| VI. Review Paper: THE 'IDEAL' SITE REVISITED FOR FUTURE GROUND BASED TELESCOPE PROJECTS Marc Sarazin |
Extremely Large Telescopes, the next generation of ground
based astronomical facilities, are in the planning
phase in various institutes worldwide. Despite
their massive appearance, these glassy mastodons might be much
more demanding than their predecessors from the environmental point of view,
thereby excluding from the race some of the world's most famous observatories.
The particularities of ELTs relevant to site selection are reviewed and
alternative strategies for global site surveys are discussed. |
| P.VI.2 (poster) 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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| VI.2 ON THE HISTORY OF SEEING MEASUREMENTS AT MOUNT MAIDANAK FOR PERIOD 1970-2000 A. Bayjumanov, S. Ilyasov, Sh. Ehgamberdiev |
Mount Maidanak (Uzbekistan) was selected as result of ten-years site servings made by Ulugh Bek Astronomical Institute of the Uzbek Academy of Scieces and Sternberg Astronomical Institute (Russia). The basic parameter of the atmosphere of a astronomical site (FWHM-the full width at half maximum of the long- exposure stellar image at zenith at wevelenth 500nm) at Mt. Maidanak have been measured by several groups of scientists using different methods and instruments. Those groups give very different values due to the limitation of the methods. In this work we present and compared seeing measurements results carried out for the period from 1970 up to 2000.
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| VI.3 DAYTIME SEEING MEASUREMENTS FOR THE ADVANCED SOLAR TELESCOPE Jacques Maurice Beckers |
The primary goal for the 3 to 4 meter aperture Advanced Solar Telescope, which is currently being designed, is very high angular resolution observations of astrophysical processes visible on the solar surface. It is essential that this telescope be located at a site with superior daytime seeing. I will describe a site survey telescope which measures the signals of the solar equivalent of a Differential Image Motion Monitor (DIMM) and a solar scintillometer. Combining the observations from both allows the measurement of both boundary/ground-based seeing and free atmosphere seeing. Observations at a number of sites in the world will be discussed and preliminary conclusions on the AST siting will be presented
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| VI.4 ASTRONOMICAL PROPERTIES OF THE WISE OBSERVATORY Noah Brosch |
The Wise Observatory operates a 1.0-meter telescope in the central Negev plateau of Israel since 1971. The quality of the site has been monitored almost since the official opening of the Observatory. I shall present records of the atmospheric extinction in the standard optical bands, of the sky brightness and the seeing size, and will describe different observing programs undertaken at the Wise Observatory. I will discuss also the possibility of remote observing with the 1.0-meter telescope (perhaps attemptng a demonstration, if the infrastructure will permit).
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| VI.5 OPTICAL SEEING AT THE MILLIMETER SITE "CERRO LA NEGRA" E. Carrasco, A. Carramiņana, J. L. Aviles and D. Mayya |
The 50m diameter Large Millimeter Telescope (LMT/GTM) is now under
construction at Cerro La Negra, in the state of Puebla, at 4640
meters above sea level. The site, one of the highest peaks of
Central Mexico, located at 19 degrees latitute offers good coverage
of Northern and Southern hemispheres. Cerro La Negra has been extensively
studied for millimeter observations during the last years. We present the
results of the first campaign of optical seeing measurements using a
Differential Image Motion Monitor. The long term goal is to characterize
the site for optical observations. A project to measure the millimeter
seeing is in progress at the site and simultaneous measurements
in both wavelength ranges are planned.
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| VI.6 IR PROPERTIES OF THE GTC 10m TELESCOPE SITE J.M. Rodriguez Espinosa, M.R. Kidger, N. Pinilla |
The selection of the GTC (an advanced 10 metre telescope) site within the ORM has been made
after a thorough campaign of meteorological, seeing, and water vapour monitoring. In this talk
I will dwell mostly on the IR properties of the site based on measurements of the precipitable
water vapour content of the atmosphere above the Observatory. Two techniques have been employed
during most of the campaign. The first one was based in the measurement of an atmospheric water
vapour absorption band in the sun spectrum reflected off the Moon surface. A second technique
consisted in the determination of the sky radiance in several mid infrared bands. At the end of
the campaign, a new technique based on measurements of GPS signal delays was also employed. The
three techniques gave consistent results. After the site campaign it can be said that the GTC site
is an excellent site for thermal infrared observations, with a sizeable fraction of nights
enjoying very low values of precipitable water vapour.
