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Updated: 2011 APR 16, 14:02 UT
Event Rank : 96
(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 2011 May 23 UT, the 168 km diameter asteroid (194) Prokne will occult a 12.0 mag star in the constellation Serpens for observers along a south-to-north path across Western Australia passing near Telfer and Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.4 mag to 11.1 mag (the magnitude of the asteroid) for at most 30.7 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 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
126 50 46 -38 0 0 17 11 18 44 18 -62 127 58 5 125 43 4 128 53 1 124 47 16
126 31 54 -37 0 0 17 11 35 45 19 -63 127 38 27 125 25 0 128 32 45 124 29 51
126 12 41 -36 0 0 17 11 51 46 20 -63 127 18 29 125 6 31 128 12 11 124 11 59
125 53 6 -35 0 0 17 12 8 47 20 -64 126 58 12 124 47 38 127 51 19 123 53 40
125 33 8 -34 0 0 17 12 25 48 21 -65 126 37 35 124 28 20 127 30 10 123 34 55
125 12 49 -33 0 0 17 12 42 48 22 -65 126 16 38 124 8 38 127 8 43 123 15 44
124 52 8 -32 0 0 17 13 0 49 23 -66 125 55 22 123 48 32 126 46 58 122 56 7
124 31 5 -31 0 0 17 13 17 50 24 -66 125 33 45 123 28 2 126 24 54 122 36 4
124 9 39 -30 0 0 17 13 35 51 25 -67 125 11 49 123 7 8 126 2 32 122 15 35
123 47 52 -29 0 0 17 13 53 52 26 -67 124 49 32 122 45 50 125 39 52 121 54 41
123 25 42 -28 0 0 17 14 12 52 27 -68 124 26 55 122 24 7 125 16 52 121 33 20
123 3 9 -27 0 0 17 14 31 53 28 -68 124 3 57 122 2 0 124 53 33 121 11 34
122 40 13 -26 0 0 17 14 49 54 29 -69 123 40 37 121 39 28 124 29 54 120 49 22
122 16 55 -25 0 0 17 15 9 55 30 -69 123 16 57 121 16 32 124 5 55 120 26 43
121 53 13 -24 0 0 17 15 28 55 31 -70 122 52 54 120 53 10 123 41 36 120 3 38
121 29 7 -23 0 0 17 15 47 56 32 -70 122 28 30 120 29 23 123 16 56 119 40 7
121 4 38 -22 0 0 17 16 7 57 34 -70 122 3 43 120 5 11 122 51 55 119 16 8
120 39 44 -21 0 0 17 16 27 57 35 -71 121 38 33 119 40 32 122 26 32 118 51 42
120 14 25 -20 0 0 17 16 47 58 37 -71 121 13 0 119 15 27 122 0 47 118 26 48
119 48 40 -19 0 0 17 17 7 59 38 -71 120 47 3 118 49 55 121 34 39 118 1 27
119 22 30 -18 0 0 17 17 28 59 40 -71 120 20 42 118 23 56 121 8 8 117 35 36
118 55 54 -17 0 0 17 17 48 60 41 -71 119 53 55 117 57 29 120 41 14 117 9 17
118 28 50 -16 0 0 17 18 9 60 43 -71 119 26 44 117 30 33 120 13 55 116 42 28
118 1 19 -15 0 0 17 18 30 61 45 -71 118 59 6 117 3 9 119 46 11 116 15 8
117 33 20 -14 0 0 17 18 51 61 47 -71 118 31 1 116 35 15 119 18 2 115 47 18
Uncertainty in time = +/- 13 secs
Prediction of 2011 Apr 16.0
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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