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Updated: 2005 AUG 06, 00:25 UT
Event Rank : 99
(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 2005 Aug 15 UT, the 166 km diameter asteroid (54) Alexandra will occult a 9.7 mag star in the constellation Scorpius for observers along a path across Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.8 mag to 11.3 mag (the magnitude of the asteroid) for at most 22.5 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, 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
137 23 13 -48 5 34 15 28 14 36 262 -55 135 34 2 -48 18 1 139 14 44 -47 51 3 134 57 24 -48 21 49 139 53 13 -47 45 37
136 59 45 -47 13 38 15 28 28 36 262 -56 135 12 27 -47 25 47 138 49 22 -46 59 29 134 36 28 -47 29 29 139 27 11 -46 54 10
136 38 32 -46 21 30 15 28 41 37 262 -57 134 53 1 -46 33 22 138 26 21 -46 7 39 134 17 38 -46 36 59 139 3 34 -46 2 27
136 19 28 -45 29 9 15 28 55 37 261 -58 134 35 37 -45 40 47 138 5 36 -45 15 34 134 0 48 -45 44 20 138 42 14 -45 10 28
136 2 24 -44 36 35 15 29 8 37 261 -59 134 20 8 -44 48 2 137 46 58 -44 23 13 133 45 51 -44 51 31 138 23 4 -44 18 13
135 47 16 -43 43 49 15 29 22 37 260 -60 134 6 28 -43 55 6 137 30 22 -43 30 38 133 32 41 -43 58 32 138 5 58 -43 25 42
135 33 58 -42 50 49 15 29 35 37 259 -60 133 54 32 -43 1 59 137 15 41 -42 37 47 133 21 13 -43 5 22 137 50 49 -42 32 54
135 22 26 -41 57 36 15 29 48 37 259 -61 133 44 16 -42 8 40 137 2 52 -41 44 41 133 11 23 -42 12 2 137 37 34 -41 39 51
135 12 34 -41 4 10 15 30 2 36 258 -62 133 35 36 -41 15 10 136 51 49 -40 51 19 133 3 7 -41 18 31 137 26 6 -40 46 31
135 4 20 -40 10 29 15 30 15 36 258 -63 133 28 28 -40 21 27 136 42 29 -39 57 41 132 56 22 -40 24 47 137 16 24 -39 52 53
134 57 40 -39 16 33 15 30 29 36 257 -64 133 22 50 -39 27 31 136 34 48 -39 3 45 132 51 5 -39 30 51 137 8 23 -38 58 58
134 52 32 -38 22 20 15 30 42 36 256 -65 133 18 38 -38 33 20 136 28 44 -38 9 32 132 47 12 -38 36 41 137 2 0 -38 4 44
134 48 52 -37 27 51 15 30 56 36 256 -66 133 15 50 -37 38 55 136 24 14 -37 14 59 132 44 41 -37 42 17 136 57 13 -37 10 10
134 46 40 -36 33 4 15 31 9 36 255 -67 133 14 24 -36 44 13 136 21 16 -36 20 6 132 43 32 -36 47 37 136 54 0 -36 15 15
134 45 53 -35 37 58 15 31 22 35 255 -67 133 14 20 -35 49 14 136 19 49 -35 24 53 132 43 42 -35 52 40 136 52 20 -35 19 59
134 46 31 -34 42 31 15 31 36 35 254 -68 133 15 35 -34 53 56 136 19 51 -34 29 16 132 45 10 -34 57 25 136 52 11 -34 24 19
134 48 33 -33 46 42 15 31 49 35 253 -69 133 18 9 -33 58 18 136 21 23 -33 33 15 132 47 56 -34 1 51 136 53 33 -33 28 13
134 51 58 -32 50 30 15 32 3 34 253 -70 133 22 3 -33 2 18 136 24 23 -32 36 48 132 51 59 -33 5 56 136 56 25 -32 31 41
