Observational campaign of the mutual phenomena of Saturn's and Jupiter’s satellites

Presentation

Mutual phenomena occur when the Earth and the Sun pass through the common plane of the orbits of the satellites: this configuration takes place when the Sun and the Earth pass in the orbital plane of the satellites, a plane close to the equatorial plane of the planet. These phenomena therefore take place around the date of the equinox on the planet.

PHEMU-PHESAT 2024-2025-2026-2027
Equinox on Jupiter in 2026 and on Saturn in 2025

Mutual phenomena occur when the Earth and the Sun pass through the common plane of the orbits of the satellites: this configuration takes place when the Sun and the Earth pass in the orbital plane of the satellites, a plane close to the equatorial plane of the planet. These phenomena therefore take place around the date of the equinox on the planet.

From 2024 to 2027, a series of eclipses and occultations will occur among the main satellites of Saturn and Jupiter due to the arrival of the equinox on these planets on May 7, 2025 and December 16, 2026, respectively. Observing these phenomena can provide valuable data and is possible even with a small telescope. However, in order to obtain scientifically usable data, it is necessary to follow a very rigorous observation protocol.

In 2015 and 2021, previous observation campaigns of the mutual phenomena of Jupiter's Galilean satellites took place. In 2015, 442 events were observable between September 1, 2014 and July 20, 2015. During this campaign (PHEMU15), 236 phenomena were observed. The same phenomenon was recorded up to 17 times, and we received more than 600 light curves. In 2021 (PHEMU21 campaign), conditions were much less favorable and only 40 phenomena could be observed.

The previous campaign to observe the mutual phenomena of Saturn's satellites took place in 2009. The observation conditions were unfavorable (equinox too close to the conjunction) and only 33 phenomena could be observed

The next mutual phenomena of Saturn's satellites will occur between May 2024 and February 2026 and those of Jupiter's satellites from May 2026 to August 2027. Observation conditions will be better for Jupiter than for Saturn due to the distance separating the equinox of the conjunction.

All the information will be found below (local prediction sites for phenomena, observation protocol). Most of this information is presented for the satellites of Jupiter but is obviously valid for the satellites of Saturn.

The observer’s guidebook

• A short guide providing tips for efficient observations
• Talks given at the workshop on the mutual events which to21ok place on February 6, 2021 on the Phemu21 campaign (in French)

Interactive tools for the observers

• Phenomena of the natural planetary: dates and visibility (ssp)
• Phenomena of the natural planetary satellites: dates and visibility (Multisat)
• Configurations and positions of the satellites of Jupiter
• Make yourself the prediction of events for the period of time you wish (caution, it takes more time)

For Jupiter's satellites: you may send your observations through the dedicated webpage
For Saturn's satellites (or for the Jupiter's ones if you did not succeedthrough the dedicated webpage): download the observation form, fill it in and send it back together with the data for each observed phenomenon to phemu@imcce.fr.

PHEMU Technical notes

• Technical note n°1: Presentation of the Galilean satellites of Jupiter and of their mutual phenomena
• Technical note n°2: Presentation of Saturn’s and Uranus’ satellites (in prep.)
• Technical note n°3: The photometric observation of the mutual events
• Technical note n°4: The observation of mutual events using a video camera
• Technical note n°5: The observation of mutual events using a CCD camera
• Technical note n°6: Examples of light curves
• Technical note n°7: The visual observation of mutual phenomena
• Technical note n°8: Bibliography related to the mutual events of the Galilean satellites
• Technical note n°9: Bibliographic note about mutual events in the Saturn, Uranus and Pluto-Charon systems
• Technical note n°10: The observation of the eclipses of Amalthea J-6 (in prep., please contact us)

Scientific and pedagogic documents

• Presentation of the satellites, the mutual phenomena and their observations (in french)
• Astrometry through photometry: Application to natural planetary satellites and Solar System objects (in english)
• Peer-reviewed article on the past and future mutual events
• Peer-reviewed article on the mutual events observed in 2015 (satellites of Jupiter)
• Peer-reviewed article on the mutual events observed in 2021 (satellites of Jupiter)
• Peer-reviewed article on the mutual events observed in 2009 (satellites of Saturn)

Past colloquiums and workshops on the mutual events

• Worshop held on February 6, 2021: presentations available on Gemini Prom-Am site
• WETO 2014: Week-End Technique Occultations “Phénomènes mutuels”, Paris 29 et 30 mars 2014
• École d’astrométrie franco-chinoise, Pékin, Chine, 7-11 avril 2008

Contact: phemu.imcce@obspm.fr

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