GEOS was formed in 1973 from several European groups (French, Italian, Spanish and Belgian). All the members of GEOS have the same aims: to observe variable stars and to analyse their observations themselves.

Other objects are also observed by GEOS: artifical satellites and minor planets, in particular minor-planet occultations. Observations are treated statistically and the procedures allow accidental, and – if there are several observers of the same star – systematic, errors to be corrected, thus improving the accuracy of the results and the light-curves.

This star’s variation was discovered photographically by Romano in 1957. It was included in the GCVS in 1978 as PXCep, and I started to observe it in 1983.

The star is usually at maximum, but on several occasions I was able to observe either a rise or the start of a fall. Finally on 1984 October 21, the first minimum was observed, and then a second one ten days later.

The star’s constant behavior, outside the minima, indicated that is was an EA type of eclipsing binary. The amplitude of the eclipses is about 2.6 mag. Secondary minimum therefore has an amplitude of 0.11 mag., which is undetectable visually.

For the apparition of P/Halley the CNRS set up RCP639 (Cooperative Research Programme), one part of which was to coordinate French amateur work. This carried out a training programme, at first by publishing (with help from ESO) an observational manual (eds: J.L. Heudier, J.C. Merlin and M. Festou), and then by a series of courses covering astrometry, photography, visual magnitude estimation, and drawing of jets. These courses were provided by J.L. Heudier, J.C. Merlin and T. Laverge, and were taken by about 100 observers. The author was asked to undertake the organization of the section so that it might become a permanent network of observers of comets and minor bodies.

Mutual events (occultations or eclipses) of Jupiter’s satellites occur every 6 years. The 1985 series was particularly favourable as it occurred when Jupiter was at opposition. An observing campaign (PHEMU85) was therefore organized by the Bureau des Longitudes, and sponsored by the CNRS under RCP (Coordinated Research Programme) 754.

The interest in observing the events lies in the precise positional information that may be obtained. Conventional (photographic) astrometry gives results to within 400 km, but mutual events give an accuracy of at least 100 km. Observation of mutual events is easy in that the Galilean satellites are bright, so large telescopes do not have to be used, and photoelectric observations in particular can be obtained from urban sites or under poor meteorological conditions. The professional workers generally employed photoelectric photometers or vidicon-type detectors, while amateurs used visual, photographic, photometric and video techniques. Two groups of amateurs were particularly involved, GEOS (European) and GEA (Spain), but individual amateurs also contributed.

Lunar occultations and occultations of stars by planets and asteroids are important tools in determining astrometric information as well as details about the occulting bodies. Successful work requires a relatively large number of small observatories, well-distributed over a large area of the Earth. This is particularly important in occultations by asteroids because the accuracy of the predictions is generally poor.

Cooperation is therefore essential. IOTA/ES (European Section of the International Occultation Timing Association) provides a means of cooperative work, and holds meetings in different European countries about once a year. Eastern European countries are included.

Some results of occultations were presented and future events discussed. A relatively cheap photoelectric system was described, very suitable for amateurs and public observatories.

Amateur observations made since 1977 show that although the ephemerides for the satellites of Jupiter published by the Jet Propulsion Laboratory are more accurate than those in the Astronomical Almanac, there are still small deviations, which may increase with time. Observation of eclipses, transits and occultations, as well as of the mutual phenomena that occur at 6-yearly intervals can provide information for correction of the ephemerides. There appear to be three groups coordinating observations: 1) in Germany, started by P. Ahnert in the early 1960s and now under H.-J. Blasberg; 2) in the U.S.A., started by J. Ashbrook in 1976, and continued by J. Westfall of the ALPO; 3) in Australia and New Zealand, led by B. Loader. These groups appear to work independently, and it would greatly help research on this subject if there were an International Centre for collecting observations of the Jovian satellites – perhaps under the supervision of the IAU – whereby all observations made anywhere in the world would be available to anyone investigating the subject. Paris, where the predictions are calculated, might be a very suitable site for such a centre.

This contribution dealt with the need for international coordination between amateur astronomers and the failure of the IUAA (International Union of Amateur Astronomers) to meet this need. [The substance of this contribution was given in Sky & Telescope,73, 482 (1987 November).The text was not received. – Eds.]

Popular observatories (PO) are an important link between astronomers and the public. Fig.1 represents the flow of information about the Cosmos and the role of POs.

The flow of information about celestial bodies starts with photon emission. The emitted photons carry the information about the moment when they are born. They transfer the encoded information through cosmic space in all directions, among others towards our planet. By ground-based or space-based instruments astronomers decode the information in the photons. The size and shape of celestial bodies are determined with great precision (by photography and interferometry). Direction from which the photons arrive determines the position of their source (astrometry). The amount of photons (photometry), their frequency (spectrophotometry) and the direction of their oscillation (polarimetry) are other information decoded from the incident photons. The observational instruments are the interface between the Cosmos and astronomers’ minds.

Comet P/Halley’s life as a “media event” started long ago, because the first use of communication (in the modern sense of the term) goes back to Rabelais, who published in Patagrueline Prognostication pour l’an 1532:

“And whyth the comete sene laste yeare and the retrograte of Saturne a greate skoundrell shalle die, all weazynge and courd in scabbes, in the hospitall, and at his death there will be horrible warre between cattes and rattes, dogges and hares, faulcons and duckes, monkes and egges.”

Since then ways of spreading ideas have progressed enormously, but comets have remained “fashionable” and each of the last six apparitions of P/Halley has been the occasion of outbursts that are far removed from the scientific view.

