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Updated: 2015 OCT 09, 02:38 UT
Event Rank : 97
(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 Dec 05 UT, the 53 km diameter asteroid (584) Semiramis will occult a 11.7 mag star in the constellation Sextans for observers along a path across Australia from Darwin across north-western Northern Territory, western Queensland and central New South Wales to Eden, passing directly over Canberra.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.0 mag to 13.5 mag (the magnitude of the asteroid) for at most 4.7 seconds.
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.
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
153 1 22 -44 0 0 17 10 32 35 38 -8 152 30 39 153 31 54 152 7 10 153 55 0
152 39 35 -43 0 0 17 10 23 36 39 -9 152 9 14 153 9 45 151 46 2 153 32 33
152 16 50 -42 0 0 17 10 14 37 39 -10 151 46 49 152 46 40 151 23 53 153 9 13
151 53 8 -41 0 0 17 10 4 37 40 -11 151 23 26 152 22 39 151 0 44 152 44 58
151 28 29 -40 0 0 17 9 55 38 41 -12 150 59 4 151 57 43 150 36 35 152 19 49
151 2 53 -39 0 0 17 9 45 38 42 -12 150 33 44 151 31 52 150 11 27 151 53 46
150 36 21 -38 0 0 17 9 35 39 43 -13 150 7 25 151 5 6 149 45 19 151 26 50
150 8 52 -37 0 0 17 9 25 39 45 -14 149 40 9 150 37 24 149 18 11 150 58 59
149 40 26 -36 0 0 17 9 15 39 46 -15 149 11 53 150 8 47 148 50 4 150 30 13
149 11 1 -35 0 0 17 9 4 40 47 -16 148 42 38 149 39 13 148 20 56 150 0 32
148 40 38 -34 0 0 17 8 54 40 48 -17 148 12 23 149 8 42 147 50 47 149 29 55
148 9 15 -33 0 0 17 8 43 40 49 -18 147 41 6 148 37 13 147 19 35 148 58 20
147 36 50 -32 0 0 17 8 32 41 51 -19 147 8 46 148 4 43 146 47 19 148 25 47
147 3 23 -31 0 0 17 8 21 41 52 -21 146 35 23 147 31 12 146 13 57 147 52 13
146 28 51 -30 0 0 17 8 10 41 53 -22 146 0 53 146 56 38 145 39 29 147 17 37
145 53 13 -29 0 0 17 7 59 41 54 -23 145 25 14 146 20 59 145 3 51 146 41 57
145 16 25 -28 0 0 17 7 48 41 56 -24 144 48 26 145 44 13 144 27 1 146 5 11
144 38 26 -27 0 0 17 7 36 41 57 -25 144 10 24 145 6 16 143 48 56 145 27 17
143 59 13 -26 0 0 17 7 25 41 58 -26 143 31 6 144 27 7 143 9 35 144 48 10
143 18 42 -25 0 0 17 7 13 41 60 -27 142 50 28 143 46 41 142 28 52 144 7 49
142 36 49 -24 0 0 17 7 1 41 61 -28 142 8 27 143 4 56 141 46 44 143 26 10
141 53 30 -23 0 0 17 6 49 41 62 -30 141 24 58 142 21 48 141 3 7 142 43 8
141 8 42 -22 0 0 17 6 37 41 64 -31 140 39 57 141 37 11 140 17 56 141 58 40
140 22 18 -21 0 0 17 6 25 41 65 -32 139 53 19 140 51 1 139 31 6 141 12 40
139 34 12 -20 0 0 17 6 12 40 67 -33 139 4 56 140 3 12 138 42 29 140 25 3
138 44 19 -19 0 0 17 6 0 40 68 -35 138 14 43 139 13 38 137 52 0 139 35 43
137 52 31 -18 0 0 17 5 47 40 69 -36 137 22 31 138 22 12 136 59 30 138 44 33
136 58 38 -17 0 0 17 5 34 39 71 -37 136 28 12 137 28 45 136 4 50 137 51 25
136 2 32 -16 0 0 17 5 21 38 72 -39 135 31 35 136 33 8 135 7 49 136 56 9
135 4 1 -15 0 0 17 5 9 38 73 -40 134 32 30 135 35 10 134 8 16 135 58 36
134 2 53 -14 0 0 17 4 55 37 74 -42 133 30 41 134 34 40 133 5 55 134 58 33
132 58 51 -13 0 0 17 4 42 36 75 -43 132 25 53 133 31 22 132 0 31 133 55 47
131 51 39 -12 0 0 17 4 29 35 77 -45 131 17 47 132 25 0 130 51 43 132 50 2
130 40 54 -11 0 0 17 4 16 34 78 -46 130 6 1 131 15 13 129 39 7 131 40 58
129 26 10 -10 0 0 17 4 2 33 79 -48 128 50 5 130 1 38 128 22 14 130 28 11
128 6 56 - 9 0 0 17 3 49 32 80 -49 127 29 27 128 43 43 127 0 27 129 11 14
126 42 31 - 8 0 0 17 3 35 31 81 -51 126 3 21 127 20 53 125 32 59 127 49 32
Uncertainty in time = +/- 2 secs
Prediction of 2015 Oct 9.0
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