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Issue 97
Messenger Issue 97

The Messenger Issue 97

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Table of Content No. 97 | 1999
Telescopes and Instrumentation
Tarenghi, M.
News from the VLT.
More...
ADS BibCode: 1999Msngr..97....1T
Authors:
Tarenghi, M.
Abstract:
During the last months, the work at ESO’s Very Large Telescope (VLT) project, both at the Paranal Observatory and in Europe, progressed very well. On the following pages is a brief description of the recent achievements and the activities that will take place in the next months.

Page 1-4 (PDF)
Ettlinger, E., Giordano, P. et al.
Performance of the VLT mirror coating unit.
More...
ADS BibCode: 1999Msngr..97....4E
Authors:
Ettlinger, E.; Giordano, P.; Schneermann, M.
Abstract:
Three sputtered aluminium film on the 8-metre-class mirrors produced in the VLT Coating Unit is very uniform along the whole radius (standard deviation 4.16%). The reflectance in the ultraviolet, visible and infrared regions is near to that which ideally can be expected.

Page 4-8 (PDF)
Sarazin, M., Navarrete, J.
Climate variability and ground-based astronomy: The VLT site flights against La Niña.
More...
ADS BibCode: 1999Msngr..97....8S
Authors:
Sarazin, M.; Navarrete, J.
Abstract:
Hopes were raised two years ago to be soon able to forecast observing conditions and thus efficiently adapt the scheduling of the observing blocks accordingly. In this brave new world, however, not everything is perfect: as if the task of building a detailed knowledge of the sites was not hard enough, climatic events such as the El Niño - La Niña Oscillation can turn decade long databases into poorly representative samples. A reanalysis of the long-term meteorological database pointed out an ever-in-creasing frequency of occurrence of bads seeing associated to a formerly quasi-inexistent NE wind direction.

Page 8-10 (PDF)
Castillo F., C., Serrano G., L.
Analysis of the Anomalous Atmospheric Circulation in Northern Chile During 1998
More...
ADS BibCode: 1999Msngr..97...10C
Authors:
Castillo F., C.; Serrano G., L.

Page 10-10 (PDF)
Ferrari, M., Derie, F.
Variable curvature mirrors
More...
ADS BibCode: 1999Msngr..97...11F
Authors:
Ferrari, M.; Derie, F.
Abstract:
Since the very beginning of the VLTI project, it has been foreseen that observations with this unique interferometer should not be limited to on-axis objects and the possibility to have a “wide” field of view (2 arcsec) was planned. It turned out that the “wide” field of view goal could not be achieved without a precise pupil management.

Page 11-12 (PDF)
Derie, F., Brunetto, E. et al.
The VLTI test siderostats are ready for first light
More...
ADS BibCode: 1999Msngr..97...12D
Authors:
Derie, F.; Brunetto, E.; Ferrari, M.
Abstract:
To allow the technical commissioning of the VLT in its early phases, without the VLT Unit Telescopes or the Auxiliary Telescopes, two test siderostats have been developed to simulate the main functions and interfaces of these telescopes.

Page 12-14 (PDF)
Christou, J. C., Bonnacini, D. et al.
Myopic deconvolution of Adaptive Optics Images
More...
ADS BibCode: 1999Msngr..97...14C
Authors:
Christou, J. C.; Bonnacini, D.; Ageorges, N.; Marchis, F.
Abstract:
Adaptive Optics produces diffractionlimited images, always leaving a residual uncorrected image and sometime PSF artifacts due, e.g., to the deformable mirror. Post-processing is in some cases necessary to complete the correction and fully restore the image. The results of applying a multi-frame iterative deconvolution algorithm to simulated and actual Adaptive Optics data are presented, showing examples of the application and demonstrating the usefulness of the technique in Adaptive Optics image post-processing. The advantage of the algorithm is that the frame-to-frame variability of the PSF is beneficial to its convergence, and the partial knowledge of the calibrated PSF during the observations is fully exploited for the convergence. The analysis considers the aspects of morphology, astrometry, photometry and the effect of noise in the images. Point sources and extended objects are considered.

Page 14-22 (PDF)
ESO
Latest News: “First Light” for VLT High-Resolution Spectrograph UVES
More...
ADS BibCode: 1999Msngr..97...22.
Authors:
ESO
Abstract:
A major new astronomical instrument for the ESO Very Large Telescope at Paranal (Chile), the UVES high-resolution spectrograph, made its first observations of astronomical objects on September 27, 1999. The astronomers are delighted with the quality of the spectra obtained at this moment of “First Light”. Although much fine-tuning still has to be done, this early success promises well for new and exciting science projects with this large European research facility.

