THE UPDATED PATH

The target star is in fact a close double (F.G.W. Struve 848) and the brightest star within the open cluster NGC 2169. The pair is relatively close at 2.6" and a P.A. of 110^o. This produces two occultation paths as shown in the above diagram. The delta mag values given are for the combined system and if the stars can be seperately monitored, much larger values will apply.

The inner sections of NGC 2169 is poorly shown on the printed predictions by Edwin Goffin due to the scale used. Below is a plot out of Guide 7 showing the inner regions with the target star marked.

The error margin easily draws in all of Brisbane (17:59 UT) and Perth (18:05 UT) along with Broken Hill (18:01 UT) with Adelaide as an outside chance at 18:02 UT.

The secondary path may be visible photometrically or visually if sufficient magnification is used and seeing permits seperately monitor the two stars in the system. This path crosses Papua New Guinea including Lae around 17:53:30 UT.

Calculation Source

This prediction update has been computed by Steve Preston, Medina (Seattle), Washington, USA based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station, Bill Owen of Table Mountain Observatory - JPL, Gordon Garradd or Loomberah, New South Wales, Australia supplemented with data from the AstDys database. The Hipparcos position of the target star has been used.

• Date and approx. UT time of event: 2001 November 28 - 18:00 UT
• Magnitude of target star: 7.3
• Magnitude drop [mag]: 1.2 (Primary - see above)
• Estimated maximum duration [s]: 23.1
• Angular distance to moon, phase of moon [deg,%]: 51, 95%
• Goffin's original chart reference: A01_1107

• Approximate width [km]: 324
• Uncertainty [path widths]: +/- 0.25 (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: TYC HIP 29126 = PPM 121967 = SAO 95282 = F.G.W. Struve 282
• Constellation: Orion
• J2000 position [h,m,s; ^o,',"]: 6h 08m 30.3633; +13^o 58' 15.819"
• Position source: Hipparcos
• Estimated accuracy ["]: 0.027" (0.023", 0.014")
• V mag [mag]: 7.3 (Primary)
• Remarks:
• The target star is in northeast Orion. It is the brightest star within the open cluster NGC 2169 and lies 50 minutes of arc southwest of xi Orionis (magnitude = 4.5).

• Number, name: (48) Doris
• Approx. diameter [km]: 221
• Source of used astrometry: USNO - Flagstaff Station (Ron Stone), TMO (Bill Owen), Gordon Garradd, AstDys
• Number of used observations: 707
• Number of rejected observations: 90
• Time covered by the observations: 1906 07 16 - 2001 11 11
• 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.