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Updated: 2020 Oct 28, 20:08 UT
Event Rank : 92
(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 Dec 03 UT, the 63 km diameter asteroid (971) Alsatia will occult a 9.4 mag star in the constellation Gemini for observers along a path across West Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.80 mag to 13.13 mag (the magnitude of the asteroid) for at most 7.9 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, 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 TYC 1897-01146-1 by 971 Alsatia on 2020 Dec 3
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
128 36 8 -37 0 0 15 9 13.0 21 32 -31 129 24 25 127 46 54 130 11 36 126 56 55 1.91
128 15 7 -36 0 0 15 9 23.8 21 33 -32 129 3 10 127 26 7 129 50 6 126 36 22 1.91
127 51 48 -35 0 0 15 9 35.0 22 33 -33 128 39 40 127 2 58 129 26 26 126 13 23 1.91
127 26 11 -34 0 0 15 9 46.6 23 34 -34 128 13 58 126 37 27 129 0 38 125 47 57 1.91
126 58 18 -33 0 0 15 9 58.6 23 34 -35 127 46 3 126 9 34 128 32 40 125 20 4 1.90
126 28 5 -32 0 0 15 10 11.1 24 35 -36 127 15 53 125 39 18 128 2 31 124 49 42 1.90
125 55 31 -31 0 0 15 10 24.1 25 36 -37 126 43 26 125 6 36 127 30 11 124 16 50 1.90
125 20 33 -30 0 0 15 10 37.5 25 36 -38 126 8 40 124 31 24 126 55 35 123 41 23 1.90
124 43 8 -29 0 0 15 10 51.4 26 37 -39 125 31 32 123 53 39 126 18 41 123 3 16 1.90
124 3 9 -28 0 0 15 11 5.8 26 38 -40 124 51 55 123 13 15 125 39 25 122 22 25 1.90
123 20 31 -27 0 0 15 11 20.6 26 39 -41 124 9 45 122 30 5 124 57 41 121 38 40 1.89
122 35 5 -26 0 0 15 11 36.0 27 40 -41 123 24 55 121 44 1 124 13 22 120 51 52 1.89
121 46 43 -25 0 0 15 11 52.0 27 40 -42 122 37 16 120 54 52 123 26 21 120 1 51 1.89
120 55 13 -24 0 0 15 12 8.4 27 41 -43 121 46 37 120 2 25 122 36 29 119 8 22 1.89
120 0 21 -23 0 0 15 12 25.5 28 42 -44 120 52 45 119 6 26 121 43 32 118 11 8 1.89
119 1 49 -22 0 0 15 12 43.2 28 43 -45 119 55 26 118 6 34 120 47 18 117 9 46 1.88
117 59 18 -21 0 0 15 13 1.5 28 44 -46 118 54 21 117 2 25 119 47 30 116 3 49 1.88
116 52 19 -20 0 0 15 13 20.6 28 46 -46 117 49 5 115 53 30 118 43 47 114 52 44 1.88
115 40 19 -19 0 0 15 13 40.4 28 47 -47 116 39 11 114 39 10 117 35 42 113 35 43 1.88
114 22 36 -18 0 0 15 14 1.2 28 48 -47 115 23 59 113 18 33 116 22 44 112 11 45 1.88
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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