ASTROMETRIC UPDATE:
OCCULTATION BY (287) NEPHTHYS - 2001 DECEMBER 18
[Prediction using OCCULT software]
The prediction given by OCCULT emerges from twilight in the Simpson Desert running northeast across southern and central Queensland to the coastline between Rockhampton and Mackay.
UPDATE: 16 DECEMBER 2001
THE UPDATED PATH
This updated path lies around 1 pathwidth to the north of that given by Occult with little difference is time. The path runs from the far southwestern corner of Queensland in twilight to the northeast towards the coast. The path reaches the coast around Mackay at 10:09:40 UT.
Calculation Source
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, Bill Owen of the Table Mountain Observatory and Gordon Garradd supplemented with data from the AstDys database. The UCAC position of the target star has been used.
Additional details of this and other events are available at Steve Preston's website at http://www.oz.net/~stevepr/Asteroids/asteroid.htm
EVENT DETAILS SUMMARY:
- Date and approx. UT time of event: 2001 December 18 - 10:09 UT
- Magnitude of target star: 10.5
- Magnitude drop [mag]: 2.6
- Estimated maximum duration [s]: 3.1
- Angular distance to moon, phase of moon [deg,%]: 41, 13%
The Occultation Path:
- Approximate width [km]: 74
- Uncertainty [path widths]: +/- 0.81 (1 sigma)
- Remarks: Uncertainities are given on the basis of the nominal star position errors and the expected asteroid positional accuracy.
Data for the target star:
- Name: TYC 2832-00889-1 = PPM 241798
- Constellation: Aquarius
- J2000 position [h,m,s; o,',"]: 23h 32m 59.0640s; -11o 46' 03.538"
- Position source: UCAC
- Estimated accuracy ["]: 0.041" (0.030", 0.030")
- V mag [mag]: 10.5
- B-V [mag]: +1.13
- Remarks:
- The target star is in eastern Aquarius. It lies 2.9 degrees northwest of omega-1 Aquarii (magnitude = 5.0).
Data for the minor planet:
- Number, name: (287) Nephthys
- Approx. diameter [km]: 67
- Source of used astrometry: US Naval Observatory - Flagstaff Station (Ron Stone), TMO - Bill Owen, Gordon Garradd, AstDys
- Number of used observations: 890
- Number of rejected observations: 66
- Time covered by the observations: 1900 09 17 - 2001 11 21
- Update computed by: Steve Preston, Medina, Washington, USA. (OrbFit).
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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