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Updated: 2008 JUN 08, 17:39 UT
Event Rank : 4
(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 Jul 20 UT, the 11 km diameter asteroid (2234) Schmadel will occult a 8.8 mag star in the constellation Norma for observers along a very narrow, large uncertainty path across Australia, running from Streaky Bay in South Australia to Burketown in northern Queensland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 7.3 mag to 16.1 mag (the magnitude of the asteroid) for at most 1.3 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
141 5 47 -10 0 0 11 25 26 39 191 -42 141 8 53 141 2 41 142 35 30 139 35 51
140 51 11 -11 0 0 11 25 17 40 191 -42 140 54 18 140 48 5 142 21 14 139 20 54
140 36 25 -12 0 0 11 25 8 41 191 -42 140 39 32 140 33 17 142 6 49 139 5 45
140 21 26 -13 0 0 11 24 58 42 191 -42 140 24 34 140 18 18 141 52 14 138 50 22
140 6 15 -14 0 0 11 24 48 43 191 -42 140 9 24 140 3 6 141 37 29 138 34 44
139 50 51 -15 0 0 11 24 38 44 191 -42 139 54 1 139 47 40 141 22 32 138 18 51
139 35 11 -16 0 0 11 24 28 45 191 -42 139 38 23 139 32 0 141 7 23 138 2 41
139 19 17 -17 0 0 11 24 17 46 191 -42 139 22 29 139 16 4 140 52 1 137 46 13
139 3 5 -18 0 0 11 24 6 47 191 -41 139 6 19 138 59 52 140 36 24 137 29 26
138 46 36 -19 0 0 11 23 55 48 191 -41 138 49 51 138 43 22 140 20 32 137 12 18
138 29 48 -20 0 0 11 23 44 49 191 -41 138 33 5 138 26 32 140 4 23 136 54 50
138 12 40 -21 0 0 11 23 33 50 191 -41 138 15 58 138 9 22 139 47 57 136 36 58
137 55 10 -22 0 0 11 23 22 51 191 -41 137 58 30 137 51 51 139 31 12 136 18 42
137 37 18 -23 0 0 11 23 10 52 191 -41 137 40 38 137 33 57 139 14 6 136 0 0
137 19 0 -24 0 0 11 22 58 53 191 -41 137 22 23 137 15 38 138 56 39 135 40 51
137 0 17 -25 0 0 11 22 46 54 191 -40 137 3 42 136 56 53 138 38 49 135 21 13
136 41 6 -26 0 0 11 22 34 55 191 -40 136 44 33 136 37 40 138 20 35 135 1 4
136 21 26 -27 0 0 11 22 21 56 191 -40 136 24 55 136 17 57 138 1 54 134 40 22
136 1 14 -28 0 0 11 22 9 58 191 -40 136 4 45 135 57 43 137 42 46 134 19 5
135 40 29 -29 0 0 11 21 56 59 191 -39 135 44 2 135 36 56 137 23 7 133 57 11
135 19 9 -30 0 0 11 21 43 60 190 -39 135 22 44 135 15 33 137 2 57 133 34 37
134 57 10 -31 0 0 11 21 30 61 190 -39 135 0 49 134 53 32 136 42 13 133 11 22
134 34 32 -32 0 0 11 21 17 62 190 -38 134 38 13 134 30 51 136 20 53 132 47 21
134 11 10 -33 0 0 11 21 4 63 190 -38 134 14 54 134 7 26 135 58 55 132 22 33
133 47 3 -34 0 0 11 20 50 64 190 -38 133 50 50 133 43 15 135 36 15 131 56 54
133 22 6 -35 0 0 11 20 37 65 190 -37 133 25 56 133 18 16 135 12 52 131 30 21
132 56 18 -36 0 0 11 20 23 66 190 -37 133 0 11 132 52 24 134 48 42 131 2 50
132 29 33 -37 0 0 11 20 9 67 189 -37 132 33 31 132 25 36 134 23 42 130 34 17
Uncertainty in time = +/- 19 secs
[Prediction of 2008 Jun 8.0]
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[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
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