RASNZ Occultation Section - Aspasia Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (409) ASPASIA - 2001 SEPTEMBER 17

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[Prediction by Edwin Goffin]

[Prediction using OCCULT software]

Goffin's path runs from just south of Perth in Western Australia across South Australia and southern Queensland to the coast just north of Brisbane. The path given by Occult lies a fraction of a path width to the south.

UPDATE: 15 September 2001

This prediction update has been computed by Steve Preston of Medina, Washington (state) in the United States based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station and Bill Owen of the Table Mountain Observatory supplemented with data from the AstDys database. The UCAC position of the target star has been used.

Summary:

This updated path lies around 1 path width to the south of that given by Goffin and around 10 seconds later. The path runs just to the south of Perth in Western Australia at 12:57 UT. The actual path covers the area between Cape Leeuwin and Mandurah although Perth lies well within the error bounds of this calculation.

On the way to Queensland, the path crosses relatively remote parts of South Australia, and the far northwestern corner of New South Wales. The path crosses the Queensland coast at low altitude (10 - 15°) at 12:59 UT with Brisbane lieing within the nominal track.

Additional details of this and other events are available at Steve Preston's website at http://www.oz.net/~stevepr/Asteroids/asteroid.htm

THE EVENT AT ONE GLIMPSE:

Date and approx. UT time of event: September 17 : 12:57 UT
Magnitude of target star: 11.14
Magnitude drop [mag]: 1.5
Estimated maximum duration [s]: 8.9
Path description: See above.
Goffin's original chart reference: A01_0945

The Occultation Path:

Approximate width [km]: 171
Uncertainty [path widths]: +/- 0.34 (1 sigma)
Map: See below
Circles along the path are OCCULT calculated exact centerline points !!!!

Data for the target star:

Name: TYC 5671-00837-1
Constellation: Serpens
J2000 position [h,m,s; ^o,',"]: 17h 32m 44.7602s; -14^o 33' 40.400"
Position source: UCAC
Estimated accuracy ["]: 0.043" (0.030", 0.030")
V mag [mag]: 11.14
Remarks:
The target star is western Serpens (Cauda). It lies 1.4 degrees northwest of xi Serpentis (magnitude = 3.5).

Data for the minor planet:

Number, name: (409) Aspasia
Approx. diameter [km]: 168
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), TMO - Bill Owen, AstDys
Number of used observations: 797
Number of rejected observations: 52
Time covered by the observations: 1902 07 07 - 2001 08 19

Data for the event:

UT date and time of least geocentric approach: 2001 September 17, 12:53.6 UT
Approx. V mag of minor planet at event [mag]: 12.29
Geocentric parallax of minor planet ["]: 3.88
Magnitude drop [mag]: 1.5
Estimated maximum duration [s]: 8.9
Apparent motion of minor planet ["/h]: 41.56
Angular distance to moon, phase of moon [deg,%]: 87, 0%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit).

Aspasia Update

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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