RASNZ Occultation Section - Schubart Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (1911) SCHUBART - 2001 MAY 31

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[Prediction using OCCULT software + finder charts]

The path given by Occult crosses the northern tip of the South Island of New Zealand and the northern outskirts of Sydney in New South Wales, Australia before running northwest across central Australia.

UPDATE: 25 May 2001

This prediction update has been computed by Steve Preston of the Medina, Washington (state) in the United States based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station supplemented with data from the AstDys database. The Tycho 2 position of the target star has been used.

Summary:

This updated path lies around 0.4" to the southwest of that given by Occult and around 30 seconds later. The new path passes to the south of the South Island although Invercargill will lie close to the edge of the error tolerance of this calculation at 10:10:40 UT. The path covers the southwestern quarter of Tasmania with Hobart on the northern edge at 10:12:10 UT. Melbourne lies within the error bounds at 10:12:35 UT and likewise for Adelaide at 10:13:15 UT. The path crosses the southern Western Australian coastline to the east of Esperence and runs to the northwest towards Shark Bay at local sunset.

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: May 31, 2001 @ 10:10 UT
Magnitude of target star: 8.3
Magnitude drop [mag]: 7.5
Estimated maximum duration [s]: 5.1
Path description: See above.

The Occultation Path:

Approximate width [km]: 88
Uncertainty [path widths]: 2.2 (1 sigma error band)
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 !!!!

Data for the target star:

Name: TYC 6199-00568-1 = SAO 183875 = PPM 264793
Constellation: Scoprius
J2000 position [h,m,s; ^o,',"]: 15h 52m 09.125s; -21^o 40' 59.21"
Position source: Tycho 2
Estimated accuracy ["]: 0.031" (0.022", 0.022")
V mag [mag]: 8.3
B-V [mag]: +0.32
Remarks:
The target star is in northwestern Scorpius and lies around 2.1 degrees northwest of the bright star delta Scorpii (currently around magnitude 1.7 and slowly fading).
A set of finder charts are available with the Occult prediction and can be viewed by clicking here.

Data for the minor planet:

Number, name: (1911) Schubart
Approx. diameter [km]: 80
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
Number of used observations: 233
Number of rejected observations: 31
Time covered by the observations: 1928 02 27 - 2001 05 18
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.050", 0.044", 94°.

Data for the event:

UT date and time of least geocentric approach: 2001 May 31, 10:09.3 UT
Approx. V mag of minor planet at event [mag]: 16.2
Geocentric parallax of minor planet ["]: 2.3607
Magnitude drop [mag]: 7.9
Estimated maximum duration [s]: 5.1
Apparent motion of minor planet ["/h]: 23.00
Angular distance to moon, phase of moon [deg,%]: 61, 67%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Schubart 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:
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[Asteroid Occultation Results]

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