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Updated: 2018 JAN 15, 15:48 UT
Event Rank : 75
(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 Mar 05 UT, the 64 km diameter asteroid (778) Theobalda will occult a 12.1 mag star in the constellation Scorpius for observers along a path across Australia, from Victor Harbour, just west of Adelaide to Kadina and south of Whyalla, then across north-western South Australia and northern Western Australia to near Broome, at low elevation.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.11 mag to 16.20 mag (the magnitude of the asteroid) for at most 4.3 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.
Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 Alt
E. Longitude Latitude U.T. Alt Az Alt Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
124 0 21 -18 52 16 15 21 25 6 127 -64 125 36 27 -19 45 1 121 47 54 -17 31 30 127 12 42 -20 33 15 ... .. .. .. .. .. ....
127 20 48 -22 5 13 15 21 32 11 125 -62 128 26 51 -22 34 28 126 8 14 -21 30 50 129 40 34 -23 4 54 124 27 0 -20 38 45 0.92
129 34 5 -24 26 21 15 21 39 14 124 -60 130 29 53 -24 47 17 128 35 8 -24 2 52 131 34 2 -25 9 51 127 18 18 -23 30 7 1.02
131 19 37 -26 25 53 15 21 46 16 123 -58 132 9 59 -26 42 13 130 27 14 -26 7 54 133 8 42 -27 0 6 129 20 34 -25 43 30 1.06
132 48 53 -28 12 41 15 21 54 18 122 -56 133 35 52 -28 26 1 132 0 26 -27 58 9 134 31 5 -28 40 43 130 59 30 -27 38 42 1.08
134 7 9 -29 50 53 15 22 1 20 121 -54 134 51 51 -30 2 2 133 21 18 -29 38 46 135 44 40 -30 14 23 132 24 2 -29 22 39 1.09
135 17 21 -31 22 44 15 22 8 22 121 -53 136 0 27 -31 32 14 134 33 19 -31 12 26 136 51 31 -31 42 46 133 38 35 -30 58 47 1.10
136 21 20 -32 49 41 15 22 15 23 120 -51 137 3 15 -32 57 52 135 38 36 -32 40 49 137 53 4 -33 6 56 134 45 40 -32 29 4 1.10
137 20 18 -34 12 43 15 22 23 25 119 -50 138 1 22 -34 19 49 136 38 31 -34 5 0 138 50 16 -34 27 39 135 46 53 -33 54 48 1.10
138 15 8 -35 32 31 15 22 30 26 118 -48 138 55 35 -35 38 43 137 34 3 -35 25 47 139 43 49 -35 45 31 136 43 22 -35 16 50 1.11
139 6 29 -36 49 37 15 22 37 27 117 -47 139 46 30 -36 55 2 138 25 54 -36 43 42 140 34 16 -37 0 57 137 35 53 -36 35 50 1.11
139 54 50 -38 4 25 15 22 44 28 116 -46 140 34 34 -38 9 9 139 14 35 -37 59 13 141 22 1 -38 14 17 138 25 2 -37 52 15 1.11
140 40 35 -39 17 13 15 22 51 29 115 -44 141 20 8 -39 21 22 140 0 31 -39 12 39 142 7 26 -39 25 49 139 11 16 -39 6 29 1.11
141 24 1 -40 28 18 15 22 59 30 114 -43 142 3 30 -40 31 54 140 44 3 -40 24 17 142 50 45 -40 35 44 139 54 57 -40 18 50 1.11
142 5 23 -41 37 51 15 23 6 31 113 -42 142 44 54 -41 40 59 141 25 25 -41 34 20 143 32 13 -41 44 16 140 36 20 -41 29 30 1.11
142 44 55 -42 46 4 15 23 13 32 112 -40 143 24 32 -42 48 46 142 4 51 -42 43 0 144 11 59 -42 51 32 141 15 41 -42 38 44 1.11
143 22 45 -43 53 5 15 23 20 33 111 -39 144 2 33 -43 55 23 142 42 31 -43 50 25 144 50 14 -43 57 42 141 53 10 -43 46 40 1.11
143 59 2 -44 59 3 15 23 28 34 110 -38 144 39 5 -45 0 59 143 18 34 -44 56 45 145 27 4 -45 2 52 142 28 57 -44 53 28 1.11
144 33 53 -46 4 3 15 23 35 35 109 -37 145 14 15 -46 5 39 143 53 7 -46 2 5 146 2 37 -46 7 9 143 3 8 -45 59 14 1.11
145 7 25 -47 8 12 15 23 42 35 108 -36 145 48 9 -47 9 29 144 26 16 -47 6 33 146 36 59 -47 10 37 143 35 51 -47 4 6 1.11
.. .. .. .. .. .. .. .. .. .. .. .. ... .. .. .. .. .. ... .. .. .. .. .. 13 38 48 -54 9 37 ... .. .. .. .. .. ....
Uncertainty in time = +/- 4 secs
Prediction of 2018 Jan 15.0
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