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Updated: 2012 Jan 14, 16:44 UT
Event Rank : 34
(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 28 UT, the 20 km diameter asteroid (1236) Thais will occult a 8.3 mag star in the constellation Lynx for observers along a path across Queensland and Northern Territory, running from Marlborough across to Darwin.
In the case of an occultation, the combined light of the asteroid and the star will drop by 7.5 mag to 15.8 mag (the magnitude of the asteroid) for at most 1.9 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, 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 2962-01001-1 by 1236 Thais on 2012 Jan 28
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
156 8 0 -28 0 0 15 28 28 12 329 -38 156 22 3 155 53 53 157 17 28 154 57 8
155 0 19 -27 0 0 15 28 32 13 330 -39 155 14 31 154 46 2 156 10 31 153 48 37
153 50 23 -26 0 0 15 28 37 14 331 -41 154 4 47 153 35 56 155 1 27 152 37 44
152 38 2 -25 0 0 15 28 43 16 331 -42 152 52 38 152 23 21 153 50 7 151 24 14
151 23 1 -24 0 0 15 28 49 17 332 -43 151 37 52 151 8 5 152 36 17 150 7 54
150 5 5 -23 0 0 15 28 56 19 333 -45 150 20 13 149 49 51 151 19 43 148 48 26
148 43 55 -22 0 0 15 29 4 20 333 -46 148 59 24 148 28 22 150 0 10 147 25 30
147 19 11 -21 0 0 15 29 12 21 334 -48 147 35 4 147 3 14 148 37 18 145 58 41
145 50 27 -20 0 0 15 29 22 23 335 -49 146 6 46 145 34 1 147 10 43 144 27 30
144 17 10 -19 0 0 15 29 32 24 336 -51 144 34 2 144 0 11 145 39 59 142 51 20
142 38 42 -18 0 0 15 29 43 26 337 -52 142 56 12 142 21 4 144 4 32 141 9 25
140 54 13 -17 0 0 15 29 56 27 338 -53 141 12 29 140 35 47 142 23 39 139 20 45
139 2 38 -16 0 0 15 30 10 29 339 -55 139 21 50 138 43 15 140 36 28 137 24 2
137 2 32 -15 0 0 15 30 26 31 340 -56 137 22 54 136 41 56 138 41 48 135 17 26
136 0 0 -14 30 36 15 30 34 31 341 -57 -14 20 53 -14 40 22 -13 42 31 -15 19 35
135 0 0 -14 3 34 15 30 42 32 342 -57 -13 53 55 -14 13 15 -13 15 52 -14 52 8
134 0 0 -13 37 40 15 30 51 33 343 -58 -13 28 6 -13 47 16 -12 50 20 -14 25 51
133 0 0 -13 12 53 15 30 59 33 343 -59 -13 3 23 -13 22 25 -12 25 54 -14 0 41
132 0 0 -12 49 12 15 31 7 34 344 -59 -12 39 46 -12 58 40 -12 2 33 -13 36 40
131 0 0 -12 26 37 15 31 16 35 345 -59 -12 17 15 -12 36 1 -11 40 16 -13 13 45
130 0 0 -12 5 7 15 31 25 35 346 -60 -11 55 48 -12 14 27 -11 19 4 -12 51 56
129 0 0 -11 44 41 15 31 33 36 346 -60 -11 35 26 -11 53 58 -10 58 55 -12 31 12
128 0 0 -11 25 19 15 31 42 36 347 -60 -11 16 7 -11 34 32 -10 39 49 -12 11 34
127 0 0 -11 7 0 15 31 51 37 348 -61 -10 57 51 -11 16 10 -10 21 45 -11 52 59
126 0 0 -10 49 44 15 32 0 37 349 -61 -10 40 38 -10 58 51 -10 4 42 -11 35 29
125 0 0 -10 33 30 15 32 9 38 350 -61 -10 24 26 -10 42 35 - 9 48 41 -11 19 1
124 0 0 -10 18 17 15 32 18 38 351 -61 -10 9 16 -10 27 20 - 9 33 41 -11 3 36
123 0 0 -10 4 6 15 32 27 39 351 -61 - 9 55 7 -10 13 6 - 9 19 41 -10 49 13
122 0 0 - 9 50 55 15 32 36 39 352 -61 - 9 41 59 - 9 59 54 - 9 6 40 -10 35 52
121 0 0 - 9 38 45 15 32 45 39 353 -61 - 9 29 51 - 9 47 41 - 8 54 40 -10 23 32
120 0 0 - 9 27 35 15 32 54 40 354 -61 - 9 18 43 - 9 36 30 - 8 43 38 -10 12 13
Uncertainty in time = +/- 4 secs
Prediction of 2012 Jan 15.0
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