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Updated: 2010 OCT 19, 21:41 UT
Event Rank : 15
(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 Feb 09 UT, the 23 km diameter asteroid (8067) Helfenstein will occult a 10.0 mag star in the constellation Cancer for observers along a narrow but widely uncertain path across south-east Australia centred from near Canberra to Portand in Victoria. The large 1-sigma uncertainty area includes Newcastle, Sydney and Melbourne.
In the case of an occultation, the combined light of the asteroid and the star will drop by 6.5 mag to 16.5 mag (the magnitude of the asteroid) for at most 1.7 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
124 36 54 -48 0 0 13 16 21 7 29 -18 124 9 15 125 4 48 ... .. .. 129 26 27
125 59 38 -47 0 0 13 16 18 8 28 -19 125 31 46 126 27 46 ... .. .. 130 52 25
127 25 51 -46 0 0 13 16 14 9 27 -21 126 57 40 127 54 19 ... .. .. 132 22 58
128 55 55 -45 0 0 13 16 10 11 26 -22 128 27 19 129 24 49 124 23 25 133 58 41
130 30 16 -44 0 0 13 16 5 12 24 -24 130 1 8 130 59 44 125 53 33 135 40 16
132 9 28 -43 0 0 13 15 58 14 23 -25 131 39 40 132 39 38 127 27 21 137 28 40
133 54 12 -42 0 0 13 15 51 15 22 -27 133 23 33 134 25 16 129 5 17 139 25 6
135 45 21 -41 0 0 13 15 43 16 20 -28 135 13 38 136 17 33 130 47 54 141 31 20
137 44 5 -40 0 0 13 15 34 18 19 -30 137 11 0 138 17 44 132 35 53 143 49 49
139 51 59 -39 0 0 13 15 23 19 17 -32 139 17 8 140 27 31 134 30 6 146 24 26
Latitude Latitude Latitude Latitude
140 0 0 -38 56 24 13 15 22 19 17 -32 -38 40 39 -39 12 19 -36 26 24 -41 42 54
141 0 0 -38 30 1 13 15 17 20 16 -32 -38 14 27 -38 45 45 -36 1 33 -41 14 25
142 0 0 -38 4 40 13 15 11 21 15 -33 -37 49 15 -38 20 13 -35 37 39 -40 47 5
143 0 0 -37 40 19 13 15 6 21 14 -34 -37 25 4 -37 55 43 -35 14 41 -40 20 53
144 0 0 -37 16 59 13 15 0 22 13 -35 -37 1 53 -37 32 14 -34 52 39 -39 55 49
145 0 0 -36 54 40 13 14 54 22 13 -35 -36 39 42 -37 9 46 -34 31 33 -39 31 52
146 0 0 -36 33 19 13 14 48 23 12 -36 -36 18 29 -36 48 18 -34 11 22 -39 9 0
147 0 0 -36 12 58 13 14 42 23 11 -37 -35 58 15 -36 27 49 -33 52 6 -38 47 13
148 0 0 -35 53 36 13 14 36 24 10 -37 -35 39 0 -36 8 20 -33 33 45 -38 26 31
149 0 0 -35 35 12 13 14 30 24 9 -38 -35 20 43 -35 49 49 -33 16 18 -38 6 52
150 0 0 -35 17 46 13 14 24 25 8 -38 -35 3 23 -35 32 17 -32 59 46 -37 48 16
151 0 0 -35 1 18 13 14 18 25 7 -39 -34 47 0 -35 15 43 -32 44 8 -37 30 43
152 0 0 -34 45 47 13 14 11 25 6 -39 -34 31 35 -35 0 7 -32 29 25 -37 14 11
153 0 0 -34 31 14 13 14 5 26 5 -40 -34 17 6 -34 45 29 -32 15 34 -36 58 42
154 0 0 -34 17 37 13 13 58 26 4 -40 -34 3 34 -34 31 47 -32 2 38 -36 44 13
155 0 0 -34 4 57 13 13 52 26 4 -40 -33 50 58 -34 19 3 -31 50 35 -36 30 45
156 0 0 -33 53 13 13 13 45 26 3 -41 -33 39 18 -34 7 15 -31 39 25 -36 18 18
157 0 0 -33 42 25 13 13 38 27 2 -41 -33 28 34 -33 56 24 -31 29 9 -36 6 50
158 0 0 -33 32 34 13 13 32 27 1 -41 -33 18 45 -33 46 29 -31 19 46 -35 56 22
159 0 0 -33 23 38 13 13 25 27 360 -42 -33 9 52 -33 37 30 -31 11 15 -35 46 54
160 0 0 -33 15 38 13 13 18 27 359 -42 -33 1 54 -33 29 27 -31 3 37 -35 38 25
161 0 0 -33 8 33 13 13 12 27 358 -42 -32 54 52 -33 22 20 -30 56 53 -35 30 55
162 0 0 -33 2 23 13 13 5 27 357 -42 -32 48 44 -33 16 9 -30 51 0 -35 24 24
163 0 0 -32 57 9 13 12 58 27 356 -42 -32 43 31 -33 10 53 -30 46 1 -35 18 51
164 0 0 -32 52 50 13 12 51 27 355 -43 -32 39 14 -33 6 33 -30 41 53 -35 14 18
165 0 0 -32 49 26 13 12 45 27 354 -43 -32 35 51 -33 3 8 -30 38 39 -35 10 42
166 0 0 -32 46 57 13 12 38 27 353 -43 -32 33 23 -33 0 38 -30 36 16 -35 8 5
167 0 0 -32 45 24 13 12 31 27 352 -43 -32 31 50 -32 59 4 -30 34 47 -35 6 26
168 0 0 -32 44 45 13 12 25 27 351 -43 -32 31 11 -32 58 25 -30 34 9 -35 5 46
169 0 0 -32 45 1 13 12 18 27 350 -43 -32 31 27 -32 58 42 -30 34 24 -35 6 4
170 0 0 -32 46 13 13 12 11 27 349 -42 -32 32 38 -32 59 53 -30 35 32 -35 7 20
171 0 0 -32 48 19 13 12 5 27 348 -42 -32 34 44 -33 2 1 -30 37 32 -35 9 34
172 0 0 -32 51 21 13 11 58 26 348 -42 -32 37 44 -33 5 3 -30 40 24 -35 12 48
173 0 0 -32 55 18 13 11 52 26 347 -42 -32 41 40 -33 9 2 -30 44 10 -35 16 59
174 0 0 -33 0 10 13 11 45 26 346 -42 -32 46 31 -33 13 55 -30 48 48 -35 22 10
175 0 0 -33 5 58 13 11 39 26 345 -42 -32 52 17 -33 19 45 -30 54 18 -35 28 19
176 0 0 -33 12 41 13 11 33 25 344 -41 -32 58 58 -33 26 31 -31 0 42 -35 35 27
177 0 0 -33 20 20 13 11 26 25 343 -41 -33 6 34 -33 34 12 -31 7 58 -35 43 35
178 0 0 -33 28 55 13 11 20 24 342 -41 -33 15 6 -33 42 50 -31 16 8 -35 52 42
179 0 0 -33 38 26 13 11 14 24 341 -40 -33 24 34 -33 52 25 -31 25 11 -36 2 49
Uncertainty in time = +/- 10 secs
Prediction of 2011 Jan 27.0
Use these links for further information:
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[Observing Details]
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