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Updated: 2008 NOV 13, 22:45 UT
Event Rank : 12
(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 2008 Nov 20 UT, the 11 km diameter asteroid (3935) Toatenmongakkai will occult a 10.3 mag star in the constellation Cancer for observers along a narrow path across Western Australia, from Karratha to Eucla.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.3 mag to 15.6 mag (the magnitude of the asteroid) for at most 3.5 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.
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
133 41 7 -38 0 0 17 44 46 23 21 -19 133 33 10 133 49 3 132 1 32 135 16 46
133 7 57 -37 0 0 17 44 14 23 22 -20 132 59 59 133 15 53 131 28 13 134 43 38
132 32 52 -36 0 0 17 43 42 24 23 -22 132 24 53 132 40 49 130 52 47 134 8 45
131 55 47 -35 0 0 17 43 8 25 24 -23 131 47 46 132 3 47 130 15 10 133 32 3
131 16 37 -34 0 0 17 42 32 26 24 -24 131 8 32 131 24 40 129 35 14 132 53 27
130 35 14 -33 0 0 17 41 55 26 25 -25 130 27 5 130 43 21 128 52 50 132 12 50
129 51 30 -32 0 0 17 41 16 27 26 -26 129 43 16 129 59 43 128 7 48 131 30 7
129 5 14 -31 0 0 17 40 35 27 28 -28 128 56 53 129 13 34 127 19 56 130 45 7
128 16 15 -30 0 0 17 39 53 28 29 -29 128 7 44 128 24 42 126 28 56 129 57 41
127 24 15 -29 0 0 17 39 8 28 30 -30 127 15 34 127 32 53 125 34 31 129 7 35
126 28 57 -28 0 0 17 38 22 28 31 -32 126 20 3 126 37 47 124 36 15 128 14 36
125 29 56 -27 0 0 17 37 33 29 32 -33 125 20 47 125 39 2 123 33 38 127 18 24
124 26 43 -26 0 0 17 36 42 29 34 -35 124 17 15 124 36 8 122 25 58 126 18 35
123 18 40 -25 0 0 17 35 48 29 35 -36 123 8 48 123 28 28 121 12 22 125 14 43
122 4 56 -24 0 0 17 34 51 29 37 -38 121 54 35 122 15 13 119 51 37 124 6 8
120 44 23 -23 0 0 17 33 51 29 38 -39 120 33 24 120 55 16 118 21 55 122 52 5
119 15 23 -22 0 0 17 32 47 29 40 -41 119 3 35 119 27 4 116 40 33 121 31 27
117 35 30 -21 0 0 17 31 37 28 42 -43 117 22 34 117 48 17 114 42 56 120 2 45
115 40 46 -20 0 0 17 30 21 28 44 -45 115 26 10 115 55 8 112 20 12 118 23 43
113 23 49 -19 0 0 17 28 55 27 46 -47 113 6 28 113 40 46 109 9 27 116 30 48
Uncertainty in time = +/- 31 secs
[Prediction of 2008 Nov 13.0]
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[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
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