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Updated: 2015 Mar 05, 03:20 UT
Event Rank : 42
(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 2015 Apr 06 UT, the 113 km diameter asteroid (2920) Automedon will occult a 12.4 mag star in the constellation Virgo for observers along a significant uncertainty path across central West Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.4 mag to 15.7 mag (the magnitude of the asteroid) for at most 6.5 seconds. The Moon, being just past full phase and nearby, may interfere.
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.
Occultation of 2UCAC 23377591 by 2920 Automedon on 2015 Apr 6
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
140 14 3 -45 21 12 10 35 14 34 86 -24 138 59 18 -45 32 2 141 26 36 -45 9 38 134 48 44 -46 0 43 145 1 27 -44 29 16
139 32 57 -44 31 24 10 35 20 34 88 -24 138 18 34 -44 41 50 140 45 8 -44 20 14 134 9 9 -45 9 7 144 18 52 -43 41 2
138 50 58 -43 41 25 10 35 25 33 89 -24 137 36 53 -43 51 26 140 2 51 -43 30 39 133 28 17 -44 17 17 143 35 40 -42 52 40
138 8 3 -42 51 13 10 35 31 33 90 -24 136 54 10 -43 0 48 139 19 44 -42 40 53 132 46 4 -43 25 8 142 51 50 -42 4 8
137 24 8 -42 0 47 10 35 37 32 91 -23 136 10 22 -42 9 54 138 35 41 -41 50 53 132 2 23 -42 32 38 142 7 18 -41 15 24
136 39 8 -41 10 3 10 35 42 32 92 -23 135 25 23 -41 18 41 137 50 38 -41 0 37 131 17 10 -41 39 44 141 22 0 -40 26 27
135 52 58 -40 18 59 10 35 48 31 93 -23 134 39 8 -40 27 7 137 4 31 -40 10 2 130 30 15 -40 46 21 140 35 51 -39 37 14
135 5 32 -39 27 32 10 35 54 30 94 -22 133 51 30 -39 35 8 136 17 13 -39 19 5 129 41 31 -39 52 25 139 48 47 -38 47 43
134 16 43 -38 35 39 10 35 59 30 95 -22 133 2 22 -38 42 41 135 28 40 -38 27 44 128 50 46 -38 57 52 139 0 43 -37 57 52
133 26 23 -37 43 16 10 36 5 29 95 -21 132 11 35 -37 49 41 134 38 42 -37 35 55 127 57 49 -38 2 35 138 11 34 -37 7 37
132 34 24 -36 50 19 10 36 10 28 96 -21 131 18 59 -36 56 4 133 47 13 -36 43 34 127 2 22 -37 6 27 137 21 12 -36 16 57
131 40 33 -35 56 43 10 36 16 27 97 -20 130 24 22 -36 1 45 132 54 2 -35 50 38 126 4 8 -36 9 21 136 29 31 -35 25 48
130 44 39 -35 2 22 10 36 22 27 98 -19 129 27 29 -35 6 37 131 58 58 -34 57 0 125 2 43 -35 11 5 135 36 21 -34 34 6
129 46 27 -34 7 9 10 36 27 26 99 -19 128 28 4 -34 10 32 131 1 48 -34 2 35 123 57 36 -34 11 27 134 41 34 -33 41 47
128 45 37 -33 10 58 10 36 33 25 100 -18 127 25 43 -33 13 21 130 2 15 -33 7 17 122 48 8 -33 10 10 133 44 58 -32 48 46
127 41 48 -32 13 38 10 36 39 24 101 -17 126 20 2 -32 14 54 129 0 0 -32 10 56 121 33 26 -32 6 52 132 46 20 -31 54 57
126 34 30 -31 14 57 10 36 44 23 102 -16 125 10 24 -31 14 55 127 54 39 -31 13 23 120 12 15 -31 1 4 131 45 24 -31 0 13
125 23 7 -30 14 39 10 36 50 21 103 -15 123 56 5 -30 13 6 126 45 40 -30 14 25 118 42 47 -29 52 0 130 41 51 -30 4 27
124 6 49 -29 12 26 10 36 55 20 104 -14 122 36 2 -29 9 1 125 32 25 -29 13 45 117 2 10 -28 38 32 129 35 16 -29 7 28
122 44 30 -28 7 48 10 37 1 19 105 -13 121 8 49 -28 2 6 124 14 0 -28 11 1 115 5 21 -27 18 36 128 25 11 -28 9 5
121 14 32 -27 0 8 10 37 7 17 106 -12 119 32 11 -26 51 25 122 49 12 -27 5 44 112 41 41 -25 48 0 127 10 57 -27 9 1
119 34 29 -25 48 25 10 37 12 15 107 -10 117 42 32 -25 35 32 121 16 12 -25 57 10 109 18 21 -23 53 38 125 51 44 -26 6 56
117 40 10 -24 31 0 10 37 18 13 107 -8 115 33 5 -24 11 44 119 32 13 -24 44 12 ... .. .. .. .. .. 124 26 21 -25 2 21
115 23 33 -23 4 39 10 37 24 11 109 -6 112 47 54 -22 33 41 117 32 25 -23 24 53 ... .. .. .. .. .. 122 53 9 -23 54 36
Uncertainty in time = +/- 14 secs
Prediction of 2015 Jan 13.0
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