|
|
Updated: 2006 AUG 09, 00:46 UT
Event Rank : 67
(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 2006 Sep 12 UT, the 44 km diameter asteroid (987) Wallia will occult a 10.2 mag star in the constellation Perseus for observers along a path across South Australia and Queensland, from Ceduna to Cairns.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.2 mag to 14.4 mag (the magnitude of the asteroid) for at most 4.3 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, 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
130 56 21 -36 0 0 19 24 24 22 9 -24 131 18 51 130 33 55 131 59 7 129 54 10
131 38 35 -35 0 0 19 24 30 23 9 -24 132 0 58 131 16 18 132 40 58 130 36 49
132 21 20 -34 0 0 19 24 37 24 8 -23 132 43 35 131 59 10 133 23 23 131 19 54
133 4 38 -33 0 0 19 24 44 25 7 -23 133 26 46 132 42 34 134 6 23 132 3 29
133 48 30 -32 0 0 19 24 52 26 7 -22 134 10 33 133 26 31 134 50 1 132 47 36
134 32 59 -31 0 0 19 25 0 27 6 -22 134 54 58 134 11 5 135 34 19 133 32 18
135 18 7 -30 0 0 19 25 8 28 5 -21 135 40 4 134 56 16 136 19 20 134 17 35
136 3 58 -29 0 0 19 25 16 29 5 -21 136 25 53 135 42 9 137 5 6 135 3 32
136 50 34 -28 0 0 19 25 25 30 4 -20 137 12 28 136 28 46 137 51 40 135 50 11
137 37 58 -27 0 0 19 25 34 31 3 -20 137 59 52 137 16 10 138 39 5 136 37 35
138 26 13 -26 0 0 19 25 44 32 2 -19 138 48 9 138 4 24 139 27 25 137 25 47
139 15 23 -25 0 0 19 25 54 33 1 -18 139 37 21 138 53 31 140 16 43 138 14 51
140 5 32 -24 0 0 19 26 4 34 0 -18 140 27 34 139 43 36 141 7 4 139 4 49
140 56 43 -23 0 0 19 26 15 35 360 -17 141 18 51 140 34 42 141 58 31 139 55 47
141 49 1 -22 0 0 19 26 26 36 359 -16 142 11 16 141 26 54 142 51 9 140 47 48
142 42 32 -21 0 0 19 26 38 37 358 -15 143 4 54 142 20 16 143 45 3 141 40 57
143 37 19 -20 0 0 19 26 50 38 356 -14 143 59 52 143 14 55 144 40 20 142 35 19
144 33 30 -19 0 0 19 27 2 39 355 -13 144 56 15 144 10 54 145 37 4 143 30 59
145 31 11 -18 0 0 19 27 15 40 354 -12 145 54 9 145 8 21 146 35 24 144 28 4
146 30 28 -17 0 0 19 27 29 41 353 -11 146 53 42 146 7 24 147 35 27 145 26 41
147 31 31 -16 0 0 19 27 42 42 352 -10 147 55 3 147 8 9 148 37 22 146 26 56
148 34 28 -15 0 0 19 27 57 43 350 -9 148 58 21 148 10 45 149 41 18 147 28 59
149 39 29 -14 0 0 19 28 12 43 349 -8 150 3 46 149 15 24 150 47 27 148 32 58
150 46 47 -13 0 0 19 28 27 44 347 -7 151 11 31 150 22 15 151 56 3 149 39 5
151 56 35 -12 0 0 19 28 43 45 345 -6 152 21 49 151 31 33 153 7 20 150 47 32
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]