| P.I.1 SATURATION MECHANISM OF THE TURBULENCE AMPLIFICATION USING HIGH SPECTRAL AND ANGULAR RESOLUTION OF VLT AND VLTI Merieme Chadid |
We know from laboratory experiments that the turbulence
level of a gas increases when it is crossed by a shock wave.
The theory correctly predicts the observational amplification rate up to
small Mach numbers (M<3). But, the existence of a supersonic turbulence is
still unknown. Moreover, due to technical limitations, laboratory experiments
cannot provide the solution. In this paper, we provide a
method to determe the amplification rate versus the Mach number by the
observation of strong shock waves occurring within the supersonic atmosphere
of pulsating stars using the spectral high resolution
spectrograph UVES of the VLT instrument. Moreover, some future plans are
mentionned to study semi-quantitatively this physical phenomenon with help of
the high angular resolution VLTi-mode. |
| P.II.1 OPTICAL PARAMETERS FOR HIGH ANGULAR RESOLUTION ASTRONOMY ESTIMATED FROM THE GSM EXPERIMENT AT SEVERAL MAJOR ASTRONOMICAL SITES IN THE WORLD F. Martin, A. Ziad, R. Conan , J. Borgnino & A. Tokovinin |
Performances of ground based astronomical observations are severely limited by atmospheric turbulence. The Generalized Seeing Monitor (GSM) is dedicated to the measurement of the optical parameters which characterize the corrugated wavefront at the ground. These parameters are Fried's parameter, the spatial coherence outerscale of the wavefront, the isoplanatism angle and time(s) constant of the turbulence . The knowledge of these parameters is necessary for definition of adaptive optics systems and long baseline interferometers and for optimization of their implementation.
The GSM instrument consists of four 10-cm telescopes with image analysis devices to sense the angle of arrival fluctuations in one direction.
So, simultaneous angle of arrival estimation at four points of the wavefront are obtained with 5ms time resolution and for sequence of 2mn long data .
A second order statistical analysis (variance, covariance,correlations) of these data leads to the values of the parameters and to their variation during the night (continuous monitoring).
Since September 1997, GSM experiment has been successfully operated at five different important astronomical sites through the world:
La Silla (CHILE-1997), Oukaimeden (MOROCCO-1998), Maydanak (OUZBEKISTAN-1998), Cerro Pachon ( CHILE-1998) and Paranal (CHILE-1998).
The results obtained at these sites , the characteristics of which are somewhat different, will be presented.
This unique GSM data bank concerning the optical parameters , permits comparison of the values of the optical parameters
and show their variability. |
| P.III.1 PROSPECTS FOR A NEW VLBI ANTENNA AT THE ISLAND OF MADEIRA Pedro Augusto |
A telescope at Madeira is a great opportunity to dramatically increase the quality of Very Long
Baseline Interferometry (VLBI) observations, those of the European VLBI Network, in particular.
It would allow the closing of an old infamous 'mid-Atlantic gap' that exists in current VLBI
observations.
We have selected three good sites for more detailed local studies in the future,
one of which should be chosen as the place to build a new radio telescope. A summary of preliminary
results from the studies being undertaken will be presented (meteorological, radio interference, soil
and ground surveys and horizon profiles). |
| P.III.2 OPERATION OF THE IAC GPS WATER VAPOUR MONITOR IN OBSERVATORY CONDITIONS N. Pinilla, M.R. Kidger, J.M. Rodriguez-Espinosa |
We describe the operation of the GPS-based water vapour monitor in the Roque de los Muchachos Observatory (La Palma, Canary Islands). The installation of the monitor is described as well as its practical operation and the steps that have been taken to automate its operation. We describe in detail the programme of verification and tests that have been carried out. We describe some of the problems that have been found with its operation, along with the steps taken to solve them in an isolated observatory environment, showing a sample of results from the water vapour monitoring campaign with the monitor that started in February 2000.
