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Updated: 2010 DEC 22, 15:40 UT
Event Rank : 99
(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 2011 Jan 02 UT, the 216 km diameter asteroid (375) Ursula will occult a 12.0 mag star in the constellation Auriga for observers along a path across eastern Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.0 mag to 12.5 mag (the magnitude of the asteroid) for at most 17.1 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
148 12 26 -41 0 0 10 41 34 3 16 -10 146 23 24 150 3 9 145 46 41 150 41 12
148 39 41 -40 0 0 10 41 34 4 16 -11 146 51 49 150 29 14 146 15 30 151 6 54
149 7 33 -39 0 0 10 41 33 5 16 -12 147 20 47 150 56 1 146 44 50 151 33 19
149 36 3 -38 0 0 10 41 32 6 15 -13 147 50 17 151 23 31 147 14 40 152 0 29
150 5 11 -37 0 0 10 41 30 7 15 -14 148 20 20 151 51 44 147 45 2 152 28 23
150 34 58 -36 0 0 10 41 28 8 15 -15 148 50 57 152 20 40 148 15 57 152 57 2
151 5 23 -35 0 0 10 41 26 9 14 -16 149 22 9 152 50 20 148 47 25 153 26 26
151 36 28 -34 0 0 10 41 24 11 14 -17 149 53 56 153 20 43 149 19 27 153 56 36
152 8 14 -33 0 0 10 41 22 12 14 -18 150 26 20 153 51 52 149 52 4 154 27 32
152 40 42 -32 0 0 10 41 19 13 13 -19 150 59 22 154 23 47 150 25 17 154 59 15
153 13 52 -31 0 0 10 41 16 14 13 -20 151 33 2 154 56 28 150 59 7 155 31 47
153 47 45 -30 0 0 10 41 13 15 13 -21 152 7 21 155 29 57 151 33 36 156 5 8
154 22 24 -29 0 0 10 41 10 16 12 -22 152 42 22 156 4 15 152 8 44 156 39 20
154 57 49 -28 0 0 10 41 6 17 12 -23 153 18 5 156 39 24 152 44 33 157 14 23
155 34 1 -27 0 0 10 41 2 18 12 -24 153 54 31 157 15 24 153 21 5 157 50 20
156 11 3 -26 0 0 10 40 58 19 11 -25 154 31 43 157 52 18 153 58 21 158 27 12
156 48 55 -25 0 0 10 40 54 20 11 -26 155 9 41 158 30 7 154 36 22 159 5 0
Uncertainty in time = +/- 3 secs
Prediction of 2010 Dec 22.0
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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