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Updated: 2017 SEP 25, 19:31 UT
Event Rank : 87
(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 2017 Nov 28 UT, the 92 km diameter asteroid (1177) Gonnessia will occult a 11.5 mag star in the constellation Sextans for observers along a path running along the western edge of Western Australia, passing near Coral Bay, Perth and Albany.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.73 mag to 15.20 mag (the magnitude of the asteroid) for at most 6.3 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.
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
109 27 37 -16 49 14 18 52 7 42 77 -38 110 2 32 -16 35 7 108 52 10 -17 3 21 110 33 32 -16 22 25 108 19 48 -17 16 4 1.05
110 1 14 -17 41 48 18 52 15 42 76 -37 110 36 8 -17 27 37 109 25 48 -17 55 59 111 7 8 -17 14 51 108 53 27 -18 8 45 1.05
110 33 56 -18 34 34 18 52 23 43 75 -36 111 8 51 -18 20 18 109 58 29 -18 48 50 111 39 51 -18 7 28 109 26 7 -19 1 40 1.05
111 5 44 -19 27 32 18 52 30 43 74 -35 111 40 42 -19 13 12 110 30 15 -19 41 53 112 11 45 -19 0 18 109 57 51 -19 54 48 1.05
111 36 43 -20 20 45 18 52 38 43 72 -34 112 11 44 -20 6 20 111 1 10 -20 35 10 112 42 50 -19 53 21 110 28 42 -20 48 10 1.05
112 6 52 -21 14 12 18 52 46 43 71 -33 112 41 59 -20 59 42 111 31 14 -21 28 43 113 13 9 -20 46 39 110 58 42 -21 41 47 1.05
112 36 14 -22 7 56 18 52 53 43 70 -32 113 11 27 -21 53 20 112 0 29 -22 22 32 113 42 44 -21 40 12 111 27 51 -22 35 41 1.05
113 4 50 -23 1 57 18 53 1 44 69 -31 113 40 12 -22 47 15 112 28 57 -23 16 39 114 11 35 -22 34 2 111 56 11 -23 29 53 1.05
113 32 42 -23 56 16 18 53 9 44 68 -30 114 8 13 -23 41 28 112 56 40 -24 11 4 114 39 44 -23 28 10 112 23 45 -24 24 24 1.04
113 59 51 -24 50 54 18 53 17 44 67 -29 114 35 32 -24 36 0 113 23 37 -25 5 49 115 7 13 -24 22 36 112 50 32 -25 19 15 1.04
114 26 17 -25 45 54 18 53 24 44 66 -29 115 2 10 -25 30 53 113 49 50 -26 0 55 115 34 2 -25 17 23 113 16 33 -26 14 27 1.04
114 52 1 -26 41 15 18 53 32 44 64 -28 115 28 9 -26 26 8 114 15 21 -26 56 24 116 0 12 -26 12 32 113 41 50 -27 10 2 1.04
115 17 5 -27 37 0 18 53 40 44 63 -27 115 53 28 -27 21 45 114 40 8 -27 52 16 116 25 44 -27 8 3 114 6 23 -28 6 2 1.04
115 41 28 -28 33 10 18 53 48 44 62 -26 116 18 8 -28 17 48 115 4 14 -28 48 34 116 50 39 -28 3 58 114 30 12 -29 2 27 1.04
116 5 11 -29 29 47 18 53 55 44 61 -25 116 42 10 -29 14 16 115 27 37 -29 45 19 117 14 57 -29 0 19 114 53 18 -29 59 19 1.04
116 28 14 -30 26 52 18 54 3 43 60 -24 117 5 33 -30 11 12 115 50 19 -30 42 32 117 38 38 -29 57 8 115 15 39 -30 56 40 1.04
116 50 37 -31 24 26 18 54 11 43 59 -23 117 28 18 -31 8 38 116 12 19 -31 40 16 118 1 43 -30 54 25 115 37 17 -31 54 33 1.04
117 12 19 -32 22 33 18 54 18 43 57 -22 117 50 25 -32 6 35 116 33 36 -32 38 32 118 24 11 -31 52 14 115 58 10 -32 52 57 1.04
117 33 21 -33 21 13 18 54 26 43 56 -21 118 11 53 -33 5 5 116 54 9 -33 37 23 118 46 2 -32 50 35 116 18 18 -33 51 57 1.04
117 53 41 -34 20 29 18 54 34 42 55 -20 118 32 42 -34 4 10 117 13 59 -34 36 49 119 7 16 -33 49 30 116 37 40 -34 51 34 1.04
118 13 19 -35 20 23 18 54 42 42 54 -19 118 52 51 -35 3 52 117 33 4 -35 36 55 119 27 52 -34 49 3 116 56 13 -35 51 50 1.04
118 32 12 -36 20 57 18 54 49 42 53 -18 119 12 19 -36 4 15 117 51 22 -36 37 42 119 47 50 -35 49 15 117 13 58 -36 52 47 1.04
118 50 21 -37 22 15 18 54 57 41 52 -17 119 31 5 -37 5 20 118 8 51 -37 39 12 120 7 7 -36 50 8 117 30 50 -37 54 30 1.04
119 7 41 -38 24 18 18 55 5 41 51 -16 119 49 6 -38 7 10 118 25 30 -38 41 30 120 25 44 -37 51 47 117 46 49 -38 57 0 1.04
Uncertainty in time = +/- 3 secs
Prediction of 2017 Sep 25.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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