|
|
Updated: 2008 SEP 17, 01:34 UT
Event Rank : 15
(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 Sep 25 UT, the 18 km diameter asteroid (2308) Schilt will occult a 9.7 mag star in the constellation Microscopium for observers along a very narrow path of significant uncertainty across the South Island of New Zealand, from Invercargill to west of Queenstown.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.9 mag to 15.6 mag (the magnitude of the asteroid) for at most 2.2 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, 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 Limit1 Path Limit2 Error Limit1 Error Limit2
E. Longitude Latitude U.T. Alt Az Alt
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
168 20 4 -48 48 29 9 32 45 76 16 -26 168 12 43 -48 48 46 168 27 26 -48 48 13 167 8 8 -48 50 53 169 31 50 -48 45 31
168 9 58 -47 20 32 9 33 5 77 18 -27 168 2 48 -47 20 48 168 17 7 -47 20 16 167 0 2 -47 22 53 169 19 43 -47 17 38
167 59 55 -45 53 2 9 33 25 79 20 -28 167 52 57 -45 53 18 168 6 53 -45 52 46 166 51 50 -45 55 20 169 7 50 -45 50 11
167 49 55 -44 25 55 9 33 45 80 24 -29 167 43 8 -44 26 11 167 56 43 -44 25 40 166 43 33 -44 28 10 168 56 8 -44 23 8
167 39 58 -42 59 8 9 34 4 81 28 -29 167 33 20 -42 59 23 167 46 35 -42 58 52 166 35 10 -43 1 20 168 44 36 -42 56 24
167 30 2 -41 32 36 9 34 24 82 34 -30 167 23 33 -41 32 51 167 36 31 -41 32 21 166 26 42 -41 34 46 168 33 13 -41 29 56
167 20 7 -40 6 17 9 34 44 83 42 -31 167 13 46 -40 6 32 167 26 27 -40 6 3 166 18 8 -40 8 25 168 21 57 -40 3 40
167 10 12 -38 40 8 9 35 4 84 53 -31 167 3 59 -38 40 22 167 16 25 -38 39 53 166 9 29 -38 42 13 168 10 48 -38 37 33
Uncertainty in time = +/- 10 secs
[Prediction of 2008 Sep 17.0]
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]