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Events of the Galilean Satellites for September 2011


Table of Events visible from New Zealand for September 2011.

Events of Jupiter's Galilean Satellites

Eclipses, occultations, transits and shadow transit of all the three inner Galilean satellites will be occurring at regular intervals during September. A table of events visible during the month from NZ is included.

Eclipses occur when a satellite moves through the shadow of Jupiter. As it moves into the shadow the satellite will gradually fade from view and disappear. When it comes out of the shadow a faint spot of light will appear and gradually brighten.
Occultations occur when a satellite moves behind Jupiter as seen from the Earth. Hence during an occultation the satellite is hidden by the planet.
Transits occur when a satellite moves across the face of Jupiter as seen from the Earth.
Shadow transits occur when the shadow of the satellite cast by the Sun moves across the face of the planet

Occultations always start at the western limb of Jupiter and end at the east. Transits always start at the eastern limb of the planet and end at the west. In both cases the satellite will appear to "sink" into the bright limb of Jupiter at the ingress and gradually emerge from the limb of Jupiter at an egress.

In general eclipse events take place when the satellite is a small distance away from Jupiter as seen from the Earth. Before opposition, as in early September, events occur to the west of the planet.

All these events can be observed through a small telescope. Note that when Jupiter is viewed through an undriven telescope its image will drift to the west. This enables the west side of the planet to be determined.

In the case of disappearances into eclipse (EcD) the satellite is likely to be visible as it fades for a minute or two after the predicted time. For reappearances (EcR) the satellite will start to emerge a minute or two before the predicted time.

At present the north pole of Jupiter is tilted slightly towards the Sun. As a result of the slight tilt eclipses and occultations appear to take place to the north of the planets equator, especially noticeable for the outer two satellites. Transits and shadow transits will cross the planet south of the equator. From New Zealand Jupiter's north pole is the lower pole of the planet.

Table of Galilean Satellite events visible from New Zealand for September 2011

The table shows the times, in UT, of events visible from New Zealand for September. To convert times to NZST before the start of NZDT on the 25th: for times greater than 12 hours UT, add 1 to the date and subtract 12 hours. Thus September 1, 12:05 UT is 0:05 am NZST on September 2 and 13:18 UT is 1:18 am. For time less than 12 hours UT, take the time shown as pm NZST. Thus September 4 at 11:42 is simply 11:42 pm on September 4.


After NZDT starts on the morning of September 25, it is necessary to add 1 to the date for times after 11 hours UT and subtract 11 hours. So September 28, 12:09 UT is 1:09am NZDT on September 29. The last event of the month, September 30 at 17:01 UT is on the morning of October 1 at 6.01am NZDT Before 11 hours add 1 to the hours to get the time, pm, NZDT. So September 26 at 09:41 UT is 10:41pm NZDT.

Times of events are adapted from those given by Dave Herald's OCCULT 4 program.

Explanation:
Satellites: 1 = Io, 2 = Europa, 3 = Ganymede, 4 = Callisto.
EcD = Eclipse disappearance, EcR = Eclipse reappearance
OcD = Occultation disappearance, OcR = Occultation reappearance
TrI = Transit Ingress (start), TrE = Transit Egress (end)
ShI = Shadow transit start, ShE = Shadow Transit end.

Date Time UT,  Event Time UT,  Event Time UT,  Event Time UT,  Event
September 1 12:05, 1 ShI 13:18, 1 TrI 14:15, 1 ShE 15:26, 1 TrE
September 2 12:47, 1 OcR      
September 3 15:02, 2 EcD      
September 4 11:42, 3 ShE 14:45, 3 TrI 16:05, 3 TrE  
September 5 12:38, 2 TrI 12:43, 2 ShE 14:59, 2 TrE  
September 7 16:49, 1 EcD      
September 8 13:58, 1 ShI 15:06, 1 TrI 16:09, 1 ShE 17:14, 1 TrE
September 9 11:18, 1 EcD 14:35, 1 OcR    
September 10 11:41, 1 TrE 17:38, 2 EcD    
September 11 13:36, 3 ShI 15:42, 3 ShE    
September 12 12:49, 2 ShI 15:02, 2 TrI 15:19, 2 ShE 17:22, 2 TrE
September 14 11:27, 2 OcR      
September 15 15:52, 1 ShI 16:54, 1 TrI 18:03, 1 ShE  
September 16 13:12, 1 EcD 16:22, 1 OcR    
September 17 10:21, 1 ShI 11:20, 1 TrI 12:31, 1 ShE 13:25, 1 TrE
September 18 10:49, 1 OcR 17:37, 3 ShI    
September 19 15:26, 2 ShI 17:23, 2 TrI 17:55, 2 ShE  
September 21 13:48, 2 OcR      
September 22 11:30, 3 OcD 12:47, 3 OcR 17:46, 1 ShI  
September 23 15:07, 1 EcD      
September 24 12:15, 1 ShI 13:06, 1 TrI 14:25, 1 ShE 15:15, 1 TrE
September 25 12:35, 1 OcR      
September 26 09:41, 1 TrE      
September 28 12:09, 2 EcD 16:07, 2 OcR    
September 29 11:30, 3 EcD 13:35, 3 EcR 14:54, 3 OcD 16:11, 3 OcR
September 30 09:49, 2 ShE 11:11, 2 TrE 17:01, 1 EcD  

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