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Events of the Galilean Satellites for January 2012


Table of Events visible from New Zealand for January 2012.

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 January. 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, although they will occur very close to the planet near the time of opposition. After opposition as in January, eclipse events occur to the east 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 planet's 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 January 2012

The table shows the times, in UT, of events visible from New Zealand for January. To convert times to NZDT: for times less than 11 hours UT, add 1 to the hours and take the time as pm NZDT. Thus January 1 at 09:05 UT is 10.05 pm NZDT on January 1. For times after 11 hours UT, add 1 to the date and subtract 11 hours. Thus January 1, 11:07 UT is 12:07 am NZDT on January 2.

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
January 2 09:05, 2 OcD 11:07, 1 OcD 11:36, 2 OcR 11:43, 2 EcD
January 3 09:37, 1 ShI 10:31, 1 TrE 11:47, 1 ShE  
January 4 09:03, 1 EcR      
January 9 11:38, 2 OcD      
January 10 10:14, 1 TrI 11:33, 1 ShI 12:25, 1 TrE  
January 11 08:54, 2 TrE 09:03, 2 ShI 10:10, 3 ShI 10:58, 1 EcR
  Jan 11 cont. 11:27, 2 ShE 12:01, 3 ShE    
January 18 08:59, 2 TrI 09:23, 1 OcD 10:47, 3 TrE 11:27, 2 TrE
  Dec 18 cont. 11:39, 2 ShI      
January 19 08:48, 1 TrE 10:08, 1 ShE    
January 20 08:49, 2 EcR      
January 25 11:18, 1 OcD 11:34, 2 TrI    
January 26 09:55, 1 ShI 10:45, 1 TrE    
January 27 08:45, 2 OcR 09:00, 2 EcD 09:18, 1 EcR 11:27, 2 EcR
January 29 09:55, 3 EcR      

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