RASNZ Occultation Section - Clorinde Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (282) CLORINDE - 2001 JUNE 18

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[Prediction by Edwin Goffin]

[Prediction using OCCULT software]

The path given by Edwin Goffin clips the southern tip of the North Island of New Zealand and crosses the northern section of the South Island. The path given by Occult (using the TAC star position) lies around 3 path widths to the south and around 1 minute earlier.

UPDATE: 15 June 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 historical data from the AstDys database. The UCAC position of the target star has been used.

Summary:

This updated path lies around 0.3" to the south and around 30 seconds earlier than that given by Goffin. The path now clips the far southeastern extremity of the South Island of New Zealand including Bluff and Stewart Island (16:36 UT).

The error tolerances for this calculation are quite large and in fact all of the southern half of the South Island stand a some chance of seeing an occultation.

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: June 18, 2001 @ 16:36 UT
Magnitude of target star: 11.22
Magnitude drop [mag]: 3.2
Estimated maximum duration [s]: 3.7
Path description: See above.
Goffin's original chart reference: A01_0620

The Occultation Path:

Approximate width [km]: 55
Uncertainty [path widths]: 2.4 (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 5700-00015-1 = TAC -11°06370
Constellation: Scutum
J2000 position [h,m,s; ^o,',"]: 18h 43m 12.057s; -11^o 38' 44.06"
Position source: UCAC 1
Estimated accuracy ["]: 0.042" (0.030", 0.030")
V mag [mag]: 11.22
Remarks:
The target star is in central southern Scutum. It lies 2.6 degrees south of delta Scuti (magnitude = 4.7) and 18' south of HIP 91847 = SAO 161766 (magnitude = 7.0).

Data for the minor planet:

Number, name: (282) Clorinde
Approx. diameter [km]: 40.0
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
Number of used observations: 278
Number of rejected observations: 32
Time covered by the observations: 1904 05 18 - 2001 05 25
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.092", 0.066", 95°.

Data for the event:

UT date and time of least geocentric approach: 2001 June 18, 16:39.8 UT
Approx. V mag of minor planet at event [mag]: 14.36
Geocentric parallax of minor planet ["]: 5.74
Magnitude drop [mag]: 3.2
Estimated maximum duration [s]: 3.7
Apparent motion of minor planet ["/h]: 34.55
Angular distance to moon, phase of moon [deg,%]: 130, 10%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Clorinde 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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