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Updated: 2010 APR 15, 17:08 UT
Event Rank : 27
(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 Apr 18 UT, the 15 km diameter asteroid (262) Valda will occult a 9.7 mag star in the constellation Leo for observers along a path across the south island of New Zealand, passing over Timaru.
In the case of an occultation, the combined light of the asteroid and the star will drop by 6.5 mag to 16.2 mag (the magnitude of the asteroid) for at most 1.8 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.
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
172 36 7 -46 0 0 10 6 49 18 336 -44 172 29 2 172 43 12 171 54 19 173 18 0
171 46 16 -45 0 0 10 6 44 19 336 -44 171 39 19 171 53 13 171 5 18 172 27 18
170 57 44 -44 0 0 10 6 38 20 337 -44 170 50 55 171 4 32 170 17 33 171 37 58
170 10 24 -43 0 0 10 6 32 21 337 -44 170 3 42 170 17 5 169 30 57 170 49 54
169 24 11 -42 0 0 10 6 26 23 338 -44 169 17 36 169 30 45 168 45 26 170 2 59
168 38 59 -41 0 0 10 6 20 24 339 -44 168 32 32 168 45 27 168 0 53 169 17 8
167 54 45 -40 0 0 10 6 13 25 339 -44 167 48 23 168 1 6 167 17 15 168 32 16
167 11 22 -39 0 0 10 6 6 26 340 -44 167 5 7 167 17 38 166 34 27 167 48 19
166 28 48 -38 0 0 10 5 59 27 340 -44 166 22 38 166 34 58 165 52 25 167 5 11
165 46 58 -37 0 0 10 5 51 28 341 -44 165 40 53 165 53 2 165 11 6 166 22 51
165 5 48 -36 0 0 10 5 44 29 342 -44 164 59 48 165 11 48 164 30 25 165 41 12
164 25 16 -35 0 0 10 5 36 30 342 -43 164 19 21 164 31 11 163 50 20 165 0 12
163 45 18 -34 0 0 10 5 27 32 343 -43 163 39 27 163 51 9 163 10 47 164 19 49
163 5 51 -33 0 0 10 5 18 33 343 -43 163 0 4 163 11 38 162 31 45 163 39 58
162 26 53 -32 0 0 10 5 10 34 344 -43 162 21 10 162 32 36 161 53 9 163 0 37
161 48 20 -31 0 0 10 5 0 35 344 -42 161 42 41 161 53 59 161 14 57 162 21 42
161 10 10 -30 0 0 10 4 51 36 345 -42 161 4 34 161 15 46 160 37 7 161 43 13
160 32 21 -29 0 0 10 4 41 37 345 -42 160 26 49 160 37 54 159 59 37 161 5 5
159 54 51 -28 0 0 10 4 31 38 346 -41 159 49 21 160 0 21 159 22 23 160 27 17
159 17 37 -27 0 0 10 4 21 39 347 -41 159 12 9 159 23 4 158 45 25 159 49 46
158 40 36 -26 0 0 10 4 10 41 347 -40 158 35 12 158 46 1 158 8 40 159 12 31
158 3 48 -25 0 0 10 4 0 42 348 -40 157 58 26 158 9 10 157 32 6 158 35 28
157 27 10 -24 0 0 10 3 49 43 348 -39 157 21 49 157 32 30 156 55 40 157 58 37
156 50 39 -23 0 0 10 3 37 44 349 -39 156 45 21 156 55 57 156 19 21 157 21 54
156 14 15 -22 0 0 10 3 26 45 350 -38 156 8 58 156 19 31 155 43 8 156 45 19
155 37 54 -21 0 0 10 3 14 46 350 -38 155 32 40 155 43 9 155 6 57 156 8 49
155 1 36 -20 0 0 10 3 2 47 351 -37 154 56 23 155 6 49 154 30 48 155 32 21
154 25 18 -19 0 0 10 2 50 48 352 -37 154 20 7 154 30 30 153 54 38 154 55 56
153 48 59 -18 0 0 10 2 37 49 352 -36 153 43 49 153 54 10 153 18 26 154 19 29
Uncertainty in time = +/- 5 secs
Prediction of 2010 Apr 16.0
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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