ASTROMETRIC UPDATE:
OCCULTATION BY (1477) BONSDORFFIA - 2000 MARCH 7
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[Prediction by Edwin Goffin]
[Prediction using OCCULT software]
[Detailed finder chart by Jan Manek]
Goffin's prediction passes midway between the Solomon Islands and Vanuatu, crossing the Queensland coast between Rockhampton and Mackay and the South Australian coast near Ceduna. The OCCULT generated path is around 0.3" to the south and 40 seconds later passing through Bundaberg on the Queensland coast and passing though the southern suburbs of Adelaide.
UPDATE: 7 March 2000
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 HIP star position.
Summary:
This calculation gives a path around 0.4" and 2.3 minutes earlier compared to Edwin Goffin's nominal prediction. The path runs over the northern Vanuatu islands, crossing the Queensland coast near Bundaberg (10:28 UT), western New South Wales (10:29 UT), the north west tip of Victoria (10:30 UT), and south east South Australia south of Adelaide around 10:30 UT.
THE EVENT AT ONE GLIMPSE:
- Date and approx. UT time of event: 2000 March 7 @ 10:28 UT
- Magnitude of target star: 8.6
- Magnitude drop [mag]: 7.3
- Estimated maximum duration [s]: 4.5
- Goffin's original chart reference: A00_0334.PS.GZ
The Occultation Path:
- Approximate width [km]: 35
- Uncertainty [path widths]: 7
- Uncertainty in time [s]: 35
- Map: See below
- Remarks:Uncertainties are given on basis of nominal star position errors and expected asteroid positional accuracy.
- Circles along the path are OCCULT calculated exact centerline points.
Data for the target star:
- Name: HIP 42247 = SAO 97965 = PPM 125483 = NSV 4149 = GSC 1395 1396
- Constellation: Cancer
- J2000 position [h,m,s; o,',"]: 8h 36m 48.003s; +18o 52' 58.11"
- Position source: Hipparcos
- Estimated accuracy ["]: 0.01" (0.01", 0.01")
- V mag [mag]: 8.61
- B-V [mag]: +0.31
- Target star is in mid Cancer, about 1 degree SW of the famous open cluster M44 - The Beehive or Praesepe. Target star is about 14 minutes east of the mira variable U Cnc or 7' west of the 8.6 mag star SAO 97971 or 7' SE of 9.5 mag star SAO 97957. There is a 9.9 mag star PPM 125477 only 3.5' SW of the target star. To see a more detailed finder chart, click here.
Data for the minor planet:
- Number, name: (1477) Bonsdorffia
- Approx. diameter [km]: 31
- Orbit source: calculation Manek
- Source of used astrometry: USNO/Flagstaff (Ron Stone)
- Number of used observations: 38 USNO
- Number of rejected observations: 5 USNO
- Time covered by the observations: 1998 07 17 - 2000 02 01
- Rms residuals ["] (RA,DE): 0.10", 0.13"
- Estimated positional accuracy at epoch of event ["]: 0.14"
Data for the event:
- UT date and time of least geocentric approach: 2000 March 7 @ 10:18:45 UTC
- Approx. V mag of minor planet at event [mag]: 16.0
- Geocentric parallax of minor planet ["]: 4.614
- Magnitude drop [mag]: 7.4
- Estimated maximum duration [s]: 4.5
- Apparent motion of minor planet ["/h]: 17.92
- Angular distance to moon, phase of moon [deg,%]: 127, 1%
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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