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Updated: 2009 JUL 16, 01:53 UT
Event Rank : 79
(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 2009 Aug 22 UT, the 72 km diameter asteroid (598) Octavia will occult a 12.1 mag star in the constellation Cetus for observers along a north-to-south path across Australia passing east of Alice Springs, then near Coober Pedy and ending near Ceduna.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.1 mag to 12.7 mag (the magnitude of the asteroid) for at most 13.7 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 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
137 23 48 -10 2 28 14 32 31 42 102 -85 137 52 50 -10 4 12 136 54 30 -10 0 38 138 32 29 -10 6 27 136 13 37 - 9 57 56
137 24 29 -11 3 28 14 32 51 42 101 -85 137 53 31 -11 5 10 136 55 11 -11 1 39 138 33 12 -11 7 23 136 14 18 -10 59 0
137 24 1 -12 4 14 14 33 12 42 100 -85 137 53 5 -12 5 55 136 54 41 -12 2 26 138 32 48 -12 8 6 136 13 46 -11 59 49
137 22 23 -13 4 47 14 33 33 43 99 -85 137 51 30 -13 6 28 136 53 1 -13 3 1 138 31 17 -13 8 37 136 12 2 -13 0 25
137 19 37 -14 5 10 14 33 54 43 98 -85 137 48 48 -14 6 49 136 50 10 -14 3 24 138 28 41 -14 8 58 136 9 6 -14 0 49
137 15 42 -15 5 22 14 34 15 43 97 -84 137 44 58 -15 7 2 136 46 10 -15 3 38 138 24 59 -15 9 10 136 4 58 -15 1 3
137 10 37 -16 5 27 14 34 36 43 96 -83 137 40 1 -16 7 6 136 40 59 -16 3 42 138 20 10 -16 9 13 135 59 39 -16 1 8
137 4 23 -17 5 23 14 34 57 43 95 -83 137 33 54 -17 7 2 136 34 37 -17 3 39 138 14 15 -17 9 10 135 53 6 -17 1 5
136 56 59 -18 5 14 14 35 18 43 94 -82 137 26 39 -18 6 53 136 27 4 -18 3 29 138 7 11 -18 9 1 135 45 21 -18 0 54
136 48 23 -19 4 59 14 35 39 43 93 -81 137 18 13 -19 6 38 136 18 18 -19 3 13 137 58 59 -19 8 47 135 36 20 -19 0 38
136 38 34 -20 4 39 14 36 0 43 92 -80 137 8 36 -20 6 20 136 8 17 -20 2 53 137 49 37 -20 8 29 135 26 4 -20 0 17
136 27 31 -21 4 17 14 36 21 43 92 -79 136 57 45 -21 5 58 135 57 1 -21 2 29 137 39 4 -21 8 9 135 14 30 -20 59 51
136 15 10 -22 3 52 14 36 41 43 91 -78 136 45 39 -22 5 35 135 44 27 -22 2 3 137 27 17 -22 7 47 135 1 36 -21 59 23
136 1 31 -23 3 25 14 37 2 43 90 -77 136 32 15 -23 5 10 135 30 32 -23 1 35 137 14 14 -23 7 24 134 47 20 -22 58 52
135 46 31 -24 2 58 14 37 23 43 89 -76 136 17 31 -24 4 44 135 15 14 -24 1 6 136 59 53 -24 7 1 134 31 38 -23 58 20
135 30 5 -25 2 31 14 37 44 42 88 -75 136 1 24 -25 4 19 134 58 30 -25 0 36 136 44 10 -25 6 39 134 14 28 -24 57 48
135 12 11 -26 2 5 14 38 5 42 87 -75 135 43 50 -26 3 56 134 40 17 -26 0 8 136 27 3 -26 6 19 133 55 46 -25 57 15
134 52 46 -27 1 40 14 38 26 42 87 -74 135 24 45 -27 3 34 134 20 29 -26 59 40 136 8 28 -27 6 1 133 35 28 -26 56 44
134 31 43 -28 1 18 14 38 47 42 86 -73 135 4 6 -28 3 15 133 59 3 -27 59 15 135 48 20 -28 5 47 133 13 29 -27 56 13
134 8 59 -29 0 59 14 39 8 41 85 -71 134 41 47 -29 3 0 133 35 54 -28 58 52 135 26 35 -29 5 36 132 49 44 -28 55 45
133 44 28 -30 0 44 14 39 29 41 84 -70 134 17 43 -30 2 48 133 10 55 -29 58 32 135 3 8 -30 5 30 132 24 6 -29 55 19
133 18 3 -31 0 32 14 39 50 41 84 -69 133 51 47 -31 2 41 132 44 0 -30 58 16 134 37 52 -31 5 29 131 56 30 -30 54 56
132 49 38 -32 0 25 14 40 11 40 83 -68 133 23 53 -32 2 40 132 15 3 -31 58 4 134 10 40 -32 5 34 131 26 47 -31 54 36
132 19 4 -33 0 23 14 40 32 40 83 -67 132 53 54 -33 2 43 131 43 54 -32 57 56 133 41 26 -33 5 44 130 54 50 -32 54 20
131 46 12 -34 0 26 14 40 52 39 82 -66 132 21 39 -34 2 52 131 10 26 -33 57 52 133 10 1 -34 6 2 130 20 28 -33 54 7
131 10 54 -35 0 34 14 41 13 39 82 -65 131 47 0 -35 3 7 130 34 26 -34 57 54 132 36 15 -35 6 26 129 43 32 -34 53 58
130 32 56 -36 0 48 14 41 34 38 81 -64 131 9 45 -36 3 28 129 55 45 -35 57 59 131 59 58 -36 6 57 129 3 49 -35 53 52
129 52 7 -37 1 6 14 41 55 37 81 -63 130 29 42 -37 3 55 129 14 8 -36 58 8 131 20 58 -37 7 35 128 21 5 -36 53 48
129 8 11 -38 1 29 14 42 16 37 81 -62 129 46 37 -38 4 27 128 29 22 -37 58 21 130 39 1 -38 8 19 127 35 5 -37 53 47
128 20 53 -39 1 55 14 42 37 36 80 -61 129 0 14 -39 5 4 127 41 8 -38 58 36 129 53 51 -39 9 10 126 45 32 -38 53 46
Uncertainty in time = +/- 10 secs
Prediction of 2009 Jul 16.0
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