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Updated: 2013 JUL 04, 05:09 UT
Event Rank : 15
(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 Aug 18 UT, the 53 km diameter asteroid (5130) Ilioneus will occult a 11.3 mag star in the constellation Pisces for observers along a path possibly across New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.7 mag to 17.0 mag (the magnitude of the asteroid) for at most 6.4 seconds.
This update is based on 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
-141 3 9 -54 0 0 15 55 15 1 306 -6 -139 37 55 -142 29 40 ... .. .. -156 53 55
-143 32 16 -53 0 0 15 55 16 3 308 -8 -142 6 41 -144 59 18 ... .. .. -159 38 6
-146 4 28 -52 0 0 15 55 19 4 310 -9 -144 38 11 -147 32 23 ... .. .. -162 31 35
-148 40 33 -51 0 0 15 55 23 6 312 -10 -147 13 9 -150 9 45 ... .. .. -165 36 49
-151 21 26 -50 0 0 15 55 30 8 314 -12 -149 52 28 -152 52 27 ... .. .. -168 57 19
-154 8 16 -49 0 0 15 55 38 10 316 -14 -152 37 11 -155 41 43 ... .. .. -172 38 31
-157 2 28 -48 0 0 15 55 49 12 318 -16 -155 28 34 -158 39 9 ... .. .. -176 49 43
-160 5 52 -47 0 0 15 56 3 14 321 -18 -158 28 15 -161 46 49 ... .. .. 178 10 16
-163 20 56 -46 0 0 15 56 20 16 323 -20 -161 38 22 -165 7 38 ... .. .. 171 28 41
-166 51 12 -45 0 0 15 56 41 19 326 -22 -165 1 53 -168 45 51 ... .. .. ... .. ..
-170 42 4 -44 0 0 15 57 6 21 329 -25 -168 43 13 -172 48 15 ... .. .. ... .. ..
-175 2 37 -43 0 0 15 57 39 23 333 -28 -172 49 24 -177 27 3 -157 12 45 ... .. ..
179 49 12 -42 0 0 15 58 20 26 338 -32 -177 33 13 176 50 51 -160 29 50 ... .. ..
173 5 42 -41 0 0 15 59 20 28 344 -37 176 36 40 168 29 19 -164 0 45 ... .. ..
Uncertainty in time = +/- 45 secs
Prediction of 2013 Jul 4.0
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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