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Updated: 2009 JUL 16, 01:33 UT
Event Rank : 43
(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 2009 Aug 18 UT, the 68 km diameter asteroid (693) Zerbinetta will occult a 12.5 mag star in the constellation Scorpius for observers along a south-to-north path across Australia beginning just west of Adelaide and running north along the Northern Territory - Queensland border.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.0 mag to 14.3 mag (the magnitude of the asteroid) for at most 9.0 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
138 31 57 - 6 0 0 10 56 46 56 180 -32 138 50 24 138 13 29 139 46 6 137 17 44
138 29 20 - 7 0 0 10 56 33 57 180 -32 138 47 49 138 10 51 139 43 38 137 14 59
138 26 40 - 8 0 0 10 56 21 58 180 -32 138 45 12 138 8 8 139 41 9 137 12 8
138 23 57 - 9 0 0 10 56 8 59 180 -33 138 42 31 138 5 22 139 38 37 137 9 12
138 21 9 -10 0 0 10 55 56 60 179 -33 138 39 47 138 2 31 139 36 3 137 6 11
138 18 17 -11 0 0 10 55 43 60 179 -33 138 36 59 137 59 35 139 33 25 137 3 4
138 15 20 -12 0 0 10 55 30 61 179 -33 138 34 6 137 56 34 139 30 45 136 59 51
138 12 18 -13 0 0 10 55 17 62 179 -33 138 31 9 137 53 28 139 28 1 136 56 31
138 9 11 -14 0 0 10 55 3 63 179 -33 138 28 6 137 50 16 139 25 13 136 53 4
138 5 58 -15 0 0 10 54 50 64 178 -33 138 24 58 137 46 57 139 22 21 136 49 30
138 2 39 -16 0 0 10 54 37 65 178 -33 138 21 45 137 43 32 139 19 24 136 45 48
137 59 13 -17 0 0 10 54 23 66 178 -33 138 18 25 137 40 0 139 16 22 136 41 58
137 55 40 -18 0 0 10 54 9 67 177 -33 138 14 58 137 36 21 139 13 15 136 37 58
137 51 59 -19 0 0 10 53 56 68 177 -33 138 11 24 137 32 33 139 10 2 136 33 50
137 48 10 -20 0 0 10 53 42 69 177 -33 138 7 43 137 28 37 139 6 43 136 29 31
137 44 13 -21 0 0 10 53 28 70 176 -32 138 3 53 137 24 32 139 3 17 136 25 2
137 40 6 -22 0 0 10 53 14 71 176 -32 137 59 55 137 20 17 138 59 43 136 20 22
137 35 50 -23 0 0 10 52 59 72 175 -32 137 55 48 137 15 52 138 56 2 136 15 30
137 31 24 -24 0 0 10 52 45 73 175 -32 137 51 31 137 11 16 138 52 13 136 10 26
137 26 46 -25 0 0 10 52 31 74 174 -32 137 47 3 137 6 29 138 48 15 136 5 9
137 21 57 -26 0 0 10 52 17 75 173 -32 137 42 24 137 1 29 138 44 8 135 59 38
137 16 56 -27 0 0 10 52 2 76 172 -32 137 37 34 136 56 17 138 39 50 135 53 52
137 11 41 -28 0 0 10 51 48 77 171 -32 137 32 31 136 50 51 138 35 22 135 47 51
137 6 13 -29 0 0 10 51 33 78 170 -31 137 27 15 136 45 11 138 30 42 135 41 33
137 0 30 -30 0 0 10 51 18 79 168 -31 137 21 45 136 39 15 138 25 51 135 34 58
136 54 32 -31 0 0 10 51 4 80 166 -31 137 16 0 136 33 3 138 20 46 135 28 5
136 48 17 -32 0 0 10 50 49 81 164 -31 137 9 59 136 26 34 138 15 28 135 20 53
136 41 44 -33 0 0 10 50 34 82 161 -31 137 3 41 136 19 46 138 9 55 135 13 19
136 34 53 -34 0 0 10 50 19 82 158 -30 136 57 6 136 12 39 138 4 7 135 5 24
136 27 42 -35 0 0 10 50 4 83 153 -30 136 50 11 136 5 11 137 58 2 134 57 6
136 20 10 -36 0 0 10 49 49 84 147 -30 136 42 57 135 57 22 137 51 39 134 48 24
136 12 15 -37 0 0 10 49 35 84 139 -30 136 35 21 135 49 9 137 44 58 134 39 15
136 3 57 -38 0 0 10 49 20 85 129 -29 136 27 22 135 40 31 137 37 57 134 29 39
135 55 14 -39 0 0 10 49 5 85 116 -29 136 18 58 135 31 28 137 30 34 134 19 33
135 46 3 -40 0 0 10 48 50 85 101 -29 136 10 9 135 21 56 137 22 49 134 8 56
Uncertainty in time = +/- 14 secs
Prediction of 2009 Jul 16.0
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