|
|
Updated: 2011 JUL 02, 00:30 UT
Event Rank : 82
(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 2011 Aug 12 UT, the 76 km diameter asteroid (696) Leonora will occult a 11.8 mag star in the constellation Perseus for observers along a path passing near Eucla in WA and then into morning twilight over central Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 13.8 mag (the magnitude of the asteroid) for at most 3.5 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
121 57 1 -39 0 0 20 58 31 19 8 -21 122 43 27 121 11 1 123 44 28 120 11 47
122 42 36 -38 0 0 20 58 34 20 8 -20 123 28 48 121 56 49 124 29 33 120 57 55
123 29 5 -37 0 0 20 58 37 21 7 -19 124 15 7 122 43 30 125 15 39 121 44 51
124 16 32 -36 0 0 20 58 40 22 6 -18 125 2 26 123 31 5 126 2 48 122 32 38
125 4 59 -35 0 0 20 58 44 23 6 -18 125 50 48 124 19 38 126 51 5 123 21 19
125 54 29 -34 0 0 20 58 48 24 5 -17 126 40 16 125 9 11 127 40 31 124 10 58
126 45 7 -33 0 0 20 58 52 25 4 -16 127 30 54 125 59 49 128 31 12 125 1 37
127 36 55 -32 0 0 20 58 56 26 3 -15 128 22 46 126 51 34 129 23 10 125 53 20
128 29 58 -31 0 0 20 59 0 27 2 -14 129 15 56 127 44 31 130 16 31 126 46 11
129 24 21 -30 0 0 20 59 5 28 2 -13 130 10 29 128 38 45 131 11 20 127 40 15
130 20 9 -29 0 0 20 59 9 29 1 -12 131 6 31 129 34 20 132 7 43 128 35 36
131 17 27 -28 0 0 20 59 14 30 360 -11 132 4 8 130 31 22 133 5 45 129 32 19
132 16 23 -27 0 0 20 59 20 31 359 -10 133 3 25 131 29 58 134 5 35 130 30 31
133 17 3 -26 0 0 20 59 25 32 358 -9 134 4 32 132 30 13 135 7 20 131 30 17
134 19 36 -25 0 0 20 59 31 33 357 -8 135 7 37 133 32 17 136 11 10 132 31 46
135 24 10 -24 0 0 20 59 37 34 355 -7 136 12 49 134 36 17 137 17 15 133 35 4
136 30 58 -23 0 0 20 59 43 35 354 -6 137 20 20 135 42 24 138 25 49 134 40 23
137 40 10 -22 0 0 20 59 50 36 353 -4 138 30 24 136 50 49 139 37 5 135 47 52
138 52 2 -21 0 0 20 59 57 36 351 -3 139 43 15 138 1 45 140 51 21 136 57 43
140 6 49 -20 0 0 21 0 4 37 350 -1 140 59 12 139 15 29 142 8 57 138 10 10
141 24 52 -19 0 0 21 0 11 38 348 0 142 18 36 140 32 17 143 30 17 139 25 30
Uncertainty in time = +/- 3 secs
Prediction of 2011 Jul 2.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]