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Updated: 2010 OCT 14, 10:41 UT
Event Rank : 58
(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 2010 Dec 09 UT, the 40 km diameter asteroid (309) Fraternitas will occult a 10.3 mag star in the constellation Pisces for observers along a path across Australia from near Cairns in northern Queensland (at leow elevation) to Bridgetown in south-west Western Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.5 mag to 14.8 mag (the magnitude of the asteroid) for at most 32.3 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
112 55 15 -37 0 0 15 38 23 26 314 -29 112 11 53 113 39 17 110 40 20 115 16 51
114 10 0 -36 0 0 15 36 38 26 313 -31 113 26 12 114 54 31 111 53 50 116 33 15
115 28 42 -35 0 0 15 34 50 26 312 -32 114 44 21 116 13 47 113 10 55 117 53 58
116 51 33 -34 0 0 15 32 59 26 311 -33 116 6 32 117 37 22 114 31 47 119 19 20
118 18 52 -33 0 0 15 31 5 26 310 -34 117 33 1 119 5 35 115 56 42 120 49 43
119 51 1 -32 0 0 15 29 7 26 308 -35 119 4 10 120 38 48 117 25 55 122 25 36
121 28 27 -31 0 0 15 27 5 26 307 -36 120 40 24 122 17 33 118 59 50 124 7 36
123 11 46 -30 0 0 15 24 59 26 306 -37 122 22 14 124 2 28 120 38 52 125 56 31
125 1 43 -29 0 0 15 22 48 25 304 -38 124 10 23 125 54 24 122 23 36 127 53 26
126 59 18 -28 0 0 15 20 33 25 303 -39 126 5 43 127 54 27 124 14 44 129 59 50
129 5 52 -27 0 0 15 18 13 24 302 -40 128 9 28 130 4 12 126 13 15 132 17 52
Latitude Latitude Latitude Latitude
130 0 0 -26 35 45 15 17 14 24 301 -41 -26 10 5 -27 1 52 -25 16 4 -27 59 55
131 0 0 -26 9 50 15 16 10 24 300 -41 -25 44 25 -26 35 42 -24 50 52 -27 33 9
132 0 0 -25 44 55 15 15 8 23 300 -41 -25 19 43 -26 10 33 -24 26 37 -27 7 27
133 0 0 -25 20 59 15 14 6 23 299 -42 -24 55 59 -25 46 24 -24 3 17 -26 42 48
134 0 0 -24 58 3 15 13 6 22 299 -42 -24 33 13 -25 23 16 -23 40 54 -26 19 12
135 0 0 -24 36 4 15 12 7 22 298 -42 -24 11 25 -25 1 6 -23 19 25 -25 56 38
136 0 0 -24 15 3 15 11 9 22 297 -43 -23 50 33 -24 39 56 -22 58 52 -25 35 5
137 0 0 -23 55 0 15 10 13 21 297 -43 -23 30 39 -24 19 44 -22 39 14 -25 14 33
138 0 0 -23 35 55 15 9 17 21 296 -43 -23 11 40 -24 0 31 -22 20 30 -24 55 2
139 0 0 -23 17 46 15 8 23 20 296 -43 -22 53 39 -23 42 16 -22 2 42 -24 36 31
140 0 0 -23 0 36 15 7 31 20 295 -43 -22 36 34 -23 25 0 -21 45 48 -24 19 1
141 0 0 -22 44 23 15 6 39 19 295 -44 -22 20 25 -23 8 41 -21 29 49 -24 2 31
142 0 0 -22 29 7 15 5 49 18 294 -44 -22 5 14 -22 53 22 -21 14 46 -23 47 1
143 0 0 -22 14 50 15 5 1 18 294 -44 -21 51 0 -22 39 1 -21 0 38 -23 32 33
144 0 0 -22 1 31 15 4 14 17 293 -44 -21 37 43 -22 25 40 -20 47 26 -23 19 6
145 0 0 -21 49 11 15 3 28 17 293 -44 -21 25 25 -22 13 18 -20 35 11 -23 6 40
146 0 0 -21 37 50 15 2 44 16 293 -44 -21 14 5 -22 1 57 -20 23 53 -22 55 17
147 0 0 -21 27 30 15 2 1 15 292 -44 -21 3 44 -21 51 36 -20 13 32 -22 44 56
148 0 0 -21 18 10 15 1 20 15 292 -44 -20 54 24 -21 42 17 -20 4 10 -22 35 39
149 0 0 -21 9 52 15 0 41 14 291 -43 -20 46 4 -21 34 1 -19 55 47 -22 27 27
150 0 0 -21 2 37 15 0 3 13 291 -43 -20 38 46 -21 26 48 -19 48 24 -22 20 21
151 0 0 -20 56 25 14 59 27 13 291 -43 -20 32 31 -21 20 40 -19 42 2 -22 14 21
152 0 0 -20 51 18 14 58 52 12 290 -43 -20 27 20 -21 15 38 -19 36 42 -22 9 29
153 0 0 -20 47 18 14 58 20 11 290 -43 -20 23 15 -21 11 43 -19 32 26 -22 5 47
154 0 0 -20 44 25 14 57 49 10 289 -42 -20 20 16 -21 8 57 -19 29 14 -22 3 16
155 0 0 -20 42 42 14 57 20 10 289 -42 -20 18 25 -21 7 21 -19 27 9 -22 1 59
156 0 0 -20 42 10 14 56 53 9 289 -41 -20 17 44 -21 6 58 -19 26 11 -22 1 56
157 0 0 -20 42 51 14 56 28 8 288 -41 -20 18 16 -21 7 49 -19 26 23 -22 3 10
158 0 0 -20 44 47 14 56 5 7 288 -41 -20 20 1 -21 9 56 -19 27 47 -22 5 44
159 0 0 -20 48 1 14 55 45 7 288 -40 -20 23 3 -21 13 23 -19 30 25 -22 9 41
160 0 0 -20 52 35 14 55 26 6 287 -40 -20 27 23 -21 18 12 -19 34 18 -22 15 3
161 0 0 -20 58 33 14 55 11 5 287 -39 -20 33 6 -21 24 25 .. .. .. -22 21 54
162 0 0 -21 5 57 14 54 57 4 287 -39 -20 40 13 -21 32 7 .. .. .. -22 30 17
163 0 0 -21 14 51 14 54 46 3 286 -38 -20 48 49 -21 41 21 .. .. .. -22 40 17
164 0 0 -21 25 20 14 54 38 2 286 -37 -20 58 57 -21 52 11 .. .. .. -22 51 59
165 0 0 -21 37 27 14 54 33 1 286 -37 -21 10 41 -22 4 42 .. .. .. -23 5 28
166 0 0 -21 51 17 14 54 31 0 285 -36 -21 24 6 .. .. .. .. .. .. .. .. ..
Uncertainty in time = +/- 38 secs
Prediction of 2010 Nov 19.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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