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Updated: 2006 JAN 20, 23:03 UT
Event Rank : 92
(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 2006 Jan 23 UT, the 179 km diameter asteroid (259) Aletheia will occult a 11.5 mag star in the constellation Taurus for observers along a wide path across Western Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 13.6 mag (the magnitude of the asteroid) for at most 47.5 seconds. Note that evening twilight may render this event undetectable.
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 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
121 4 13 -33 0 0 11 24 9 39 7 -5 122 7 57 120 0 14 123 8 55 118 58 32
120 48 0 -32 0 0 11 24 29 40 7 -5 121 51 6 119 44 38 122 51 28 118 43 32
120 31 29 -31 0 0 11 24 49 41 8 -5 121 34 0 119 28 43 122 33 48 118 28 11
120 14 41 -30 0 0 11 25 10 42 8 -5 121 16 38 119 12 28 122 15 54 118 12 30
119 57 36 -29 0 0 11 25 31 43 8 -6 120 59 1 118 55 55 121 57 46 117 56 27
119 40 13 -28 0 0 11 25 53 44 9 -6 120 41 9 118 39 3 121 39 25 117 40 3
119 22 34 -27 0 0 11 26 15 45 9 -6 120 23 1 118 21 51 121 20 50 117 23 19
119 4 36 -26 0 0 11 26 37 46 9 -7 120 4 37 118 4 21 121 2 0 117 6 14
118 46 22 -25 0 0 11 27 0 46 10 -7 119 45 57 117 46 31 120 42 56 116 48 49
118 27 50 -24 0 0 11 27 23 47 10 -7 119 27 1 117 28 23 120 23 38 116 31 3
118 9 0 -23 0 0 11 27 46 48 11 -7 119 7 49 117 9 55 120 4 4 116 12 56
117 49 52 -22 0 0 11 28 10 49 11 -8 118 48 21 116 51 7 119 44 16 115 54 29
117 30 26 -21 0 0 11 28 34 50 12 -8 118 28 36 116 32 0 119 24 12 115 35 40
117 10 42 -20 0 0 11 28 58 51 13 -8 118 8 34 116 12 34 119 3 53 115 16 31
116 50 39 -19 0 0 11 29 23 52 13 -8 117 48 15 115 52 48 118 43 18 114 57 0
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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