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Updated: 2012 NOV 16, 11:01 UT
Event Rank : 33
(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 2012 Dec 22 UT, the 96 km diameter asteroid (4834) Thoas will occult a 11.6 mag star in the constellation Leo Minor for observers along a path across Australia, from Cobram at dawn across western New South Wales (in morning twilight) and central Queensland to Cape York, and across Papua - New Guinea from Daru to Aitape.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.8 mag to 16.4 mag (the magnitude of the asteroid) for at most 6.4 seconds.
This update is based on 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
146 6 7 -38 0 0 18 54 17 11 353 0 146 39 10 145 33 6 148 54 59 143 17 53
145 56 57 -37 0 0 18 54 18 12 353 -1 146 29 33 145 24 22 148 43 31 143 10 57
145 48 0 -36 0 0 18 54 20 13 353 -2 146 20 11 145 15 50 148 32 24 143 4 9
145 39 16 -35 0 0 18 54 21 14 353 -2 146 11 3 145 7 31 148 21 37 142 57 27
145 30 45 -34 0 0 18 54 23 15 353 -3 146 2 9 144 59 22 148 11 8 142 50 52
145 22 25 -33 0 0 18 54 25 16 353 -3 145 53 27 144 51 24 148 0 55 142 44 22
145 14 16 -32 0 0 18 54 27 17 353 -4 145 44 57 144 43 35 147 50 59 142 37 58
145 6 16 -31 0 0 18 54 29 18 354 -5 145 36 38 144 35 56 147 41 19 142 31 38
144 58 26 -30 0 0 18 54 32 19 354 -5 145 28 29 144 28 24 147 31 52 142 25 23
144 50 45 -29 0 0 18 54 34 20 354 -6 145 20 30 144 21 1 147 22 39 142 19 12
144 43 11 -28 0 0 18 54 37 21 354 -6 145 12 39 144 13 44 147 13 39 142 13 4
144 35 46 -27 0 0 18 54 39 22 354 -7 145 4 58 144 6 35 147 4 51 142 7 0
144 28 27 -26 0 0 18 54 42 23 354 -8 144 57 24 143 59 31 146 56 14 142 0 59
144 21 16 -25 0 0 18 54 45 24 354 -8 144 49 58 143 52 34 146 47 48 141 55 0
144 14 10 -24 0 0 18 54 48 25 354 -9 144 42 39 143 45 42 146 39 32 141 49 4
144 7 10 -23 0 0 18 54 51 26 354 -9 144 35 26 143 38 56 146 31 26 141 43 10
144 0 16 -22 0 0 18 54 55 27 354 -10 144 28 19 143 32 14 146 23 29 141 37 18
143 53 27 -21 0 0 18 54 58 28 354 -10 144 21 19 143 25 36 146 15 40 141 31 28
143 46 43 -20 0 0 18 55 2 29 354 -11 144 14 24 143 19 3 146 8 0 141 25 39
143 40 3 -19 0 0 18 55 5 30 354 -12 144 7 34 143 12 33 146 0 27 141 19 51
143 33 27 -18 0 0 18 55 9 31 354 -12 144 0 48 143 6 7 145 53 2 141 14 4
143 26 56 -17 0 0 18 55 13 32 354 -13 143 54 7 142 59 44 145 45 44 141 8 17
143 20 27 -16 0 0 18 55 17 33 354 -13 143 47 31 142 53 24 145 38 32 141 2 32
143 14 2 -15 0 0 18 55 21 34 354 -14 143 40 58 142 47 7 145 31 27 140 56 47
143 7 40 -14 0 0 18 55 25 35 354 -14 143 34 28 142 40 52 145 24 27 140 51 2
143 1 21 -13 0 0 18 55 29 36 354 -15 143 28 3 142 34 40 145 17 34 140 45 16
142 55 5 -12 0 0 18 55 34 37 354 -16 143 21 40 142 28 30 145 10 45 140 39 31
142 48 51 -11 0 0 18 55 38 38 354 -16 143 15 20 142 22 21 145 4 2 140 33 46
142 42 39 -10 0 0 18 55 43 39 354 -17 143 9 3 142 16 14 144 57 23 140 28 0
142 36 29 - 9 0 0 18 55 47 40 354 -17 143 2 48 142 10 9 144 50 50 140 22 13
142 30 20 - 8 0 0 18 55 52 41 354 -18 142 56 36 142 4 5 144 44 20 140 16 26
142 24 14 - 7 0 0 18 55 57 42 354 -18 142 50 26 141 58 2 144 37 55 140 10 37
142 18 8 - 6 0 0 18 56 2 43 354 -19 142 44 17 141 52 0 144 31 33 140 4 48
142 12 4 - 5 0 0 18 56 7 44 354 -19 142 38 11 141 45 58 144 25 16 139 58 57
142 6 1 - 4 0 0 18 56 12 45 354 -20 142 32 5 141 39 57 144 19 1 139 53 5
141 59 59 - 3 0 0 18 56 18 46 354 -20 142 26 2 141 33 57 144 12 51 139 47 11
141 53 58 - 2 0 0 18 56 23 47 354 -21 142 19 59 141 27 57 144 6 43 139 41 16
141 47 57 - 1 0 0 18 56 28 48 354 -21 142 13 58 141 21 57 144 0 38 139 35 18
141 41 57 0 0 0 18 56 34 49 354 -22 142 7 57 141 15 57 143 54 37 139 29 19
141 35 57 1 0 0 18 56 39 50 354 -22 142 1 58 141 9 57 143 48 38 139 23 18
141 29 58 2 0 0 18 56 45 51 354 -23 141 55 59 141 3 56 143 42 41 139 17 14
Uncertainty in time = +/- 13 secs
Prediction of 2012 Dec 3.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
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