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Updated: 2018 FEB 27, 17:45 UT
Event Rank : 58
(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 19 UT, the 64.1 km diameter asteroid (778) Theobalda will occult a 11.5 mag star in the constellation Scorpius for observers along a path across Australia, from near Darwin across The Northern Territory, south-west Queensland and New South Wales to eastern Victoria near Mallacoota.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.63 mag to 16.08 mag (the magnitude of the asteroid) for at most 6.8 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.
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 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
116 3 17 10 0 0 18 26 3 26 141 -58 115 41 32 116 25 1 114 56 46 117 9 26 0.14
116 46 6 9 0 0 18 26 10 27 141 -58 116 24 29 117 7 41 115 40 2 117 51 49 0.14
117 28 20 8 0 0 18 26 17 28 141 -57 117 6 51 117 49 47 116 22 41 118 33 39 0.14
118 10 2 7 0 0 18 26 24 30 141 -57 117 48 40 118 31 22 117 4 45 119 15 0 0.14
118 51 14 6 0 0 18 26 31 31 141 -56 118 29 58 119 12 27 117 46 17 119 55 52 0.14
119 31 58 5 0 0 18 26 39 32 141 -55 119 10 48 119 53 5 118 27 20 120 36 19 0.14
120 12 17 4 0 0 18 26 47 33 141 -55 119 51 12 120 33 19 119 7 55 121 16 23 0.14
120 52 12 3 0 0 18 26 55 35 141 -54 120 31 13 121 13 10 119 48 5 121 56 5 0.14
121 31 47 2 0 0 18 27 3 36 141 -54 121 10 51 121 52 41 120 27 52 122 35 28 0.14
122 11 3 1 0 0 18 27 12 37 141 -53 121 50 10 122 31 53 121 7 18 123 14 34 0.14
122 50 1 0 0 0 18 27 20 38 141 -52 122 29 12 123 10 49 121 46 26 123 53 25 0.14
123 28 45 - 1 0 0 18 27 29 39 141 -52 123 7 58 123 49 31 122 25 17 124 32 3 0.14
Latitude Latitude Latitude Latitude
124 0 0 - 1 48 39 18 27 37 40 141 -51 - 2 21 4 - 1 16 19 - 3 27 48 - 0 10 12 0.14
125 0 0 - 3 22 37 18 27 52 42 140 -50 - 3 55 13 - 2 50 5 - 5 2 19 - 1 43 36 0.14
126 0 0 - 4 57 7 18 28 7 44 140 -49 - 5 29 52 - 4 24 26 - 6 37 17 - 3 17 38 0.13
127 0 0 - 6 31 59 18 28 23 46 140 -47 - 7 4 51 - 5 59 10 - 8 12 31 - 4 52 7 0.13
128 0 0 - 8 7 1 18 28 39 48 139 -46 - 8 39 59 - 7 34 7 - 9 47 51 - 6 26 51 0.13
129 0 0 - 9 42 1 18 28 56 50 139 -45 -10 15 3 - 9 9 3 -11 23 2 - 8 1 39 0.13
130 0 0 -11 16 48 18 29 14 52 139 -43 -11 49 52 -10 43 47 -12 57 54 - 9 36 19 0.13
131 0 0 -12 51 8 18 29 32 53 138 -42 -13 24 13 -12 18 8 -14 32 15 -11 10 40 0.13
132 0 0 -14 24 52 18 29 50 55 137 -41 -14 57 54 -13 51 54 -16 5 52 -12 44 29 0.13
