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Updated: 2021 APR 16, 06:02 UT
Event Rank : 100
(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 May 18 UT, the 186.4 km diameter asteroid (154) Bertha will occult a 12.4 mag star in the constellation Corona Australis for observers along a fairly broad path across Australia, from Jabru across central Northern Territory and western South Australia to Border Village.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.04 mag to 12.87 mag (the magnitude of the asteroid) for at most 17.0 seconds.
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, 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 UCAC4-225-180822 by 154 Bertha on 2021 May 18
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
135 40 11 0 0 0 18 47 21.5 45 184 -30 134 48 54 136 31 23 134 39 23 136 40 53 -0.10
135 29 40 - 1 0 0 18 47 28.7 46 184 -30 134 38 22 136 20 53 134 28 50 136 30 23 -0.09
135 19 2 - 2 0 0 18 47 36.1 47 184 -31 134 27 42 136 10 18 134 18 10 136 19 48 -0.09
135 8 17 - 3 0 0 18 47 43.6 48 184 -31 134 16 54 135 59 36 134 7 21 136 9 7 -0.09
134 57 26 - 4 0 0 18 47 51.2 49 184 -32 134 5 58 135 48 49 133 56 25 135 58 20 -0.09
134 46 27 - 5 0 0 18 47 59.0 50 184 -32 133 54 54 135 37 54 133 45 19 135 47 27 -0.09
134 35 19 - 6 0 0 18 48 6.9 51 184 -33 133 43 40 135 26 53 133 34 5 135 36 27 -0.09
134 24 4 - 7 0 0 18 48 14.8 52 184 -33 133 32 18 135 15 45 133 22 41 135 25 20 -0.09
134 12 40 - 8 0 0 18 48 22.9 53 184 -33 133 20 46 135 4 29 133 11 8 135 14 5 -0.09
134 1 8 - 9 0 0 18 48 31.2 54 184 -34 133 9 4 134 53 5 132 59 24 135 2 43 -0.09
133 49 26 -10 0 0 18 48 39.5 55 184 -34 132 57 12 134 41 33 132 47 30 134 51 13 -0.09
133 37 34 -11 0 0 18 48 47.9 56 184 -35 132 45 10 134 29 53 132 35 26 134 39 35 -0.09
133 25 33 -12 0 0 18 48 56.4 57 183 -35 132 32 56 134 18 3 132 23 9 134 27 47 -0.09
133 13 20 -13 0 0 18 49 5.1 58 183 -36 132 20 30 134 6 4 132 10 41 134 15 51 -0.09
133 0 57 -14 0 0 18 49 13.8 59 183 -36 132 7 53 133 53 55 131 58 1 134 3 44 -0.09
132 48 23 -15 0 0 18 49 22.6 60 183 -37 131 55 2 133 41 36 131 45 8 133 51 28 -0.09
132 35 36 -16 0 0 18 49 31.6 61 183 -37 131 41 59 133 29 6 131 32 1 133 39 1 -0.09
132 22 37 -17 0 0 18 49 40.6 62 183 -37 131 28 42 133 16 25 131 18 41 133 26 23 -0.09
132 9 25 -18 0 0 18 49 49.7 63 182 -38 131 15 11 133 3 32 131 5 6 133 13 34 -0.08
131 56 0 -19 0 0 18 49 58.9 64 182 -38 131 1 25 132 50 27 130 51 17 133 0 32 -0.08
131 42 20 -20 0 0 18 50 8.1 65 182 -38 130 47 24 132 37 9 130 37 11 132 47 18 -0.08
131 28 26 -21 0 0 18 50 17.5 66 182 -39 130 33 6 132 23 37 130 22 49 132 33 50 -0.08
131 14 16 -22 0 0 18 50 26.9 67 181 -39 130 18 32 132 9 51 130 8 10 132 20 9 -0.08
130 59 49 -23 0 0 18 50 36.5 68 181 -39 130 3 40 131 55 51 129 53 13 132 6 13 -0.08
130 45 6 -24 0 0 18 50 46.1 69 181 -40 129 48 29 131 41 35 129 37 58 131 52 2 -0.08
130 30 5 -25 0 0 18 50 55.7 70 180 -40 129 32 59 131 27 2 129 22 22 131 37 35 -0.08
130 14 46 -26 0 0 18 51 5.4 71 180 -40 129 17 9 131 12 13 129 6 26 131 22 51 -0.08
129 59 7 -27 0 0 18 51 15.2 72 180 -41 129 0 58 130 57 6 128 50 9 131 7 50 -0.08
129 43 7 -28 0 0 18 51 25.1 73 179 -41 128 44 24 130 41 40 128 33 29 130 52 30 -0.08
129 26 46 -29 0 0 18 51 35.0 74 178 -41 128 27 27 130 25 54 128 16 25 130 36 51 -0.08
129 10 2 -30 0 0 18 51 45.0 75 178 -41 128 10 5 130 9 48 127 58 57 130 20 52 -0.08
128 52 55 -31 0 0 18 51 55.0 75 177 -41 127 52 18 129 53 19 127 41 2 130 4 30 -0.08
128 35 22 -32 0 0 18 52 5.1 76 176 -42 127 34 3 129 36 28 127 22 39 129 47 47 -0.08
128 17 23 -33 0 0 18 52 15.2 77 175 -42 127 15 20 129 19 12 127 3 48 129 30 39 -0.08
127 58 55 -34 0 0 18 52 25.4 78 173 -42 126 56 6 129 1 31 126 44 25 129 13 6 -0.08
127 39 59 -35 0 0 18 52 35.6 79 171 -42 126 36 21 128 43 22 126 24 31 128 55 6 -0.08
127 20 31 -36 0 0 18 52 45.9 80 169 -42 126 16 1 128 24 45 126 4 1 128 36 38 -0.08
127 0 30 -37 0 0 18 52 56.2 81 167 -42 125 55 6 128 5 37 125 42 56 128 17 41 -0.08
126 39 54 -38 0 0 18 53 6.6 82 164 -43 125 33 32 127 45 58 125 21 12 127 58 11 -0.08
Uncertainty in time = +/- 2 secs
Prediction of 2021 Apr 16.0
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