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ASTROMETRIC UPDATE:
OCCULTATION BY (48) DORIS - 2001 NOVEMBER 28

[Prediction by Edwin Goffin]

[Prediction using OCCULT software]

The prediction given by Goffin runs from the nothern New South Wales coast west across the head of the Great Australian Bight to the far southern coast of Western Australia. The path given by Occult lies a fraction of a path width to the north.


UPDATE: 22 November 2001

THE UPDATED PATH

Doris Update

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 110o. 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.

Doris Finder Detailed

This updated path for the primary component lies around half a path width to the north of that given by Goffin and around a minute later. The path runs along the Queensland/New South Wales border covering the country between Brisbane city and Grafton at 17:59 UT. Further west, the path crosses central South Australia including Woomera and Coober Pedy around 18:02 UT. Further west the path covers all of the southern most sections of Western Australia including the southern Perth metropolitan areas around 18:05 UT.

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.

EVENT DETAILS SUMMARY: The Occultation Path: Data for the target star: Data for the minor planet:

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.

Use these links for further information:
[Planetary Occultations] [Using the Predictions]
[Observing Details] [Timing Details] [Reporting Details] [Report Form]
[Asteroid Occultation Results]


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