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Updated: 2011 NOV 10, 21:25 UT
Event Rank : 100
(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 Dec 13 UT, the 256 km diameter asteroid (15) Eunomia will occult a 10.1 mag star in the constellation Perseus for observers along a very broad path across Australia from Cooktown across Queensland and central South Australia to west of Ceduna, and across Papua - New Guinea near Baniara.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.2 mag to 8.1 mag (the magnitude of the asteroid) for at most 28.7 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.
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 38 56 -33 0 0 10 20 3 8 40 -1 128 49 57 132 26 37 128 32 23 132 43 45
131 38 50 -32 0 0 10 20 0 9 39 -2 129 51 46 133 24 43 129 34 31 133 41 34
132 37 13 -31 0 0 10 19 58 10 39 -3 130 51 57 134 21 26 130 35 0 134 38 1
133 34 13 -30 0 0 10 19 55 12 38 -4 131 50 36 135 16 52 131 33 55 135 33 12
134 29 56 -29 0 0 10 19 51 13 38 -6 132 47 51 136 11 7 132 31 26 136 27 13
135 24 27 -28 0 0 10 19 48 14 37 -7 133 43 49 137 4 16 133 27 38 137 20 10
136 17 52 -27 0 0 10 19 44 16 37 -8 134 38 34 137 56 24 134 22 36 138 12 7
137 10 16 -26 0 0 10 19 39 17 37 -9 135 32 13 138 47 37 135 16 28 139 3 8
138 1 43 -25 0 0 10 19 35 18 36 -10 136 24 51 139 37 58 136 9 17 139 53 19
138 52 18 -24 0 0 10 19 30 19 36 -12 137 16 32 140 27 31 137 1 9 140 42 42
139 42 6 -23 0 0 10 19 24 21 36 -13 138 7 20 141 16 20 137 52 7 141 31 22
140 31 8 -22 0 0 10 19 19 22 35 -14 138 57 19 142 4 29 138 42 16 142 19 23
141 19 30 -21 0 0 10 19 13 23 35 -15 139 46 34 142 52 1 139 31 39 143 6 47
142 7 15 -20 0 0 10 19 7 24 35 -16 140 35 8 143 38 58 140 20 21 143 53 37
142 54 24 -19 0 0 10 19 1 25 35 -17 141 23 3 144 25 25 141 8 24 144 39 57
143 41 3 -18 0 0 10 18 54 27 34 -18 142 10 23 145 11 23 141 55 51 145 25 49
144 27 12 -17 0 0 10 18 47 28 34 -20 142 57 12 145 56 56 142 42 46 146 11 16
145 12 55 -16 0 0 10 18 40 29 34 -21 143 43 31 146 42 5 143 29 11 146 56 20
145 58 15 -15 0 0 10 18 32 30 34 -22 144 29 24 147 26 54 144 15 9 147 41 4
146 43 14 -14 0 0 10 18 24 32 33 -23 145 14 53 148 11 24 145 0 43 148 25 29
147 27 53 -13 0 0 10 18 16 33 33 -24 146 0 0 148 55 38 145 45 55 149 9 39
148 12 16 -12 0 0 10 18 8 34 33 -25 146 44 47 149 39 38 146 30 46 149 53 36
148 56 24 -11 0 0 10 18 0 35 33 -26 147 29 18 150 23 25 147 15 21 150 37 21
149 40 20 -10 0 0 10 17 51 36 33 -27 148 13 33 151 7 3 147 59 40 151 20 56
150 24 6 - 9 0 0 10 17 42 38 33 -28 148 57 36 151 50 33 148 43 45 152 4 23
151 7 43 - 8 0 0 10 17 32 39 32 -30 149 41 28 152 33 57 149 27 39 152 47 45
151 51 13 - 7 0 0 10 17 23 40 32 -31 150 25 11 153 17 16 150 11 25 153 31 3
152 34 39 - 6 0 0 10 17 13 41 32 -32 151 8 47 154 0 33 150 55 2 154 14 18
153 18 2 - 5 0 0 10 17 3 42 32 -33 151 52 17 154 43 50 151 38 34 154 57 34
154 1 24 - 4 0 0 10 16 53 44 32 -34 152 35 45 155 27 8 152 22 3 155 40 51
154 44 46 - 3 0 0 10 16 43 45 32 -35 153 19 11 156 10 28 153 5 29 156 24 12
155 28 12 - 2 0 0 10 16 32 46 32 -36 154 2 37 156 53 54 153 48 56 157 7 38
156 11 41 - 1 0 0 10 16 21 47 32 -37 154 46 6 157 37 26 154 32 25 157 51 10
Uncertainty in time = +/- 3 secs
Prediction of 2011 Nov 11.0
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