134 56 48 -31 53 52 15 32 16 34 252 -71 133 27 15 -32 5 56 136 28 53 -31 39 53 132 57 20 -32 9 38 137 0 49 -31 34 40
135 3 1 -30 56 46 15 32 30 33 251 -72 133 33 46 -31 9 7 136 34 52 -30 42 29 133 3 58 -31 12 55 137 6 44 -30 37 9
135 10 40 -29 59 11 15 32 43 33 251 -73 133 41 37 -30 11 52 136 42 22 -29 44 31 133 11 54 -30 15 46 137 14 13 -29 39 3
135 19 45 -29 1 3 15 32 57 32 250 -73 133 50 50 -29 14 7 136 51 26 -28 45 59 133 21 10 -29 18 8 137 23 17 -28 40 21
135 30 20 -28 2 21 15 33 10 32 249 -74 134 1 25 -28 15 50 137 2 5 -27 46 48 133 31 47 -28 19 59 137 33 59 -27 41 0
135 42 26 -27 3 1 15 33 23 31 249 -75 134 13 27 -27 16 58 137 14 22 -26 46 56 133 43 48 -27 21 16 137 46 22 -26 40 56
135 56 7 -26 3 0 15 33 37 31 248 -76 134 26 56 -26 17 29 137 28 22 -25 46 18 133 57 15 -26 21 57 138 0 30 -25 40 5
136 11 27 -25 2 13 15 33 50 30 247 -76 134 41 57 -25 17 18 137 44 9 -24 44 51 134 12 11 -25 21 57 138 16 29 -24 38 22
136 28 31 -24 0 37 15 34 4 29 247 -77 134 58 34 -24 16 21 138 1 50 -23 42 28 134 28 41 -24 21 13 138 34 26 -23 35 42
136 47 25 -22 58 6 15 34 17 29 246 -77 135 16 53 -23 14 35 138 21 32 -22 39 5 134 46 49 -23 19 41 138 54 27 -22 32 0
137 8 17 -21 54 34 15 34 31 28 246 -78 135 36 59 -22 11 54 138 43 24 -21 34 35 135 6 42 -22 17 15 139 16 43 -21 27 7
137 31 16 -20 49 55 15 34 44 27 245 -78 135 59 0 -21 8 13 139 7 37 -20 28 49 135 28 27 -21 13 51 139 41 26 -20 20 55
137 56 33 -19 44 1 15 34 57 26 245 -78 136 23 5 -20 3 24 139 34 25 -19 21 37 135 52 11 -20 9 22 140 8 50 -19 13 13
138 24 20 -18 36 42 15 35 11 25 244 -78 136 49 25 -18 57 19 140 4 4 -18 12 49 136 18 7 -19 3 40 140 39 14 -18 3 50
138 54 56 -17 27 47 15 35 24 24 243 -78 137 18 15 -17 49 50 140 36 56 -17 2 9 136 46 25 -17 56 37 141 13 2 -16 52 30
139 28 42 -16 17 1 15 35 38 23 243 -78 137 49 50 -16 40 44 141 13 30 -15 49 20 137 17 23 -16 48 1 141 50 44 -15 38 52
140 6 3 -15 4 7 15 35 51 22 242 -77 138 24 32 -15 29 48 141 54 21 -14 33 57 137 51 19 -15 37 39 142 33 1 -14 22 29
140 47 37 -13 48 41 15 36 5 21 242 -77 139 2 48 -14 16 43 142 40 19 -13 15 30 138 28 38 -14 25 16 143 20 50 -13 2 47
141 34 11 -12 30 12 15 36 18 20 241 -76 139 45 12 -13 1 6 143 32 34 -11 53 13 139 9 53 -13 10 29 144 15 32 -11 38 54
142 26 53 -11 7 59 15 36 31 18 241 -75 140 32 34 -11 42 29 144 32 50 -10 26 3 139 55 45 -11 52 52 145 19 10 -10 9 34
143 27 22 - 9 40 59 15 36 45 17 241 -73 141 25 57 -10 20 7 145 43 55 - 8 52 15 140 47 14 -10 31 47 146 35 11 - 8 32 39
144 38 15 - 8 7 34 15 36 58 15 240 -72 142 27 0 - 8 53 2 147 10 47 - 7 8 46 141 45 44 - 9 6 22 148 10 11 - 6 44 7
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