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Updated: 2008 JUL 25, 05:09 UT
Event Rank : 0
(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 Aug 24 UT, the 174 km diameter asteroid (0) 2002 GZ31 will occult a 12.3 mag star in the constellation Libra for observers along a path across Antarctica. TNO event of high uncertainty possibly passing over Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 10.4 mag to 22.7 mag (the magnitude of the asteroid) for at most 15.4 seconds.
This update is based on 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
109 3 50 -85 55 29 12 10 48 20 322 -12 99 7 26 -84 4 9 137 33 52 -87 34 23 ... .. .. .. .. .. ... .. .. .. .. ..
123 44 12 -85 59 25 12 10 55 19 307 -13 108 35 50 -84 18 18 159 6 40 -87 5 37 ... .. .. .. .. .. ... .. .. .. .. ..
138 38 47 -85 48 56 12 11 2 18 292 -14 118 55 57 -84 24 17 174 17 43 -86 19 5 ... .. .. .. .. .. ... .. .. .. .. ..
152 21 30 -85 23 55 12 11 10 18 278 -15 129 43 56 -84 20 45 -175 14 24 -85 20 34 ... .. .. .. .. .. ... .. .. .. .. ..
164 5 46 -84 45 48 12 11 17 17 266 -16 140 28 42 -84 6 49 -167 38 2 -84 12 42 ... .. .. .. .. .. ... .. .. .. .. ..
173 49 30 -83 56 21 12 11 24 15 256 -17 150 41 24 -83 42 18 -161 41 30 -82 55 48 ... .. .. .. .. .. ... .. .. .. .. ..
-178 6 27 -82 56 39 12 11 31 14 248 -18 160 3 30 -83 7 26 -156 41 16 -81 28 19 ... .. .. .. .. .. ... .. .. .. .. ..
-171 16 6 -81 46 47 12 11 39 13 241 -19 168 28 50 -82 22 37 -152 7 24 -79 46 18 ... .. .. .. .. .. ... .. .. .. .. ..
-165 15 12 -80 25 25 12 11 46 11 235 -20 176 0 50 -81 27 55 -147 30 43 -77 39 53 ... .. .. .. .. .. ... .. .. .. .. ..
-159 40 58 -78 48 54 12 11 53 10 230 -21 -177 11 17 -80 22 48 -141 43 45 -74 30 21 ... .. .. .. .. .. ... .. .. .. .. ..
-154 5 35 -76 47 57 12 12 0 7 224 -22 -170 54 57 -79 5 35 ... .. .. .. .. .. ... .. .. .. .. .. ... .. .. .. .. ..
-147 18 49 -73 46 36 12 12 8 4 217 -24 -164 53 59 -77 32 17 ... .. .. .. .. .. ... .. .. .. .. .. ... .. .. .. .. ..
Uncertainty in time = +/- 25238 secs
[Prediction of 2008 Apr 29.0]
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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