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 4 path widths to the south of that given by Edwin Goffin and around 40 seconds later in expected times. The path now passes through Bass Straight without making landfall. However, Melbourne lies well within the error band of this calculation at 14:19 UT.

Observers are warned at the target star is quite faint (magnitude = 11.7) and users of small telescopes may have difficulty locating the field.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: July 28, 2001 @ 14:19 UT
• Magnitude of target star: 11.73
• Magnitude drop [mag]: 1.9
• Estimated maximum duration [s]: 5.2
• Path description: See above.
• Goffin's original chart reference: A01_0737

• Approximate width [km]: 47
• Uncertainty [path widths]: 2.3 (one sigma)
• Map: See below
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: TYC 7932-00116-1
• Constellation: Sagittarius
• J2000 position [h,m,s; ^o,',"]: 19h 33m 23.0824s; -37^o 47' 06.986"
• Position source: UCAC + TYC 2 Proper Motion Data
• Estimated accuracy ["]: 0.043" (0.031", 0.031")
• V mag [mag]: 11.73
• Remarks:
• The target star is in southern Sagittarius. It lies around 3.3 degrees northeast of alpha Sagittarii (magnitude = 4.0)

• Number, name: (731) Sorga
• Approx. diameter [km]: 46.6
• Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
• Number of used observations: 238
• Number of rejected observations: 25
• Time covered by the observations: 1916 01 30 - 2001 07 01
• Residuals ["] (RA,DE): 0.073", 0.005" (1 sigma)

• UT date and time of least geocentric approach: 2001 July 28, 14:20.8 UT
• Approx. V mag of minor planet at event [mag]: 13.42
• Geocentric parallax of minor planet ["]: 5.28
• Magnitude drop [mag]: 1.9
• Estimated maximum duration [s]: 5.2
• Apparent motion of minor planet ["/h]: 26.92
• Angular distance to moon, phase of moon [deg,%]: 62, 62%
• 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.