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Updated: 2008 JUN 21, 22:43 UT
Event Rank : 22
(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 2008 Jul 25 UT, the 24 km diameter asteroid (265) Anna will occult a 11.6 mag star in the constellation Telescopium for observers along a significant uncertainty path running across eastern Tasmania, central Victoria, centred over the Dandenongs, just east of Melbourne, then across western New South Wales, western Queensland and eastern Northern Territory.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.4 mag to 13.9 mag (the magnitude of the asteroid) for at most 1.8 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
134 47 56 -10 0 0 12 1 14 38 159 -44 134 54 52 134 41 0 135 37 59 133 57 53
135 8 12 -11 0 0 12 1 9 39 159 -45 135 15 10 135 1 15 135 58 26 134 18 0
135 28 33 -12 0 0 12 1 3 40 159 -45 135 35 32 135 21 34 136 18 57 134 38 10
135 48 59 -13 0 0 12 0 57 41 159 -46 135 56 0 135 41 59 136 39 36 134 58 24
136 9 32 -14 0 0 12 0 51 42 159 -46 136 16 34 136 2 29 137 0 21 135 18 44
136 30 11 -15 0 0 12 0 45 43 159 -47 136 37 15 136 23 7 137 21 15 135 39 9
136 50 58 -16 0 0 12 0 39 44 159 -47 136 58 4 136 43 51 137 42 17 135 59 40
137 11 53 -17 0 0 12 0 32 45 158 -48 137 19 2 137 4 44 138 3 29 136 20 19
137 32 57 -18 0 0 12 0 26 46 158 -48 137 40 9 137 25 46 138 24 51 136 41 6
137 54 12 -19 0 0 12 0 19 47 158 -49 138 1 26 137 46 58 138 46 25 137 2 2
138 15 38 -20 0 0 12 0 13 48 158 -49 138 22 54 138 8 21 139 8 11 137 23 7
138 37 15 -21 0 0 12 0 6 49 158 -50 138 44 35 138 29 56 139 30 10 137 44 24
138 59 6 -22 0 0 11 59 59 50 157 -50 139 6 28 138 51 43 139 52 24 138 5 51
139 21 10 -23 0 0 11 59 52 51 157 -51 139 28 36 139 13 44 140 14 53 138 27 31
139 43 29 -24 0 0 11 59 45 52 157 -51 139 50 59 139 36 0 140 37 38 138 49 25
140 6 4 -25 0 0 11 59 37 53 157 -51 140 13 38 139 58 31 141 0 41 139 11 33
140 28 57 -26 0 0 11 59 30 54 156 -52 140 36 34 140 21 19 141 24 2 139 33 56
140 52 7 -27 0 0 11 59 23 55 156 -52 140 59 49 140 44 26 141 47 43 139 56 37
141 15 37 -28 0 0 11 59 15 56 156 -52 141 23 24 141 7 51 142 11 46 140 19 35
141 39 28 -29 0 0 11 59 8 57 155 -52 141 47 19 141 31 38 142 36 11 140 42 52
142 3 42 -30 0 0 11 59 0 59 155 -53 142 11 38 141 55 46 143 1 1 141 6 30
142 28 19 -31 0 0 11 58 52 60 155 -53 142 36 20 142 20 18 143 26 16 141 30 29
142 53 22 -32 0 0 11 58 44 61 154 -53 143 1 28 142 45 15 143 51 59 141 54 52
143 18 51 -33 0 0 11 58 36 62 154 -53 143 27 4 143 10 39 144 18 11 142 19 40
143 44 50 -34 0 0 11 58 28 63 153 -53 143 53 9 143 36 32 144 44 55 142 44 55
144 11 20 -35 0 0 11 58 20 64 153 -53 144 19 45 144 2 55 145 12 11 143 10 38
144 38 22 -36 0 0 11 58 12 65 152 -53 144 46 54 144 29 50 145 40 4 143 36 51
145 6 0 -37 0 0 11 58 3 66 151 -53 145 14 39 144 57 21 146 8 34 144 3 37
145 34 15 -38 0 0 11 57 55 67 151 -53 145 43 2 145 25 28 146 37 44 144 30 58
146 3 10 -39 0 0 11 57 46 68 150 -53 146 12 5 145 54 16 147 7 38 144 58 56
146 32 48 -40 0 0 11 57 38 69 149 -53 146 41 52 146 23 45 147 38 18 145 27 33
147 3 13 -41 0 0 11 57 29 70 148 -53 147 12 25 146 54 1 148 9 47 145 56 53
148 0 0 -42 47 55 11 57 13 72 147 -53 -42 30 20 -43 5 31 -40 41 32 -44 55 37
149 0 0 -44 36 9 11 56 57 73 144 -53 -44 18 56 -44 53 24 -42 32 21 -46 41 14
150 0 0 -46 18 39 11 56 42 75 142 -52 -46 1 48 -46 35 32 -44 17 26 -48 21 5
Uncertainty in time = +/- 6 secs
[Prediction of 2008 Jun 21.0]
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