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Updated: 2014 Oct 11, 20:35 UT
Event Rank : 23
(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 2015 Jan 15 UT, the 39 km diameter asteroid (731) Sorga will occult a 12.4 mag star in the constellation Virgo for observers along a path across north-western Queensland, central Australia, and western South Australia, passing near Port Moresby, Cloncurry and Mount Isa.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.0 mag to 15.3 mag (the magnitude of the asteroid) for at most 10.9 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
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 2UCAC 36300611 by 731 Sorga on 2015 Jan 15
Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2
E. Longitude Latitude U.T. Alt Az Alt
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 37 50 -34 3 59 15 26 38 9 68 -35 123 47 49 -34 12 3 125 24 25 -33 56 45 115 32 23 -35 47 9 129 9 7 -33 25 27
129 0 38 -31 36 43 15 27 14 14 65 -37 128 26 45 -31 40 59 129 33 26 -31 32 44 124 43 14 -32 12 25 132 25 3 -31 13 57
131 59 4 -29 31 12 15 27 49 17 64 -39 131 31 19 -29 34 1 132 26 14 -29 28 33 128 38 10 -29 53 35 134 52 29 -29 15 44
134 16 14 -27 37 3 15 28 25 20 63 -41 133 51 54 -27 39 3 134 40 10 -27 35 9 131 23 36 -27 52 46 136 50 59 -27 25 56
136 7 45 -25 50 21 15 29 1 22 62 -43 135 45 40 -25 51 50 136 29 34 -25 48 57 133 32 42 -26 1 57 138 29 50 -25 42 12
137 41 27 -24 9 8 15 29 37 25 62 -44 137 20 57 -24 10 15 138 1 44 -24 8 5 135 18 33 -24 17 54 139 54 15 -24 3 7
139 1 52 -22 32 11 15 30 12 26 62 -46 138 42 34 -22 33 1 139 21 0 -22 31 24 136 47 58 -22 38 52 141 7 33 -22 27 47
140 11 57 -20 58 41 15 30 48 28 62 -47 139 53 35 -20 59 19 140 30 10 -20 58 7 138 5 0 -21 3 46 142 11 59 -20 55 35
141 13 42 -19 28 5 15 31 24 30 62 -48 140 56 5 -19 28 32 141 31 10 -19 27 40 139 12 18 -19 31 53 143 9 8 -19 26 1
142 8 34 -17 59 57 15 32 0 32 62 -49 141 51 35 -18 0 15 142 25 26 -17 59 40 140 11 42 -18 2 42 144 0 12 -17 58 43
142 57 39 -16 33 56 15 32 35 33 62 -50 142 41 11 -16 34 7 143 14 0 -16 33 46 141 4 32 -16 35 50 144 46 4 -16 33 26
143 41 46 -15 9 47 15 33 11 34 62 -51 143 25 44 -15 9 52 143 57 42 -15 9 43 141 51 50 -15 10 58 145 27 28 -15 9 53
144 21 35 -13 47 17 15 33 47 36 63 -52 144 5 56 -13 47 17 144 37 9 -13 47 18 142 34 21 -13 47 51 146 4 57 -13 47 55
144 57 38 -12 26 15 15 34 22 37 63 -53 144 42 19 -12 26 11 145 12 53 -12 26 20 143 12 44 -12 26 17 146 38 59 -12 27 20
145 30 21 -11 6 32 15 34 58 38 64 -54 145 15 18 -11 6 24 145 45 19 -11 6 41 143 47 26 -11 6 6 147 9 56 -11 8 1
Uncertainty in time = +/- 32 secs
Prediction of 2014 Dec 5.0
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[Observing Details]
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