This prediction update has been computed by Steve Preston of the Medina, Washington (state) in the United States based on astrometry from data from the AstDys database. The HIP position of the target star has been used.

Summary:

This new updated path lies around 0.4" to the north of the path given by Occult with little difference in time. After crossing the Great Australian Bight, the path crosses central South Australia (20:05 UT) and southwestern Queensland to emerge from the Queensland coast around Maryborough during local twilight (20:06:30 UT).

As there has been no recent astrometry, the uncertainty of this event is quite large. Certainly Perth, Adelaide and possibly Sydney lie within a reasonable distance of the updated path.

THE EVENT AT ONE GLIMPSE:

• Date and approx. UT time of event: July 17, 2001 @ 20:05 UT
• Magnitude of target star: 9.85
• Magnitude drop [mag]: 6.3
• Estimated maximum duration [s]: 3.4
• Path description: See above.
• Goffin's original chart reference: A01_0738

• Approximate width [km]: 75
• Uncertainty [path widths]: 3.2
• Map: See below
• Remarks: Uncertainities are given on the basis of the nominal star position errors and the expected asteroid positional accuracy.
• Circles along the path are OCCULT calculated exact centerline points !!!!

• Name: HIP 9810 = GSC 630 744 = SAO 110336 = PPM 145286
• Constellation: Pisces
• J2000 position [h,m,s; ^o,',"]: 2h 06m 12.993s; +9^o 26' 21.84"
• Position source: HIP
• V mag [mag]: 9.85
• B-V [mag]: +0.64
• Remarks:
• The target star is in far eastern Pisces near the border with Cetus. The target star lies only 1.7 degrees north-west of xi-1 Ceti (magnitude = 4.4).

• Number, name: (738) Alagasta
• Approx. diameter [km]: 64.8
• Source of used astrometry: AstDys
• Number of used observations: 340
• Number of rejected observations: 43
• Time covered by the observations: 1908 02 25 - 2000 11 21

• UT date and time of least geocentric approach: 2001 July 17, 20:07.5 UT
• Approx. V mag of minor planet at event [mag]: 16.12
• Geocentric parallax of minor planet ["]: 2.76
• Magnitude drop [mag]: 6.3
• Estimated maximum duration [s]: 3.4
• Apparent motion of minor planet ["/h]: 29.88
• Angular distance to moon, phase of moon [deg,%]: 42, 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.