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| VI.7 METHODOLOGY FOR CLIMATIC CARTOGRAPHY Francisco Josi Ferrer |
The information about the climate is of great importance for scientific, economic as well
as environmental fields. However its use has not been widely extended due to a lack of basic
climatic and applicated climatic cartography. The reason for this is the absence of both,
flexible and rigourous methodology in order to generate the information needed for the application
projects. The methodology described here may have important social effects since it migth allow
the supply of enough climatic information for the planning, design and management of several
economical and environmental activities.
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| VI.8 OPTICAL SEEING AND IR TRANSPARENCY IN THE UPPER ATACAMA DESERT Riccardo Giovanelli |
As a result of its interest in building a very large
IR/optical telescope at a high altitude site, Cornell University has undertaken a campaign of atmospheric tests
to ascertain the quality of Upper Atacama Desert sites for
optical and infrared Astronomy. Since early 1998, a series
of seeing runs, complemented by radiosonde launches, have
been carried out at several sites in the vicinity of the
Chajnantor Plateau, which has been chosen as the future site
of ALMA. The seeing measurements have been carried out
initially at the plateau level of 5050 m elevation, followed
by a series of runs at a minor elevation emerging some 150 m above the plateau, and measurements are planned for the
austral Winter of 2000 at a summit near 5400 m. The results
of these measurements, carried out with a Differential Image
Motion Monitoring device which operates at 0.5 micron
wavelength, will be reported. In addition, we shall discuss
the potential impact of the extremely low water vapor
content of the atmosphere on infrared observations. |
| VI.9 RADIO SOLAR OBSERVATORY IN PERU Walter R. Guevara Day |
We present the development and implementation project of the Radio Solar Observatory, that will operate, initially, in the decimetric wide band and to begin the activities radioastronomic in Peru. Furthermore, We will be indicated the different places of our territory where the quality of sky and of the environment are very good for the astronomic observation in the range of radio frequencies, visible and infra red too.
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| VI.10 NIGHTTIME SEEING MEASUREMENTS AT Mt. MAIDANAK WITH A DIFFERENTIAL IMAGE MOTION MONITOR FOR THE PERIOD 1996-2000 Sabit Ilyasov |
Mount Maidanak (66 56' E, 38 41' N) is located 400 km south from
Tashkent (the capital of Uzbekistan). It is an isolated summit at 2600 m
altitude belonging to the Pamir Alai mountain system. The site survey at
Mt. Maidanak started at the end of 60-s and continued up to the
beginning of the 90-s. Measurements of a basic parameter of the
atmosphere of the astronomical site (FWHM: the full width at half
maximum of the long-exposure stellar image et zenith at wavelength
500nm) at Mt. Maidanak have been repeatedly made by several groups of
researchers using different methods and instruments. But those groups
give slightly different values due to the limitation of the methods and
systematic errors of the instruments used. In this work we present the
results of the nighttime seeing measurements obtained at Mt.Maidanak
for the period from August 1996 up to March 2000. Measurements were
carried out with a Differential Image Motion Monitor (DIMM). The results
were compared to the estimates of seeing obtained with a similar DIMM at
La Silla and Paranal Observatories in Chile for the period 1989-1995.
The median value of the seeing at Mt. Maidanak for the entire period of
observations is 0.69 arcsec. For the La Silla and Paranal Observatories,
the value of this parameter are 0.87 and 0.66 arcsec, respectively. It
is indicated that Mt. Maidanak is one of the most favourable site for
high-resolution astronomical observations in the world.
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| VI.11 GSM CAMPAIGN AT OUKAIMEDEN I- OPTICAL CHARACTERIZATION OF THE SITE Abdelhadi Jabiri |
A measurements campaign is carried out at Oukaimeden
site, in collaboration with the Astrophysics Department
of Nice University. The monitoring of the Atmospheric
Optical Paramaters (AOP) like the spatial-coherence outer
scale, the seeing and the isoplanatic angle is achieved
during 10 nights in April 1998 with the GSM instrument
(Generalized Seeing Monitor). This instrument equipped
with 4 identical modules, based on the observation of
the angle of arrival fluctuations, allows the analysis
of perturbed wave front at four points. The main results
of the AOP parameters obtained during this campaign are
presented and discussed.
