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Updated: 2013 JAN 26, 16:52 UT
Event Rank : 79
(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 2013 Feb 14 UT, the 45 km diameter asteroid (351) Yrsa will occult a 10.8 mag star in the constellation Leo for observers along a path beginning over Tasmania, near Launceston and Hobart. The path then passes over Victoria, South Australia and Western Australia, near Melbourne, Port Augusta and Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.5 mag to 11.9 mag (the magnitude of the asteroid) for at most 4.6 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
153 36 14 -50 0 0 13 42 56 16 4 -27 154 13 49 152 58 21 155 4 27 152 6 18
152 59 2 -49 0 0 13 43 2 16 5 -28 153 36 10 152 21 35 154 26 12 151 30 8
152 20 15 -48 0 0 13 43 8 17 5 -29 152 57 0 151 43 12 153 46 29 150 52 17
151 39 55 -47 0 0 13 43 15 18 6 -30 152 16 19 151 3 12 153 5 20 150 12 46
150 58 1 -46 0 0 13 43 23 19 7 -31 151 34 7 150 21 36 152 22 44 149 31 33
150 14 32 -45 0 0 13 43 31 20 8 -32 150 50 23 149 38 22 151 38 39 148 48 40
149 29 27 -44 0 0 13 43 39 21 8 -33 150 5 5 148 53 29 150 53 4 148 4 3
148 42 44 -43 0 0 13 43 48 22 9 -34 149 18 13 148 6 56 150 5 58 147 17 42
147 54 21 -42 0 0 13 43 57 23 10 -35 148 29 43 147 18 40 149 17 18 146 29 34
147 4 15 -41 0 0 13 44 6 24 11 -35 147 39 33 146 28 38 148 27 2 145 39 36
146 12 23 -40 0 0 13 44 17 25 12 -36 146 47 39 145 36 46 147 35 5 144 47 45
145 18 40 -39 0 0 13 44 27 26 13 -37 145 53 58 144 43 1 146 41 25 143 53 56
144 23 2 -38 0 0 13 44 38 26 14 -38 144 58 25 143 47 18 145 45 57 142 58 4
143 25 24 -37 0 0 13 44 50 27 15 -39 144 0 54 142 49 30 144 48 36 142 0 2
142 25 37 -36 0 0 13 45 2 28 16 -39 143 1 19 141 49 31 143 49 15 140 59 45
141 23 37 -35 0 0 13 45 15 29 17 -40 141 59 34 140 47 14 142 47 49 139 57 3
140 19 12 -34 0 0 13 45 28 29 18 -41 140 55 29 139 42 29 141 44 8 138 51 47
139 12 14 -33 0 0 13 45 42 30 19 -41 139 48 55 138 35 5 140 38 5 137 43 46
138 2 31 -32 0 0 13 45 56 31 21 -42 138 39 41 137 24 51 139 29 27 136 32 46
136 49 48 -31 0 0 13 46 11 31 22 -42 137 27 33 136 11 30 138 18 4 135 18 30
135 33 49 -30 0 0 13 46 27 32 23 -43 136 12 16 134 54 47 137 3 40 134 0 41
134 14 14 -29 0 0 13 46 43 32 25 -43 134 53 31 133 34 19 135 45 58 132 38 55
132 50 40 -28 0 0 13 47 0 33 26 -43 133 30 56 132 9 41 134 24 37 131 12 43
131 22 36 -27 0 0 13 47 18 33 28 -43 132 4 3 130 40 21 132 59 13 129 41 31
129 49 26 -26 0 0 13 47 37 33 30 -43 130 32 18 129 5 39 131 29 15 128 4 32
128 10 22 -25 0 0 13 47 57 33 32 -43 128 54 58 127 24 44 129 54 5 126 20 49
126 24 24 -24 0 0 13 48 18 33 33 -43 127 11 8 125 36 27 128 12 52 124 29 1
124 30 9 -23 0 0 13 48 40 33 35 -43 125 19 33 123 39 15 126 24 33 122 27 19
122 25 40 -22 0 0 13 49 4 33 38 -42 123 18 31 121 30 55 124 27 41 120 12 58
Latitude Latitude Latitude Latitude
121 0 0 -21 21 53 13 49 20 33 39 -41 -20 57 39 -21 46 25 -20 25 7 -22 20 16
120 0 0 -20 56 42 13 49 31 32 40 -41 -20 32 40 -21 21 1 -20 0 25 -21 54 33
119 0 0 -20 32 44 13 49 42 32 41 -41 -20 8 55 -20 56 51 -19 36 55 -21 30 5
118 0 0 -20 9 59 13 49 53 32 42 -40 -19 46 21 -20 33 54 -19 14 36 -21 6 52
117 0 0 -19 48 27 13 50 4 31 43 -40 -19 24 58 -20 12 10 -18 53 28 -20 44 53
116 0 0 -19 28 5 13 50 14 31 43 -39 -19 4 46 -19 51 39 -18 33 28 -20 24 7
115 0 0 -19 8 54 13 50 24 31 44 -39 -18 45 44 -19 32 18 -18 14 38 -20 4 34
114 0 0 -18 50 53 13 50 35 30 45 -38 -18 27 52 -19 14 9 -17 56 56 -19 46 12
113 0 0 -18 34 1 13 50 45 30 46 -37 -18 11 8 -18 57 9 -17 40 22 -19 29 1
112 0 0 -18 18 18 13 50 54 29 47 -37 -17 55 32 -18 41 19 -17 24 56 -19 13 1
111 0 0 -18 3 44 13 51 4 29 47 -36 -17 41 4 -18 26 38 -17 10 37 -18 58 11
Uncertainty in time = +/- 5 secs
Prediction of 2013 Jan 27.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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[Asteroid Occultation Results]
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