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Updated: 2012 Mar 09, 18:35 UT
Event Rank : 34
(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 2012 Apr 02 UT, the 34 km diameter asteroid (860) Ursina will occult a 11.2 mag star in the constellation Scorpius for observers along a path across Northern Territory and eastern South Australia, passing over Gawler near Adelaide.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.9 mag to 15.1 mag (the magnitude of the asteroid) for at most 6.2 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.
Occultation of UCAC2 15323166 by 860 Ursina on 2012 Apr 2
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
133 59 47 -10 0 0 18 15 29 60 166 -43 133 50 20 134 9 14 133 13 51 134 45 42
134 10 12 -11 0 0 18 15 47 61 166 -43 134 0 43 134 19 41 133 24 8 134 56 16
134 20 40 -12 0 0 18 16 5 62 166 -43 134 11 10 134 30 11 133 34 26 135 6 54
134 31 13 -13 0 0 18 16 24 63 166 -42 134 21 40 134 40 46 133 44 48 135 17 37
134 41 50 -14 0 0 18 16 42 64 166 -42 134 32 15 134 51 25 133 55 14 135 28 27
134 52 33 -15 0 0 18 17 1 65 166 -42 134 42 55 135 2 11 134 5 44 135 39 22
135 3 22 -16 0 0 18 17 20 66 166 -41 134 53 41 135 13 3 134 16 19 135 50 25
135 14 18 -17 0 0 18 17 39 67 165 -41 135 4 34 135 24 2 134 27 0 136 1 36
135 25 22 -18 0 0 18 17 58 68 165 -40 135 15 35 135 35 9 134 37 48 136 12 56
135 36 35 -19 0 0 18 18 18 69 165 -40 135 26 44 135 46 25 134 48 44 136 24 26
135 47 57 -20 0 0 18 18 37 70 165 -40 135 38 2 135 57 52 134 59 48 136 36 7
135 59 30 -21 0 0 18 18 57 71 165 -39 135 49 31 136 9 29 135 11 2 136 48 0
136 11 15 -22 0 0 18 19 17 72 165 -39 136 1 12 136 21 17 135 22 26 137 0 5
136 23 12 -23 0 0 18 19 36 73 165 -38 136 13 4 136 33 19 135 34 1 137 12 25
136 35 23 -24 0 0 18 19 56 74 165 -38 136 25 10 136 45 35 135 45 48 137 24 59
136 47 48 -25 0 0 18 20 17 75 164 -37 136 37 31 136 58 6 135 57 49 137 37 50
137 0 30 -26 0 0 18 20 37 76 164 -37 136 50 7 137 10 53 136 10 5 137 50 58
137 13 28 -27 0 0 18 20 57 77 164 -36 137 3 0 137 23 57 136 22 36 138 4 24
137 26 46 -28 0 0 18 21 18 78 164 -36 137 16 11 137 37 20 136 35 24 138 18 11
137 40 23 -29 0 0 18 21 38 79 164 -35 137 29 42 137 51 4 136 48 30 138 32 19
137 54 21 -30 0 0 18 21 59 80 163 -35 137 43 33 138 5 9 137 1 56 138 46 51
138 8 42 -31 0 0 18 22 20 81 163 -34 137 57 47 138 19 37 137 15 42 139 1 46
138 23 28 -32 0 0 18 22 40 82 163 -34 138 12 26 138 34 30 137 29 52 139 17 9
138 38 39 -33 0 0 18 23 1 83 163 -33 138 27 29 138 49 50 137 44 25 139 32 59
138 54 19 -34 0 0 18 23 22 84 162 -33 138 43 1 139 5 38 137 59 25 139 49 20
139 10 29 -35 0 0 18 23 43 85 162 -32 138 59 2 139 21 56 138 14 52 140 6 12
139 27 11 -36 0 0 18 24 4 86 161 -31 139 15 35 139 38 48 138 30 49 140 23 40
139 44 27 -37 0 0 18 24 25 86 159 -31 139 32 41 139 56 14 138 47 19 140 41 44
140 2 20 -38 0 0 18 24 46 87 156 -30 139 50 24 140 14 17 139 4 22 141 0 27
140 20 53 -39 0 0 18 25 7 87 116 -30 140 8 46 140 33 1 139 22 2 141 19 53
140 40 8 -40 0 0 18 25 29 87 351 -29 140 27 49 140 52 27 139 40 21 141 40 5
141 0 8 -41 0 0 18 25 50 86 346 -28 140 47 37 141 12 39 139 59 23 142 1 4
141 20 57 -42 0 0 18 26 11 86 344 -28 141 8 13 141 33 41 140 19 10 142 22 56
141 42 38 -43 0 0 18 26 32 85 343 -27 141 29 40 141 55 36 140 39 45 142 45 44
142 5 15 -44 0 0 18 26 54 84 343 -26 141 52 3 142 18 27 141 1 13 143 9 31
142 28 53 -45 0 0 18 27 15 83 342 -26 142 15 26 142 42 20 141 23 37 143 34 24
Uncertainty in time = +/- 12 secs
Prediction of 2012 Mar 10.0
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