Edwin Goffin's original prediction for this event crosses eastern Australia, in a line from about Cairns to Adelaide.

David Herald's OCCULT software suggests a path about 2/3 of a track width further west, and across the Simpson desert.

NEW UPDATE (23 NOVEMBER 1998):

Jan Manek of the Stefanik Observatory, Prague, has computed an update for this event based on 33 astrometric positions from Ron Stone at the US Naval Observatory, Flagstaff Station, and 12 positions from Bill Owen at Table Mountain Observatory obtained between June and November. The update was computed using the HIPPARCOS position of the star. Manek notes that no further astrometry will be available so this may be regarded as a final update.

Manek computes a path which crosses central Queensland (crossing the coast about Townsville), eastern NSW, and eastern Victoria. This path is now a little to the east of Goffin's original prediction. Manek notes that the new path differs substantially from the previous update path (which was well off the Earth) as Ganymed is a nearby asteroid and is subject to strong perturbations.

The uncertainty in the path is about 1.5 track widths, and uncertainty in the time about 15 seconds.

Predicted appulse times are:

• TOWNSVILLE : 16h 31m UT
• MELBOURNE : 16h 36m UT

NOTE:

• Manek predicts a magnitude drop at occultation of about 0.8, rather than the 1.3 predicted by Goffin, based on the V magnitude of the star in the HIPPARCOS catalogue.
• Circles near the track on the map below show the true centreline according to precise OCCULT calculations.

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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