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| VI.12 THE CONTRIBUTION OF INDIVIDUAL ATMOSPHERIC LAYERS TO OPTICAL INSTABILITY OVER VARIOUS REGIONS OF THE NIS COUNTRIES AS DEDUCTED FROM AEROLOGY DATA Pavel Kovadlo |
This paper investigates large-scale characteristics of
optical instability of the Earth's atmosphere up to 30.5 km
altitude calculated from network aerology data for the NIS
(New Independent States) territory. An estimate is made of
the contribution of the boundary layer and the free atmosphere
to optical instability over different regions during one year. The mean duration of optically quiet periods in the atmosphere is determined. It is found that over the territory of yakutia and the Far East the optical instability fluctuations have a double annual cycle.
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| VI.13 NEW ASTRONOMICAL STATION OF VALENCIA UNIVERSITY OBSERVATORY A. Lopez Garcia, J.A. Moraqo Fernandez, J. Pastor Erades, Flores Martinez |
Valencia University Observatory holds a joint project with amateur 'Asociacion Valenciana de Astronomia' (AVA) to operate several telescopes at 'Centro Astronomico del Alto Turia' (CAAT), a new astronomical station 100 km far from Valencia at a 1300 meters high plateau.
First telescope, a double 30-20 cm refractor of 3 meters focal length, is operative since may 1998.
Second telescope, a 50 cm reflector, will be placed on mountain by the end of 2000.
Both telescopes will be dedicated mainly to minor planets and comets astrometry and photometry research projects as well as students and doctoral fellows training on new instruments and observing programs.
Astronomical and climate conditions of this and other previously selected sites are described.
The influence of seasonal and daily conditions on astrometric and photometric results is investigated in order to get the best results with these telescopes and the limit site conditions for a bigger instrument (one meter wide) to be placed at CAAT in the next years.
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| VI.14 SITE SURVEYING FOR THE FAST IN GUIZHOU PROVINCE OF CHINA Rendong Nan |
Five hundred meter Aperture Spherical Telescope (FAST) has
been proposed for construction in the unique Kast area of
southwest China. FAST is an Arecibo-type antenna with a number
of technical innovations. At least 400 Karst depressions
were investigated with Remote Sensing and the Geographical
Information System, and selected as the canditates for the
telescope site locations. More than ten depressions were
imaged at a resolution of 5 m/pixel, showing suitable
profiles for large spherical reflector. The analysis on
the hydrogeology, engineering geology, and resource environments also shows advantage of the region as the site
location of the project FAST. |
| P.VI.3 (poster) 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. |
| VI.16 SITE SURVEY AT CHAJNANTOR FOR THE ALMA PROJECT Angel Otarola |
Chajnantor has been selected as the site for the Atacama Large Millimeter
Array (ALMA). Site surveying has been going on since 1995 as a shared effort
between ESO, NRAO and NRO, with contributions from Onsala Space Observatory,
Mullard Radio Astronomy Observatory, CfA and Cornell.
The instruments presently deployed at Chajnantor are: two 183 GHz water line
radiometers, two radio seeing monitors, 225 GHz and 850 GHz tipping radiometers,
weather stations, a double frequency GPS receiver, surveillance cameras and a
seismometer. The monitoring of atmospheric parameters have been complemented with radiosonde measurements to perform studies on the location and variation of the turbulent layer. During the period 1998-1999 the CfA group installed and operated in a collaborative effort a Fourier Transform Spectrometer (FTS) to monitor the atmospheric transmission in the range 300 GHz to 3 THz.
Here we will give a short description of the instruments available at Chajnantor, the Local Area Network (LAN) implemented to link all the individual data aquisition computers and the GPS-based time signal used for time synchronisation of the computers in the network.
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| VI.17 INDIAN ASTRONOMICAL OBSERVATORY, HANLE R. Cowsik, R. Srinivasan &T.P. Prabhu |
The Indian Astronomical Observatory, Hanle, is the high-altitude (4500 m) astronomical station of the Indian Institute of Astrophysics, Bangalore, situated in Ladakh region of Himalayas (32d 47m 46s N latitude and 78d 57m 51s E longitude). The site is being characterised since 1995 and is being developed for astronomy beginning with a 2-m telescope to be installed in September 2000 and a 50-cm photometric telescope to be set up in collaboration with the Washington University, St. Louis, shortly thereafter.
The site survey data available consists of information on clouds since 1995 January, Automated Weather Station data since 1996 July, periodic measurements of seeing since 1998 July, and 220-GHz radiometric data since 1999 December. There is also some additional information available on sky brightness, atmospheric aerosols and water vapour content.
