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Updated: 2009 DEC 27, 13:47 UT
Event Rank : 80
(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 Jan 30 UT, the 83 km diameter asteroid (1241) Dysona will occult a 11.7 mag star in the constellation Auriga for observers along a path across Queensland, western New South Wales and Victoria and south-eastern South Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.4 mag to 15.1 mag (the magnitude of the asteroid) for at most 6.4 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 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
140 39 28 -42 0 0 11 44 40 3 358 -17 140 4 5 141 15 1 139 16 55 142 2 56
140 38 46 -41 0 0 11 44 40 4 358 -17 140 3 55 141 13 47 139 17 28 142 0 58
140 38 56 -40 0 0 11 44 39 5 358 -18 140 4 36 141 13 26 139 18 49 141 59 56
140 39 57 -39 0 0 11 44 38 6 357 -19 140 6 5 141 13 59 139 20 57 141 59 49
140 41 47 -38 0 0 11 44 37 7 357 -19 140 8 22 141 15 21 139 23 49 142 0 35
140 44 24 -37 0 0 11 44 36 8 357 -20 140 11 24 141 17 32 139 27 25 142 2 11
140 47 45 -36 0 0 11 44 34 9 357 -21 140 15 10 141 20 29 139 31 43 142 4 35
140 51 50 -35 0 0 11 44 33 10 357 -22 140 19 38 141 24 11 139 36 41 142 7 46
140 56 38 -34 0 0 11 44 31 11 357 -22 140 24 47 141 28 37 139 42 18 142 11 43
141 2 6 -33 0 0 11 44 29 12 357 -23 140 30 35 141 33 46 139 48 34 142 16 24
141 8 15 -32 0 0 11 44 27 13 357 -24 140 37 3 141 39 35 139 55 27 142 21 48
141 15 3 -31 0 0 11 44 25 14 357 -24 140 44 9 141 46 5 140 2 56 142 27 54
141 22 29 -30 0 0 11 44 22 15 357 -25 140 51 52 141 53 15 140 11 2 142 34 40
141 30 33 -29 0 0 11 44 20 16 357 -26 141 0 11 142 1 3 140 19 42 142 42 7
141 39 14 -28 0 0 11 44 17 17 357 -27 141 9 7 142 9 28 140 28 57 142 50 12
141 48 31 -27 0 0 11 44 14 18 357 -27 141 18 38 142 18 31 140 38 46 142 58 57
141 58 24 -26 0 0 11 44 11 19 356 -28 141 28 43 142 28 11 140 49 9 143 8 19
142 8 52 -25 0 0 11 44 8 20 356 -29 141 39 24 142 38 28 141 0 5 143 18 19
142 19 55 -24 0 0 11 44 4 21 356 -30 141 50 38 142 49 20 141 11 35 143 28 57
142 31 34 -23 0 0 11 44 1 22 356 -30 142 2 27 143 0 48 141 23 37 143 40 11
142 43 47 -22 0 0 11 43 57 23 356 -31 142 14 49 143 12 52 141 36 12 143 52 2
142 56 34 -21 0 0 11 43 53 24 356 -32 142 27 45 143 25 31 141 49 20 144 4 30
143 9 57 -20 0 0 11 43 49 25 355 -33 142 41 15 143 38 45 142 3 0 144 17 34
143 23 53 -19 0 0 11 43 45 26 355 -33 142 55 19 143 52 35 142 17 13 144 31 14
143 38 25 -18 0 0 11 43 40 27 355 -34 143 9 57 144 7 0 142 31 59 144 45 31
143 53 31 -17 0 0 11 43 36 28 355 -35 143 25 9 144 22 1 142 47 18 145 0 24
144 9 12 -16 0 0 11 43 31 29 355 -36 143 40 55 144 37 38 143 3 11 145 15 55
144 25 29 -15 0 0 11 43 26 29 354 -37 143 57 15 144 53 50 143 19 37 145 32 2
144 42 21 -14 0 0 11 43 21 30 354 -37 144 14 11 145 10 39 143 36 37 145 48 47
144 59 49 -13 0 0 11 43 16 31 354 -38 144 31 41 145 28 5 143 54 11 146 6 9
145 17 54 -12 0 0 11 43 10 32 354 -39 144 49 48 145 46 8 144 12 20 146 24 10
145 36 36 -11 0 0 11 43 5 33 353 -40 145 8 30 146 4 49 144 31 4 146 42 50
145 55 55 -10 0 0 11 42 59 34 353 -40 145 27 50 146 24 8 144 50 24 147 2 9
Uncertainty in time = +/- 4 secs
Prediction of 2009 Dec 27.0
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