RASNZ Occultation Section - Parthenope Occultation Update

ASTROMETRIC UPDATE:
OCCULTATION BY (11) PARTHENOPE - 2000 OCTOBER 4

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[Prediction by Edwin Goffin]

[Prediction using OCCULT software]

[Detailed finder chart by Jan Manek]

Goffin's path runs east across the Timor Sea to just clip the very north-west tip of the Northern Territory including the Tiwi Islands. The path then crosses the southern portions of Papua New Guinea and southern New Britain. The path given by OCCULT lies around 0.5 of a path width to the north and around 15 seconds earlier.

UPDATE: 28 September 2000

This prediction update has been computed by Jan Manek of the Stefanik Observatory based on astrometry from Ron Stone of the US Naval Observatory - Flagstaff Station, Bill Owen of the Table Mountain Observatory and positions measured by the Hipparcos mission. The Hipparcos position of the target star has been used.

Summary:

This update indicates no shift in the predicted path relative to that given by Goffin with only a small (0.1 minute) move to a later time. It includes the northen halves of Bathurst and Melville Islands off the coast from Darwin (10:37:20 UT) before passing across the southern sections of Papua New Guinea and New Britain. Daru lies on the southern limit of the path (10:38:00 UT) with Lae near the northern edge (10:38:15 UT).

The presence of a 40% moon only 1 degree from the target star will complicate the situation for small telescopes.

THE EVENT AT ONE GLIMPSE:

Date and approx. UT time of event: October 4, 2000 @ 10:38 UT
Magnitude of target star: 6.7
Magnitude drop [mag]: 4.5
Estimated maximum duration [s]: 6.6
Path description: See above.
Goffin's original chart reference: A00_1004

The Occultation Path:

Approximate width [km]: 170
Uncertainty [path widths]: 0.5
Uncertainty in time [s]: 10
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: HIP 88396 = SAO 186169 = PPM 267740 = TYC 6842-00899-1

Constellation: Sagittarius

J2000 position [h,m,s; ^o,',"]: 18h 03m 01.711s; -22^o 43' 06.58"

Position source: Hipparcos

Estimated accuracy ["]: 0.01" (0.01", 0.01")

Johnson V mag [mag]: 6.73

B-V [mag]: -0.06

Remarks:

The target star is in western Sagittarius, about 6.3 degrees north-west of the magnitude = 2.8 star lambda Sagittarii. The target star is one of the brightest between the open cluster/nebula M20 also known as the Trifid Nebula and the neighbouring open cluster M21.
To see a detailed finder chart, click here.

Data for the minor planet:

Number, name: (11) Parthenope
Approx. diameter [km]: 162
Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), TMO (Bill Owen), Hipparcos
Number of used observations: 57 USNO, 30 TMO, 83 Hip
Number of rejected observations: 8 USNO, 2 TMO, 1 Hip
Time covered by the observations: 1990 09 09 - 2000 07 19
RMS residuals ["] (RA,DE): 0.05", 0.04"
Estimated positional accuracy at epoch of event ["]: 0.05"

Data for the event:

UT date and time of least geocentric approach: 2000 October 4, 10:35.0 UT
Approx. V mag of minor planet at event [mag]: 11.2
Geocentric parallax of minor planet ["]: 4.025
Magnitude drop [mag]: 4.5
Estimated maximum duration [s]: 6.6
Apparent motion of minor planet ["/h]: 55.63
Angular distance to moon, phase of moon [deg,%]: 1, 40%
Update computed by: Jan Manek, Stefanik Observatory, Prague, Czech Republic.

Parthenope 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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