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Updated: 2021 Mar 17, 03:49 UT
Event Rank : 99
(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 2021 Apr 19 UT, the 100 km diameter asteroid (63) Ausonia will occult a 12.0 mag star in the constellation Scorpius for observers along a path across West Australia, passing over Broome.
In the case of an occultation, the combined light of the asteroid and the star will drop by only 0.30 mag to 10.77 mag (the magnitude of the asteroid) for at most 31.8 seconds. This event may not be observable visually.
This update is based on, 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, in particular 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 UCAC4 291-116838 by 63 Ausonia on 2021 Apr 19
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
121 2 43 -10 0 0 17 52 6.7 61 143 -61 120 34 14 121 31 9 120 17 33 121 47 45 0.26
121 11 39 -11 0 0 17 52 39.7 62 143 -61 120 43 6 121 40 8 120 26 23 121 56 46 0.26
121 20 24 -12 0 0 17 53 12.9 63 142 -61 120 51 47 121 48 58 120 35 2 122 5 38 0.25
121 28 59 -13 0 0 17 53 46.5 64 141 -60 121 0 18 121 57 38 120 43 30 122 14 21 0.25
121 37 25 -14 0 0 17 54 20.3 65 140 -60 121 8 38 122 6 9 120 51 47 122 22 56 0.25
121 45 43 -15 0 0 17 54 54.3 66 139 -60 121 16 50 122 14 33 120 59 55 122 31 23 0.25
121 53 53 -16 0 0 17 55 28.5 67 138 -60 121 24 53 122 22 50 121 7 55 122 39 43 0.24
122 1 56 -17 0 0 17 56 3.0 68 136 -59 121 32 49 122 31 0 121 15 46 122 47 58 0.24
122 9 52 -18 0 0 17 56 37.7 69 135 -59 121 40 37 122 39 4 121 23 30 122 56 7 0.24
122 17 43 -19 0 0 17 57 12.5 70 134 -58 121 48 19 122 47 4 121 31 7 123 4 12 0.23
122 25 30 -20 0 0 17 57 47.6 71 132 -58 121 55 56 122 55 0 121 38 39 123 12 13 0.23
122 33 12 -21 0 0 17 58 22.8 71 130 -58 122 3 29 123 2 52 121 46 5 123 20 12 0.23
122 40 51 -22 0 0 17 58 58.2 72 128 -57 122 10 57 123 10 43 121 53 27 123 28 8 0.23
122 48 28 -23 0 0 17 59 33.7 73 126 -57 122 18 23 123 18 31 122 0 46 123 36 4 0.22
122 56 3 -24 0 0 18 0 9.4 74 124 -56 122 25 45 123 26 19 122 8 2 123 43 59 0.22
123 3 38 -25 0 0 18 0 45.2 74 121 -56 122 33 7 123 34 7 122 15 15 123 51 54 0.22
123 11 13 -26 0 0 18 1 21.1 75 118 -55 122 40 28 123 41 55 122 22 28 123 59 51 0.22
123 18 48 -27 0 0 18 1 57.2 76 115 -54 122 47 48 123 49 46 122 29 40 124 7 51 0.22
123 26 26 -28 0 0 18 2 33.3 76 112 -54 122 55 10 123 57 39 122 36 52 124 15 53 0.21
123 34 6 -29 0 0 18 3 9.5 77 108 -53 123 2 33 124 5 36 122 44 6 124 24 0 0.21
123 41 50 -30 0 0 18 3 45.8 77 104 -53 123 10 0 124 13 38 122 51 22 124 32 12 0.21
123 49 38 -31 0 0 18 4 22.1 78 99 -52 123 17 29 124 21 45 122 58 41 124 40 30 0.21
123 57 32 -32 0 0 18 4 58.5 78 94 -51 123 25 4 124 29 59 123 6 4 124 48 56 0.21
124 5 33 -33 0 0 18 5 34.9 78 89 -51 123 32 44 124 38 21 123 13 31 124 57 30 0.20
124 13 42 -34 0 0 18 6 11.4 79 84 -50 123 40 30 124 46 51 123 21 5 125 6 13 0.20
124 21 59 -35 0 0 18 6 47.8 79 79 -50 123 48 24 124 55 32 123 28 46 125 15 7 0.20
124 30 26 -36 0 0 18 7 24.3 79 73 -49 123 56 27 125 4 24 123 36 34 125 24 14 0.20
124 39 5 -37 0 0 18 8 0.8 79 68 -48 124 4 40 125 13 28 123 44 32 125 33 33 0.20
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