This prediction update has been computed by Stephen Kerr based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station. The ACT position of the target star has been used.

Summary:

This updated path lies close to that predicted by OCCULT. It lies around 0.7" to the north-west of that predicted by Goffin with little difference in the expected time. The path crosses the central part of the island of New Guinea near the border between Papua New Guinea and Irian Jaya (15:50 UT). The path then crosses the Gove Peninsula in the Northern Territory (15:54 UT) before passing across the central parts of the Northern Territory and Western Australia crossing the coastline just to the north of Perth (16:02 UT).

Observers should note that only 10 asteroid positions have been used in this update and as such is possibly less certain then most updates. It is likely that a further update will be possible nearer the time of the event.

When consulting the update map below, observers should note that the actual path is marked by the circles rather than the time graduated lines.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: December 12, 2000 @ 16:00 UT
• Magnitude of target star: 10.78
• Magnitude drop [mag]: 3.3
• Estimated maximum duration [s]: 10.3
• Path description: See above.
• Goffin's original chart reference: A00_1216

• Approximate width [km]: 50
• Map: See below
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: TYC 0227 00356
• Constellation: Hydra
• J2000 position [h,m,s; ^o,',"]: 9h 19m 49.846s; +1^o 08' 41.73"
• Position source: ACT
• Estimated accuracy ["]: 0.08" (0.06", 0.05")
• V mag [mag]: 10.78
• B-V [mag]: +0.60
• Remarks:
• The target star is in north-western Hydra. It lies 1.8 degrees south-east of the magnitude 3.9 star theta Hydrae. The target star is 53' to the north-east of the magnitude 6.7 star SAO 117553 and only 3' south-west of the magnitude 10.0 star PPM 155697.

• Number, name: (219) Thusnelda
• Approx. diameter [km]: 43.6
• Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone)
• Number of used observations: 10
• Number of rejected observations: 0
• Time covered by the observations: 2000 11 13 - 2000 11 29

• UT date and time of least geocentric approach: 2000 December 12, 15:43 UT
• Approx. V mag of minor planet at event [mag]: 14.04
• Geocentric parallax of minor planet ["]: 4.21
• Magnitude drop [mag]: 3.3
• Estimated maximum duration [s]: 10.3
• Apparent motion of minor planet ["/h]: 10.04
• Angular distance to moon, phase of moon [deg,%]: 45, 98%
• Update computed by: Stephen Kerr (Win OCCULT 1.3).

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.