|
|
Updated: 2008 SEP 26, 02:18 UT
Event Rank : 97
(The event Rank is a measure of the likelihood of observing an event, and is equal to the probability of at least one successful observation by a team of two observers spaced 1/8 path width just inside opposite sides of the predicted path. An event rank of 100 indicates that the prediction is expected to be very accurate).
THE UPDATED PATH
Note: The duration given in the line below is the interval during which the occultation shadow sweeps across the Earth - please see the minute markers on the map to determine the approximate time for your location.
On 2008 Oct 01 UT, the 87 km diameter asteroid (568) Cheruskia will occult a 11.5 mag star in the constellation Pegasus for observers along a wide path across New Zealand, passing over Wellington and near Auckland and Christchurch.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.9 mag to 13.1 mag (the magnitude of the asteroid) for at most 8.1 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/
EVENT DETAILS SUMMARY :Important Note regarding Accuracy:
The uncertainty interval in path widths given above (and shown as a 1-sigma uncertainty ellipse on the plot) refers to RMS deviation and is applied as a +/- range. In other words, a path uncertainty of 1.0 path widths means that the actual center of the asteroid's shadow path should fall within plus or minus 1 path width of the plotted path center. However path errors larger than 1 sigma have been observed so observers should be alert for primary occultations within plus or minus 3 sigma of the updated path.
Further, almost all asteroidal satellites discovered so far have been found within 10 diameters of the asteroid (since this distance is deep enough within the gravitational well to be stable over long timescales). Therefore, if monitoring for secondary events, observing out to about 10 path-widths either side of the predicted track remains worthwhile.
We therefore recommend that you monitor for events if your observing location is up to +/- 10 path-widths from the predicted track. If not monitoring for occultations by secondary bodies you should observe from locations within 3 sigma of the nominal path.
In terms of time, the predictions are now usually accurate to about +/- 0.3 minute so you should be most attentive during the predicted minute of the event. However if intending to catch a potential satellite occultation you should start observing at least 10 times the predicted central duration before the predicted closest approach time for your location, and continue for a similar period afterwards.
Centre Star Star Sun Path Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
174 14 54 -44 0 0 11 43 12 22 338 -42 173 23 56 175 6 26 172 45 34 175 46 0
174 26 42 -43 0 0 11 43 6 23 338 -43 173 36 26 175 17 31 172 58 35 175 56 32
174 39 53 -42 0 0 11 43 0 24 338 -44 173 50 16 175 30 3 173 12 54 176 8 34
174 54 26 -41 0 0 11 42 53 25 337 -45 174 5 25 175 44 0 173 28 30 176 22 2
175 10 18 -40 0 0 11 42 46 26 337 -46 174 21 50 175 59 19 173 45 20 176 36 55
175 27 27 -39 0 0 11 42 39 27 336 -47 174 39 29 176 15 57 174 3 22 176 53 10
175 45 52 -38 0 0 11 42 32 27 336 -48 174 58 22 176 33 53 174 22 35 177 10 45
176 5 30 -37 0 0 11 42 24 28 335 -49 175 18 25 176 53 6 174 42 58 177 29 38
176 26 22 -36 0 0 11 42 16 29 335 -50 175 39 39 177 13 35 175 4 29 177 49 49
176 48 25 -35 0 0 11 42 8 30 334 -51 176 2 3 177 35 18 175 27 9 178 11 16
177 11 40 -34 0 0 11 42 0 31 334 -52 176 25 36 177 58 14 175 50 55 178 33 59
Uncertainty in time = +/- 3 secs
[Prediction of 2008 Sep 26.0]
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]