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Updated: 2020 AUG 15, 19:04 UT
Event Rank : 95
(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 2020 Sep 10 UT, the 60 km diameter asteroid (218) Bianca will occult a 11.0 mag star in the constellation Cetus for observers along a path across Western Australia from Derby to a little north of Perth.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.60 mag to 13.47 mag (the magnitude of the asteroid) for at most 7.8 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, astrometry for the asteroid kindly provided by Bill Owen, astrometry for the asteroid kindly provided by the IAU Minor Planet Center.
This work has made use of data from the European Space Agency (ESA)mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, inparticular the institutions participating in the Gaia Multilateral Agreement.
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.
Occultation of TYC 0058-00449-1 by 218 Bianca on 2020 Sep 10
Centre Star Star Sun Path Limits Error Limits Alt
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
110 16 49 -34 0 0 15 37 32.4 12 76 -58 109 7 38 111 21 41 108 1 31 112 16 29 -1.59
111 52 32 -33 0 0 15 37 22.0 13 75 -59 110 50 4 112 51 46 109 51 10 113 42 14 -1.61
113 16 21 -32 0 0 15 37 11.3 15 75 -61 112 18 51 114 11 17 111 25 7 114 58 21 -1.63
114 30 42 -31 0 0 15 37 0.2 16 74 -62 113 37 3 115 22 14 112 47 14 116 6 36 -1.63
115 37 16 -30 0 0 15 36 48.9 17 74 -63 114 46 43 116 26 2 113 59 59 117 8 10 -1.64
116 37 16 -29 0 0 15 36 37.4 18 74 -64 115 49 15 117 23 44 115 5 1 118 4 0 -1.65
117 31 35 -28 0 0 15 36 25.7 19 73 -66 116 45 42 118 16 8 116 3 32 118 54 47 -1.65
118 20 56 -27 0 0 15 36 13.8 20 73 -67 117 36 51 119 3 49 116 56 26 119 41 7 -1.66
119 5 52 -26 0 0 15 36 1.7 21 73 -68 118 23 19 119 47 19 117 44 24 120 23 26 -1.66
119 46 49 -25 0 0 15 35 49.4 22 73 -69 119 5 37 120 27 2 118 27 58 121 2 5 -1.66
120 24 9 -24 0 0 15 35 36.9 23 73 -70 119 44 7 121 3 16 119 7 35 121 37 25 -1.67
120 58 10 -23 0 0 15 35 24.3 23 74 -71 120 19 9 121 36 20 119 43 36 122 9 41 -1.67
121 29 8 -22 0 0 15 35 11.5 24 74 -72 120 51 1 122 6 27 120 16 19 122 39 5 -1.67
121 57 14 -21 0 0 15 34 58.6 25 74 -73 121 19 55 122 33 48 120 45 58 123 5 49 -1.68
122 22 41 -20 0 0 15 34 45.5 25 74 -74 121 46 3 122 58 35 121 12 46 123 30 2 -1.68
122 45 36 -19 0 0 15 34 32.3 26 75 -75 122 9 36 123 20 56 121 36 53 123 51 53 -1.68
123 6 9 -18 0 0 15 34 19.0 26 75 -76 122 30 41 123 40 58 121 58 29 124 11 28 -1.69
123 24 25 -17 0 0 15 34 5.6 27 75 -77 122 49 26 123 58 47 122 17 41 124 28 54 -1.69
123 40 32 -16 0 0 15 33 52.0 27 76 -78 123 5 57 124 14 29 122 34 35 124 44 17 -1.70
123 54 32 -15 0 0 15 33 38.3 28 76 -79 123 20 19 124 28 9 122 49 18 124 57 39 -1.70
124 6 31 -14 0 0 15 33 24.5 28 77 -80 123 32 37 124 39 51 123 1 52 125 9 6 -1.71
124 16 33 -13 0 0 15 33 10.6 28 77 -81 123 42 53 124 49 37 123 12 23 125 18 40 -1.71
124 24 39 -12 0 0 15 32 56.6 29 78 -82 123 51 12 124 57 31 123 20 54 125 26 23 -1.71
124 30 52 -11 0 0 15 32 42.5 29 78 -83 123 57 35 125 3 35 123 27 26 125 32 19 -1.72
124 35 14 -10 0 0 15 32 28.3 29 79 -84 124 2 5 125 7 50 123 32 2 125 36 28 -1.72
124 37 46 - 9 0 0 15 32 14.1 29 79 -85 124 4 42 125 10 18 123 34 44 125 38 51 -1.73
124 38 29 - 8 0 0 15 31 59.7 30 80 -86 124 5 27 125 10 58 123 35 31 125 39 30 -1.73
124 37 23 - 7 0 0 15 31 45.3 30 80 -87 124 4 20 125 9 52 123 34 24 125 38 23 1.74
124 34 27 - 6 0 0 15 31 30.8 30 81 -88 124 1 22 125 6 59 123 31 23 125 35 33 1.74
124 29 42 - 5 0 0 15 31 16.2 30 82 -88 123 56 31 125 2 18 123 26 27 125 30 56 1.75
124 23 5 - 4 0 0 15 31 1.5 30 82 -88 123 49 46 124 55 49 123 19 35 125 24 33 1.76
124 14 35 - 3 0 0 15 30 46.8 30 83 -87 123 41 5 124 47 29 123 10 44 125 16 21 1.76
124 4 9 - 2 0 0 15 30 32.1 29 83 -86 123 30 26 124 37 17 122 59 52 125 6 20 1.77
123 51 45 - 1 0 0 15 30 17.2 29 84 -85 123 17 46 124 25 8 122 46 55 124 54 25 1.77
123 37 20 0 0 0 15 30 2.4 29 84 -84 123 3 0 124 11 2 122 31 51 124 40 34 1.78
Uncertainty in time = +/- 3 secs
Prediction of 2020 Aug 15.0
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