ASTROMETRIC UPDATE:
OCCULTATION BY (205) MARTHA - 1999 OCTOBER 24
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[Prediction by Edwin Goffin]
[Prediction using OCCULT software]
Goffin's prediction suggests a path across the centre of the South Island of New Zealand. OCCULT's path lies a little to the west.
UPDATE: 23 October 1999
This prediction update is supplied by Jan Manek of the Stefanik Observatory, Prague, and is based on USNO/Flagstaff astrometry for the minor planet and the ACT/TRC star position.
Summary:
The update astrometry moves the track about 0.5" to the east and slightly off New Zealand, with a time about 1 minute later than Goffin's prediction. However due to uncertainties all NZ observers should try for this event. Note that the almost Full Moon may complicate finding the target star.
Approx time for Auckland: 12h 50m 30s UT
THE EVENT AT ONE GLIMPSE:
- Date and approx. UT time of event: October 24, 1999 @ 12:51 UT
- Magnitude of target star: 9.6
- Magnitude drop [mag]: 4.0
- Estimated maximum duration [s]: 13.0
- Path description: The path runs very close to the eastern North Island of New Zealand.
The Occultation Path:
- Approximate width [km]: 130
- Uncertainty [path widths]: 1.2
- Uncertainty in time [s]: 20
- Map: See below
- Remarks: Uncertainities are given on the basis of the nominal errors in the observations.
Data for the target star:
- Name: SAO 127925 = PPM 173684 = TYC 0576 00471 1
- Constellation: Pisces
- J2000 position [h,m,s; o,',"]: 23h 02m 55.734s; -02o 13' 23.36"
- Position source: ACT
- Estimated accuracy ["]: 0.02" (0.02", 0.01")
- V mag [mag]: 9.55
- B-V [mag]: +0.28
- Remarks:
- TYCHO quality flag is 3 (high) with 'no duplicity' flag.
- Target star is in western Pisces, 1.6 degrees south of 4.5 mag star beta Psc. There is 11.9 mag star GSC 0576.0170 only 1' north of target.
Data for the minor planet:
- Number, name: (205) Martha
- Approx. diameter [km]: 83.5
- Orbit source: calculation Manek
- Source of used astrometry: USNO/Flagstaff (Ron Stone)
- Number of used observations: 31 USNO
- Number of rejected observations: 8 USNO
- Time covered by the observations: 1998 04 04 - 1999 10 17
- Rms residuals ["] (RA,DE): 0.06", 0.06"
- Estimated positional accuracy at epoch of event ["]: 0.06"
Data for the event:
- UT date and time of least geocentric approach: 12:43:30 UT
- Approx. V mag of minor planet at event [mag]: 13.6
- Geocentric parallax of minor planet ["]: 4.688
- Magnitude drop [mag]: 4.0
- Estimated maximum duration [s]: 13.0
- Apparent motion of minor planet ["/h]: 17.12
- Angular distance to moon, phase of moon [deg,%]: 38, 99%
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]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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