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Updated: 2009 DEC 27, 14:03 UT
Event Rank : 52
(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 Feb 08 UT, the 38 km diameter asteroid (189) Phthia will occult a 11.5 mag star in the constellation Taurus for observers along a narrow but uncertain path beginning near Sydney and moving north-west past Newcastle and Coonabarrabran. Then into Queensland near Charleville and Longreach, ending near Normanton.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.1 mag to 13.4 mag (the magnitude of the asteroid) for at most 18.6 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 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
165 35 26 -44 52 43 13 24 46 9 303 -30 164 46 31 -44 39 41 166 28 1 -45 6 55 162 58 46 -44 11 33 168 59 10 -45 48 44
160 12 36 -41 25 7 13 25 52 14 307 -34 159 40 22 -41 17 23 160 45 49 -41 33 10 158 25 16 -40 59 42 162 11 35 -41 54 20
156 44 22 -38 38 43 13 26 57 18 309 -36 156 18 12 -38 32 57 157 11 2 -38 44 40 155 16 15 -38 19 30 158 18 24 -38 59 56
154 6 51 -36 12 22 13 28 3 21 310 -39 153 44 0 -36 7 40 154 30 0 -36 17 11 152 49 31 -35 56 38 155 27 57 -36 29 25
151 59 9 -33 58 48 13 29 9 23 311 -40 151 38 28 -33 54 48 152 20 4 -34 2 53 150 48 55 -33 45 21 153 12 7 -34 13 13
150 11 26 -31 54 23 13 30 14 25 311 -42 149 52 17 -31 50 52 150 30 46 -31 57 57 149 6 15 -31 42 33 151 18 43 -32 6 58
148 38 8 -29 56 58 13 31 20 28 311 -44 148 20 8 -29 53 50 148 56 17 -30 0 10 147 36 46 -29 46 22 149 41 12 -30 8 12
147 15 46 -28 5 11 13 32 26 30 311 -45 146 58 40 -28 2 19 147 33 0 -28 8 5 146 17 24 -27 55 32 148 15 34 -28 15 22
146 2 2 -26 18 1 13 33 31 31 311 -47 145 45 39 -26 15 23 146 18 31 -26 20 41 145 6 5 -26 9 8 146 59 12 -26 27 22
144 55 17 -24 34 45 13 34 37 33 311 -48 144 39 29 -24 32 19 145 11 9 -24 37 14 144 1 19 -24 26 30 145 50 18 -24 43 25
143 54 18 -22 54 50 13 35 43 35 311 -49 143 39 1 -22 52 33 144 9 41 -22 57 9 143 2 1 -22 47 7 144 47 32 -23 2 57
142 58 13 -21 17 50 13 36 48 36 311 -50 142 43 20 -21 15 41 143 13 9 -21 20 1 142 7 21 -21 10 34 143 49 55 -21 25 28
142 6 18 -19 43 23 13 37 54 38 310 -52 141 51 47 -19 41 21 142 20 52 -19 45 27 141 16 39 -19 36 30 142 56 43 -19 50 37
141 18 0 -18 11 12 13 39 0 39 310 -53 141 3 48 -18 9 16 141 32 16 -18 13 10 140 29 24 -18 4 38 142 7 18 -18 18 5
140 32 54 -16 41 3 13 40 5 40 309 -54 140 18 58 -16 39 11 140 46 53 -16 42 56 139 45 13 -16 34 46 141 21 14 -16 47 37
139 50 37 -15 12 42 13 41 11 42 309 -55 139 36 55 -15 10 55 140 4 22 -15 14 30 139 3 44 -15 6 40 140 38 7 -15 19 0
139 10 52 -13 46 0 13 42 17 43 308 -56 138 57 23 -13 44 17 139 24 24 -13 47 44 138 24 40 -13 40 11 139 57 38 -13 52 4
138 33 24 -12 20 46 13 43 22 44 307 -57 138 20 6 -12 19 7 138 46 45 -12 22 27 137 47 49 -12 15 9 139 19 31 -12 26 38
137 58 1 -10 56 54 13 44 28 45 306 -58 137 44 52 -10 55 18 138 11 12 -10 58 32 137 12 58 -10 51 27 138 43 34 -11 2 35
137 24 32 - 9 34 15 13 45 34 46 305 -59 137 11 32 - 9 32 42 137 37 35 - 9 35 50 136 39 58 - 9 28 58 138 9 36 - 9 39 47
Uncertainty in time = +/- 23 secs
Prediction of 2009 Dec 27.0
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