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Updated: 2008 OCT 31, 21:38 UT
Event Rank : 29
(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 2008 Dec 12 UT, the 12 km diameter asteroid (281) Lucretia will occult a 9.7 mag star in the constellation Gemini for observers along a narrow and uncertain path beginning south of Mackay and running north-west though central northern parts of Queensland. Then into the Northern Territory passing south of Darwin, before ending over Western Australia north-west of Kununurra.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.4 mag to 14.1 mag (the magnitude of the asteroid) for at most 1.6 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
157 56 26 -27 0 0 15 18 31 31 353 -33 158 6 1 157 46 50 158 49 30 157 2 29
156 24 19 -26 0 0 15 18 51 32 354 -34 156 34 6 156 14 30 157 18 30 155 29 9
154 48 22 -25 0 0 15 19 13 33 356 -36 154 58 23 154 38 18 155 43 51 153 51 46
153 8 5 -24 0 0 15 19 36 34 357 -37 153 18 24 152 57 44 154 5 8 152 9 49
151 22 54 -23 0 0 15 20 0 35 359 -39 151 33 33 151 12 12 152 21 46 150 22 38
149 32 3 -22 0 0 15 20 27 36 1 -40 149 43 6 149 20 57 150 33 7 148 29 23
147 34 37 -21 0 0 15 20 55 37 3 -42 147 46 10 147 23 0 148 38 19 146 29 2
145 29 20 -20 0 0 15 21 26 38 5 -44 145 41 29 145 17 6 146 36 18 144 20 8
Latitude Latitude Latitude Latitude
144 0 0 -19 19 43 15 21 48 39 6 -45 -19 14 8 -19 25 18 -18 48 46 -19 51 1
143 0 0 -18 53 49 15 22 2 39 7 -46 -18 48 17 -18 59 21 -18 23 5 -19 24 53
142 0 0 -18 28 50 15 22 17 39 8 -46 -18 23 20 -18 34 20 -17 58 19 -18 59 42
141 0 0 -18 4 46 15 22 32 39 9 -47 -17 59 18 -18 10 14 -17 34 27 -18 35 25
140 0 0 -17 41 37 15 22 47 40 11 -48 -17 36 11 -17 47 3 -17 11 30 -18 12 5
139 0 0 -17 19 22 15 23 2 40 12 -48 -17 13 59 -17 24 46 -16 49 26 -17 49 39
138 0 0 -16 58 2 15 23 16 40 13 -49 -16 52 40 -17 3 24 -16 28 16 -17 28 8
137 0 0 -16 37 35 15 23 31 40 14 -49 -16 32 15 -16 42 55 -16 7 59 -17 7 31
136 0 0 -16 18 2 15 23 46 40 15 -50 -16 12 44 -16 23 21 -15 48 35 -16 47 48
135 0 0 -15 59 22 15 24 1 40 16 -50 -15 54 6 -16 4 39 -15 30 4 -16 28 59
134 0 0 -15 41 36 15 24 15 40 17 -51 -15 36 21 -15 46 51 -15 12 25 -16 11 4
133 0 0 -15 24 42 15 24 30 40 18 -51 -15 19 28 -15 29 56 -14 55 39 -15 54 2
132 0 0 -15 8 41 15 24 45 40 19 -52 -15 3 28 -15 13 53 -14 39 45 -15 37 54
131 0 0 -14 53 32 15 24 59 40 20 -52 -14 48 21 -14 58 43 -14 24 44 -15 22 38
130 0 0 -14 39 15 15 25 14 40 21 -52 -14 34 5 -14 44 26 -14 10 33 -15 8 15
129 0 0 -14 25 51 15 25 28 40 22 -52 -14 20 42 -14 31 0 -13 57 15 -14 54 44
128 0 0 -14 13 18 15 25 43 40 23 -53 -14 8 10 -14 18 27 -13 44 48 -14 42 6
127 0 0 -14 1 37 15 25 57 40 24 -53 -13 56 31 -14 6 45 -13 33 12 -14 30 20
126 0 0 -13 50 48 15 26 11 39 25 -53 -13 45 42 -13 55 55 -13 22 27 -14 19 26
125 0 0 -13 40 50 15 26 25 39 26 -53 -13 35 45 -13 45 56 -13 12 34 -14 9 24
124 0 0 -13 31 44 15 26 39 39 27 -53 -13 26 40 -13 36 49 -13 3 31 -14 0 14
123 0 0 -13 23 29 15 26 53 39 28 -53 -13 18 25 -13 28 34 -12 55 20 -13 51 55
122 0 0 -13 16 5 15 27 7 38 29 -53 -13 11 2 -13 21 9 -12 47 59 -13 44 28
121 0 0 -13 9 33 15 27 20 38 30 -53 -13 4 30 -13 14 36 -12 41 29 -13 37 53
120 0 0 -13 3 51 15 27 34 38 31 -53 -12 58 49 -13 8 54 -12 35 49 -13 32 10
119 0 0 -12 59 1 15 27 47 37 31 -53 -12 53 59 -13 4 4 -12 31 1 -13 27 18
118 0 0 -12 55 2 15 28 1 37 32 -53 -12 50 0 -13 0 5 -12 27 3 -13 23 17
Uncertainty in time = +/- 7 secs
[Prediction of 2008 Oct 31.0]
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