RASNZ Occultation Section - Normannia Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (1256) NORMANNIA - 2001 AUGUST 13

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[Prediction using OCCULT software + finder charts]

The path given by Occult approaches the North Island of New Zealand from the north east. The path crosses the Auckland area before running to the south of Tasmania.

UPDATE: 9 August 2001

This prediction update has been computed by Steve Preston of 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 one path width to the north of that given by Occult and around 45 seconds earlier. The new path crosses the northern Auckland metropolitan area around 14:27:30 UT. The error band of this calculation makes an occultation a possibility in a band between Whangarei and Hamilton and Tauranga.

Further west the path runs to the south of Tasmania with Hobart near the northern edge of the error band at 14:30:30 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: August 13, 2001 @ 14:28 UT
Magnitude of target star: 9.6
Magnitude drop [mag]: 5.6
Estimated maximum duration [s]: 6.0
Path description: See above.

The Occultation Path:

Approximate width [km]: 85
Uncertainty [path widths]: 1.9 (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 5751-00606-1 = PPM 236897 = SAO 163234
Constellation: Sagittarius
J2000 position [h,m,s; ^o,',"]: 20h 04m 38.8685s; -14^o 59' 56.005"
Position source: UCAC position + Tycho 2 proper motion
Estimated accuracy ["]: 0.042" (0.030", 0.030")
V mag [mag]: 9.6
Remarks:
The target star is in far northeastern Sagittarius near the boder with Capricornus. It lies 1.7 degrees northeast of 61 Sagittarii (magnitude = 5.0) and four degrees west of beta Capricorni (magnitude = 3.1).
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: (1256) Normannia
Approx. diameter [km]: 69
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), AstDys
Number of used observations: 237
Number of rejected observations: 36
Time covered by the observations: 1930 05 25 - 2001 07 20
Uncertainy Ellipse ["] (major axis, minor axis, PA): 0.058", 0.050", 80°.

Data for the event:

UT date and time of least geocentric approach: 2001 August 13, 14:32.3 UT
Approx. V mag of minor planet at event [mag]: 15.1
Geocentric parallax of minor planet ["]: 3.274
Magnitude drop [mag]: 5.5
Estimated maximum duration [s]: 6.0
Apparent motion of minor planet ["/h]: 21.37
Angular distance to moon, phase of moon [deg,%]: 126, 37%
Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit)

Normannia 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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