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Updated: 2015 JAN 03, 22:54 UT
Event Rank : 96
(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 2015 Feb 27 UT, the 139 km diameter asteroid (128) Nemesis will occult a 11.9 mag star in the constellation Cancer for observers along a path across Australia beginning near Canberra and Wagga Wagga. The path moves west, though central South Australia, ending near Exmouth in Western Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.8 mag to 12.0 mag (the magnitude of the asteroid) for at most 16.2 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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
155 50 15 -40 0 0 14 20 52 15 326 -41 157 57 5 153 40 19 159 41 30 151 48 29
154 4 19 -39 0 0 14 21 1 17 327 -42 156 11 55 151 53 23 157 56 48 150 0 30
152 16 15 -38 0 0 14 21 12 19 328 -44 154 24 53 150 4 0 156 10 28 148 9 46
150 25 43 -37 0 0 14 21 23 20 330 -45 152 35 43 148 11 49 154 22 13 146 15 53
148 32 23 -36 0 0 14 21 36 22 331 -46 150 44 4 146 16 24 152 31 45 144 18 24
146 35 48 -35 0 0 14 21 50 23 333 -47 148 49 35 144 17 18 150 38 45 142 16 45
144 35 31 -34 0 0 14 22 5 25 334 -48 146 51 50 142 13 56 148 42 49 140 10 18
Latitude Latitude Latitude Latitude
143 0 0 -33 13 48 14 22 18 26 335 -48 -32 7 16 -34 22 9 -31 12 39 -35 21 5
142 0 0 -32 45 27 14 22 26 27 336 -49 -31 39 19 -33 53 22 -30 45 0 -34 51 55
141 0 0 -32 17 38 14 22 35 28 337 -49 -31 11 53 -33 25 8 -30 17 53 -34 23 17
140 0 0 -31 50 21 14 22 43 28 338 -49 -30 44 59 -32 57 26 -29 51 16 -33 55 13
139 0 0 -31 23 37 14 22 52 29 339 -50 -30 18 37 -32 30 17 -29 25 12 -33 27 43
138 0 0 -30 57 26 14 23 2 30 339 -50 -29 52 47 -32 3 43 -28 59 40 -33 0 47
137 0 0 -30 31 48 14 23 11 31 340 -50 -29 27 31 -31 37 42 -28 34 40 -32 34 26
136 0 0 -30 6 44 14 23 20 31 341 -50 -29 2 48 -31 12 16 -28 10 13 -32 8 40
135 0 0 -29 42 15 14 23 30 32 342 -50 -28 38 38 -30 47 25 -27 46 20 -31 43 29
134 0 0 -29 18 20 14 23 40 32 343 -50 -28 15 3 -30 23 9 -27 23 0 -31 18 54
133 0 0 -28 55 0 14 23 50 33 344 -50 -27 52 2 -29 59 28 -27 0 14 -30 54 54
132 0 0 -28 32 15 14 24 0 34 345 -50 -27 29 36 -29 36 23 -26 38 2 -30 31 31
131 0 0 -28 10 5 14 24 10 34 346 -50 -27 7 44 -29 13 54 -26 16 25 -30 8 45
130 0 0 -27 48 31 14 24 20 35 347 -50 -26 46 28 -28 52 2 -25 55 22 -29 46 35
129 0 0 -27 27 33 14 24 31 35 348 -50 -26 25 46 -28 30 45 -25 34 54 -29 25 3
128 0 0 -27 7 11 14 24 41 36 349 -50 -26 5 41 -28 10 6 -25 15 2 -29 4 7
127 0 0 -26 47 25 14 24 52 36 350 -50 -25 46 11 -27 50 3 -24 55 44 -28 43 49
126 0 0 -26 28 15 14 25 3 37 351 -50 -25 27 16 -27 30 37 -24 37 2 -28 24 9
125 0 0 -26 9 42 14 25 14 37 352 -50 -25 8 58 -27 11 48 -24 18 55 -28 5 5
124 0 0 -25 51 46 14 25 25 38 353 -49 -24 51 16 -26 53 36 -24 1 24 -27 46 40
123 0 0 -25 34 26 14 25 36 38 354 -49 -24 34 10 -26 36 2 -23 44 29 -27 28 53
122 0 0 -25 17 44 14 25 47 38 355 -49 -24 17 40 -26 19 5 -23 28 10 -27 11 44
121 0 0 -25 1 38 14 25 58 39 356 -48 -24 1 47 -26 2 46 -23 12 27 -26 55 12
120 0 0 -24 46 9 14 26 9 39 357 -48 -23 46 31 -25 47 5 -22 57 20 -26 39 19
119 0 0 -24 31 18 14 26 21 39 358 -48 -23 31 51 -25 32 1 -22 42 50 -26 24 4
118 0 0 -24 17 4 14 26 32 40 359 -47 -23 17 48 -25 17 35 -22 28 55 -26 9 28
117 0 0 -24 3 27 14 26 43 40 0 -47 -23 4 22 -25 3 47 -22 15 37 -25 55 30
116 0 0 -23 50 27 14 26 55 40 1 -46 -22 51 32 -24 50 37 -22 2 56 -25 42 10
115 0 0 -23 38 6 14 27 6 40 3 -46 -22 39 20 -24 38 5 -21 50 51 -25 29 29
114 0 0 -23 26 21 14 27 18 40 4 -45 -22 27 44 -24 26 11 -21 39 22 -25 17 27
113 0 0 -23 15 14 14 27 29 40 5 -45 -22 16 46 -24 14 55 -21 28 31 -25 6 3
112 0 0 -23 4 45 14 27 41 41 6 -44 -22 6 25 -24 4 18 -21 18 16 -24 55 18
111 0 0 -22 54 54 14 27 52 41 7 -44 -21 56 40 -23 54 18 -21 8 38 -24 45 12
110 0 0 -22 45 40 14 28 4 41 8 -43 -21 47 34 -23 44 57 -20 59 36 -24 35 44
109 0 0 -22 37 4 14 28 16 41 9 -42 -21 39 4 -23 36 14 -20 51 12 -24 26 55
108 0 0 -22 29 6 14 28 27 41 10 -42 -21 31 12 -23 28 10 -20 43 24 -24 18 45
107 0 0 -22 21 45 14 28 39 41 12 -41 -21 23 57 -23 20 44 -20 36 13 -24 11 14
106 0 0 -22 15 3 14 28 50 41 13 -40 -21 17 19 -23 13 56 -20 29 40 -24 4 22
Uncertainty in time = +/- 7 secs
Prediction of 2015 Jan 3.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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