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Updated: 2009 MAR 20, 20:35 UT
Event Rank : 99
(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 May 01 UT, the 256 km diameter asteroid (31) Euphrosyne will occult a 11.2 mag star in the constellation Telescopium for observers along a path across north-west Western Australia passing over Karratha, Carnarvon and Shark Bay.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.9 mag to 12.9 mag (the magnitude of the asteroid) for at most 18.8 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
118 5 46 -15 0 0 19 53 53 56 183 -35 116 48 47 119 22 17 116 11 39 119 58 52
117 44 29 -16 0 0 19 54 0 57 182 -35 116 27 1 119 1 29 115 49 38 119 38 17
117 22 46 -17 0 0 19 54 8 58 182 -36 116 4 46 118 40 17 115 27 8 119 17 19
117 0 35 -18 0 0 19 54 15 59 181 -36 115 42 1 118 18 39 115 4 6 118 55 56
116 37 55 -19 0 0 19 54 23 60 181 -37 115 18 45 117 56 33 114 40 33 118 34 8
116 14 45 -20 0 0 19 54 30 61 181 -37 114 54 56 117 34 0 114 16 25 118 11 52
115 51 3 -21 0 0 19 54 38 62 180 -37 114 30 33 117 10 57 113 51 42 117 49 7
115 26 47 -22 0 0 19 54 46 63 179 -38 114 5 34 116 47 23 113 26 22 117 25 53
115 1 56 -23 0 0 19 54 54 64 179 -38 113 39 58 116 23 17 113 0 22 117 2 7
114 36 28 -24 0 0 19 55 2 65 178 -39 113 13 41 115 58 36 112 33 42 116 37 49
114 10 21 -25 0 0 19 55 10 66 177 -39 112 46 43 115 33 19 112 6 19 116 12 55
113 43 34 -26 0 0 19 55 18 67 177 -39 112 19 1 115 7 24 111 38 10 115 47 25
113 16 3 -27 0 0 19 55 26 68 176 -40 111 50 33 114 40 49 111 9 13 115 21 16
112 47 47 -28 0 0 19 55 34 69 175 -40 111 21 16 114 13 33 110 39 26 114 54 27
112 18 44 -29 0 0 19 55 43 70 174 -40 110 51 7 113 45 31 110 8 46 114 26 55
111 48 49 -30 0 0 19 55 51 71 172 -41 110 20 5 113 16 43 109 37 9 113 58 37
111 18 1 -31 0 0 19 55 59 72 171 -41 109 48 4 112 47 4 109 4 33 113 29 31
Latitude Latitude Latitude Latitude
110 0 0 -33 24 15 19 56 20 74 167 -42 -30 37 51 -36 7 53 -29 16 49 -37 25 36
109 0 0 -35 8 4 19 56 35 76 163 -42 -32 26 43 -37 46 55 -31 8 13 -39 2 25
108 0 0 -36 46 7 19 56 50 77 158 -42 -34 9 31 -39 20 27 -32 53 25 -40 33 51
Uncertainty in time = +/- 5 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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