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Updated: 2011 Dec 15, 18:19 UT
Event Rank : 74
(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 Jan 24 UT, the 42 km diameter asteroid (678) Fredegundis will occult a 11.9 mag star in the constellation Taurus for observers along a path across south-eastern Queensland, beginning near Harvey Bay, running across northern and central New South Wales and western Victoria, leaving near Mount Gambier.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.0 mag to 12.3 mag (the magnitude of the asteroid) for at most 12.0 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.
Occultation of TYC 1861-01228-1 by 678 Fredegundis on 2012 Jan 24
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
137 5 46 -45 0 0 13 20 59 20 345 -22 136 35 8 137 36 37 135 48 21 138 24 33
137 35 57 -44 0 0 13 20 39 21 345 -23 137 5 37 138 6 30 136 19 17 138 53 58
138 7 47 -43 0 0 13 20 18 22 344 -24 137 37 43 138 38 4 136 51 48 139 25 8
138 41 16 -42 0 0 13 19 56 23 343 -25 138 11 25 139 11 19 137 25 52 139 58 1
139 16 22 -41 0 0 13 19 33 24 343 -26 138 46 43 139 46 13 138 1 28 140 32 36
139 53 5 -40 0 0 13 19 9 25 342 -27 139 23 37 140 22 46 138 38 38 141 8 54
140 31 26 -39 0 0 13 18 44 26 342 -28 140 2 7 141 0 59 139 17 21 141 46 54
141 11 26 -38 0 0 13 18 19 26 341 -29 140 42 13 141 40 52 139 57 38 142 26 37
141 53 5 -37 0 0 13 17 52 27 340 -30 141 23 57 142 22 26 140 39 30 143 8 4
142 36 25 -36 0 0 13 17 24 28 339 -31 142 7 20 143 5 43 141 22 58 143 51 18
143 21 28 -35 0 0 13 16 55 29 338 -33 142 52 24 143 50 45 142 8 4 144 36 19
144 8 16 -34 0 0 13 16 25 29 338 -34 143 39 11 144 37 34 142 54 51 145 23 10
144 56 52 -33 0 0 13 15 55 30 337 -35 144 27 45 145 26 13 143 43 21 146 11 54
145 47 19 -32 0 0 13 15 23 31 336 -36 145 18 7 146 16 45 144 33 37 147 2 35
146 39 41 -31 0 0 13 14 50 31 335 -37 146 10 23 147 9 15 145 25 42 147 55 17
147 34 3 -30 0 0 13 14 16 32 334 -38 147 4 35 148 3 46 146 19 42 148 50 4
148 30 29 -29 0 0 13 13 41 33 333 -39 148 0 50 149 0 25 147 15 40 149 47 3
149 29 7 -28 0 0 13 13 5 33 332 -41 148 59 13 149 59 17 148 13 43 150 46 20
150 30 2 -27 0 0 13 12 27 34 330 -42 149 59 51 151 0 30 149 13 56 151 48 2
151 33 22 -26 0 0 13 11 49 34 329 -43 151 2 51 152 4 12 150 16 26 152 52 19
152 39 17 -25 0 0 13 11 9 35 328 -44 152 8 22 153 10 32 151 21 23 153 59 20
153 47 58 -24 0 0 13 10 28 35 327 -45 153 16 36 154 19 42 152 28 56 155 9 17
154 59 37 -23 0 0 13 9 45 35 325 -47 154 27 42 155 31 55 153 39 16 156 22 26
156 14 29 -22 0 0 13 9 1 35 324 -48 155 41 57 156 47 26 154 52 36 157 39 2
Uncertainty in time = +/- 10 secs
Prediction of 2011 Dec 16.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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