RASNZ Occultation Section - Fortuna Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (19) FORTUNA - 2001 MAY 19

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[Prediction by Edwin Goffin]

[Prediction using OCCULT software]

The path given by Edwin Goffin runs from the Indian Ocean at low altitude to cross the Western Australian coast line around the Northwest Cape area, crossing the central northern parts of Australian to enter the Coral Sea between Tully and Cairns on the north Queensland coast. The path given by Occult is indistinguishable.

UPDATE: 17 May 2001

This prediction update has been computed by Steve Preston of the Medina, Washington (state) in the United States based on astrometry from the AstDys database. The Tycho-2 position of the target star has been used.

Summary:

This updated path lies around 0.75 of a path width to the south and only around 5 seconds later than that given by Edwin Goffin. The path passes between Exmouth and Carnarvon on the Western Australian coastline (18:43:20 UT) before running east across the arid areas of northern Australia. The path runs just to the north of Mount Isa (18:44 UT) before crossing the north Queensland coast between Ingham and Innisfail (18:44:15 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 19, 2001 @ 18:44 UT
Magnitude of target star: 10.64
Magnitude drop [mag]: 1.6
Estimated maximum duration [s]: 5.1
Path description: See above.
Goffin's original chart reference: A01_0501

The Occultation Path:

Approximate width [km]: 150
Uncertainty [path widths]: 1.0 (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 5246-00472-1 = PPM 201245
Constellation: Aquarius
J2000 position [h,m,s; ^o,',"]: 23h 11m 08.937s; -3^o 43' 02.11"
Position source: Tycho-2
Estimated accuracy ["]: 0.040" (0.027", 0.030")
V mag [mag]: 10.64
B-V [mag]: +0.65
Remarks:
The target star is in northern Aquarius near the border with Pisces. The target star lies 2.45 degrees north-northwest of phi Aquarii (magnitude = 4.2).

Data for the minor planet:

Number, name: (19) Fortuna
Approx. diameter [km]: 149.0
Source of used astrometry: AstDys
Number of used observations: 1221
Number of rejected observations: 141
Time covered by the observations: 1900 02 12 - 2000 07 23
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.043", 0.029", 68°.

Data for the event:

UT date and time of least geocentric approach: 2001 May 19, 18:46.8 UT
Approx. V mag of minor planet at event [mag]: 12.02
Geocentric parallax of minor planet ["]: 3.70
Magnitude drop [mag]: 1.6
Estimated maximum duration [s]: 5.1
Apparent motion of minor planet ["/h]: 61.18
Angular distance to moon, phase of moon [deg,%]: 31, 12%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Fortuna 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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