Abstract. Generally speaking, variable stars are
monitored through multi-site
observing campaigns which coordinate telescopes at various
longitudes. A new practice is to use networks of
robotic telescopes devoted to these programmes.
In the first issue of African Skies/Cieux Africains we
discussed the advantages and drawbacks of such campaigns.
In this issue we
describe the NORT (Network of Oriental Robotic Telescopes) project
which we are promoting in North African and Middle-Eastern countries.
Sommaire. Généralement, des campagnes d'observation mettant en jeu des télescopes répartis sur plusieurs sites de différentes longitudes sont organisées pour observer les étoiles variables. Une nouvelle technologie se développe; il s
'agit de réseaux consacrés à l'observation des étoiles variables et impliquant des télescopes automatisés.
Dans le premier numéro de African Skies/Cieux Africains nous avons
discuté les avantages et les inconvénients des campagnes. Dans ce numéro nous décrirons le NORT (Réseau de Télescopes Robotisés en Pays d'Orient) que nous promouvons en Afrique du Nord
et dans les Pays d'Orient.
(This paper is updated from the Proceedings of IAU Symposium 177 on ``The Carbon Star Phenomenon,'' held on May 27-31, 1996, in Antalya, Turkey; editor: Robert F. Wing; to be published by Kluwer).
Global networks of automated telescopes (GNATs) were proposed by Budding (1993, 1995), Crawford (1992, 1993, 1995), Querci and Querci (1991), Querci et al. (1993, 1995a,b) and Querci (1995). Here we would like to describe the philosophy of the NORT project, which is a network of 1.5- to 2.0-m automated telescopes for photometric and spectrographic research dedicated to variable stars, and which are to be installed at high-altitude desert sites from Morocco to China.
The NORT will mainly deal with variable objects such as red giants, planetary nebulae and post-novae, to stimulate asteroseismology of long-period variables and to contribute to progress in our understanding of these objects. Examples of scientific objectives for robotic telescopes are given in Querci and Querci (1997a).
As various characteristic times of variation have to be searched for, continuous monitoring of selected typical objects is required. This requirement can only be satisfied through having telescopes at the ``best'' sites, i.e. semi-desert countries, around the world.
A number of such countries lie along the tropic of Cancer, from Morocco to the Chinese deserts. The longitude interval they cover is complementary to that covered by the USA, where robotic telescopes already exist. Although a number of these oriental countries had great astronomers in the past, few are now actively participating in astrophysical research. However, their universities, their sites (high mountains in semi-desert climate) and their desire for development can provide strong support for progress in astrophysics.
In the NORT project, we propose :
All the equipment will be fully robotic. Each day, all the collected observations will be transmitted directly to all the universities and members of the network via the Internet and/or ARABSAT. The data reduction and interpretation could be done jointly, thus further promoting shared scientific and technical progress.
This network is supported by :
The oriental countries are suitable because they have high mountains (3000 - 4000 m) in semi-desert areas (north-tropical latitude from 15° to 35° ), and consequently a large number of nights each year with a clear sky and low telluric absorption. Furthermore, these countries are in a longitude interval (about 10° West to 110° East) complementary to some automated stations already devoted to variable star research at sites in Hawaii, Arizona, Chile, Italy, and South Africa.
In using 12-year archives of METEOSAT and NOAA data, we
discovered
a set of meteorologically very good sites (Figure 1) from Morocco to the
Taklamakan and
Gobi deserts in China. The selected sites should ideally be subjected to
different airstreams.
The pre-selected sites for the NORT project are shown in Figure 2. In order of increasing longitude they are: the High Atlas in Morocco,
Hoggar in Algeria, Sinaï in Egypt, northern Saudi Arabia, Yemen, Oman, Iran,
northern Pakistan, India and western China.
The final site selection will be based on local astronomical tests such as seeing measurements. A minimum number of stations should be able to follow the variable stars each night, without interruption, throughout the year. Also, the accessibility of these sites will evidently be a significant factor in the selection (Querci and Querci, 1997b).
