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Updated: 2008 SEP 04, 17:41 UT
Event Rank : 71
(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 Sep 12 UT, the 70 km diameter asteroid (746) Marlu will occult a 11.7 mag star in the constellation Microscopium for observers along a path across eastern Australia from Newcastle to Bowen in twilight.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 13.7 mag (the magnitude of the asteroid) for at most 7.5 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 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
153 25 30 -35 52 45 8 22 0 50 100 -10 152 55 30 -35 52 59 153 55 19 -35 52 23 152 6 31 -35 53 3 154 43 15 -35 51 27
153 9 49 -34 43 40 8 22 13 50 102 -10 152 40 11 -34 43 50 153 39 17 -34 43 21 151 51 47 -34 43 48 154 26 39 -34 42 31
152 53 4 -33 34 18 8 22 27 49 103 -10 152 23 45 -33 34 24 153 22 13 -33 34 3 151 35 53 -33 34 15 154 9 3 -33 33 20
152 35 15 -32 24 37 8 22 40 49 105 -10 152 6 14 -32 24 39 153 4 5 -32 24 26 151 18 50 -32 24 23 153 50 27 -32 23 50
152 16 21 -31 14 34 8 22 54 48 106 -10 151 47 36 -31 14 31 152 44 55 -31 14 28 151 0 39 -31 14 8 153 30 51 -31 14 0
151 56 21 -30 4 7 8 23 8 48 107 -9 151 27 51 -30 3 59 152 24 41 -30 4 6 150 41 17 -30 3 27 153 10 13 -30 3 46
151 35 16 -28 53 13 8 23 21 47 108 -9 151 6 58 -28 52 59 152 3 23 -28 53 18 150 20 46 -28 52 18 152 48 34 -28 53 7
151 13 3 -27 41 49 8 23 35 46 110 -9 150 44 56 -27 41 29 151 40 58 -27 42 0 149 59 2 -27 40 37 152 25 50 -27 41 58
150 49 40 -26 29 51 8 23 48 46 111 -9 150 21 43 -26 29 24 151 17 25 -26 30 8 149 36 4 -26 28 21 152 2 2 -26 30 17
150 25 5 -25 17 16 8 24 2 45 112 -8 149 57 16 -25 16 42 150 52 42 -25 17 40 149 11 49 -25 15 26 151 37 5 -25 18 1
149 59 15 -24 3 59 8 24 15 44 113 -8 149 31 32 -24 3 18 150 26 46 -24 4 32 148 46 15 -24 1 49 151 10 57 -24 5 5
149 32 6 -22 49 58 8 24 29 43 114 -8 149 4 28 -22 49 7 149 59 32 -22 50 39 148 19 18 -22 47 24 150 43 36 -22 51 25
149 3 35 -21 35 6 8 24 42 43 115 -7 148 35 59 -21 34 6 149 30 58 -21 35 57 147 50 52 -21 32 7 150 14 56 -21 36 58
148 33 35 -20 19 19 8 24 56 42 116 -7 148 6 1 -20 18 9 149 0 58 -20 20 20 147 20 54 -20 15 52 149 44 54 -20 21 37
148 2 2 -19 2 31 8 25 10 41 117 -6 147 34 26 -19 1 9 148 29 26 -19 3 43 146 49 16 -18 58 33 149 13 23 -19 5 17
147 28 49 -17 44 35 8 25 23 40 118 -6 147 1 9 -17 43 0 147 56 16 -17 45 59 146 15 51 -17 40 3 148 40 18 -17 47 53
146 53 46 -16 25 23 8 25 37 39 119 -5 146 26 0 -16 23 35 147 21 19 -16 27 1 145 40 30 -16 20 14 148 5 29 -16 29 16
146 16 45 -15 4 48 8 25 50 37 120 -5 145 48 49 -15 2 43 146 44 27 -15 6 41 145 3 2 -14 58 56 147 28 50 -15 9 20
145 37 33 -13 42 38 8 26 4 36 121 -4 145 9 24 -13 40 16 146 5 27 -13 44 49 144 23 15 -13 35 58 146 50 8 -13 47 54
Uncertainty in time = +/- 6 secs
[Prediction of 2008 Sep 4.0]
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[Observing Details]
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