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Updated: 2017 Nov 08, 22:08 UT
Event Rank : 99
(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 2018 Jan 02 UT, the 86 km diameter asteroid (494) Virtus will occult a 10.0 mag star in the constellation Leo for observers along a path across Tasmania, passing over Hobart, central Victoria, passing over Melbourne, south-western New South Wales, northern South Australia and northern West Australia leaving near Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.03 mag to 14.00 mag (the magnitude of the asteroid) for at most 14.3 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, astrometry for the asteroid kindly provided by Bill Owen, astrometry for the asteroid kindly provided by the IAU Minor Planet Center. This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
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 TYC 1418-01036-1 by 494 Virtus on 2018 Jan 2
Centre Star Star Sun Path Limits Error Limits Alt
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
145 35 49 -45 0 0 14 27 59 11 44 -22 147 18 50 143 45 47 148 13 56 142 40 27 -2.91
145 45 12 -44 0 0 14 28 10 12 44 -23 147 25 51 143 57 56 148 19 46 142 54 24 -2.92
145 49 45 -43 0 0 14 28 22 13 44 -24 147 28 25 144 4 46 148 21 19 143 2 41 -2.93
145 49 44 -42 0 0 14 28 34 13 44 -25 147 26 46 144 6 38 148 18 50 143 5 44 2.94
145 45 25 -41 0 0 14 28 48 14 44 -26 147 21 6 144 3 48 148 12 30 143 3 50 2.94
145 36 57 -40 0 0 14 29 2 15 44 -27 147 11 36 143 56 30 148 2 27 142 57 14 2.95
145 24 29 -39 0 0 14 29 16 15 45 -28 146 58 23 143 44 52 147 48 49 142 46 6 2.95
145 8 7 -38 0 0 14 29 32 16 45 -29 146 41 30 143 29 0 147 31 40 142 30 32 2.95
144 47 53 -37 0 0 14 29 48 16 45 -30 146 21 2 143 8 58 147 11 3 142 10 35 2.94
144 23 49 -36 0 0 14 30 4 17 46 -31 145 56 59 142 44 47 146 46 59 141 46 16 2.94
143 55 52 -35 0 0 14 30 22 17 46 -32 145 29 20 142 16 22 146 19 27 141 17 30 2.94
143 23 58 -34 0 0 14 30 40 18 47 -33 144 58 2 141 43 40 145 48 24 140 44 12 2.93
142 48 1 -33 0 0 14 30 59 18 47 -34 144 22 59 141 6 29 145 13 46 140 6 10 2.93
142 7 48 -32 0 0 14 31 19 18 48 -35 143 44 3 140 24 36 144 35 25 139 23 6 2.92
141 23 6 -31 0 0 14 31 39 19 49 -36 143 1 2 139 37 41 143 53 11 138 34 38 2.92
140 33 35 -30 0 0 14 32 1 19 50 -37 142 13 41 138 45 18 143 6 50 137 40 12 2.91
139 38 47 -29 0 0 14 32 23 19 50 -38 141 21 40 137 46 50 142 16 5 136 39 5 2.91
138 38 8 -28 0 0 14 32 47 19 51 -39 140 24 31 136 41 26 141 20 32 135 30 12 2.90
137 30 48 -27 0 0 14 33 11 19 52 -40 139 21 40 135 27 54 140 19 41 134 11 58 2.90
136 15 38 -26 0 0 14 33 37 19 53 -41 138 12 17 134 4 24 139 12 51 132 41 57 2.90
134 50 57 -25 0 0 14 34 5 18 54 -42 136 55 16 132 28 7 137 59 7 130 55 56 2.90
133 14 7 -24 0 0 14 34 34 18 55 -42 135 28 58 130 34 1 136 37 10 128 45 41 2.91
131 20 40 -23 0 0 14 35 6 17 57 -43 133 50 56 128 11 32 135 5 6 125 49 11 2.93
129 1 42 -22 0 0 14 35 42 16 58 -43 131 56 57 124 48 22 133 19 53 ... .. .. 2.97
128 0 0 -21 37 45 14 35 57 15 59 -44 -20 24 48 -22 55 49 -19 45 49 -23 42 13 2.91
127 0 0 -21 18 35 14 36 11 15 59 -44 -20 6 29 -22 35 36 -19 27 55 -23 21 18 2.92
126 0 0 -21 1 46 14 36 23 14 60 -44 -19 50 23 -22 17 54 -19 12 10 -23 3 1 2.93
125 0 0 -20 47 15 14 36 36 13 60 -43 -19 36 27 -22 2 40 -18 58 32 -22 47 19 2.93
124 0 0 -20 35 0 14 36 47 13 61 -43 -19 24 40 -21 49 51 -18 46 58 -22 34 8 2.94
123 0 0 -20 24 58 14 36 58 12 61 -43 -19 14 59 -21 39 24 -18 37 27 -22 23 24 2.96
122 0 0 -20 17 9 14 37 9 11 62 -43 -19 7 24 -21 31 18 -18 29 59 -22 15 6 2.97
121 0 0 -20 11 31 14 37 19 11 62 -43 -19 1 53 -21 25 31 -18 24 32 -22 9 13 2.98
120 0 0 -20 8 5 14 37 28 10 62 -42 -18 58 28 -21 22 3 -18 21 7 -22 5 45 3.00
119 0 0 -20 6 50 14 37 36 9 63 -42 -18 57 8 -21 20 55 -18 19 44 -22 4 41 3.02
118 0 0 -20 7 48 14 37 44 8 63 -41 -18 57 54 -21 22 8 -18 20 24 -22 6 3 3.04
117 0 0 -20 11 0 14 37 51 7 64 -41 -19 0 47 -21 25 42 -18 23 8 -22 9 53 3.06
116 0 0 -20 16 28 14 37 57 7 64 -40 -19 5 49 -21 31 42 -18 27 57 -22 16 12 3.10
115 0 0 -20 24 15 14 38 2 6 64 -40 -19 13 2 -21 40 9 -18 34 54 -22 25 6 3.13
114 0 0 -20 34 23 14 38 7 5 65 -39 -19 22 29 -21 51 8 -18 44 1 -22 36 38 3.18
113 0 0 -20 46 58 14 38 11 4 65 -38 -19 34 14 -22 4 43 -18 55 22 -22 50 54 3.26
112 0 0 -21 2 4 14 38 14 3 65 -38 -19 48 21 -22 21 2 .. .. .. -23 8 1 3.37
Uncertainty in time = +/- 4 secs
Prediction of 2017 Nov 8.0
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