133 0 0 -15 57 47 18 30 8 57 137 -39 -16 30 45 -15 24 52 -17 38 34 -14 17 34 0.13
134 0 0 -17 29 41 18 30 27 59 136 -38 -18 2 33 -16 56 53 -19 10 10 -15 49 46 0.12
135 0 0 -19 0 25 18 30 46 61 135 -37 -19 33 10 -18 27 44 -20 40 30 -17 20 53 0.12
136 0 0 -20 29 50 18 31 4 63 134 -35 -21 2 25 -19 57 18 -22 9 25 -18 50 45 0.12
137 0 0 -21 57 45 18 31 23 64 133 -34 -22 30 9 -21 25 24 -23 36 45 -20 19 14 0.12
138 0 0 -23 24 3 18 31 42 66 132 -33 -23 56 14 -22 51 55 -25 2 24 -21 46 10 0.12
139 0 0 -24 48 38 18 32 1 68 130 -31 -25 20 34 -24 16 44 -26 26 15 -23 11 27 0.12
140 0 0 -26 11 22 18 32 19 69 129 -30 -26 43 3 -25 39 43 -27 48 11 -24 34 58 0.12
141 0 0 -27 32 11 18 32 38 71 127 -29 -28 3 35 -27 0 48 -29 8 8 -25 56 36 0.12
142 0 0 -28 51 0 18 32 56 72 125 -27 -29 22 6 -28 19 55 -30 26 2 -27 16 19 0.12
143 0 0 -30 7 46 18 33 14 74 122 -26 -30 38 34 -29 37 0 -31 41 51 -28 34 1 0.11
144 0 0 -31 22 27 18 33 32 75 120 -25 -31 52 55 -30 52 0 -32 55 32 -29 49 40 0.11
145 0 0 -32 35 0 18 33 49 76 117 -24 -33 5 9 -32 4 53 -34 7 4 -31 3 14 0.11
146 0 0 -33 45 26 18 34 7 78 113 -22 -34 15 14 -33 15 40 -35 16 27 -32 14 42 0.11
147 0 0 -34 53 43 18 34 23 79 109 -21 -35 23 10 -34 24 18 -36 23 40 -33 24 3 0.11
148 0 0 -35 59 53 18 34 40 80 104 -20 -36 28 59 -35 30 49 -37 28 45 -34 31 16 0.11
149 0 0 -37 3 56 18 34 56 81 97 -19 -37 32 40 -36 35 13 -38 31 42 -35 36 24 0.11
150 0 0 -38 5 53 18 35 12 82 90 -18 -38 34 16 -37 37 31 -39 32 33 -36 39 26 0.11
151 0 0 -39 5 46 18 35 27 82 81 -17 -39 33 48 -38 37 46 -40 31 21 -37 40 25 0.12
152 0 0 -40 3 38 18 35 42 83 71 -16 -40 31 18 -39 36 0 -41 28 7 -38 39 22 0.12
153 0 0 -40 59 31 18 35 56 83 59 -15 -41 26 50 -40 32 13 -42 22 55 -39 36 19 0.12
154 0 0 -41 53 27 18 36 11 83 47 -14 -42 20 25 -41 26 31 -43 15 46 -40 31 19 0.12
155 0 0 -42 45 29 18 36 24 83 35 -13 -43 12 6 -42 18 54 -44 6 45 -41 24 24 0.12
156 0 0 -43 35 41 18 36 38 83 24 -12 -44 1 57 -43 9 26 -44 55 53 -42 15 38 0.11
157 0 0 -44 24 4 18 36 51 82 15 -11 -44 50 0 -43 58 9 -45 43 15 -43 5 3 0.11
158 0 0 -45 10 43 18 37 4 82 7 -10 -45 36 19 -44 45 8 -46 28 53 -43 52 43 0.11
159 0 0 -45 55 40 18 37 16 81 1 -9 -46 20 57 -45 30 25 -47 12 50 -44 38 39 0.11
160 0 0 -46 38 59 18 37 28 80 355 -8 -47 3 57 -46 14 3 -47 55 11 -45 22 56 0.11
161 0 0 -47 20 43 18 37 40 80 351 -8 -47 45 22 -46 56 5 -48 35 57 -46 5 36 0.11
Uncertainty in time = +/- 7 secs
Prediction of 2018 Feb 27.0
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