The available information is summarized below:
Number of spectroscopic nights: 256 per year
Number of photometric nights: 193 per year
Annual precipitation (rain+snow) : <10cm
Low ambient temperature and relative humidity
Low concentration of atmospheric aerosols
Low atmospheric water vapour
Dark skies and low pollution
Median seeing : 1 arcsec or better
The general conditions at the site make it appear a twin of Andese region in northern Chile which is antipodal to Hanle.
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| VI.18 THE GALILEO TELESCOPE AT ORM: SITE CHARACTERIZATION Ignazio Porceddu |
Temperature gradients, wind and relative humidity represent a small although significative signature of the site where a telescope is being operated.
Such a basic meteorological parameters at ORM can be pretty variable when different observing sites are considered.
Here we present a characterization of the Italian National Telescope "Galileo", where a comparison is done with data coming from other ORM sites.
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| VI.19 STUDY ON THE ENVIRONMENT OF THE KARST REGION FOR THE FAST (FIVE HUNDRED METER APERTURE SPHERICAL RADIO TELESCOPE) SITE Yuhai Qiu |
There are many karst depressions in the south of Guizhou province, one of those might be selected as the site of FAST project. A series of radio interference measurements and climate survey at several depressions have been carried out for study of the environment of FAST site. The result of such survey looks quite promising.
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| VI.20 COMPARISON OF THE PAMPA LA BOLA AND LLANO DE CHAJNANTOR SITES IN NORTHERN CHILE Seiichi Sakamoto |
We have been monitoring since 1996 meteorological conditions at two possible LMSA/ALMA sites –
Pampa la Bola and Llano de Chajnantor – in northern Chile. Identical weather stations were used to
monitor wind speed, wind direction, atmospheric temperature, relative humidity, and solar radiation flux
every 20 minutes. Appearances of the diurnal and seasonal variations of these parameters are found to be
basically the same, except that, at Llano de Chajnantor, (1) the wind is marginally stronger, (2) the
turbulent wake is slightly smaller, (3) the surface water vapor pressure is marginally higher, and (4)
the fraction of fine weather estimated from solar radiation flux is marginally lower. Inversion of the
surface temperature due to the inversion layer was observed in the summer mornings. Through comparison
of the 220 GHz atmospheric transmission at Pampa la Bola with that measured at Llano de Chajnantor by
the NRAO, the atmospheric transparency was found slightly better at Llano de Chajnantor, possibly reflecting
the difference of the fractional time above the inversion layer. Any of the aforementioned site-to-site
differences, however, are much smaller than the diurnal and seasonal variations at each site.
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| VI.21 ASTRONOMICAL OBSERVATIONS AT MILLIMETER AND SUB-MILLIMETER WAVELENGTHS AT OWIENAT MOUNTAIN, EGYPT Mosalam Shaltout |
In recent years, there is a developments in the techniques and instrumentation used for ground-based astronomical observations at millimeter and sub-millimeter wavelengths. The wavelength band of interest (5mm to 300um) is determined both by the nature of the instrumentation, and by the opacity of the earth’s atmosphere. Plans for construction of a large millimeter and sub-millimeter wavelength telescopes are progressing rapidly in Europe, Japan, and the United States, and discussions of collaboration between the various projects are already underway. The Eastern part of Owienat Mountain is located in the Western - Southern corner of Egypt with coordinates (Latitude 22o 10\ N, longitude 25o 10\ E).
The elevation is more than 1500 m over the sea level. It is not in the mid-way between the Western Europe and South Africa only, but it completely satisfy two important conditions for the millimeter and sub-millimeter observations are:
- The site is very far from population centers, which affords it a degree of freedom from artificial interference . - High frequency waves are harder to transmit and receive and they are hindered by moisture in the earth’s atmosphere . Owienat Mountain located in the heart of he greatest desert (Sahara) in the north of Africa , it is the driest site in the world. Owienat atmospheric transparency is excellent , and the site almost cloudless all the year round , where the total sky cover is one Oktas as annual mean. The suggested telescope is similar to 30m radio telescope built in 1985 by Max-Planck- Institute for Radio astronomy in Bonn , Germany and constructed below the mountain top of Pico Veleta ( Sierra Nevada in Southern Spain ). This 30 m radio telescope for astronomical observations in the lower mm wavelength range. With its excellent surface accuracy this telescope can be used down to a wavelength of 0.87 mm. |
| VI.22 SITE TESTING FOR THE UPSO-TIFR OPTICAL TELESCOPE IN DEVASTHAL Chelliah Subramonia Stalin & Ram Sagar |
This presentation gives the results of the site testing observations carried
out during 1997-99 for locating the 3 m UPSO-TIFR modern optical telescope.
