RASNZ Occultation Section - Justitia Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (269) JUSTITIA - 2001 JULY 14

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[Prediction using OCCULT software + finder charts]

The path given by Occult crosses the southern Sydney metropolitan area and just to the north of Canberra. In South Australia, the path runs just south of Adelaide.

UPDATE: 13 July 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 UCAC position of the target star has been used combined with proper motion information from Tycho 2.

Summary:

This updated path lies around 0.5 of a path width to the south and around 2.5 minutes later than that given by Occult. The new path crosses the New South Wales coastline around Wollongong around 12:07 UT. Running just to the north of Canberra the path continues on to pass just to the south of Adelaide at 12:08:45 UT and includes much of Kangaroo Island. The path also passes close to the Western Australian south coast around Albany at 12:10:30 albeit at very low altitude.

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: July 14, 2001 @ 12:07 UT
Magnitude of target star: 10.2
Magnitude drop [mag]: 2.2
Estimated maximum duration [s]: 11.1
Path description: See above.

The Occultation Path:

Approximate width [km]: 53
Uncertainty [path widths]: 1.1 (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 5777-00642-1 = PPM 205168
Constellation: Aquarius
J2000 position [h,m,s; ^o,',"]: 21h 24m 59.3041s; -09^o 58' 44.162"
Position source: UCAC position + Tycho 2 proper motion
Estimated accuracy ["]: 0.042" (0.030", 0.030")
V mag [mag]: 10.2
B-V [mag]: +1.44
Remarks:
The target star is in southern Aquarius near the Capricornus border. It lies only 14' south-southeast of 19 Aquarii (magnitude = 5.7).
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: (269) Justitia
Approx. diameter [km]: 53
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
Number of used observations: 329
Number of rejected observations: 47
Time covered by the observations: 1916 05 12 - 2001 07 05
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.064", 0.044", 78°.

Data for the event:

UT date and time of least geocentric approach: 2001 July 14, 11:48.3 UT
Approx. V mag of minor planet at event [mag]: 12.2
Geocentric parallax of minor planet ["]: 7.594
Magnitude drop [mag]: 2.2
Estimated maximum duration [s]: 11.1
Apparent motion of minor planet ["/h]: 20.52
Angular distance to moon, phase of moon [deg,%]: 70, 43%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Justitia 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]
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[Asteroid Occultation Results]

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