ASTROMETRIC UPDATE:
OCCULTATION BY (194) PROKNE - 1999 NOVEMBER 2
THIS UPDATE REPLACES THE PREVIOUS UPDATE OF 27 OCTOBER.
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[Prediction by Edwin Goffin]
[Prediction using OCCULT software]
Both the Goffin and OCCULT predictions suggest a path crossing central New Zealand.
NEW UPDATE: 30 October 1999
This prediction update has been computed by Jan Manek based on USNO/Flagstaff and TMO astrometry for the minor planet and the TRC star position.
Summary:
The updated path is shifted about 0.5 path width NORTH of Goffin's nominal prediction, with a time about 0.7 minutes later.
The path runs over both of New Zealand's islands at ~12:03.5 UT. Although the North Island is favoured slightly more, inherent uncertainities mean that observers from over the entire country have an excellent chance of seeing the event.
The drop in brightness at occultation is 1.7 magnitudes - easily good enough to be seen by visual observers - and the uncertainity is only 0.75 path width with almost 16 seconds of 'totality'. The 9.7 mag star should be visible in a 4 inch telescope or larger.
This event provides an extremely good opportunity for all NZ occultation observers.
Approx time for Auckland/Wellington/Christchurch: 12h 03.5m UT
THE EVENT AT ONE GLIMPSE:
- Date and approx. UT time of event: November 2, 1999 @ 12:03 UT
- Magnitude of target star: 9.7
- Magnitude drop [mag]: 1.7
- Estimated maximum duration [s]: 15.6
- Path description: Across New Zealand.
The Occultation Path:
- Approximate width [km]: 185
- Uncertainty [path widths]: 0.75
- Uncertainty in time [s]: 15
- 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: PPM 186134 = TYC 5303 00317 1
- Constellation: Eridanus
- J2000 position [h,m,s; o,',"]: 03h 44m 20.869s; -09o 05' 39.72"
- Position source: TRC 1.0
- Estimated accuracy ["]: 0.04" (0.03", 0.02")
- V mag [mag]: 9.67
- B-V [mag]: +0.46
- Remarks:
- TYCHO quality flag is 3 (high) with 'no duplicity' flag.
- The target star is in northern Eridanus, only 43' NNE of 3.5 mag star delta Eridani.
Data for the minor planet:
- Number, name: (194) Prokne
- Approx. diameter [km]: 174
- Orbit source: calculation Manek
- Source of used astrometry: USNO/Flagstaff (Ron Stone), TMO (Bill Owen)
- Number of used observations: 23 USNO, 16 TMO
- Number of rejected observations: 1 USNO, 1 TMO
- Time covered by the observations: 1998 02 26 - 1999 10 22
- Rms residuals ["] (RA,DE): 0.09", 0.06"
- Estimated positional accuracy at epoch of event ["]: 0.09"
Data for the event:
- UT date and time of least geocentric approach: 11:58 46 UT
- Approx. V mag of minor planet at event [mag]: 11.2
- Geocentric parallax of minor planet ["]: 5.835
- Magnitude drop [mag]: 1.7
- Estimated maximum duration [s]: 15.6
- Apparent motion of minor planet ["/h]: 36.80
- Angular distance to moon, phase of moon [deg,%]: 101, 30%
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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[Reporting Details]
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[Asteroid Occultation Results]
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