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Updated: 2008 SEP 11, 16:33 UT
Event Rank : 8
(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 2008 Oct 12 UT, the 17 km diameter asteroid (5814) 1988 XW1 will occult a 10.5 mag star in the constellation Piscis Austrinus for observers along a narrow, large uncertainty path across southern New Zealand, centred over Waihoaka.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.8 mag to 16.3 mag (the magnitude of the asteroid) for at most 3.3 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
155 2 43 -18 0 0 11 31 31 70 239 -52 155 7 59 154 57 28 156 33 7 153 33 17
155 18 14 -19 0 0 11 31 9 70 242 -51 155 23 31 155 12 56 156 49 15 153 48 10
155 34 16 -20 0 0 11 30 47 70 244 -51 155 39 36 155 28 56 157 5 58 154 3 34
155 50 52 -21 0 0 11 30 24 70 247 -50 155 56 15 155 45 30 157 23 17 154 19 28
156 8 2 -22 0 0 11 30 2 71 250 -50 156 13 27 156 2 37 157 41 13 154 35 54
156 25 48 -23 0 0 11 29 40 71 252 -49 156 31 16 156 20 20 157 59 47 154 52 53
156 44 10 -24 0 0 11 29 17 71 255 -49 156 49 41 156 38 39 158 19 1 155 10 25
157 3 11 -25 0 0 11 28 54 71 258 -48 157 8 45 156 57 37 158 38 56 155 28 33
157 22 51 -26 0 0 11 28 32 71 261 -47 157 28 28 157 17 14 158 59 34 155 47 18
157 43 12 -27 0 0 11 28 9 71 264 -47 157 48 53 157 37 31 159 20 56 156 6 40
158 4 16 -28 0 0 11 27 47 71 267 -46 158 10 1 157 58 32 159 43 5 156 26 42
158 26 5 -29 0 0 11 27 24 70 269 -46 158 31 54 158 20 17 160 6 3 156 47 25
158 48 41 -30 0 0 11 27 1 70 272 -45 158 54 34 158 42 49 160 29 51 157 8 51
159 12 6 -31 0 0 11 26 38 70 274 -44 159 18 3 159 6 9 160 54 33 157 31 2
159 36 23 -32 0 0 11 26 16 69 277 -44 159 42 25 159 30 21 161 20 11 157 54 0
160 1 33 -33 0 0 11 25 53 69 279 -43 160 7 40 159 55 27 161 46 48 158 17 48
160 27 41 -34 0 0 11 25 30 69 282 -42 160 33 53 160 21 29 162 14 27 158 42 29
160 54 49 -35 0 0 11 25 7 68 284 -42 161 1 6 160 48 32 162 43 11 159 8 4
161 23 0 -36 0 0 11 24 45 68 286 -41 161 29 23 161 16 37 163 13 5 159 34 37
161 52 18 -37 0 0 11 24 22 67 287 -40 161 58 48 161 45 49 163 44 12 160 2 12
162 22 48 -38 0 0 11 23 59 66 289 -40 162 29 24 162 16 12 164 16 37 160 30 52
163 0 0 -39 10 2 11 23 33 66 291 -39 -38 57 38 -39 22 24 -35 34 2 -42 38 9
164 0 0 -40 56 15 11 22 53 64 293 -38 -40 44 22 -41 8 7 -37 29 33 -44 16 7
165 0 0 -42 34 54 11 22 16 63 295 -36 -42 23 29 -42 46 18 -39 16 32 -45 47 14
166 0 0 -44 6 42 11 21 41 62 297 -35 -43 55 42 -44 17 41 -40 55 54 -47 12 10
167 0 0 -45 32 20 11 21 9 61 298 -34 -45 21 43 -45 42 56 -42 28 25 -48 31 28
168 0 0 -46 52 20 11 20 40 59 299 -33 -46 42 4 -47 2 34 -43 54 44 -49 45 37
169 0 0 -48 7 12 11 20 12 58 300 -32 -47 57 16 -48 17 7 -45 15 26 -50 55 5
170 0 0 -49 17 23 11 19 46 57 300 -31 -49 7 45 -49 27 0 -46 30 59 -52 0 14
Uncertainty in time = +/- 27 secs
[Prediction of 2008 Sep 11.0]
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[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
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