Page 22-23 (PDF)
Lamy, H., Hutsemekers, D.
Erratum : A procedure for deriving accurate linear polarimetric measurements
More...
ADS BibCode: 1999Msngr..97...23L
Authors:
Lamy, H.; Hutsemekers, D.
Abstract:
Erratum

Page 23-23 (PDF)
Sterzik, M., Weilenmann, U.
3.6-m Telescope Control System Upgrade Completed
More...
ADS BibCode: 1999Msngr..97...25S
Authors:
Sterzik, M.; Weilenmann, U.
Abstract:
New highlights can be reported from the 3.6-m upgrade project: the full VLTcompliant Telescope Control System (TCS) has been finally tested and commissioned during recent technical-time periods. On August 9th it has been successfully put into routine operation. Let us briefly recall the milestones passed. The "heart" of the telescope, the servo control system for the axis, was completely modified. The telescope control is now based on so-called “Local Control Units” (LCUs), an identical hardware platform to that used at the VLT. It substitutes the over 20 years old TCS running on HP1000 computers. In contrast to the VLT and NTT, the 3.6-m is an equatorial mounted telescope, and the entire control SW had to be modified and adapted for controlling the alpha and delta axis. With the broad usage of standardised architectures and software concepts at the 3.6-m, which were originally designed and developed for the VLT, we intend to gain operational stability, quality, and maintainability. However, it also requires to replace proven components like the old, incremental encoders with optical strip encoders which are required to read the telescope position. The new encoders are supposed to deliver a five times higher resolution, but once we tested the performance of them in practice, we encountered an unexpected problem: in extreme telescope positions, implying several tens of tons of weight on the axis, the tight tolerances (±100 mm) required for reliable readings of the position were exceeded, thus loosing control over the telescope. Through careful adjustment of the heads we were able to restrict the “dead zone” to a very small region in the Northwest. In September, a dynamical mount for the reading heads will be installed, which is expected to completely solve this problem.

Page 25-25 (PDF)
The La Silla News Page
Hainaut, O.
News from the NTT: O. Hainaut and the NTT Team
More...
ADS BibCode: 1999Msngr..97...24H
Authors:
Hainaut, O.
Abstract:
The editors of the La Silla News Page would like to welcome readers of the fourteenth edition of a page devoted to reporting on technical updates and observational achievements at La Silla. We would like this page to inform the astronomical community of changes made to telescopes, instruments, operations, and of instrumental performances that cannot be reported conveniently elsewhere. Contributions and inquiries to this page from the community are most welcome.

Page 24-24 (PDF)
Reports from Observers
Courbin, F., Magain, P. et al.
Deconvolving spectra of lensing galaxies, QSO hosts, and more ...
More...
ADS BibCode: 1999Msngr..97...26C
Authors:
Courbin, F.; Magain, P.; Sohy, S.; Lidman, C.; Meylan, G.
Abstract:
High spatial resolution undoubtedly plays a key role in most major advances in observational astrophysics. In this context, considerable effort has been devoted to the development of numerical methods aimed at improving the spatial resolution of astronomical images. However, the most commonly used techniques (e.g., Richardson 1972, Lucy 1974, Skilling & Bryan 1984) tend to produce the so-called “deconvolution artefacts” (oscillations in the vicinity of high spatial frequency structures) which alter the photometric and astrometric properties of the original data. Recently, Magain, Courbin & Sohy (1998ab; hereafter MCS) proposed and implemented a new deconvolution algorithm which overcomes such drawbacks. Its success is mainly the consequence of a deliberate choice to achieve an improved resolution rather than an infinite one, hence avoiding retrieving spatial frequencies forbidden by the sampling theorem.

Page 26-29 (PDF)
Leisy, P., Francois, P. et al.
Emission-line-object survey in the LMC with the WFI: new faint planetary nebulae
More...
ADS BibCode: 1999Msngr..97...29L
Authors:
Leisy, P.; Francois, P.; Fouqué, P.
Abstract:
The authors' goal is a large survey (10 square degrees in total) of two regions in the SMC and the LMC, to identify new fainter emission-line objects (as PNe, H II regions, Be stars, symbiotic stars, young stars, etc.). They concentrate their efforts mostly on PNe and H II regions. The new candidates allow to derive accurately the full PNe luminosity function in the Magellanic Clouds (MCs), which is still poorly known for faint objects.

Page 29-31 (PDF)
Announcements
ESO
Personnel Movements
More...
ADS BibCode: 1999Msngr..97...31.
Authors:
ESO

Page 31-32 (PDF)
ESO
List of Scientific Preprints
More...
ADS BibCode: 1999Msngr..97R..32.
Authors:
ESO

Page 32-32 (PDF)

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