An international network of observation for the International Year of Astronomy

1. J.-E. Arlot, A. Vienne, A.-C. Levasseur-Regourd French Committee for IYA 2009 An international networkof observation for theInternational Year of Astronomy Athens, CAP2007

2. An opportunity • The equinox on Jupiter will take place in 2009 and the French committee for IYA09 will take this opportunity to propose coordinated observations gathered on a unique Internet site providing analysis and global results. Athens, CAP2007

3. The events • The equinox on Jupiter will occur in 2009, allowing the occurrence of many events such as eclipses of the Galilean satellites by the planet Jupiter, occultations and transits and also mutual phenomena among the satellites themselves. Athens, CAP2007

4. When do occur these events? They occur when the planetocentric declination of the Sun and the Earth become zero: it is the equinox on the planet Athens, CAP2007

5. These events are spectacular for everyone. Athens, CAP2007

6. Observations of these events • These events are very easily observable, even with a small telescope and a numerical camera, since the Galilean satellites are very bright. • These events are spectacular since the satellites will disappear within a few seconds. Athens, CAP2007

7. Case of mutual event We will record the quantity of light received from the implied satellites depending on time in UTC within an accuracy of 0.1 second of time Athens, CAP2007

8. Observations worldwide We propose: - that these events be observed worldwide by amateur astronomers, students, pupils - that they send their observation to a central web site which will propose to every observer - an analysis of his observation - provides a data base of all the observations. Athens, CAP2007

9. The Galilean satellites • Many explanations could be provided as on the Galilean satellites themselves (physics and dynamics studied through the observation of such events). • They are among the most interesting bodies (with volcanoes, ice,…) of the solar system, some possibly suitable for life (Europa). Athens, CAP2007

10. History of astronomy • These bodies allow to recall the history of astronomy: the Galilean satellites were the first celestial objects extensively observed from Earth and they became the first reliable clock available for measuring longitudes • They allowed to measure the light speed. Athens, CAP2007

11. Results and publications • At the end of the observational campaign, the results will be emphasized and the scientific benefits from these observations will be explained and published. • Pedagogic material will be made from observations by students and pupils (determination of light speed,…) • Scientific results will be published using amateur astronomers data (IMCCE has the experience of such an association) Athens, CAP2007

12. Conclusion • We must use the opportunity of the Jovian equinox occurring only every 6 years and occurring in 2009. • We should make a pedagogical action with a worldwide echo. Athens, CAP2007