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Updated: 2009 FEB 06, 00:12 UT
Event Rank : 100
(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 Mar 21 UT, the 208 km diameter asteroid (13) Egeria will occult a 11.8 mag star in the constellation Leo Minor for observers along a path firstly passing across Papua New Guinea. Then in Australia from the Northern Territory just east of Darwin to south-west Western Australia passing over Leonora, Merredin and ending between Busselton and Albany.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.3 mag to 10.5 mag (the magnitude of the asteroid) for at most 23.8 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, 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
108 28 25 -43 0 0 11 58 0 0 37 -12 ... .. .. 110 12 4 ... .. .. 110 38 58
109 29 27 -42 0 0 11 58 0 2 36 -13 107 47 16 111 11 18 107 20 38 111 37 44
110 29 12 -41 0 0 11 57 59 3 36 -14 108 48 46 112 9 21 108 22 36 112 35 22
111 27 46 -40 0 0 11 57 58 4 35 -15 109 48 58 113 6 21 109 23 14 113 31 57
112 25 17 -39 0 0 11 57 57 5 34 -16 110 48 0 114 2 23 110 22 40 114 27 37
113 21 49 -38 0 0 11 57 55 7 34 -17 111 45 58 114 57 33 111 21 1 115 22 26
114 17 29 -37 0 0 11 57 53 8 33 -18 112 42 58 115 51 57 112 18 22 116 16 30
115 12 22 -36 0 0 11 57 51 9 33 -19 113 39 5 116 45 38 113 14 49 117 9 53
116 6 32 -35 0 0 11 57 48 10 32 -20 114 34 24 117 38 41 114 10 27 118 2 39
117 0 5 -34 0 0 11 57 45 11 32 -20 115 29 1 118 31 11 115 5 21 118 54 53
117 53 3 -33 0 0 11 57 41 13 31 -21 116 23 0 119 23 11 115 59 35 119 46 38
118 45 31 -32 0 0 11 57 37 14 31 -22 117 16 23 120 14 44 116 53 14 120 37 58
119 37 32 -31 0 0 11 57 33 15 30 -23 118 9 17 121 5 56 117 46 21 121 28 57
120 29 11 -30 0 0 11 57 29 16 30 -24 119 1 44 121 56 48 118 39 1 122 19 37
121 20 30 -29 0 0 11 57 24 18 29 -25 119 53 47 122 47 24 119 31 16 123 10 2
122 11 32 -28 0 0 11 57 18 19 29 -26 120 45 31 123 37 47 120 23 11 124 0 15
123 2 21 -27 0 0 11 57 13 20 28 -27 121 36 58 124 28 0 121 14 48 124 50 19
123 52 59 -26 0 0 11 57 7 21 28 -28 122 28 10 125 18 5 122 6 10 125 40 16
124 43 30 -25 0 0 11 57 1 23 28 -29 123 19 12 126 8 6 122 57 20 126 30 9
125 33 56 -24 0 0 11 56 54 24 27 -30 124 10 6 126 58 4 123 48 22 127 20 1
126 24 19 -23 0 0 11 56 47 25 27 -31 125 0 55 127 48 4 124 39 17 128 9 54
127 14 42 -22 0 0 11 56 40 26 26 -32 125 51 41 128 38 6 125 30 9 128 59 51
128 5 8 -21 0 0 11 56 32 27 26 -33 126 42 27 129 28 14 126 21 1 129 49 55
128 55 40 -20 0 0 11 56 24 29 25 -34 127 33 15 130 18 30 127 11 54 130 40 7
129 46 19 -19 0 0 11 56 16 30 25 -35 128 24 9 131 8 56 128 2 51 131 30 30
130 37 8 -18 0 0 11 56 7 31 25 -36 129 15 10 131 59 36 128 53 55 132 21 7
131 28 10 -17 0 0 11 55 58 32 24 -37 130 6 21 132 50 30 129 45 9 133 12 0
132 19 27 -16 0 0 11 55 49 34 24 -38 130 57 44 133 41 43 130 36 34 134 3 12
133 11 2 -15 0 0 11 55 39 35 23 -39 131 49 22 134 33 16 131 28 13 134 54 45
134 2 57 -14 0 0 11 55 29 36 23 -40 132 41 18 135 25 12 132 20 9 135 46 41
134 55 15 -13 0 0 11 55 19 37 22 -41 133 33 33 136 17 33 133 12 25 136 39 3
135 47 57 -12 0 0 11 55 8 38 22 -42 134 26 11 137 10 22 134 5 2 137 31 55
136 41 8 -11 0 0 11 54 57 40 21 -43 135 19 15 138 3 43 134 58 3 138 25 18
137 34 50 -10 0 0 11 54 46 41 21 -44 136 12 46 138 57 36 135 51 32 139 19 15
138 29 5 - 9 0 0 11 54 34 42 20 -45 137 6 47 139 52 7 136 45 31 140 13 50
139 23 56 - 8 0 0 11 54 22 43 20 -46 138 1 23 140 47 17 137 40 2 141 9 5
140 19 27 - 7 0 0 11 54 9 45 19 -47 138 56 34 141 43 9 138 35 9 142 5 4
141 15 41 - 6 0 0 11 53 56 46 19 -48 139 52 25 142 39 48 139 30 54 143 1 50
142 12 40 - 5 0 0 11 53 43 47 18 -49 140 48 59 143 37 17 140 27 22 143 59 26
143 10 30 - 4 0 0 11 53 30 48 17 -50 141 46 19 144 35 38 141 24 34 144 57 56
144 9 12 - 3 0 0 11 53 16 49 17 -51 142 44 28 145 34 57 142 22 35 145 57 25
145 8 52 - 2 0 0 11 53 2 51 16 -52 143 43 31 146 35 17 143 21 29 146 57 56
146 9 33 - 1 0 0 11 52 47 52 15 -53 144 43 31 147 36 43 144 21 19 147 59 34
147 11 20 0 0 0 11 52 32 53 14 -54 145 44 33 148 39 19 145 22 9 149 2 24
148 14 18 1 0 0 11 52 17 54 13 -54 146 46 40 149 43 12 146 24 5 150 6 32
Uncertainty in time = +/- 3 secs
[Prediction of 2009 Feb 6.0]
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