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Updated: 2011 DEC 15, 19:14 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 2012 Feb 08 UT, the 81 km diameter asteroid (109) Felicitas will occult a 11.1 mag star in the constellation Auriga for observers along a path beginning near Kununurra in Western Australia. The path then moves south-east through central Australia, and into NSW near Broken Hill, and in Victoria near Bendigo and Melbourne at low altitude.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.5 mag to 12.2 mag (the magnitude of the asteroid) for at most 13.9 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
149 7 36 -41 0 0 13 54 2 1 322 -34 148 30 26 149 44 56 148 7 29 150 8 10
148 5 28 -40 0 0 13 54 1 3 322 -35 147 29 7 148 41 59 147 6 39 149 4 42
147 5 21 -39 0 0 13 54 0 4 323 -36 146 29 44 147 41 5 146 7 44 148 3 19
146 7 4 -38 0 0 13 53 58 5 323 -36 145 32 9 146 42 5 145 10 35 147 3 52
145 10 30 -37 0 0 13 53 56 6 324 -37 144 36 15 145 44 51 144 15 4 146 6 13
144 15 31 -36 0 0 13 53 53 8 325 -38 143 41 53 144 49 15 143 21 5 145 10 14
143 22 1 -35 0 0 13 53 50 9 325 -39 142 48 57 143 55 10 142 28 30 144 15 46
142 29 53 -34 0 0 13 53 46 10 326 -40 141 57 22 143 2 29 141 37 14 143 22 45
141 39 1 -33 0 0 13 53 42 11 326 -40 141 7 1 142 11 7 140 47 12 142 31 3
140 49 21 -32 0 0 13 53 37 12 327 -41 140 17 49 141 20 58 139 58 18 141 40 36
140 0 47 -31 0 0 13 53 31 14 327 -42 139 29 42 140 31 57 139 10 27 140 51 18
139 13 15 -30 0 0 13 53 26 15 327 -42 138 42 34 139 43 59 138 23 35 140 3 4
138 26 40 -29 0 0 13 53 19 16 328 -43 137 56 23 138 57 0 137 37 38 139 15 51
137 40 59 -28 0 0 13 53 13 17 328 -44 137 11 4 138 10 57 136 52 33 138 29 33
136 56 7 -27 0 0 13 53 5 19 329 -44 136 26 34 137 25 44 136 8 15 137 44 7
136 12 2 -26 0 0 13 52 58 20 329 -45 135 42 48 136 41 19 135 24 41 136 59 30
135 28 40 -25 0 0 13 52 50 21 329 -46 134 59 44 135 57 38 134 41 49 136 15 37
134 45 58 -24 0 0 13 52 41 22 330 -46 134 17 19 135 14 39 133 59 34 135 32 27
134 3 53 -23 0 0 13 52 32 23 330 -47 133 35 30 134 32 17 133 17 55 134 49 55
133 22 21 -22 0 0 13 52 23 25 330 -47 132 54 14 133 50 31 132 36 48 134 7 59
132 41 22 -21 0 0 13 52 13 26 331 -48 132 13 28 133 9 17 131 56 11 133 26 36
132 0 51 -20 0 0 13 52 2 27 331 -48 131 33 10 132 28 33 131 16 1 132 45 44
131 20 47 -19 0 0 13 51 52 28 331 -48 130 53 18 131 48 16 130 36 16 132 5 20
130 41 6 -18 0 0 13 51 41 29 332 -49 130 13 49 131 8 25 129 56 54 131 25 21
130 1 48 -17 0 0 13 51 29 31 332 -49 129 34 41 130 28 56 129 17 52 130 45 46
129 22 49 -16 0 0 13 51 17 32 332 -50 128 55 51 129 49 48 128 39 9 130 6 31
128 44 8 -15 0 0 13 51 4 33 332 -50 128 17 19 129 10 58 128 0 41 129 27 36
128 5 42 -14 0 0 13 50 52 34 333 -50 127 39 0 128 32 24 127 22 28 128 48 57
127 27 29 -13 0 0 13 50 38 35 333 -50 127 0 55 127 54 4 126 44 26 128 10 32
126 49 28 -12 0 0 13 50 25 37 333 -51 126 22 59 127 15 56 126 6 35 127 32 21
126 11 35 -11 0 0 13 50 11 38 333 -51 125 45 13 126 37 58 125 28 51 126 54 19
125 33 51 -10 0 0 13 49 56 39 334 -51 125 7 32 126 0 8 124 51 14 126 16 27
124 56 11 - 9 0 0 13 49 41 40 334 -51 124 29 57 125 22 25 124 13 40 125 38 40
124 18 35 - 8 0 0 13 49 26 41 334 -51 123 52 24 124 44 45 123 36 9 125 0 59
123 41 1 - 7 0 0 13 49 10 42 334 -51 123 14 52 124 7 8 122 58 39 124 23 20
Uncertainty in time = +/- 5 secs
Prediction of 2011 Dec 16.0
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