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Updated: 2018 Aug 12, 18:38 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 2018 Oct 13 UT, the 132 km diameter asteroid (654) Zelinda will occult a 11.4 mag star in the constellation Andromeda for observers along a path across northern Queensland, Northern Territory, north-western South Australia and south-eastern West Australia, running from Cape Melville, over Alice Springs, to Point Culver.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.01 mag to 11.87 mag (the magnitude of the asteroid) for at most 12.8 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, 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 2799-00091-1 by 654 Zelinda on 2018 Oct 13
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 48 17 -37 0 0 13 14 32 7 27 -34 120 35 8 123 2 12 120 24 46 123 12 48 0.83
122 38 6 -36 0 0 13 14 30 9 26 -35 121 25 21 123 51 38 121 15 3 124 2 12 0.85
123 28 31 -35 0 0 13 14 27 10 26 -36 122 16 7 124 41 44 122 5 51 124 52 15 0.86
124 19 35 -34 0 0 13 14 24 11 25 -37 123 7 27 125 32 32 122 57 14 125 43 1 0.87
125 11 20 -33 0 0 13 14 20 12 25 -39 123 59 25 126 24 5 123 49 14 126 34 32 0.88
126 3 50 -32 0 0 13 14 17 13 24 -40 124 52 5 127 16 27 124 41 55 127 26 53 0.88
126 57 7 -31 0 0 13 14 12 15 24 -41 125 45 28 128 9 39 125 35 19 128 20 5 0.89
127 51 15 -30 0 0 13 14 8 16 23 -42 126 39 39 129 3 47 126 29 31 129 14 12 0.89
128 46 18 -29 0 0 13 14 2 17 22 -44 127 34 41 129 58 53 127 24 33 130 9 19 0.89
129 42 20 -28 0 0 13 13 57 18 22 -45 128 30 37 130 55 2 128 20 29 131 5 29 0.90
130 39 24 -27 0 0 13 13 51 19 21 -46 129 27 32 131 52 17 129 17 22 132 2 46 0.90
131 37 34 -26 0 0 13 13 44 21 21 -48 130 25 30 132 50 43 130 15 18 133 1 14 0.90
132 36 56 -25 0 0 13 13 37 22 20 -49 131 24 35 133 50 25 131 14 21 134 0 59 0.90
133 37 35 -24 0 0 13 13 30 23 20 -50 132 24 51 134 51 28 132 14 35 135 2 7 0.90
134 39 35 -23 0 0 13 13 22 24 19 -52 133 26 25 135 53 59 133 16 5 136 4 42 0.91
135 43 3 -22 0 0 13 13 14 26 18 -53 134 29 21 136 58 2 134 18 57 137 8 51 0.91
136 48 6 -21 0 0 13 13 5 27 18 -54 135 33 46 138 3 46 135 23 17 138 14 41 0.91
137 54 49 -20 0 0 13 12 55 28 17 -56 136 39 47 139 11 18 136 29 11 139 22 20 0.91
139 3 23 -19 0 0 13 12 45 29 16 -57 137 47 30 140 20 47 137 36 48 140 31 57 0.91
140 13 54 -18 0 0 13 12 34 31 15 -59 138 57 5 141 32 22 138 46 15 141 43 41 0.91
141 26 35 -17 0 0 13 12 23 32 14 -60 140 8 39 142 46 14 139 57 41 142 57 45 0.91
142 41 34 -16 0 0 13 12 11 33 14 -62 141 22 25 144 2 36 141 11 16 144 14 19 0.91
143 59 7 -15 0 0 13 11 59 34 13 -63 142 38 33 145 21 42 142 27 13 145 33 39 0.91
145 19 27 -14 0 0 13 11 45 36 12 -65 143 57 16 146 43 49 143 45 43 146 56 2 0.91
146 42 51 -13 0 0 13 11 31 37 11 -66 145 18 51 148 9 16 145 7 3 148 21 48 0.91
148 9 40 -12 0 0 13 11 17 38 9 -68 146 43 35 149 38 26 146 31 30 149 51 19 0.91
Uncertainty in time = +/- 1 secs
Prediction of 2018 Aug 12.0
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