This prediction update has been computed by Steve Preston of the Medina, Washington (state) in the United States based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station and Bill Owen of the Table Mountain Observatory supplemented with data from the AstDys database. The Tycho 2 position of the target star has been used.

Summary:

This updated path lies around 1 path width to the south of that given by Edwin Goffin and around two minutes later in expected times. The path now the southern territories of the Solomon Islands (10:33 UT) before running on across the Coral Sea to the Queensland coast around Cairns (10:35 UT). The path then runs into remote central Australia where it finally leaves the Earth's surface.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: August 2, 2001 @ 10:35 UT
• Magnitude of target star: 10.5
• Magnitude drop [mag]: 1.8
• Estimated maximum duration [s]: 10.1
• Path description: See above.
• Goffin's original chart reference: A01_0814

• Approximate width [km]: 122
• Uncertainty [path widths]: 1.0 (one sigma)
• Map: See below
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: TYC 1082-00137-1
• Constellation: Delphinus
• J2000 position [h,m,s; ^o,',"]: 20h 22m 08.8701s; +13^o 01' 53.167"
• Position source: Tycho 2
• Estimated accuracy ["]: 0.104" (0.070", 0.078")
• V mag [mag]: 10.9
• Remarks:
• The target star is in western Delphinus. It lies around 2.8 degrees west of eta Delphini (magnitude = 5.4) and 8.7 degrees northeast of Altair (alpha Aquilae - magnitude = 0.9).

• Number, name: (176) Iduna
• Approx. diameter [km]: 121
• Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), Table Mountain Observatory (Bill Owen), AstDys
• Number of used observations: 287
• Number of rejected observations: 26
• Time covered by the observations: 1900 11 11 - 2001 07 22
• Residuals ["] (RA,DE): 0.031", 0.028" (1 sigma)

• UT date and time of least geocentric approach: 2001 August 2, 10:27.4 UT
• Approx. V mag of minor planet at event [mag]: 12.5
• Geocentric parallax of minor planet ["]: 4.240
• Magnitude drop [mag]: 1.8
• Estimated maximum duration [s]: 10.1
• Apparent motion of minor planet ["/h]: 28.73
• Angular distance to moon, phase of moon [deg,%]: 39, 97%
• Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit).

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.