We propose an outline for a decade of collaboration on variable star
research as follows:
- firstly, by obtaining time-series photometry, which measures the stellar
flux variation at specific wavelengths and leads to knowledge of
the evolution and the internal structure of the stars,
- later, by spectrography which, in its low resolution modes, yields the
stellar abundance variations, and, in its high resolution modes, is able
to give the physical parameters of the stars and their dynamical
behaviour,
- and, finally, by interferometry at visible wavelengths to obtain the
diameter variations of the stars and detailed descriptions of
their external layers. There exists also the possibility of the
serendipitous discovery of extra-solar planets through the use of this
technique.
A French committee was created within the CNRS in October 1994 to deal with the educational aspects of the project. Doctoral students are jointly supervised by the student's home institute and this committee. The committee comprises 8 members who are professors in astronomy and astrophysics, astrophysicists specializing in instrumentation, and theoretical astrophysicists specializing in stellar variability. The technical training courses have already been held at OHP. PhD theses of North African and Middle-Eastern students are in progress on stellar variability of various spectral-type stars. The students are sponsored by grants from their home institutions or French Embassies.
Many 60-cm diameter telescopes dedicated to the training of students from Universities and youth science clubs are currently in operation in these countries. Furthermore, the mechanical structure calculations of 1.5- to 2.0-m diameter scientific telescopes for the NORT project have been completed at OMP.
During the ``First International Conference on Space and
Astronomy'' held in Amman, Hachemite Kingdom of Jordan, in September
1994, scientific discussions took place between astronomers from (by longitude):
Morocco, France, Libya, Egypt, Lebanon, Iraq, Jordan, and Yemen, on the astrophysical research projects that should be done with networks.
The Second Arab Astronomical Conference, also held in Amman in September
1997, included the NORT project in its recommendations: ``Supporting Prof. François Querci's proposition concerning the NORT activities in the Arab World, which aims at increasing scientific and technological cooperation with this network."
Contacts are in progress with numerous countries, among them with the following African ones (by
longitude): Mauritania, Morocco, Algeria, Tunisia, Libya and Egypt. If
scientists from other African countries are interested, they are welcome to
participate.
This project was endorsed by the United Nations Committee on the Peaceful Uses of Outer Space, at its General Assembly in December 1996 following the sixth UN/ESA Workshop on Basic Space Science: Ground-based and Space-borne Astronomy (Bonn, Germany, 9-13 September 1996, Kluwer Publ.).
We had this idea of a Network of Oriental Robotic Telescopes some years ago. We told our Moroccan colleagues about it and one of us (F.Q.) visited some oriental countries. If the project succeeds, as we hope it will, it should allow several oriental countries to leapfrog into contemporary astrophysics through the pursuit of progressive scientific development and research, as emphasized by Querci and Querci (1997a).
We should like to emphasize the fact that long-term monitoring of variable stars through global automated dedicated networks has implications for a ``new field of astronomy - astroeconomics,'' according to Budding (1995) and Crawford (1995). Owing to scheduling and other constraints at major observatories, current multi-site campaigns allow intensive monitoring of variable stars for a very limited period - usually one to two weeks per annum. A number of asteroseismology space missions are planned which will allow dedicated monitoring over much longer periods. However, the small aperture of these spaceborne telescopes and the limited mission lifetime (typically a few years), means that the benefits of such missions will be limited. Global networks of automatic telescopes will therefore play an increasingly important role in the exploration of the exciting astrophysical domain of time-variable phenomena.
Finally, by detecting the critical phases of variability of the studied objects through permanent follow-up, the networks will promote a new type of collaboration with the large-scale facilities (e.g. very large optical/IR telescopes, long-baseline interferometers, or the Hubble Space Telescope) required at these critical phases. In this way networks of small and medium sized telescopes may be used to initiate astronomically developing countries into the very sophisticated and expensive technologies used at international large-scale facilities.
