Project Jupiter

1. Generally try to make around 12 observations, more if possible, but cover at least one complete orbit (as judged by when it reaches the maximum separations – resist the temptation to look up the orbital period in a book! After all, this project is to find things for ourselves, not look up information!).
   The observations may be terminated before 12 to 18 sets are obtained if the intermediate results produce an accuracy in determining the mass of Jupiter that is acceptable to the observer.
2. The observing sessions do not have to be on consecutive days. Even when days are planned to be skipped, a skipped observing session due to clouds 10 does not present a hindrance. The same applies to personal affairs that may preclude observing on a given day.
3. The observing sessions need not be equally spaced in time. The program that processes the observing data compensates for skipped days, irregular observation times of day, and so on.
4. Make sure your data is for the same moon. As the moon of your choice for project Jupiter nears Jupiter, its identity may be confused with the other moons. It may be easier to measure and record separations for all of the moons of Jupiter, or to start the observation sessions when the selected moon is at its maximum separation. It is permissible to submit data for more than one of Jupiter’s moons for this Project Jupiter, but separate out the observation data for the different moons on separate Attachment A forms.
5. Transits in front of the planet reveal the different surface brightness of the satellites themselves: Callisto and Ganymede very dark, Io a faint grey, and Europa usually invisible against the bright clouds. Therefore, visual recordings of a satellite in transit, while possible, are not likely.

10 Record show that Galileo’s observations of Jupiter’s moons on January 14, 1610 were not made because it was cloudy. Clouds just do not respect anybody!