This prediction update has been computed by Steve Kerr of Rockhampton, Queensland, Australia based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station. The Tycho 2 position of the target star has been used.

Summary:

This updated path lies around 0.5" to the east of that given by Goffin and around one minute earlier. The new path crosses the Gulf of Carpentaria entering Queensland around Normanton (11:23 UT) before running south across western Queensland and New South Wales. The path crosses into Victoria around Swan Hill before crossing the western parts of the Melbourne metropolitan area around 11:28 UT. The path then crosses the western quarter of Tasmania (11:29 UT).

The error margin in this calculation is quite small and will predominantly be due to uncertainties in the star position.

The target star is relatively faint and the asterod bright leading to a fairly small magnitude fall for this event. Any observer who can comfortably monitor the target star will most probably see the asteroid during any occultation.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: September 9 : 11:28 UT
• Magnitude of target star: 11.12
• Magnitude drop [mag]: 1.2
• Estimated maximum duration [s]: 9.8
• Path description: See above.
• Goffin's original chart reference: A01_0937

• Approximate width [km]: 70
• Uncertainty [km]: 100 (95% confidence)
• Map: See below
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: TYC 0480-00876-1
• Constellation: Aquila
• J2000 position [h,m,s; ^o,',"]: 19h 48m 22.833s; +0^o 10' 52.33"
• Position source: TYC 2
• V mag [mag]: 11.12
• B-V [mag]: +0.817
• Remarks:
• The target star is central Aquila. It lies 1.3 degrees south west of eta Aquilae (magnitude = 3.9).

• Number, name: (258) Tyche
• Approx. diameter [km]: 67
• Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone)
• Number of used observations: 28
• Number of rejected observations: 0
• Time covered by the observations: 2001 06 01 - 2001 08 30

• UT date and time of least geocentric approach: 2001 September 9, 11:18.7 UT
• Approx. V mag of minor planet at event [mag]: 11.86
• Geocentric parallax of minor planet ["]: 6.26
• Magnitude drop [mag]: 1.2
• Estimated maximum duration [s]: 9.8
• Apparent motion of minor planet ["/h]: 24.30
• Angular distance to moon, phase of moon [deg,%]: 120, 64%
• Update computed by: Steve Kerr, Rockhampton, Queensland Australia. (Win Occult V1.4).

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.