This prediction update has been computed by Graham Blow based on astrometry from Alex Liu in Western Australia. The ACT position of the target star has been used.

Summary:

Note that the astrometric reduction has been carried out against GSC star positions, which may lead to a less accurate overall result.

The update suggests a shift of about 3 track widths eastwards with the occultation time about one minute later than that predicted by OCCULT.

The path remains over northwestern Australia.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: October 6, 1999 @ 12:15 UT
• Magnitude of target star: 10.3
• Magnitude drop [mag]: 0.7
• Estimated maximum duration [s]: 17.5
• Path description: See above.

• Approximate width [km]: 178

• Name: TYC 0604 00379
• Constellation: Pisces
• J2000 position [h,m,s; ^o,',"]: 00h 42m 35.829s; +08^o 51' 49.39"
• Position source: ACT
• V mag [mag]: 10.3

• Number, name: (85) Io
• Approx. diameter [km]: 178
• Source of used astrometry: Liu
• Number of used observations: 6
• Number of rejected observations: -
• Time covered by the observations: 1998 10 04

• UT date and time of least geocentric approach: 12:05:36 UT
• Approx. V mag of minor planet at event [mag]: 10.1
• Geocentric parallax of minor planet ["]: 6.97
• Magnitude drop [mag]: 0.7
• Estimated maximum duration [s]: 17.5
• Apparent motion of minor planet ["/h]: 40.03
• Angular distance to moon, phase of moon [deg,%]: 144, 9%
• Update computed by: Blow

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.