|
|
Updated: 2008 OCT 31, 00:01 UT
Event Rank : 68
(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 Dec 06 UT, the 74 km diameter asteroid (983) Gunila will occult a 11.7 mag star in the constellation Taurus for observers along a somewhat uncertain path across or near south eastern Tasmania passing near Hobart and possibly Launceston.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.9 mag to 14.5 mag (the magnitude of the asteroid) for at most 4.7 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 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
142 35 0 -47 0 0 13 8 12 20 12 -19 141 30 26 143 40 14 139 38 20 145 36 51
143 52 12 -46 0 0 13 8 6 22 10 -20 142 48 0 144 57 7 140 56 35 146 53 14
145 10 23 -45 0 0 13 8 0 23 9 -21 144 6 26 146 15 4 142 15 33 148 10 52
146 29 40 -44 0 0 13 7 54 24 8 -22 145 25 53 147 34 14 143 35 22 149 29 53
147 50 12 -43 0 0 13 7 47 25 7 -23 146 46 29 148 54 44 144 56 10 150 50 26
149 12 8 -42 0 0 13 7 40 26 5 -25 148 8 23 150 16 44 146 18 5 152 12 40
150 35 36 -41 0 0 13 7 33 27 4 -26 149 31 43 151 40 23 147 41 16 153 36 47
152 0 48 -40 0 0 13 7 25 28 3 -27 150 56 40 153 5 54 149 5 54 155 2 58
153 27 55 -39 0 0 13 7 17 29 1 -28 152 23 24 154 33 27 150 32 7 156 31 27
154 57 10 -38 0 0 13 7 8 30 360 -29 153 52 9 156 3 16 152 0 7 158 2 28
Uncertainty in time = +/- 6 secs
[Prediction of 2008 Oct 31.0]
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]