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Updated: 2009 JUL 16, 00:59 UT
Event Rank : 71
(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 11 UT, the 56 km diameter asteroid (1149) Volga will occult a 10.8 mag star in the constellation Taurus for observers along a path beginning over Ceduna in South Australia, and passing near Woomera before moving into Queensland and morning twilight.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.3 mag to 16.1 mag (the magnitude of the asteroid) for at most 1.9 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
118 47 32 -40 0 0 20 18 25 8 44 -31 119 38 28 117 57 6 121 4 10 116 34 22
120 32 33 -39 0 0 20 18 26 10 42 -30 121 23 49 119 41 49 122 50 11 118 18 42
122 19 32 -38 0 0 20 18 28 12 41 -28 123 11 16 121 28 23 124 38 30 120 4 40
124 8 47 -37 0 0 20 18 30 13 40 -27 125 1 7 123 17 5 126 29 29 121 52 34
126 0 41 -36 0 0 20 18 33 15 39 -25 126 53 47 125 8 17 128 23 34 123 42 44
127 55 40 -35 0 0 20 18 36 17 37 -24 128 49 43 127 2 23 130 21 16 125 35 32
129 54 14 -34 0 0 20 18 39 19 36 -22 130 49 27 128 59 52 132 23 10 127 31 24
131 56 58 -33 0 0 20 18 43 20 35 -20 132 53 38 131 1 18 134 30 1 129 30 51
Latitude Latitude Latitude Latitude
132 0 0 -32 58 33 20 18 43 20 35 -20 -33 25 38 -32 31 45 -34 11 14 -31 47 53
133 0 0 -32 30 4 20 18 45 21 34 -19 -32 56 59 -32 3 26 -33 42 19 -31 19 48
134 0 0 -32 2 8 20 18 47 22 33 -18 -32 28 54 -31 35 39 -33 13 58 -30 52 15
135 0 0 -31 34 47 20 18 49 23 33 -17 -32 1 24 -31 8 26 -32 46 12 -30 25 16
136 0 0 -31 8 0 20 18 51 24 32 -17 -31 34 28 -30 41 47 -32 19 1 -29 58 52
137 0 0 -30 41 48 20 18 54 25 31 -16 -31 8 7 -30 15 44 -31 52 25 -29 33 2
138 0 0 -30 16 12 20 18 56 25 30 -15 -30 42 23 -29 50 16 -31 26 26 -29 7 47
139 0 0 -29 51 12 20 18 59 26 30 -14 -30 17 15 -29 25 25 -31 1 4 -28 43 8
140 0 0 -29 26 50 20 19 1 27 29 -13 -29 52 44 -29 1 10 -30 36 20 -28 19 6
141 0 0 -29 3 5 20 19 4 28 28 -12 -29 28 52 -28 37 32 -30 12 14 -27 55 40
142 0 0 -28 39 57 20 19 6 29 27 -11 -29 5 37 -28 14 32 -29 48 46 -27 32 52
143 0 0 -28 17 28 20 19 9 29 26 -10 -28 43 0 -27 52 11 -29 25 57 -27 10 41
144 0 0 -27 55 38 20 19 12 30 25 -9 -28 21 3 -27 30 27 -29 3 47 -26 49 9
145 0 0 -27 34 27 20 19 14 31 25 -8 -27 59 45 -27 9 23 -28 42 17 -26 28 15
146 0 0 -27 13 55 20 19 17 31 24 -7 -27 39 7 -26 48 58 -28 21 27 -26 8 1
147 0 0 -26 54 3 20 19 20 32 23 -6 -27 19 8 -26 29 12 -28 1 18 -25 48 25
148 0 0 -26 34 51 20 19 23 33 22 -5 -26 59 50 -26 10 6 -27 41 49 -25 29 29
149 0 0 -26 16 20 20 19 26 33 21 -4 -26 41 13 -25 51 41 -27 23 1 -25 11 13
150 0 0 -25 58 29 20 19 29 34 20 -3 -26 23 16 -25 33 55 -27 4 55 -24 53 37
151 0 0 -25 41 19 20 19 32 34 19 -2 -26 6 1 -25 16 51 -26 47 30 -24 36 41
152 0 0 -25 24 51 20 19 35 35 18 -1 -25 49 27 -25 0 27 -26 30 47 -24 20 26
153 0 0 -25 9 3 20 19 39 35 17 0 -25 33 34 -24 44 45 -26 14 45 -24 4 51
Uncertainty in time = +/- 2 secs
Prediction of 2009 Jul 16.0
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