Edwin Goffin's original prediction indicates an event very favourably placed for south-eastern Australia, the shadow crossing the Adelaide region of south Australia and mid to northern New South Wales.

FINAL UPDATE (3 December 1998):

Jan Manek of the Stefanik Observatoy in Prague has provided a final update for this event based on 11 asteroid positions obtained by Bill Owen at Table Mountain Observatory between September 30 and November 10. The HIPPARCOS position of the star has been used in reductions, thereby essentially reducing any error in the star position to zero.

• This final update gives a path about 0.5 track-widths north of Manek's preliminary update. The track crosses northern Tasmania and the north of the North Island, with Auckland City now a little south of centre. (But see comments below). Observers in this region have a very high probability of observing an occultation. However Manek notes that: "Due to uncertainities, all observers in the northern part of the North Island should try to observe. Tasmania will probably not have a chance due to twilight and the faint target star."
  
  
• Predicted event times remain the same as for the preliminary update; viz:
  
  
  • AUCKLAND, NZ : 09h 55.5m UT
  • TASMANIA : 10h 01m UT
  
  
• Formal uncertainties in the path have dropped from 1.5 to 0.8 path-widths.
  
• Formal uncertainties in the event time are now about 20 seconds.

The event will occur in a dark sky for New Zealand observers. Observers in Tasmania will have problems with twilight as sunset occurs at about 9:35 UT, and the star involved is magnitude 9.6.

IMPORTANT NOTE FOR NORTH ISLAND OBSERVERS:

This is a very important event and it will be crucial that a sufficiently good geographical spread of observers takes place to ensure an excellent diameter/shape result. It will not be helpful if 50 observers within Auckland all time short events, because their proximity will make large amounts of data redundant!

What is needed is for as many observers as possible with portable equipment to take their telescopes to locations other than Auckland City. These locations should be separated from each other by at least 10 km perpendicular to the track. I would strongly encourage more portable observers to make the effort to travel further distances - perhaps even as far as Whangarei or Hamilton - in the interests of obtaining a strong scientific result. It will be crucial that the region between Hamilton and Whangarei is covered adequately by observers.

Remember that if you observe from a temporary site you should set up close to some easily recognised landmark (e.g. a road intersection) so that you will later be able to determine your latitude and longitude (to 1") and height (to 30m) from a NZMS map. Such information will be essential in utilising any timings you obtain.

The uncertainty in the track is now less than one path width. However bear in mind that the path could shift either south or north compared to the path on the map below. Consequently it will be imperative that all observers in the northern half of the North Island also monitor the event very carefully. A negative observation could provide a definitive constraining tangent on the southern location of the occultation track, and hence the planet's diameter.

It would be helpful if observers throughout the region could co-ordinate with each other to avoid people doubling up by observing on the same occultation chord - perhaps Grant Christie and the Auckland Observatory will be able to assist with this(?).

If you observe - and whether you see an occultation or not - it would be very helpful if all observers could fill in a report form. You can download a report form here. Return it to Graham Blow as soon as possible after the event.

Good luck!

UPDATE MAP:

The following map has been prepared using OCCULT software. Manek notes that:

• The path given in OCCULT charts is for mid-latitudes systematically shifted to the north (in the southern hemisphere) by about 20km.
• Circles along the path are OCCULT exactly calculated centerline points!

IMPORTANT NOTE!

Astrometric updates such as these should not be taken as definitive, but rather only as an indication of where the true track may lie relative to the original predicted track. Observers must bear in mind that later astrometry, in which the target star is measured in the same field as the asteroid, may still reveal substantial changes to the predicted track and time of the event. For this reason it is most important that observers far from the predicted track still monitor the event.

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