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Updated: 2005 JUL 02, 01:41 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 Jul 10 UT, the 166 km diameter asteroid (54) Alexandra will occult a 11.0 mag star in the constellation Scorpius for observers along a path across the south-east corner of Western Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.6 mag to 10.6 mag (the magnitude of the asteroid) for at most 20.6 seconds. This event might be difficult to see visually. Twilight might also interfere.
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
132 57 35 -40 28 24 9 19 3 39 108 -15 131 28 45 -40 25 52 134 24 30 -40 29 19 130 58 6 -40 24 37 134 53 37 -40 29 17
132 23 47 -39 20 55 9 19 17 38 109 -14 130 55 38 -39 17 48 133 50 0 -39 22 24 130 25 12 -39 16 21 134 18 53 -39 22 33
131 48 40 -38 12 40 9 19 32 38 110 -14 130 21 4 -38 8 55 133 14 17 -38 14 45 129 50 48 -38 7 14 133 42 58 -38 15 6
131 12 9 -37 3 34 9 19 46 37 111 -13 129 44 58 -36 59 7 132 37 18 -37 6 18 129 14 51 -36 57 12 133 5 49 -37 6 52
130 34 7 -35 53 32 9 20 1 36 112 -12 129 7 14 -35 48 20 131 58 56 -35 56 58 128 37 12 -35 46 8 132 27 19 -35 57 46
129 54 30 -34 42 26 9 20 15 35 113 -11 128 27 46 -34 36 24 131 19 6 -34 46 39 127 57 45 -34 33 55 131 47 24 -34 47 42
129 13 8 -33 30 10 9 20 29 34 114 -10 127 46 23 -33 23 13 130 37 40 -33 35 13 127 16 21 -33 20 23 131 5 55 -33 36 33
128 29 52 -32 16 34 9 20 44 33 115 -9 127 2 56 -32 8 36 129 54 29 -32 22 34 126 32 48 -32 5 24 130 22 45 -32 24 11
127 44 30 -31 1 29 9 20 58 32 116 -8 126 17 11 -30 52 22 129 9 23 -31 8 31 125 46 53 -30 48 45 129 37 43 -31 10 28
126 56 48 -29 44 42 9 21 13 31 117 -7 125 28 52 -29 34 18 128 22 9 -29 52 54 124 58 19 -29 30 13 128 50 37 -29 55 13
126 6 30 -28 25 59 9 21 27 30 118 -6 124 37 39 -28 14 6 127 32 32 -28 35 30 124 6 45 -28 9 28 128 1 12 -28 38 14
125 13 12 -27 5 2 9 21 42 28 118 -5 123 43 7 -26 51 27 126 40 13 -27 16 4 123 11 44 -26 46 11 127 9 10 -27 19 16
124 16 28 -25 41 29 9 21 56 27 119 -4 122 44 44 -25 25 53 125 44 49 -25 54 16 122 12 41 -25 19 52 126 14 9 -25 58 1
123 15 42 -24 14 52 9 22 11 26 120 -2 121 41 45 -23 56 52 124 45 49 -24 29 43 121 8 50 -23 49 56 125 15 41 -24 34 6
122 10 7 -22 44 34 9 22 25 24 121 -1 120 33 13 -22 23 37 123 42 35 -23 1 53 119 59 7 -22 15 33 124 13 8 -23 7 2
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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