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Updated: 2011 APR 16, 13:37 UT
Event Rank : 85
(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 May 18 UT, the 112 km diameter asteroid (1467) Mashona will occult a 12.1 mag star in the constellation Crater for observers along a south-to-north path across Western Australia passing near Esperance, Southern Cross, Meekatharra and Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.5 mag to 14.5 mag (the magnitude of the asteroid) for at most 35.1 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, 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 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
123 38 48 -44 16 9 12 7 53 60 335 -39 122 55 58 -44 17 6 124 21 43 -44 15 5 122 3 47 -44 18 6 125 14 10 -44 13 37
123 10 4 -42 39 49 12 8 42 61 335 -39 122 28 22 -42 40 43 123 51 51 -42 38 49 121 37 35 -42 41 38 124 42 54 -42 37 26
122 43 0 -41 4 46 12 9 32 63 334 -40 122 2 20 -41 5 37 123 23 44 -41 3 50 121 12 48 -41 6 29 124 13 31 -41 2 31
122 17 23 -39 30 54 12 10 22 64 333 -40 121 37 39 -39 31 41 122 57 10 -39 30 0 120 49 16 -39 32 30 123 45 48 -39 28 46
121 53 3 -37 58 5 12 11 11 66 332 -40 121 14 12 -37 58 50 122 31 59 -37 57 14 120 26 52 -37 59 36 123 19 33 -37 56 3
121 29 53 -36 26 14 12 12 1 67 331 -40 120 51 49 -36 26 57 122 8 1 -36 25 25 120 5 26 -36 27 41 122 54 37 -36 24 18
121 7 45 -34 55 15 12 12 51 68 329 -40 120 30 24 -34 55 56 121 45 9 -34 54 29 119 44 55 -34 56 38 122 30 52 -34 53 24
120 46 33 -33 25 4 12 13 40 70 327 -39 120 9 52 -33 25 42 121 23 17 -33 24 19 119 25 11 -33 26 22 122 8 11 -33 23 17
120 26 13 -31 55 34 12 14 30 71 325 -39 119 50 8 -31 56 12 121 2 20 -31 54 52 119 6 12 -31 56 50 121 46 29 -31 53 52
120 6 39 -30 26 43 12 15 19 72 323 -39 119 31 8 -30 27 19 120 42 12 -30 26 2 118 47 53 -30 27 55 121 25 39 -30 25 4
119 47 48 -28 58 26 12 16 9 73 320 -39 119 12 49 -28 59 0 120 22 50 -28 57 46 118 30 12 -28 59 35 121 5 39 -28 56 50
119 29 36 -27 30 38 12 16 59 75 317 -39 118 55 6 -27 31 11 120 4 10 -27 29 59 118 13 4 -27 31 45 120 46 24 -27 29 5
119 12 2 -26 3 16 12 17 48 76 314 -39 118 37 58 -26 3 49 119 46 9 -26 2 39 117 56 29 -26 4 21 120 27 50 -26 1 46
118 55 2 -24 36 17 12 18 38 77 309 -39 118 21 23 -24 36 48 119 28 45 -24 35 40 117 40 23 -24 37 20 120 9 56 -24 34 49
118 38 35 -23 9 36 12 19 28 78 304 -38 118 5 18 -23 10 7 119 11 55 -23 9 0 117 24 46 -23 10 37 119 52 39 -23 8 10
118 22 38 -21 43 11 12 20 17 78 299 -38 117 49 42 -21 43 40 118 55 37 -21 42 36 117 9 35 -21 44 10 119 35 56 -21 41 47
118 7 10 -20 16 57 12 21 7 79 292 -38 117 34 33 -20 17 27 118 39 50 -20 16 23 116 54 49 -20 17 56 119 19 46 -20 15 35
117 52 10 -18 50 53 12 21 57 80 285 -38 117 19 50 -18 51 21 118 24 33 -18 50 19 116 40 27 -18 51 50 119 4 7 -18 49 32
117 37 37 -17 24 54 12 22 46 80 277 -37 117 5 32 -17 25 22 118 9 44 -17 24 21 116 26 29 -17 25 50 118 48 59 -17 23 34
117 23 29 -15 58 57 12 23 36 80 269 -37 116 51 39 -15 59 25 117 55 21 -15 58 24 116 12 52 -15 59 53 118 34 19 -15 57 38
117 9 46 -14 33 0 12 24 26 80 261 -37 116 38 9 -14 33 27 117 41 25 -14 32 27 115 59 38 -14 33 55 118 20 7 -14 31 42
116 56 27 -13 6 58 12 25 15 80 253 -36 116 25 1 -13 7 26 117 27 55 -13 6 26 115 46 45 -13 7 53 118 6 23 -13 5 41
116 43 32 -11 40 50 12 26 5 79 246 -36 116 12 16 -11 41 17 117 14 50 -11 40 18 115 34 12 -11 41 44 117 53 5 -11 39 33
116 31 0 -10 14 31 12 26 54 79 239 -35 115 59 53 -10 14 58 117 2 9 -10 13 59 115 22 0 -10 15 25 117 40 13 -10 13 14
116 18 51 - 8 47 59 12 27 44 78 234 -35 115 47 53 - 8 48 26 116 49 53 - 8 47 27 115 10 9 - 8 48 52 117 27 48 - 8 46 42
Uncertainty in time = +/- 29 secs
Prediction of 2011 Apr 16.0
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