Based on an extensive site survey conducted during 1980 - 1990 in the Shivalik
Hills of the Central Himalayan range, a promising site Devasthal
(longitude = 79 41'E , latitude = 29 23'N) has
been identified. The surroundings of Devasthal are thinly populated and it is
logistically well suited for establishing modern optical observational
facilities. Meteorological measurements show the prevailing wind direction at Devasthal as NW. For a large fraction of the night time, variation in the ambient temperature is less than a degree and wind speed is less than 10 m/s. During spectroscopic nights (>200 in a year) relative humidity is less than 80% for about 70% of the time. Seeing measurements using Differential Image Motion (DIMM) techniques have been carried out close to ground at two locations namely Site 1 (Altitude = 2420 m) and Site 2 (Altitude = 2540 m) in Devasthal during 1997 to 1999. Our observations for Site 1 carried over 88 nights (during 1997 and 1998) yield a median seeing value of 1.4". For Devasthal Site 2, observations carried over 80 nights (during 1998 and 1999) yield a median seeing value of 1.1". Devasthal Site 2 has therefore been selected for locating a modern 3m optical telescope. Microthermal measurements carried out quasi-simultaneously with DIMM both at Site 1 and Site 2 showed that the major contribution to seeing comes from the 6-12m slab above ground of the atmosphere and significant gain in seeing (about 0.6") can be achieved by locating the telescope at a height of about 13m above the ground. Atmospheric extinction at Devasthal are 0.40 +/- 0.01, 0.22 +/- 0.01, 0.12 +/- 0.01 and 0.06 +/- 0.01 in Johnson U, B, V and R bands respectively. |
| VI.23 NON TECHNICAL CONSIDERATIONS IN THE SITTING OF ASTRONOMICAL TELESCOPES Paul Vanden Bout |
Modern techniques for characterizing the atmosphere have allowed astronomers to transform site selection into more of a science and less of an art. Nevertheless, non-technical considerations still play a major role in telescope site selection. These are largely political in nature. National interests, environmental concerns, operational considerations, demands of those providing funds, and personal preferences can have an overwhelming effect on site choice, for better or for worse. Examples are given of telescopes that benefitted and were harmed by considerations well outside the purely technical aspects we can now define with greater and greater precision.
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| VI.24 SITE MONITORING RESULTS AT THE TEIDE OBSERVATORY A. M. Varela, C. Munoz-Tunon, A. G. de Gurtubai, T. J. Mahoney |
There are very few sites in the world that combine both the
climatological conditions and image quality required for
astronomical observations. The Observatorio del Teide (OT) at Tenerife and
the Observatorio del Roque de los Muchachos at La Palma in the Canaries
are among those that have also attracted the construction of new-generation
large telescopes. So far, more than thirty scientific
institutions from fourteen countries have installed telescopes and
astronomical instrumentation at the canarian observatories.
Statistical results are presented for a long-period database at the Observatorio
del Teide and allow us to confirm the OT as one of the best observatories in
the world, with typically sub-arcsecond mean and median seeing values (~0.7"),
reaching values better than 1" in a 80% of cases and with favourable
meteorological conditions. |
| VI.25 ASTRONOMICAL SITES IN UKRAINE: GROUND BASED TELESCOPES LIGHT AND RADIO POLLUTION Vavilova I.B., Konovalenko A.A., Tarady V.K., Yatskiv Ya.S |
The problem of a light/radio pollution at the astronomical sites in Ukraine (university observatories,
largest decametric radio telescope UTR-2 near Kharkiv,
Crimean astrophysical observatory, radio telescopes RT-22 and RT-70 in Crimea, Main astronomical observatory near Kyiv, 2-m telescope at the Peak Terscol at the Northern Caucasus)is analysed for each of these sites.
Methods to overcome some aspects of this problem are presented.
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| VI.26 SITE TESTING IN CHILE FOR THE EXTREMELY LARGE TELESCOPE Alistair Walker |
In 1999 CTIO initiated a systematic investigation of
the Atacama region of Northern Chile in the context of
locating a site for the Extremely Large Telescope (30-100 m). The site testing plans have evolved, following the
setting up of collaborations both within the US and with
ESO. I will present an overview of this program. |
| P.VI.1 (poster) 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. |