THE UPDATED PATH

This updated path lies around three path widths to the southeast and around 1 minute later. The nominal path does not make landfall but passes by the North Island between 12:24 UT and 12:25 and then moves past the southern tip of the South Island around 12:26 UT.

It should be pointed out that this update has been calculated without the benefit of much recent high quality astrometry and as such the error margin is quite large. In reality much of New Zealand (both islands) stand a reasonble chance of observing and event. In some ways, this update should be considered an alternative prediction !!

Calculation Source

This prediction update has been computed by Steve Preston, Medina (Seattle), Washington, USA based on astrometry from the AstDys database. The Hipparcos position of the target star has been used.

• Date and approx. UT time of event: 2001 October 21: 12:25 UT
• Magnitude of target star: 7.3
• Magnitude drop [mag]: 7.7
• Estimated maximum duration [s]: 5.4
• Angular distance to moon, phase of moon [deg,%]: 126, 25%
• Goffin's original chart reference: A01_1053

• Approximate width [km]: 87
• Uncertainty [path widths]: +/- 3.79 (1 sigma)
• 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 9828 = SAO 92795 = PPM 117950
• Constellation: Aries
• J2000 position [h,m,s; ^o,',"]: 2h 06m 29.615s; +13^o 27' 42.82"
• Position source: Hipparcos
• Estimated accuracy ["]: 0.013" (0.011", 0.007")
• V mag [mag]: 7.33
• B-V [mag]: +1.04
• Remarks:
• The target star is in southwestern Aries. It lies 2.4 degrees southwest of 19 Arietis (magnitude = 5.7)

• Number, name: (3148) Grechko
• Approx. diameter [km]: 51.5
• Source of used astrometry: AstDys
• Number of used observations: 197
• Number of rejected observations: 6
• Time covered by the observations: 1964 01 13 - 2001 09 29
• 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.