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Updated: 2011 NOV 10, 21:18 UT
Event Rank : 37
(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 2011 Dec 11 UT, the 19 km diameter asteroid (1642) Hill will occult a 10.3 mag star in the constellation Perseus for observers along a path across Australia from Cape York in far north Queensland across northern Northern Territory and north-western Western Australia to Moora.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.5 mag to 14.8 mag (the magnitude of the asteroid) for at most 2.1 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
112 56 12 -33 0 0 14 33 21 23 353 -28 112 43 21 113 9 7 111 57 14 113 56 15
113 41 57 -32 0 0 14 33 11 24 352 -30 113 29 3 113 54 54 112 42 48 114 42 12
114 29 34 -31 0 0 14 33 0 25 351 -31 114 16 37 114 42 34 113 30 10 115 30 6
115 19 7 -30 0 0 14 32 49 26 351 -32 115 6 6 115 32 12 114 19 24 116 20 2
116 10 44 -29 0 0 14 32 37 27 350 -33 115 57 36 116 23 54 115 10 35 117 12 7
117 4 29 -28 0 0 14 32 25 28 349 -34 116 51 15 117 17 47 116 3 49 118 6 27
118 0 31 -27 0 0 14 32 12 29 348 -36 117 47 8 118 13 57 116 59 14 119 3 10
118 58 58 -26 0 0 14 31 59 29 347 -37 118 45 25 119 12 35 117 56 56 120 2 27
120 0 1 -25 0 0 14 31 44 30 346 -38 119 46 16 120 13 50 118 57 7 121 4 28
121 3 51 -24 0 0 14 31 30 31 345 -39 120 49 52 121 17 54 119 59 55 122 9 26
122 10 42 -23 0 0 14 31 14 32 344 -41 121 56 28 122 25 2 121 5 35 123 17 37
123 20 52 -22 0 0 14 30 58 32 343 -42 123 6 18 123 35 31 122 14 21 124 29 20
124 34 39 -21 0 0 14 30 41 33 341 -43 124 19 44 124 49 41 123 26 30 125 44 56
125 52 29 -20 0 0 14 30 23 33 340 -45 125 37 7 126 7 57 124 42 25 127 4 55
127 14 50 -19 0 0 14 30 4 34 339 -46 126 58 58 127 30 50 126 2 31 128 29 50
128 42 21 -18 0 0 14 29 44 34 337 -47 128 25 52 128 58 58 127 27 20 130 0 25
130 15 48 -17 0 0 14 29 23 35 336 -49 129 58 35 130 33 11 128 57 34 131 37 37
131 56 16 -16 0 0 14 29 0 35 334 -50 131 38 8 132 14 35 130 34 3 133 22 42
133 45 8 -15 0 0 14 28 36 35 332 -51 133 25 51 134 4 39 132 17 58 135 17 30
135 44 27 -14 0 0 14 28 10 35 330 -53 135 23 41 136 5 31 134 10 55 137 24 38
137 57 15 -13 0 0 14 27 42 35 328 -54 137 34 28 138 20 27 136 15 10 139 48 21
Latitude Latitude Latitude Latitude
138 0 0 -12 58 50 14 27 42 35 328 -54 -12 49 4 -13 8 38 -12 14 6 -13 44 29
139 0 0 -12 34 3 14 27 29 35 327 -54 -12 24 23 -12 43 46 -11 49 43 -13 19 17
140 0 0 -12 10 39 14 27 17 34 326 -55 -12 1 4 -12 20 17 -11 26 41 -12 55 29
141 0 0 -11 48 36 14 27 5 34 325 -55 -11 39 6 -11 58 9 -11 4 59 -12 33 5
142 0 0 -11 27 54 14 26 52 34 325 -56 -11 18 27 -11 37 23 -10 44 35 -12 12 2
143 0 0 -11 8 30 14 26 41 34 324 -56 -10 59 8 -11 17 55 -10 25 29 -11 52 20
144 0 0 -10 50 25 14 26 29 33 323 -56 -10 41 6 -10 59 46 -10 7 40 -11 33 58
145 0 0 -10 33 37 14 26 17 33 322 -56 -10 24 21 -10 42 55 - 9 51 6 -11 16 54
146 0 0 -10 18 5 14 26 6 33 321 -56 -10 8 52 -10 27 20 - 9 35 48 -11 1 8
147 0 0 -10 3 49 14 25 54 32 321 -57 - 9 54 38 -10 13 1 - 9 21 44 -10 46 40
148 0 0 - 9 50 48 14 25 43 32 320 -57 - 9 41 40 - 9 59 58 - 9 8 53 -10 33 27
149 0 0 - 9 39 1 14 25 32 31 319 -57 - 9 29 55 - 9 48 9 - 8 57 16 -10 21 31
150 0 0 - 9 28 28 14 25 22 31 319 -57 - 9 19 24 - 9 37 35 - 8 46 52 -10 10 49
151 0 0 - 9 19 9 14 25 11 30 318 -57 - 9 10 7 - 9 28 14 - 8 37 40 -10 1 22
152 0 0 - 9 11 4 14 25 1 30 317 -56 - 9 2 2 - 9 20 7 - 8 29 40 - 9 53 10
153 0 0 - 9 4 11 14 24 51 29 317 -56 - 8 55 11 - 9 13 13 - 8 22 53 - 9 46 12
154 0 0 - 8 58 31 14 24 41 29 316 -56 - 8 49 31 - 9 7 32 - 8 17 16 - 9 40 28
155 0 0 - 8 54 3 14 24 31 28 316 -56 - 8 45 5 - 9 3 4 - 8 12 52 - 9 35 58
156 0 0 - 8 50 48 14 24 21 27 315 -55 - 8 41 50 - 8 59 48 - 8 9 38 - 9 32 41
157 0 0 - 8 48 46 14 24 12 27 315 -55 - 8 39 48 - 8 57 46 - 8 7 36 - 9 30 38
158 0 0 - 8 47 56 14 24 3 26 314 -55 - 8 38 58 - 8 56 57 - 8 6 46 - 9 29 49
159 0 0 - 8 48 20 14 23 54 25 314 -54 - 8 39 21 - 8 57 20 - 8 7 8 - 9 30 14
Uncertainty in time = +/- 5 secs
Prediction of 2011 Nov 11.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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