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Updated: 2010 MAR 18, 18:20 UT
Event Rank : 51
(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 2010 May 05 UT, the 61 km diameter asteroid (218) Bianca will occult a 13.4 mag star in the constellation Serpens for observers along a fairly narrow path across eastern Australia across north-western Tasmania and then from Yarram in eastern Victoria to Gladstone in Queensland. Canberra is just on the path, Melbourne, Sydney and Brisbane just outside the one sigma limit.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.3 mag to 12.3 mag (the magnitude of the asteroid) for at most 9.2 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 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
141 58 56 -45 8 35 14 15 34 26 62 -61 141 17 13 -45 11 36 142 39 56 -45 5 34 139 28 43 -45 19 9 144 20 22 -44 57 56
143 21 31 -43 39 24 14 15 53 28 61 -63 142 42 24 -43 42 22 144 0 3 -43 36 26 141 0 57 -43 49 48 145 34 42 -43 28 56
144 32 40 -42 12 14 14 16 11 29 61 -64 143 55 40 -42 15 9 145 9 9 -42 9 19 142 19 59 -42 22 28 146 38 59 -42 1 57
145 34 23 -40 46 54 14 16 30 31 60 -66 144 59 10 -40 49 46 146 9 9 -40 44 2 143 28 19 -40 56 58 147 34 53 -40 36 46
146 28 14 -39 23 15 14 16 48 32 60 -67 145 54 32 -39 26 4 147 1 31 -39 20 25 144 27 46 -39 33 9 148 23 45 -39 13 17
147 15 24 -38 1 8 14 17 7 33 60 -68 146 43 1 -38 3 55 147 47 25 -37 58 21 145 19 46 -38 10 54 149 6 36 -37 51 19
147 56 49 -36 40 26 14 17 25 35 61 -69 147 25 36 -36 43 11 148 27 44 -36 37 41 146 5 23 -36 50 4 149 44 14 -36 30 45
148 33 16 -35 21 3 14 17 43 36 61 -71 148 3 3 -35 23 45 149 3 12 -35 18 20 146 45 31 -35 30 33 150 17 21 -35 11 30
149 5 21 -34 2 52 14 18 2 37 61 -72 148 36 2 -34 5 32 149 34 25 -34 0 11 147 20 52 -34 12 15 150 46 28 -33 53 26
149 33 35 -32 45 48 14 18 20 38 61 -73 149 5 3 -32 48 26 150 1 52 -32 43 9 147 51 59 -32 55 5 151 12 3 -32 36 29
149 58 23 -31 29 46 14 18 39 39 62 -74 149 30 33 -31 32 23 150 25 57 -31 27 9 148 19 21 -31 38 56 151 34 28 -31 20 33
150 20 5 -30 14 42 14 18 57 40 62 -75 149 52 54 -30 17 16 150 47 2 -30 12 6 148 43 23 -30 23 46 151 54 2 -30 5 35
150 39 1 -29 0 31 14 19 15 41 63 -76 150 12 25 -29 3 4 151 5 24 -28 57 57 149 4 24 -29 9 30 152 11 1 -28 51 30
150 55 24 -27 47 9 14 19 34 41 64 -77 150 29 20 -27 49 41 151 21 17 -27 44 37 149 22 42 -27 56 3 152 25 39 -27 38 13
151 9 29 -26 34 34 14 19 52 42 64 -78 150 43 53 -26 37 4 151 34 54 -26 32 3 149 38 29 -26 43 23 152 38 8 -26 25 43
151 21 26 -25 22 41 14 20 11 43 65 -79 150 56 16 -25 25 10 151 46 26 -25 20 12 149 52 0 -25 31 25 152 48 38 -25 13 55
151 31 25 -24 11 28 14 20 29 44 66 -79 151 6 38 -24 13 56 151 56 2 -24 9 0 150 3 24 -24 20 8 152 57 18 -24 2 46
151 39 35 -23 0 52 14 20 48 44 67 -80 151 15 9 -23 3 19 152 3 50 -22 58 25 150 12 51 -23 9 28 153 4 15 -22 52 14
151 46 2 -21 50 50 14 21 6 45 68 -81 151 21 56 -21 53 16 152 9 58 -21 48 25 150 20 28 -21 59 23 153 9 36 -21 42 16
151 50 53 -20 41 20 14 21 24 45 69 -81 151 27 5 -20 43 45 152 14 32 -20 38 56 150 26 24 -20 49 50 153 13 27 -20 32 50
151 54 13 -19 32 20 14 21 43 46 70 -82 151 30 41 -19 34 44 152 17 36 -19 29 56 150 30 42 -19 40 46 153 15 53 -19 23 52
151 56 8 -18 23 47 14 22 1 46 71 -82 151 32 51 -18 26 10 152 19 16 -18 21 23 150 33 30 -18 32 9 153 16 57 -18 15 22
Uncertainty in time = +/- 12 secs
Prediction of 2010 Mar 19.0
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