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 supplemented with data from the AstDys database. The UCAC position of the target star has been used.

Summary:

This updated path lies around 3 path widths to the south of that given by Edwin Goffin with little difference in expected times. The path crosses northern New Caledonia at 16:39:30 UT. Across the Coral Sea, the path enters Queensland around the Bundaberg/Maryborough area at 16:41 UT. Running west across southern Queensland and central South Australia, the path passes back into the Great Australian Bight at Ceduna at 16:44 UT. The path runs off shore from the southern Western Australian coastline over the period 16:45 to 16:46 UT.

Brisbane lies within the error tolerance of the calculation at 16:41 UT while Perth and Adelaide lie just beyond the error band at 16:46 and 16:43 UT respectively.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: July 23, 2001 @ 16:42 UT
• Magnitude of target star: 9.61
• Magnitude drop [mag]: 2.8
• Estimated maximum duration [s]: 6.1
• Path description: See above.
• Goffin's original chart reference: A01_0712

• Approximate width [km]: 75
• Uncertainty [path widths]: 1.4 (one sigma)
• Map: See below
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: TYC 6356-00645-1 = PPM 271729 = HD 198558
• Constellation: Capricornus
• J2000 position [h,m,s; ^o,',"]: 20h 51m 42.9419s; -20^o 51' 12.825"
• Position source: UCAC
• Estimated accuracy ["]: 0.042" (0.030", 0.030")
• V mag [mag]: 9.61
• B-V [mag]: +0.424
• Remarks:
• The target star is in central Capricornus. It lies 1.4 degrees northeast of 17 Capricorni (magnitude = 5.9).

• Number, name: (77) Frigga
• Approx. diameter [km]: 71.0
• Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
• Number of used observations: 707
• Number of rejected observations: 62
• Time covered by the observations: 1901 08 23 - 2001 06 22
• Residuals ["] (RA,DE): 0.067", 0.052" (1 sigma)

• UT date and time of least geocentric approach: 2001 July 23, 16:45.0 UT
• Approx. V mag of minor planet at event [mag]: 12.32
• Geocentric parallax of minor planet ["]: 4.94
• Magnitude drop [mag]: 2.8
• Estimated maximum duration [s]: 6.1
• Apparent motion of minor planet ["/h]: 32.40
• Angular distance to moon, phase of moon [deg,%]: 148, 12%
• 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.