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Updated: 2012 MAR 31, 12:38 UT
Event Rank : 45
(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 May 17 UT, the 45 km diameter asteroid (132) Aethra will occult a 12.8 mag star in the constellation Centaurus for observers along a path firstly passing over South Island New Zealand near Invercargill. Then in Australia the path begins over Sydney and moves north-west near Orange and Dubbo, then through western parts of Queensland near Mount Isa.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.4 mag to 11.8 mag (the magnitude of the asteroid) for at most 3.3 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.
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
130 4 50 0 0 0 14 29 25 52 177 -67 130 18 29 129 51 12 130 57 37 129 12 18
130 30 23 - 1 0 0 14 29 18 53 177 -68 130 44 3 130 16 43 131 23 16 129 37 43
130 56 17 - 2 0 0 14 29 10 54 178 -70 131 9 59 130 42 35 131 49 18 130 3 30
131 22 34 - 3 0 0 14 29 3 55 178 -71 131 36 19 131 8 50 132 15 45 130 29 38
131 49 15 - 4 0 0 14 28 55 56 179 -72 132 3 3 131 35 28 132 42 37 130 56 9
132 16 22 - 5 0 0 14 28 48 57 179 -73 132 30 13 132 2 32 133 9 55 131 23 4
132 43 55 - 6 0 0 14 28 40 58 180 -74 132 57 49 132 30 2 133 37 42 131 50 24
133 11 56 - 7 0 0 14 28 32 59 181 -75 133 25 54 132 57 59 134 5 58 132 18 11
133 40 26 - 8 0 0 14 28 24 60 181 -76 133 54 29 133 26 25 134 34 44 132 46 26
134 9 27 - 9 0 0 14 28 16 61 182 -77 134 23 34 133 55 22 135 4 3 133 15 10
134 39 0 -10 0 0 14 28 8 62 183 -78 134 53 12 134 24 50 135 33 55 133 44 24
135 9 7 -11 0 0 14 28 0 63 184 -79 135 23 24 134 54 51 136 4 23 134 14 11
Latitude Latitude Latitude Latitude
136 0 0 -12 38 47 14 27 46 64 186 -81 -12 11 10 -13 6 18 -10 51 27 -14 24 20
137 0 0 -14 31 10 14 27 30 66 188 -83 -14 4 14 -14 58 0 -12 46 32 -16 14 9
138 0 0 -16 19 12 14 27 15 68 190 -85 -15 52 55 -16 45 23 -14 37 8 -17 59 44
139 0 0 -18 3 0 14 27 0 69 193 -86 -17 37 20 -18 28 34 -16 23 24 -19 41 11
140 0 0 -19 42 40 14 26 45 71 196 -87 -19 17 37 -20 7 39 -18 5 25 -21 18 37
141 0 0 -21 18 22 14 26 30 72 200 -87 -20 53 53 -21 42 47 -19 43 22 -22 52 10
142 0 0 -22 50 13 14 26 16 73 204 -86 -22 26 17 -23 14 5 -21 17 21 -24 21 58
143 0 0 -24 18 21 14 26 2 74 208 -85 -23 54 56 -24 41 42 -22 47 32 -25 48 8
144 0 0 -25 42 55 14 25 49 75 213 -83 -25 19 59 -26 5 46 -24 14 3 -27 10 48
145 0 0 -27 4 1 14 25 36 75 218 -82 -26 41 35 -27 26 24 -25 37 2 -28 30 6
146 0 0 -28 21 49 14 25 23 76 224 -81 -27 59 50 -28 43 45 -26 56 38 -29 46 10
