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Updated: 2012 Feb 24, 10:00 UT
Event Rank : 46
(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 Apr 15 UT, the 45 km diameter asteroid (132) Aethra will occult a 11.7 mag star in the constellation Lupus for observers along a path across Tasmania, eastern Victoria, central New South Wales and western Queensland, passing over Hobart, Launceston, Traralgon and Benalla and near Melbourne.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.9 mag to 12.0 mag (the magnitude of the asteroid) for at most 6.3 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.
Occultation of UCAC2 11583294 by 132 Aethra on 2012 Apr 15
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
147 19 39 -44 26 44 11 58 44 47 117 -45 146 57 35 -44 23 22 147 41 39 -44 30 0 145 55 36 -44 13 24 148 43 2 -44 38 36
147 15 5 -43 16 29 11 59 2 46 118 -46 146 53 22 -43 13 5 147 36 44 -43 19 47 145 52 20 -43 3 1 148 37 8 -43 28 28
147 8 54 -42 5 34 11 59 19 46 119 -47 146 47 31 -42 2 8 147 30 14 -42 8 54 145 47 22 -41 51 57 148 29 43 -42 17 42
147 1 8 -40 53 57 11 59 37 45 120 -48 146 40 2 -40 50 28 147 22 10 -40 57 20 145 40 43 -40 40 8 148 20 48 -41 6 17
146 51 48 -39 41 34 11 59 54 45 121 -48 146 31 0 -39 38 1 147 12 34 -39 45 0 145 32 26 -39 27 31 148 10 25 -39 54 7
146 40 57 -38 28 21 12 0 12 44 122 -49 146 20 24 -38 24 43 147 1 28 -38 31 52 145 22 31 -38 14 1 147 58 36 -38 41 11
146 28 35 -37 14 14 12 0 29 43 123 -49 146 8 14 -37 10 31 146 48 51 -37 17 50 145 10 59 -36 59 34 147 45 21 -37 27 23
146 14 40 -35 59 8 12 0 46 42 124 -50 145 54 32 -35 55 19 146 34 44 -36 2 50 144 57 50 -35 44 5 147 30 39 -36 12 38
145 59 12 -34 42 58 12 1 4 41 125 -51 145 39 15 -34 39 3 146 19 6 -34 46 47 144 43 2 -34 27 29 147 14 29 -34 56 53
145 42 10 -33 25 38 12 1 21 41 126 -51 145 22 22 -33 21 35 146 1 54 -33 29 34 144 26 34 -33 9 39 146 56 50 -33 40 2
145 23 31 -32 7 1 12 1 39 40 127 -51 145 3 50 -32 2 50 145 43 7 -32 11 6 144 8 23 -31 50 28 146 37 40 -32 21 57
145 3 10 -30 47 0 12 1 56 39 128 -52 144 43 35 -30 42 39 145 22 40 -30 51 15 143 48 24 -30 29 48 146 16 54 -31 2 32
144 41 3 -29 25 26 12 2 14 38 129 -52 144 21 33 -29 20 53 145 0 29 -29 29 52 143 26 32 -29 7 29 145 54 29 -29 41 38
144 17 5 -28 2 8 12 2 31 36 130 -52 143 57 37 -27 57 22 144 36 28 -28 6 46 143 2 41 -27 43 20 145 30 19 -28 19 7
143 51 7 -26 36 54 12 2 48 35 130 -53 143 31 40 -26 31 54 144 10 29 -26 41 47 142 36 43 -26 17 9 145 4 17 -26 54 46
143 23 0 -25 9 31 12 3 6 34 131 -53 143 3 30 -25 4 13 143 42 24 -25 14 40 142 8 25 -24 48 39 144 36 14 -25 28 23
142 52 31 -23 39 41 12 3 23 33 132 -53 142 32 57 -23 34 4 143 11 59 -23 45 9 141 37 35 -23 17 31 144 6 0 -23 59 43
142 19 25 -22 7 3 12 3 41 31 133 -53 141 59 43 -22 1 3 142 39 1 -22 12 53 141 3 55 -21 43 24 143 33 19 -22 28 26
141 43 22 -20 31 13 12 3 58 30 133 -53 141 23 28 -20 24 46 142 3 10 -20 37 29 140 27 2 -20 5 47 142 57 56 -20 54 10
141 3 57 -18 51 37 12 4 16 28 134 -52 140 43 46 -18 44 38 141 24 1 -18 58 24 139 46 26 -18 24 3 142 19 28 -19 16 27
140 20 36 -17 7 34 12 4 33 27 135 -52 140 0 0 -16 59 56 140 41 1 -17 14 59 139 1 27 -16 37 23 141 37 25 -17 34 40
139 32 31 -15 18 8 12 4 50 25 135 -51 139 11 23 -15 9 42 139 53 27 -15 26 19 138 11 9 -14 44 41 140 51 8 -15 48 1
138 38 37 -13 22 1 12 5 8 23 136 -51 138 16 44 -13 12 32 139 0 16 -13 31 11 137 14 9 -12 44 21 139 59 43 -13 55 26
137 37 16 -11 17 18 12 5 25 21 136 -50 137 14 19 -11 6 26 137 59 54 -11 27 47 136 8 19 -10 33 54 139 1 52 -11 55 22
Uncertainty in time = +/- 10 secs
Prediction of 2012 Feb 24.0
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