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Updated: 2012 Mar 31, 09:46 UT
Event Rank : 40
(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 13 UT, the 120 km diameter asteroid (596) Scheila will occult a 10.9 mag star in the constellation Ophiuchus for observers along a large uncertainty path across Queensland, western New South Wales, western Victoria and eastern South Australia, running from Cairns to Adelaide.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.3 mag to 13.0 mag (the magnitude of the asteroid) for at most 32.9 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 25111057 by 596 Scheila on 2012 Apr 13
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
146 40 13 - 9 49 12 14 22 54 40 105 -88 147 29 47 - 9 54 51 145 49 50 - 9 43 12 150 9 10 -10 11 23 142 56 4 - 9 20 34
146 36 48 -10 49 32 14 23 24 40 104 -87 147 26 21 -10 55 8 145 46 27 -10 43 36 150 5 45 -11 11 30 142 52 54 -10 21 11
146 32 10 -11 49 34 14 23 53 41 103 -86 147 21 45 -11 55 7 145 41 49 -11 43 40 150 1 16 -12 11 21 142 48 20 -11 21 27
146 26 21 -12 49 18 14 24 23 41 102 -86 147 15 59 -12 54 50 145 35 57 -12 43 27 149 55 44 -13 10 58 142 42 24 -12 21 22
146 19 22 -13 48 47 14 24 53 41 102 -85 147 9 4 -13 54 17 145 28 53 -13 42 57 149 49 10 -14 10 21 142 35 7 -13 20 59
146 11 11 -14 48 2 14 25 22 41 101 -84 147 1 1 -14 53 31 145 20 35 -14 42 13 149 41 32 -15 9 32 142 26 29 -14 20 19
146 1 48 -15 47 3 14 25 52 41 100 -83 146 51 48 -15 52 31 145 11 3 -15 41 14 149 32 51 -16 8 31 142 16 30 -15 19 22
145 51 14 -16 45 51 14 26 21 41 99 -82 146 41 25 -16 51 20 145 0 18 -16 40 3 149 23 7 -17 7 21 142 5 9 -16 18 10
145 39 28 -17 44 29 14 26 51 42 98 -81 146 29 52 -17 49 59 144 48 19 -17 38 40 149 12 18 -18 6 2 141 52 26 -17 16 44
145 26 28 -18 42 56 14 27 20 42 97 -80 146 17 8 -18 48 27 144 35 4 -18 37 6 149 0 24 -19 4 34 141 38 20 -18 15 5
145 12 14 -19 41 15 14 27 50 42 97 -79 146 3 10 -19 46 47 144 20 31 -19 35 22 148 47 24 -20 3 0 141 22 49 -19 13 14
144 56 42 -20 39 24 14 28 20 42 96 -79 145 47 59 -20 44 59 144 4 41 -20 33 29 148 33 15 -21 1 19 141 5 52 -20 11 12
144 39 53 -21 37 26 14 28 49 42 95 -78 145 31 31 -21 43 5 143 47 29 -21 31 28 148 17 57 -21 59 33 140 47 25 -21 8 59
144 21 43 -22 35 22 14 29 19 41 94 -77 145 13 44 -22 41 3 143 28 55 -22 29 19 148 1 27 -22 57 42 140 27 28 -22 6 36
144 2 10 -23 33 11 14 29 48 41 93 -76 144 54 37 -23 38 57 143 8 55 -23 27 4 147 43 44 -23 55 48 140 5 56 -23 4 4
143 41 10 -24 30 54 14 30 18 41 93 -75 144 34 6 -24 36 45 142 47 27 -24 24 42 147 24 44 -24 53 51 139 42 47 -24 1 24
143 18 41 -25 28 33 14 30 48 41 92 -74 144 12 8 -25 34 29 142 24 27 -25 22 15 147 4 24 -25 51 51 139 17 57 -24 58 34
142 54 39 -26 26 7 14 31 17 41 91 -73 143 48 40 -26 32 10 141 59 50 -26 19 43 146 42 42 -26 49 50 138 51 21 -25 55 37
142 29 0 -27 23 37 14 31 47 40 91 -72 143 23 36 -27 29 47 141 33 34 -27 17 5 146 19 33 -27 47 48 138 22 54 -26 52 32
142 1 38 -28 21 3 14 32 16 40 90 -71 142 56 54 -28 27 21 141 5 32 -28 14 24 145 54 54 -28 45 45 137 52 31 -27 49 19
141 32 29 -29 18 26 14 32 46 40 89 -70 142 28 27 -29 24 53 140 35 40 -29 11 37 145 28 40 -29 43 42 137 20 6 -28 45 58
141 1 27 -30 15 46 14 33 15 40 89 -69 141 58 10 -30 22 22 140 3 51 -30 8 47 145 0 46 -30 41 40 136 45 32 -29 42 29
140 28 25 -31 13 3 14 33 45 39 88 -68 141 25 57 -31 19 49 139 29 59 -31 5 52 144 31 6 -31 39 38 136 8 41 -30 38 52
139 53 16 -32 10 16 14 34 15 39 88 -67 140 51 40 -32 17 14 138 53 56 -32 2 53 143 59 33 -32 37 38 135 29 24 -31 35 6
139 15 51 -33 7 26 14 34 44 38 87 -66 140 15 12 -33 14 37 138 15 33 -32 59 50 143 26 2 -33 35 38 134 47 32 -32 31 10
138 36 2 -34 4 32 14 35 14 38 87 -65 139 36 24 -34 11 57 137 34 41 -33 56 41 142 50 24 -34 33 40 134 2 54 -33 27 3
137 53 39 -35 1 34 14 35 43 37 86 -64 138 55 6 -35 9 15 136 51 10 -34 53 26 142 12 30 -35 31 43 133 15 18 -34 22 45
137 8 29 -35 58 31 14 36 13 37 86 -63 138 11 6 -36 6 29 136 4 47 -35 50 4 141 32 10 -36 29 48 132 24 30 -35 18 13
136 20 20 -36 55 21 14 36 43 36 86 -62 137 24 14 -37 3 38 135 15 19 -36 46 34 140 49 14 -37 27 52 131 30 14 -36 13 25
135 28 58 -37 52 3 14 37 12 35 86 -61 136 34 14 -38 0 41 134 22 31 -37 42 54 140 3 29 -38 25 57 130 32 12 -37 8 18
134 34 6 -38 48 37 14 37 42 35 85 -60 135 40 52 -38 57 38 133 26 6 -38 39 2 139 14 41 -39 24 1 129 30 5 -38 2 50
133 35 25 -39 44 58 14 38 11 34 85 -59 134 43 48 -39 54 25 132 25 44 -39 34 56 138 22 35 -40 22 3 128 23 28 -38 56 56
Uncertainty in time = +/- 54 secs
Prediction of 2012 Mar 31.0
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