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Updated: 2011 JUL 02, 01:51 UT
Event Rank : 98
(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 29 UT, the 127 km diameter asteroid (426) Hippo will occult a 10.0 mag star in the constellation Perseus for observers along a path across WA from Bunbury (low altitude) to Kununurra, and Darwin.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.3 mag to 14.2 mag (the magnitude of the asteroid) for at most 6.4 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
116 41 30 -32 0 0 19 19 7 7 31 -42 117 34 0 115 49 4 118 11 51 115 11 21
117 27 39 -31 0 0 19 19 8 8 30 -41 118 19 40 116 35 43 118 57 10 115 58 22
118 13 31 -30 0 0 19 19 9 9 30 -41 119 5 4 117 22 3 119 42 15 116 45 2
118 59 8 -29 0 0 19 19 10 10 29 -41 119 50 15 118 8 6 120 27 8 117 31 24
119 44 32 -28 0 0 19 19 12 11 29 -40 120 35 17 118 53 54 121 11 53 118 17 30
120 29 47 -27 0 0 19 19 13 13 29 -40 121 20 10 119 39 31 121 56 31 119 3 23
121 14 55 -26 0 0 19 19 15 14 28 -39 122 4 58 120 24 59 122 41 5 119 49 6
121 59 58 -25 0 0 19 19 17 15 28 -39 122 49 43 121 10 20 123 25 38 120 34 41
122 44 58 -24 0 0 19 19 19 16 28 -38 123 34 27 121 55 37 124 10 10 121 20 10
123 29 58 -23 0 0 19 19 21 17 27 -37 124 19 12 122 40 52 124 54 46 122 5 36
124 15 0 -22 0 0 19 19 23 19 27 -37 125 4 2 123 26 7 125 39 26 122 51 1
125 0 6 -21 0 0 19 19 26 20 26 -36 125 48 57 124 11 25 126 24 13 123 36 27
125 45 18 -20 0 0 19 19 28 21 26 -36 126 34 0 124 56 47 127 9 10 124 21 57
126 30 40 -19 0 0 19 19 31 22 26 -35 127 19 13 125 42 17 127 54 18 125 7 33
127 16 12 -18 0 0 19 19 34 23 25 -34 128 4 39 126 27 56 128 39 40 125 53 17
128 1 57 -17 0 0 19 19 37 25 25 -33 128 50 20 127 13 46 129 25 18 126 39 12
128 47 59 -16 0 0 19 19 40 26 25 -33 129 36 19 127 59 51 130 11 15 127 25 20
129 34 18 -15 0 0 19 19 44 27 24 -32 130 22 37 128 46 12 130 57 32 128 11 42
130 20 57 -14 0 0 19 19 48 28 24 -31 131 9 16 129 32 52 131 44 13 128 58 22
131 7 59 -13 0 0 19 19 51 30 24 -30 131 56 21 130 19 52 132 31 20 129 45 22
131 55 27 -12 0 0 19 19 55 31 23 -29 132 43 52 131 7 17 133 18 54 130 32 45
132 43 23 -11 0 0 19 19 59 32 23 -29 133 31 54 131 55 8 134 7 0 131 20 33
133 31 49 -10 0 0 19 20 4 33 23 -28 134 20 28 132 43 27 134 55 40 132 8 48
134 20 49 - 9 0 0 19 20 8 34 22 -27 135 9 37 133 32 19 135 44 57 132 57 34
135 10 26 - 8 0 0 19 20 13 36 22 -26 135 59 26 134 21 45 136 34 54 133 46 53
136 0 42 - 7 0 0 19 20 17 37 21 -25 136 49 56 135 11 49 137 25 35 134 36 48
136 51 42 - 6 0 0 19 20 22 38 21 -24 137 41 11 136 2 34 138 17 2 135 27 23
137 43 28 - 5 0 0 19 20 27 39 20 -23 138 33 15 136 54 3 139 9 19 136 18 41
138 36 4 - 4 0 0 19 20 33 41 20 -22 139 26 11 137 46 20 140 2 31 137 10 45
139 29 35 - 3 0 0 19 20 38 42 19 -21 140 20 5 138 39 29 140 56 42 138 3 40
140 24 4 - 2 0 0 19 20 44 43 19 -20 141 14 59 139 33 35 141 51 56 138 57 28
141 19 36 - 1 0 0 19 20 50 44 18 -19 142 11 0 140 28 40 142 48 18 139 52 15
142 16 17 0 0 0 19 20 56 46 18 -17 143 8 12 141 24 50 143 45 53 140 48 5
143 14 10 1 0 0 19 21 2 47 17 -16 144 6 40 142 22 11 144 44 48 141 45 3
Uncertainty in time = +/- 3 secs
Prediction of 2011 Jul 2.0
Use these links for further information:
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[Observing Details]
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