RASNZ Occultation Section - Meliboea Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (137) MELIBOEA - 2001 MAY 12

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[Prediction using OCCULT software]

The path given by Occult using the Tycho 2 position of the star runs from the central Queensland area at very low altitude and at local sunrise across the Northern Territory just to the south of Alice Springs. The path then crosses the Gibson Desert and the Pilbara area of Western Australia before emerging at the coastline around Onlsow and clipping the tip of North West Cape.

UPDATE: 10 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. The Tycho-2 position of the target star has been used.

Summary:

This updated path lies around 0.5 path width to the south of that given by Occult with little difference in time. After crossing central Queensland at very low altitudes and at local sunrise, the path runs just to the south of Alice Springs (19:52:30 UT). Crossing the Gibson Desert and the Pilbara area, the path crosses the Onslow area and the North West Cape (19:53:50 UT).

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 12, 2001 @ 19:53 UT
Magnitude of target star: 11.1
Magnitude drop [mag]: 1.3
Estimated maximum duration [s]: 11.6
Path description: See above.

The Occultation Path:

Approximate width [km]: 146
Uncertainty [path widths]: 0.9 (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 5594-00603-1
Constellation: Libra
J2000 position [h,m,s; ^o,',"]: 15h 19m 26.574s; -8^o 04' 50.13"
Position source: Tycho - 2
Estimated accuracy ["]: 0.105" (0.069", 0.079")
V mag [mag]: 11.1
Remarks:
The target star is in central-northern Libra. It lies only 1.4 degrees north-northeast of beta Librae (magnitude = 2.6). The Occult prediction for this event includes finder charts and can be reached by clicking here.

Data for the minor planet:

Number, name: (137) Meliboea
Approx. diameter [km]: 145
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone)
Number of used observations: 53
Number of rejected observations: 6
Time covered by the observations: 1998 10 24 - 2001 04 25
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.028", 0.023", 100°.

Data for the event:

UT date and time of least geocentric approach: 2001 Mary 12, 20.05 UT
Approx. V mag of minor planet at event [mag]: 12.0
Geocentric parallax of minor planet ["]: 4.785
Magnitude drop [mag]: 1.3
Estimated maximum duration [s]: 11.6
Apparent motion of minor planet ["/h]: 33.61
Angular distance to moon, phase of moon [deg,%]: 65, 74%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Meliboea 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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