Planck-Institut für Radioastronomie, Bonn) AB(Max-Planck-Institut für Radioastronomie, Bonn) AC(Institut für Astronomie und Astrophysik, Technische Universität, Berlin)
Abstract:
The large-scale structure of the universe is dominated by clustering. Most galaxies seem to be members of pairs, groups, clusters, and superclusters. To that degree we are able to recognize a hierarchical structure of the universe. Our local group of galaxies (LG) is centred on two large spiral galaxies: the Andromeda nebula and our own galaxy. Three sr:naller galaxies - like M 33 - and at least 23 dwarf galaxies (KraanKorteweg and Tammann, 1979, Astronomische Nachrichten, 300, 181) can be found in the evironment of these two large galaxies. Neighbouring groups have comparable sizes (about 1 Mpc in extent) and comparable numbers of bright members. Small dwarf galaxies cannot at present be observed at great distances.

ADS BibCode:
1981Msngr..25...12A
Author(s)/Affiliation(s):
Auriere, M.
AA(Pic-du-Midi Observatory)
Abstract:
There are numerous astrophysical arguments to stimulate an observer who wishes to study the poorly known central parts of globular clusters. Two considerations are particularly exciting. The theories of dynamical evolution of these stellar systems systematically predict the development of a central singularity; now, if it exists, what is its physical counterpart? In the observational field, we know that at least 15 globular cluster cores are associated with X-ray sources. Such phenomena occur preferentially in concentrated globular clusters. High spatial resolution is needed to disentangle individual stars in the central overcrowded fields. We are currently observing several concentrated globular clusters at Pic-du-Midi Observatory where excellent seeing is not rare. The splendid observations reported at La Silla with the 1.5 m Danish telescope (THE MESSENGER No. 17, p. 14) show that this instrument in its site may be very effective for such research. At any rate, the southern sky is particularly suited for globular cluster studies: it contains more than 100 from the about 140 known galactic globular clusters. Many objects of great interest, as 47 Tuc, the core of which is shown in Fig. 1, are invisible from France.

ADS BibCode:
1981Msngr..25...13.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25...14.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25...16M
Author(s)/Affiliation(s):
Madsen, C.
AA(ESO)
Abstract:
As is weil known to the readers of the MESSENGER, the ESO Sky Atlas Laboratory was established to set up and undertake the production of the ESO/SRC Sky surveys. To fulfil its duties, a number of dark rooms were set up and, after some years of hard work, techniques were developed which permit limited mass-production without sacrificing the quality which has become the hallmark of this project.

ADS BibCode:
1981Msngr..25...19K
Author(s)/Affiliation(s):
Krautter, J.; Gahm, G.
AA(ESO) AB(Stockholm Observatory)
Abstract:
T Tauri stars are low-mass (= 3 M0 pre-main-sequence stars. They have been recognized the first time as an individual group of stars in 1945 by Alfred Joy. They show irregular photometrie variability and are located without exception in, or very close to, dark clouds. In 1958 another pioneer of variablestar research, George Herbig, proposed a number of spectroscopic criteria:

ADS BibCode:
1981Msngr..25...21F
Author(s)/Affiliation(s):
Fricke, K. J.; Kollatschny, W.
AA(Universitäts-Sternwarte Göttingen) AB(Universitäts-Sternwarte Göttingen)
Abstract:
If there is substantial disagreement between an observational result and its expectation from established theory, astronomers tend to speak of a "problem". One of those problems which bothered optical and UV astronomers during the past years is the discrepancy of the observed ratio of the Lya and Hß line intensities with the value of this ratio predicted by simple recombination theory for a photoionized hydrogen gas.

ADS BibCode:
1981Msngr..25...21.
Author(s)/Affiliation(s):
ESO
AA(ESO)
Abstract:
Proceedings of the ESO Conference on "Scientific Importance of High Angular Resolution at Infrared and Optical Wavelengths" Now Available

ADS BibCode:
1981Msngr..25...23.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25...23A
Author(s)/Affiliation(s):
Adam, G.
AA(Observatoire de Lyon)
Abstract:
Between the two world wars, a few people were, surprisingly, still concerned by extraterrestrial problems. One of them was Edwin Hubble, who discovered the so-calied expansion of the universe, after proving the extragalactic nature of the great nearby spiral galaxies. Since then, astronomers have tried to understand the large-scale geometry of that newly opened universe. It is a long and still unsuccessfull story.

ADS BibCode:
1981Msngr..25...26P
Author(s)/Affiliation(s):
Perrier, C.
AA(ESO)
Abstract:
Since visible speckle interferometry has been developed ten years ago, efforts have been made to extend this technique to the infrared range for angular size measurements. Using the experience obtained on Kilt Peak by Sibille, Chelli and Lena (1979, Astronomy and Astrophysics, 79, 315), an IR speckle interferometer has been developed at the La Silla observatory in connection with the installation of the IR photometer designed for the 3.6 m Cassegrain focus.

ADS BibCode:
1981Msngr..25...28.
Author(s)/Affiliation(s):
ESO
AA(ESO)
Abstract:
A revlsed Shapley-Ames catalog of bright galaxies by Allan Sandage and Gustav Tammann has just been published by the Carnegie Institution of Washington.

ADS BibCode:
1981Msngr..25...29D
Author(s)/Affiliation(s):
Diethelm, R.
AA(Astronomisches Institut der Universität Basel)
Abstract:
The MESSENGER contains many articles relerring to exciting celestial objects 01 more or less "exotic" nature. In this note the description 01 the photometric behaviour of only a small group 01 stars is presented, which nevertheless have proven to be important in the quest for measuring distances, and which may hold keys lor the theory 01 stellar evolution. These stars show periodic variations of their apparent brightness due to a radial pulsation instability 01 their outer atmospheres. Commonly they have been divided into two major subgroups, the RR Lyrae stars whose periods lie between a few hours and roughly one day, and the Cepheid variables with periods of more than one day. While the first - also called cluster-type variables - are considered to be members 01 the oldest stellar population 01 our Galaxy, the latter are thought to belong primarily to the younger stellar population.

ADS BibCode:
1981Msngr..25Q..31.
Author(s)/Affiliation(s):
Hofstadt, D.
AA(ESO)
Abstract:
ESO tue seleccionada para alojar el servicio de coordinaci6n europea dei telescopio espacial

ADS BibCode:
1981Msngr..25R..31.
Author(s)/Affiliation(s):
ESO
AA(ESO)

ADS BibCode:
1981Msngr..25S..31.
Author(s)/Affiliation(s):
ESO
AA(ESO)
Abstract:
151. M. W. Pakull: HD 36705 - A New Bright X-ray Emitting RS CVn Star. Astronomy and Astrophysics, Letters. June 1981.