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Early in on the morning of 12th August 2009, the only total eclipse of a Jovian moon this year will be observable from the UK if the weather permits....
The eclipse will happen when the shadow of Ganymede moves across the disk of Europa, the event will start with first contact at 01:44:48 and end at 02:02:27 UT (02:44:48 - 03:02:27 BST) with the period of totality being 62 seconds. Unfortunately this is a Wednesday morning and those taking the opportunity to observe this event will probably not be at their best for the rest of the normal working day.
The event should be visible in a small telescope, if you can normally see the Galilean moons you should be able to see the effects of this. The moons will get ever closer and then Europa will start to fade and disappear just before they meet, Europa will then to fade in again up to full brightness, slightly after the end of the eclipse, Ganymede will partially occult Europa.
The animation below is a simulation of what you might see with a large amateur telescope, minus the atmospheric extinction and disturbances, the event has been speeded up by 122 times.
 Simulation of what you might see with a large telescope
The approximate timings (UT) for these events are:
Eclipse P1: 01:44:48
(the penumbra of Ganymede's shadow first touches the disk of Europa)
Eclipse U1: 01:46:21
(the umbra of Ganymede's shadow first touches the disk of Europa)
Eclipse U2: 01:52:58
(totality starts, the umbra of Ganymede's shadow completely covers the disk of Europa)
Eclipse U3: 01:54:00
(totality ends, the umbra of Ganymede's shadow starts to uncover the disk of Europa)
Eclipse U4: 02:00:42
(the umbra of Ganymede's shadow leaves the disk of Europa)
Eclipse P4: 02:02:27
(the penumbra of Ganymede's shadow leaves the disk of Europa)
Occultation first contact: 02:05:12
(the leading limb of Ganymede first touches the limb of Europa)
Occultation last contact: 02:17:00
(the trailing limb of Ganymede leaves the limb of Europa)
The animation below is a close-up view of these events, giving a clearer view of what will be happening. Again this is speeded-up.
 Close-up simulation of Ganymede and Europa
While all of those rare events are going on, and more commonly, the moon Io will be casting it’s own shadow and transiting across the disk of Jupiter itself, Io’s eclipsing starts at 01:11:00, followed by the start of it’s transit at: 01:14:30. The eclipse ends at: 03:32:36 and transit ends at: 03:36:36, ending a busy night for Jupiter and it’s Galilean moons.
 Io transiting the disk of Jupiter and casting it's shadow.
If anybody manages to get images of these events, please contact the Webmaster to have them posted on the website.
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