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Updated: 2015 OCT 08, 21:09 UT
Event Rank : 59
(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 2015 Nov 15 UT, the 37 km diameter asteroid (131) Vala will occult a 10.5 mag star in the constellation Gemini for observers along a path across north Queensland beginning in morning twilight just west of Mackay and moving north-west.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.7 mag to 14.2 mag (the magnitude of the asteroid) for at most 9.6 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
152 5 31 -26 0 0 18 28 25 34 335 -6 152 22 37 151 48 23 152 58 30 151 12 23
151 1 22 -25 0 0 18 28 49 36 336 -8 151 18 24 150 44 20 151 54 7 150 8 30
149 57 13 -24 0 0 18 29 13 37 337 -9 150 14 11 149 40 15 150 49 44 149 4 33
148 53 0 -23 0 0 18 29 38 38 337 -10 149 9 53 148 36 5 149 45 19 148 0 31
147 48 38 -22 0 0 18 30 4 40 338 -11 148 5 29 147 31 46 148 40 48 146 56 18
146 44 6 -21 0 0 18 30 31 41 339 -12 147 0 54 146 27 16 147 36 9 145 51 52
145 39 19 -20 0 0 18 30 59 42 340 -14 145 56 6 145 22 31 146 31 16 144 47 10
144 34 15 -19 0 0 18 31 27 43 340 -15 144 51 0 144 17 28 145 26 8 143 42 9
143 28 49 -18 0 0 18 31 56 45 341 -16 143 45 35 143 12 3 144 20 41 142 36 44
142 23 0 -17 0 0 18 32 26 46 342 -17 142 39 45 142 6 13 143 14 52 141 30 54
141 16 43 -16 0 0 18 32 56 47 343 -19 141 33 29 140 59 55 142 8 37 140 24 34
140 9 55 -15 0 0 18 33 28 48 344 -20 140 26 42 139 53 5 141 1 53 139 17 41
139 2 32 -14 0 0 18 34 0 49 345 -21 139 19 22 138 45 41 139 54 37 138 10 11
137 54 31 -13 0 0 18 34 33 51 346 -23 138 11 24 137 37 37 138 46 44 137 2 2
136 45 49 -12 0 0 18 35 7 52 347 -24 137 2 45 136 28 51 137 38 13 135 53 8
135 36 21 -11 0 0 18 35 41 53 348 -25 135 53 21 135 19 19 136 28 57 134 43 27
134 26 4 -10 0 0 18 36 16 54 349 -27 134 43 9 134 8 57 135 18 55 133 32 53
133 14 53 - 9 0 0 18 36 52 55 351 -28 133 32 3 132 57 40 134 8 1 132 21 24
132 2 43 - 8 0 0 18 37 29 57 352 -29 132 20 0 131 45 24 132 56 11 131 8 54
130 49 31 - 7 0 0 18 38 7 58 354 -31 131 6 55 130 32 4 131 43 21 129 55 18
Uncertainty in time = +/- 13 secs
Prediction of 2015 Oct 9.0
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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