Planetariums are continuing to open in Europe and recent years have seen several organizations and meetings devoted to their use. How should a planetarium show be constructed? What are the principles to be followed and the pit-falls to be avoided? This is a problem, because people running planetariums are only rarely astronomers. One great debate centres around the question of whether to use a pre-recorded show or a “live” one.

An automatic show allows a constant level of presentation, however tired or incompetent the lecturer. The Sun rises at the right moment, just as the chosen music starts and either a piece of text or a picture appears. Simultaneous effects can be incorporated, even complicated ones, which often explains a difficult point better.

The glory of the heavens is available to everyone, and anyone, whatever their level of scientific knowledge, is able to appreciate their beauty, poetry and mystery. They are a window to the inaccessible and the unknown and have always attracted attention and aroused Man’s curiosity. This natural fascination for the universe is a precious card in the popularization of astronomy. Three centuries ago, Fontenelle knew how to exploit it in his Entretiens sur la pluralité des mondes, which made him famous. Many others followed him in the 18th and 19th centuries, of which Camille Flammarion may be mentioned especially. Printings of his famous Astronomie Populaire grossed 130000 copies between 1879 and 1924.

Science nowadays does not arouse the same enthusiasm as it did in Flammarion’s day. Since the development of astrophysics, astronomy has become ever more complex, making the task of those who wish to explain new developments more difficult.

Every journal with a small circulation has the same problems and Ciel et Terre is no exception. The basic cause is the same everywhere: the first thousand copies is far more expensive than the second and subsequent thousands by a factor of 6 to 8 times. This obviously arises from the cost of origination of material. All low-circulations journals have the same financial problems.

We have found that it is beneficial to periodically review the following points: the printing process, the format, the frequency, the editorial team, distribution, promotion, subscription fee, etc. In recent years we have found this process to lead to considerable savings.

Some interesting methods of popularizing astronomy in various countries were reviewed, and may be divided into two types: active and passive methods. Active methods include:

1. 1. Astronomy in the countryside. Astronomical camps for both children and grownups, who normally live in towns, to learn basic astronomical facts. (Italy)

2. 2. Astro-puppets. Visitors to an observatory are greeted by puppets (Copernicus, Galileo, etc.) who not only give talks, but also converse with the audience. (Argentina)

3. 3. Hand-operated devices. A simple orrery showing the movement of the Earth, and other devices that viewers operate for themselves. (India)

4. 4. Graphical calendars. Several popular observatories collaborate to produce a yearly calendar showing planetary rising and setting times, etc. (Czechoslovakia)

5. 5. Amateur clubs. High-school and university students became so interested in astronomy that they formed their own group and now produce a magazine and carry out observing, etc. in a country where there is no professional astronomical institution. (Paraguay)

6. 6. An interdisciplinary approach. Various meetings and workshops are arranged to bring together astronomy, physics, biology, geology, etc., leading to a better understanding of modern science. (Japan)

7. 7. Astronomical competitions. Everything from children’s drawings to special tests and papers, sometimes connected with special events. Also awards for the best work of popularization in a given year. (Worldwide)

Passive methods are far more traditional, and include planetarium shows, including special ones for pilgrims (India); special exhibitions; radio and television programmes; public lectures; popular magazines usually edited for special groups of readers. Finally, what about humorous astronomical stories or pictures, is that active or passive?

CEMEA [Centres d’Entraînement aux Méthodes d’Education Active – Centres for Training Methods of Active Education] exists to encourage better understanding of science among teachers, organisers of youth groups, leaders of summer camps, etc. Its activities with regard to astronomy were described.

Support from firms is of increasing importance in amateur astronomy. Two projects were described. In the first, a company running a winter resort in Argentina was persuaded to hold Halley observation sessions at their site in the Cordillera de los Andes. A similar event was later held by the same company at a new resort in southern France. The second project involved interesting a professional journal for construction engineers in producing a special issue devoted to Comet Halley. This was speedily exhausted, most of the demand for back numbers coming not from the engineers themselves but from their families.

In 1982, the Association Astronomique de Franche Comté prepared a slide show entitled “Meet History’s Comet”. This had been so successful, being presented in more than 100 towns, that a second show entitled “Worlds in the Sky” about the Solar System had been prepared and made by an audio-visual workshop. The high cost (20 000 Fr) had been largely covered by a grant.

In order to convey the dimensions and relative scale of the Solar System all sizes and distances are reduced by a factor of 109, resulting in a solar diameter of 1.4m, a diameter of 5 mm for Mercury, and a mean Sun–Pluto distance of close to 6 km. Stainless steel models of the planets (and the Moon) are mounted at appropriate distances from a yellow steel sphere representing the Sun. Ten of these Solar System Promenades have been constructed in Switzerland.

Following the introduction of a videotext system in France using MINITEL terminals, the Association Française d’Astronomie organized an astronomical information service. This covers celestial and space events, location of the planets, lists of societies and clubs, bibliography, etc. A practical demonstration of the system in use was given.

This contribution summarized the situation in the United Kingdom where there are 5 organisations that are concerned with astronomical observation, but where there are hopes that a single unifying committee may be formed. Practical work for pupils was essential and many examples of simple equipment and practical applications were shown.

From 1985 March 26 to April 5, a special public astronomical education campaign was mounted in 16 stations of the Paris Metro. Apart from static displays, items included two planetariums, mirror-making, numerous round-table discussions, astronomical films, etc. Millions of people saw some part of these displays and surveys showed that many returned several times. The event was coordinated by the Association Nationale Science Techniques Jeunesse [National Association for Youth Science and Technology] and involved many official and private bodies, 30 astronomical groups, and 420 employees of the RATP [Régie autonome des transport parisiens – Paris city transport authority].