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Updated: 2009 MAR 20, 20:26 UT
Event Rank : 20
(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 Apr 30 UT, the 33 km diameter asteroid (430) Hybris will occult a 11.5 mag star in the constellation Crater for observers along a path across western South Australia and Northern Territory.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.8 mag to 15.3 mag (the magnitude of the asteroid) for at most 4.1 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, 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
132 25 23 -36 20 2 12 7 53 65 342 -45 132 14 17 -36 20 10 132 36 30 -36 19 54 130 57 55 -36 20 55 133 53 4 -36 18 43
132 13 10 -34 46 52 12 8 13 67 341 -45 132 2 16 -34 47 0 132 24 4 -34 46 44 130 47 23 -34 47 43 133 39 9 -34 45 36
132 1 37 -33 14 41 12 8 33 68 340 -45 131 50 55 -33 14 49 132 12 20 -33 14 33 130 37 23 -33 15 29 133 26 4 -33 13 29
131 50 42 -31 43 24 12 8 52 70 339 -46 131 40 11 -31 43 31 132 1 14 -31 43 16 130 27 53 -31 44 10 133 13 44 -31 42 14
131 40 21 -30 12 54 12 9 12 71 337 -46 131 30 0 -30 13 1 131 50 43 -30 12 47 130 18 50 -30 13 39 133 2 4 -30 11 47
131 30 31 -28 43 8 12 9 32 73 336 -46 131 20 19 -28 43 15 131 40 44 -28 43 1 130 10 12 -28 43 51 132 51 2 -28 42 3
131 21 9 -27 14 1 12 9 51 74 334 -46 131 11 6 -27 14 8 131 31 13 -27 13 54 130 1 56 -27 14 42 132 40 34 -27 12 58
131 12 14 -25 45 28 12 10 11 75 331 -46 131 2 18 -25 45 35 131 22 10 -25 45 22 129 54 1 -25 46 8 132 30 38 -25 44 27
131 3 43 -24 17 26 12 10 31 77 329 -46 130 53 54 -24 17 32 131 13 32 -24 17 20 129 46 26 -24 18 5 132 21 11 -24 16 26
130 55 35 -22 49 50 12 10 50 78 325 -46 130 45 52 -22 49 56 131 5 17 -22 49 44 129 39 9 -22 50 28 132 12 11 -22 48 51
130 47 48 -21 22 37 12 11 10 79 321 -46 130 38 11 -21 22 43 130 57 24 -21 22 31 129 32 9 -21 23 14 132 3 37 -21 21 39
130 40 21 -19 55 43 12 11 30 80 316 -46 130 30 50 -19 55 49 130 49 52 -19 55 37 129 25 25 -19 56 19 131 55 27 -19 54 46
130 33 13 -18 29 5 12 11 49 81 310 -46 130 23 47 -18 29 11 130 42 39 -18 28 59 129 18 56 -18 29 41 131 47 40 -18 28 9
130 26 24 -17 2 39 12 12 9 82 302 -46 130 17 2 -17 2 45 130 35 45 -17 2 33 129 12 43 -17 3 14 131 40 15 -17 1 44
130 19 52 -15 36 22 12 12 29 83 293 -46 130 10 34 -15 36 28 130 29 9 -15 36 17 129 6 43 -15 36 57 131 33 10 -15 35 28
130 13 37 -14 10 12 12 12 48 83 282 -46 130 4 23 -14 10 17 130 22 51 -14 10 6 129 0 57 -14 10 46 131 26 26 -14 9 18
130 7 38 -12 44 3 12 13 8 83 269 -45 129 58 27 -12 44 9 130 16 49 -12 43 58 128 55 24 -12 44 37 131 20 2 -12 43 10
130 1 55 -11 17 55 12 13 28 83 257 -45 129 52 47 -11 18 0 130 11 3 -11 17 49 128 50 4 -11 18 29 131 13 56 -11 17 1
Uncertainty in time = +/- 14 secs
Prediction of 2009 Mar 20.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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