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Updated: 2013 JAN 26, 17:01 UT
Event Rank : 67
(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 2013 Feb 18 UT, the 61 km diameter asteroid (402) Chloe will occult a 11.6 mag star in the constellation Orion for observers along a path beginning over Victoria near Melbourne, Ballarat and Bendigo. The path moves north-east into New South Wales near Deniliquin and Parkes, before ending near Brisbane.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.0 mag to 13.4 mag (the magnitude of the asteroid) for at most 5.4 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
139 23 15 -43 0 0 10 51 59 30 342 -12 140 2 38 138 44 11 141 12 44 137 36 7
140 3 44 -42 0 0 10 52 8 31 341 -13 140 42 48 139 24 58 141 52 22 138 17 27
140 45 7 -41 0 0 10 52 17 32 340 -14 141 23 55 140 6 37 142 33 1 138 59 36
141 27 26 -40 0 0 10 52 27 32 339 -15 142 6 1 140 49 11 143 14 44 139 42 34
142 10 45 -39 0 0 10 52 36 33 338 -16 142 49 8 141 32 40 143 57 33 140 26 25
142 55 4 -38 0 0 10 52 46 34 337 -17 143 33 19 142 17 9 144 41 29 141 11 10
143 40 27 -37 0 0 10 52 57 34 335 -18 144 18 36 143 2 38 145 26 36 141 56 53
144 26 56 -36 0 0 10 53 7 35 334 -19 145 5 2 143 49 12 146 12 58 142 43 35
145 14 36 -35 0 0 10 53 18 36 333 -20 145 52 40 144 36 54 147 0 36 143 31 21
146 3 30 -34 0 0 10 53 30 36 332 -22 146 41 36 145 25 46 147 49 36 144 20 14
146 53 41 -33 0 0 10 53 41 37 330 -23 147 31 51 146 15 54 148 40 1 145 10 17
147 45 15 -32 0 0 10 53 53 37 329 -24 148 23 33 147 7 21 149 31 58 146 1 35
148 38 17 -31 0 0 10 54 5 38 328 -25 149 16 45 148 0 14 150 25 31 146 54 13
149 32 52 -30 0 0 10 54 17 38 326 -26 150 11 34 148 54 36 151 20 48 147 48 16
150 29 7 -29 0 0 10 54 30 38 325 -28 151 8 6 149 50 35 152 17 55 148 43 49
151 27 9 -28 0 0 10 54 43 39 323 -29 152 6 30 150 48 17 153 17 0 149 41 0
152 27 7 -27 0 0 10 54 57 39 322 -30 153 6 54 151 47 52 154 18 15 150 39 55
153 29 11 -26 0 0 10 55 10 39 320 -32 154 9 28 152 49 26 155 21 48 151 40 44
154 33 30 -25 0 0 10 55 24 39 318 -33 155 14 24 153 53 12 156 27 54 152 43 35
155 40 19 -24 0 0 10 55 39 39 317 -34 156 21 55 154 59 20 157 36 47 153 48 40
156 49 50 -23 0 0 10 55 53 39 315 -36 157 32 16 156 8 6 158 48 45 154 56 10
158 2 23 -22 0 0 10 56 9 39 313 -37 158 45 47 157 19 44 160 4 9 156 6 21
159 18 17 -21 0 0 10 56 24 39 311 -39 160 2 49 158 34 34 161 23 24 157 19 30
160 37 57 -20 0 0 10 56 40 38 310 -41 161 23 50 159 53 0 162 47 3 158 35 56
162 1 54 -19 0 0 10 56 56 38 308 -42 162 49 23 161 15 28 164 15 45 159 56 4
Uncertainty in time = +/- 5 secs
Prediction of 2013 Jan 27.0
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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