147 0 0 -29 36 26 14 25 11 76 229 -79 -29 14 54 -29 57 56 -28 12 58 -30 59 7
148 0 0 -30 48 0 14 24 59 76 234 -78 -30 26 53 -31 9 5 -29 26 10 -32 9 6
149 0 0 -31 56 39 14 24 48 76 239 -76 -31 35 55 -32 17 19 -30 36 23 -33 16 12
150 0 0 -33 2 29 14 24 36 76 244 -75 -32 42 8 -33 22 46 -31 43 43 -34 20 34
151 0 0 -34 5 37 14 24 26 75 249 -74 -33 45 39 -34 25 32 -32 48 18 -35 22 18
152 0 0 -35 6 10 14 24 15 75 253 -72 -34 46 34 -35 25 45 -33 50 14 -36 21 31
153 0 0 -36 4 16 14 24 5 74 256 -71 -35 44 59 -36 23 30 -34 49 39 -37 18 19
154 0 0 -36 59 59 14 23 55 74 260 -70 -36 41 2 -37 18 54 -35 46 39 -38 12 47
155 0 0 -37 53 26 14 23 46 73 262 -69 -37 34 48 -38 12 2 -36 41 19 -39 5 3
156 0 0 -38 44 43 14 23 37 72 265 -68 -38 26 23 -39 3 1 -37 33 46 -39 55 11
157 0 0 -39 33 55 14 23 28 72 267 -67 -39 15 53 -39 51 56 -38 24 5 -40 43 17
158 0 0 -40 21 7 14 23 19 71 269 -66 -40 3 21 -40 38 52 -39 12 22 -41 29 26
159 0 0 -41 6 25 14 23 11 70 270 -65 -40 48 55 -41 23 53 -39 58 42 -42 13 43
160 0 0 -41 49 52 14 23 3 70 272 -64 -41 32 38 -42 7 6 -40 43 9 -42 56 12
161 0 0 -42 31 34 14 22 55 69 273 -63 -42 14 34 -42 48 33 -41 25 48 -43 36 58
162 0 0 -43 11 35 14 22 47 68 274 -62 -42 54 49 -43 28 20 -42 6 43 -44 16 5
163 0 0 -43 49 59 14 22 39 67 275 -61 -43 33 26 -44 6 30 -42 45 59 -44 53 37
164 0 0 -44 26 49 14 22 32 67 275 -60 -44 10 29 -44 43 7 -43 23 40 -45 29 37
165 0 0 -45 2 9 14 22 25 66 276 -59 -44 46 2 -45 18 15 -43 59 49 -46 4 10
166 0 0 -45 36 4 14 22 18 65 276 -58 -45 20 9 -45 51 58 -44 34 29 -46 37 19
167 0 0 -46 8 35 14 22 12 64 277 -57 -45 52 51 -46 24 18 -45 7 45 -47 9 6
168 0 0 -46 39 47 14 22 5 64 277 -56 -46 24 14 -46 55 18 -45 39 40 -47 39 36
169 0 0 -47 9 42 14 21 59 63 277 -55 -46 54 20 -47 25 3 -46 10 16 -48 8 50
170 0 0 -47 38 23 14 21 53 62 277 -55 -47 23 11 -47 53 34 -46 39 36 -48 36 53
171 0 0 -48 5 53 14 21 47 62 277 -54 -47 50 51 -48 20 54 -47 7 44 -49 3 45
172 0 0 -48 32 14 14 21 41 61 277 -53 -48 17 21 -48 47 6 -47 34 41 -49 29 31
173 0 0 -48 57 29 14 21 35 60 277 -52 -48 42 45 -49 12 12 -48 0 31 -49 54 11
174 0 0 -49 21 39 14 21 30 60 277 -52 -49 7 4 -49 36 14 -48 25 14 -50 17 49
175 0 0 -49 44 48 14 21 24 59 276 -51 -49 30 21 -49 59 14 -48 48 55 -50 40 26
176 0 0 -50 6 57 14 21 19 58 276 -50 -49 52 37 -50 21 15 -49 11 34 -51 2 5
177 0 0 -50 28 8 14 21 14 58 276 -49 -50 13 56 -50 42 19 -49 33 14 -51 22 47
178 0 0 -50 48 22 14 21 9 57 275 -49 -50 34 18 -51 2 26 -49 53 57 -51 42 34
Uncertainty in time = +/- 5 secs
Prediction of 2012 Mar 31.0
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