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Updated: 2011 Aug 23, 05:29 UT
Event Rank : 15
(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 2011 Oct 08 UT, the 69 km diameter asteroid (7641) 1986 TT6 will occult a 9.1 mag star in the constellation Orion for observers along a large uncertainty path across Northern Territory, South Australia and western Victoria.
In the case of an occultation, the combined light of the asteroid and the star will drop by 7.7 mag to 16.8 mag (the magnitude of the asteroid) for at most 4.8 seconds.
This update is based on 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 TYC 0734-00321-1 by 7641 1986 TT6 on 2011 Oct 8
Centre Star Star Sun Path Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
139 49 6 -45 0 0 18 52 17 34 15 -12 139 20 33 140 17 34 135 6 0 144 25 38
139 46 52 -44 0 0 18 52 12 35 15 -13 139 18 48 140 14 52 135 8 35 144 18 48
139 44 9 -43 0 0 18 52 7 36 16 -13 139 16 32 140 11 42 135 10 25 144 11 43
139 40 58 -42 0 0 18 52 2 37 16 -14 139 13 47 140 8 5 135 11 32 144 4 23
139 37 20 -41 0 0 18 51 57 38 16 -14 139 10 33 140 4 3 135 11 58 143 56 49
139 33 16 -40 0 0 18 51 52 39 17 -14 139 6 52 139 59 35 135 11 45 143 49 2
139 28 47 -39 0 0 18 51 46 40 17 -15 139 2 45 139 54 45 135 10 55 143 41 1
139 23 54 -38 0 0 18 51 41 41 17 -15 138 58 13 139 49 31 135 9 30 143 32 47
139 18 37 -37 0 0 18 51 35 41 18 -16 138 53 16 139 43 55 135 7 30 143 24 20
139 12 58 -36 0 0 18 51 30 42 18 -16 138 47 56 139 37 57 135 4 57 143 15 41
139 6 57 -35 0 0 18 51 24 43 19 -17 138 42 13 139 31 38 135 1 52 143 6 49
139 0 34 -34 0 0 18 51 18 44 19 -17 138 36 7 139 24 59 134 58 16 142 57 44
138 53 51 -33 0 0 18 51 12 45 20 -17 138 29 39 139 17 59 134 54 10 142 48 26
138 46 46 -32 0 0 18 51 6 46 20 -18 138 22 49 139 10 40 134 49 35 142 38 56
138 39 21 -31 0 0 18 51 0 47 21 -18 138 15 39 139 3 1 134 44 31 142 29 14
138 31 36 -30 0 0 18 50 54 48 21 -19 138 8 7 138 55 3 134 38 59 142 19 18
138 23 32 -29 0 0 18 50 47 49 22 -19 138 0 15 138 46 45 134 33 0 142 9 11
138 15 7 -28 0 0 18 50 41 50 23 -20 137 52 2 138 38 9 134 26 33 141 58 50
138 6 23 -27 0 0 18 50 34 50 23 -20 137 43 30 138 29 13 134 19 40 141 48 17
137 57 19 -26 0 0 18 50 28 51 24 -21 137 34 36 138 19 59 134 12 21 141 37 30
137 47 56 -25 0 0 18 50 21 52 25 -21 137 25 23 138 10 26 134 4 36 141 26 30
137 38 14 -24 0 0 18 50 14 53 26 -21 137 15 50 138 0 35 133 56 24 141 15 17
137 28 12 -23 0 0 18 50 7 54 27 -22 137 5 57 137 50 24 133 47 48 141 3 51
137 17 50 -22 0 0 18 50 0 55 28 -22 136 55 43 137 39 54 133 38 45 140 52 10
137 7 9 -21 0 0 18 49 53 55 29 -23 136 45 9 137 29 5 133 29 17 140 40 15
136 56 8 -20 0 0 18 49 46 56 30 -23 136 34 15 137 17 57 133 19 23 140 28 6
136 44 46 -19 0 0 18 49 39 57 31 -24 136 23 0 137 6 30 133 9 4 140 15 42
136 33 5 -18 0 0 18 49 32 58 32 -24 136 11 24 136 54 42 132 58 19 140 3 3
136 21 3 -17 0 0 18 49 25 58 33 -25 135 59 27 136 42 35 132 47 8 139 50 9
136 8 40 -16 0 0 18 49 17 59 34 -25 135 47 9 136 30 7 132 35 30 139 36 59
135 55 56 -15 0 0 18 49 10 60 36 -26 135 34 29 136 17 19 132 23 26 139 23 32
135 42 50 -14 0 0 18 49 2 60 37 -26 135 21 27 136 4 9 132 10 56 139 9 49
135 29 22 -13 0 0 18 48 55 61 39 -27 135 8 2 135 50 38 131 57 58 138 55 49
135 15 32 -12 0 0 18 48 47 62 40 -27 134 54 15 135 36 45 131 44 33 138 41 31
135 1 18 -11 0 0 18 48 40 62 42 -28 134 40 4 135 22 30 131 30 39 138 26 54
134 46 42 -10 0 0 18 48 32 63 44 -28 134 25 29 135 7 51 131 16 17 138 11 59
Uncertainty in time = +/- 26 secs
Prediction of 2011 Aug 4.0
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