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Updated: 2013 JUN 12, 16:15 UT
Event Rank : 99
(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 09 UT, the 175 km diameter asteroid (89) Julia will occult a 12.1 mag star in the constellation Pegasus for observers along a path across Australia from South Australia, near Adelaide to Ceduna. Then into WA ending in the north near Derby.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.1 mag to 9.9 mag (the magnitude of the asteroid) for at most 19.4 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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 Limit1 Path Limit2 Error Limit1 Error Limit2
E. Longitude Latitude U.T. Alt Az Alt
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
151 38 54 -45 17 1 20 59 37 6 301 -1 147 37 31 -44 19 21 ... .. .. .. .. .. 145 53 23 -43 57 16 ... .. .. .. .. ..
143 40 6 -40 45 30 20 59 53 13 306 -5 141 29 48 -40 23 58 146 8 19 -41 13 7 140 22 27 -40 13 51 147 42 59 -41 32 29
139 30 17 -37 34 54 21 0 10 17 308 -7 137 46 43 -37 21 59 141 21 29 -37 50 32 136 51 27 -37 15 45 142 27 54 -38 0 45
136 32 34 -34 52 33 21 0 26 21 310 -9 135 2 17 -34 43 51 138 7 26 -35 2 59 134 13 27 -34 39 38 139 2 55 -35 9 42
134 13 21 -32 26 36 21 0 42 24 311 -10 132 51 16 -32 20 26 135 38 37 -32 34 1 132 6 33 -32 17 29 136 27 58 -32 38 47
132 18 38 -30 11 49 21 0 58 26 311 -11 131 2 14 -30 7 22 133 37 28 -30 17 16 130 20 24 -30 5 17 134 22 47 -30 20 47
130 41 4 -28 5 21 21 1 14 29 312 -12 129 28 51 -28 2 8 131 55 13 -28 9 23 128 49 12 -28 0 41 132 37 41 -28 12 2
129 16 14 -26 5 23 21 1 30 31 312 -13 128 7 16 -26 3 7 130 26 49 -26 8 21 127 29 18 -26 2 9 131 7 8 -26 10 21
128 1 17 -24 10 42 21 1 46 33 312 -13 126 54 54 -24 9 10 129 9 3 -24 12 51 126 18 17 -24 8 35 129 47 40 -24 14 21
126 54 13 -22 20 24 21 2 2 35 312 -14 125 49 57 -22 19 29 127 59 42 -22 21 54 125 14 27 -22 19 12 128 36 57 -22 23 0
125 53 36 -20 33 51 21 2 18 37 312 -14 124 51 5 -20 33 25 126 57 12 -20 34 49 124 16 31 -20 33 23 127 33 20 -20 35 35
124 58 23 -18 50 30 21 2 34 39 311 -15 123 57 21 -18 50 29 126 0 25 -18 51 1 123 23 34 -18 50 40 126 35 36 -18 51 32
124 7 45 -17 9 58 21 2 50 40 311 -15 123 7 58 -17 10 17 125 8 26 -17 10 6 122 34 51 -17 10 39 125 42 50 -17 10 23
123 21 3 -15 31 53 21 3 6 42 311 -16 122 22 20 -15 32 30 124 20 35 -15 31 42 121 49 48 -15 33 1 124 54 19 -15 31 47
122 37 46 -13 55 59 21 3 22 43 310 -16 121 39 59 -13 56 51 123 36 20 -13 55 31 121 7 56 -13 57 30 124 9 29 -13 55 26
121 57 30 -12 22 1 21 3 38 45 309 -16 121 0 30 -12 23 7 122 55 14 -12 21 19 120 28 53 -12 23 54 123 27 53 -12 21 6
121 19 55 -10 49 49 21 3 54 46 309 -16 120 23 36 -10 51 6 122 16 55 -10 48 53 119 52 20 -10 51 59 122 49 8 -10 48 32
120 44 43 - 9 19 10 21 4 10 48 308 -16 119 48 59 - 9 20 38 121 41 5 - 9 18 3 119 18 2 - 9 21 36 122 12 57 - 9 17 36
120 11 40 - 7 49 56 21 4 26 49 307 -17 119 16 26 - 7 51 34 121 7 30 - 7 48 39 118 45 46 - 7 52 37 121 39 3 - 7 48 6
119 40 34 - 6 21 59 21 4 43 50 306 -17 118 45 46 - 6 23 45 120 35 56 - 6 20 33 118 15 20 - 6 24 53 121 7 13 - 6 19 54
Uncertainty in time = +/- 5 secs
Prediction of 2013 Apr 8.0
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