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| P.V.1 PRINCIPAL COMPONENT ANALYSIS APPLIED TO SEEING PREDICTION A. Garcia de Gurtubai, A. M. Varela, C. Muñoz-Tuñon & T.J. Mahoney |
A principal component study is presented of mean temporal values
corresponding to seeing, air temperature, relative humidity, barometric
pressure, wind speeed and wind direction parameters obtained at the Roque de los
Muchachos Observatory (La Palma) during 90 nights in 1999. The main goal
of this analysis is perform a least-squares fit in a six-dimensional space
in order to generate a routine to allow us establish reliable seeing
prediction from the meteorological input data.
In this contibution we present the techniques and the preliminary
results. |
| P.VI.1 ITALIAN SITE TESTING ACTIVITIES IN ANTARTICA L.Valenziano, N.Mandolesi |
We report on the site testing activities performed by Italian researchers
in Antarctica. Antarctica is considered the best astronomical site on our
planet in the Infrared, Submillimetric and Millimetric range. Italy is
involved in astrophysical research in antarctica since the '80s, both from
a sea-level site (Baia Terra Nova) and from the High Plateau (Dome C).
Data were collected at both sites. Comparison within Antarctica and other
site is presented, focussing on the Infrared, Submillimetric and
Millimetric range. |
| P.VI.2 THE POTENTIAL OF THE ISLAND OF MADEIRA FOR OPTICAL ASTRONOMY Pedro Augusto |
Ever since the British study (QJRAS, 1981, 22, 266) conducted in the 1970s when looking for a site to build a new observatory in the Northern Hemisphere, the island of Madeira has been forgotten. And yet, the chosen site (in the Canary islands) is only a short distance from Madeira. As pointed out by then, Madeira (Encumeada Alta) has the best seeing of all sites, half of the time less than 1". This, compared with sites such as the Canary islands or Hawaii with good seeing only one-third to half of the time. The reasons for Encumeada Alta not having a British observatory today had to do with the unfortunate fact that the cloud inversion layer in Madeira is all year floating about the highest peaks, since these in Madeira are only about 1800 m high. In Summer, however, the conditions are excellent for
optical observations. During a whole year, the same British study estimated that about one-third of the time it is possible to conduct good quality optical observations at
Encumeada Alta (compared to half of the year for Hawaii or the Canary islands).
This year, the University of Madeira is planning to build a semi-portable dome-observatory at Encumeada Alta, hoping to determine on-site if the seeing is as good as it used to be
over 20 years ago. Furthermore, a modestly sized 30 cm telescope will be used to produce imaging and spectroscopy of astronomical targets, making the best of the clear nights
available. In the future, if conditions are shown to be worthy, a larger telescope might be placed in a permanent observatory.
We are planning to conduct careful measurements at this and other potential sites in Madeira, using diverse equipment, namely a seeing tower and a meteorological station. Given the lack of data throughout most of the island, it is possible that we uncover an even better site than Encumeada Alta.
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| P.VI.3 SITE CHARACTERIZATION AT THE "OBSERVATORIO GUILLERMO HARO" E. Carrasco, A. Carramiñana, M. Ortiz and S. Pacheco |
The results of a long term site monitoring programme are
presented. The atmospheric extinction in the UBVRI passbands and the sky
brigthness has been measured for several months at the
"Observatorio Guillermo Haro", located in Cananea, Mexico, at 2480m
above sea level. The results of a seeing measurements campaign
using a Differential Image Motion Monitor (DIMM) are also included. The
"Observatorio Guillermo Haro" is one of the two professional
observatories in Mexico. The observatory has been working over a decade and
various site measurements have been reported. Nevertheless, this
site characterization programme shows for the first time
a systematic study of the site conditions. |
| P.VII.1 A MINIMAL WEATHER STATION SET-UP FOR USEFUL OBSERVATORY MICROCLIMATE CHARACTERIZATION T.J. Mahoney, C. Muñoz-Tuñon, A.M. Varela & A.G. de Gurtubai |
A profile is presented of a minimally equipped weather station and
the mode of its operation that would
be useful for characterizing an observatory's microclimate in terms of
latitude, altitude, continentality/oceanicity and topography. The need
for long-term (over decades, not years) continuous monitoring is
stressed. Reference is made to the GTC and other meteorological monitoring
campaigns and suggestions offered on how these can be used as a basis
for further campaigns aimed at characterizing the long-term microclimatology
of astronomical observatories.
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