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Updated: 2011 APR 16, 13:26 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 2011 May 13 UT, the 168 km diameter asteroid (194) Prokne will occult a 9.2 mag star in the constellation Serpens for observers along a south-to-north across eastern Australia passing near Sydney, Brisbane and Rockhampton.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.2 mag to 11.3 mag (the magnitude of the asteroid) for at most 26.0 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
152 14 59 -44 0 0 17 26 42 41 352 -38 153 18 23 151 11 42 153 43 48 150 46 25
152 12 19 -43 0 0 17 26 53 42 352 -38 153 14 41 151 10 5 153 39 40 150 45 13
152 9 49 -42 0 0 17 27 5 43 352 -38 153 11 12 151 8 34 153 35 47 150 44 6
152 7 29 -41 0 0 17 27 17 44 352 -38 153 7 55 151 7 10 153 32 8 150 43 4
152 5 17 -40 0 0 17 27 29 45 351 -38 153 4 50 151 5 51 153 28 41 150 42 7
152 3 14 -39 0 0 17 27 41 46 351 -39 153 1 56 151 4 39 153 25 26 150 41 15
152 1 19 -38 0 0 17 27 54 47 351 -39 152 59 12 151 3 32 153 22 23 150 40 27
151 59 31 -37 0 0 17 28 6 48 351 -39 152 56 38 151 2 30 153 19 31 150 39 43
151 57 51 -36 0 0 17 28 19 49 351 -39 152 54 14 151 1 33 153 16 49 150 39 4
151 56 17 -35 0 0 17 28 32 50 350 -39 152 51 59 151 0 42 153 14 18 150 38 29
151 54 51 -34 0 0 17 28 46 51 350 -39 152 49 53 150 59 55 153 11 55 150 37 58
151 53 31 -33 0 0 17 28 59 52 350 -39 152 47 55 150 59 12 153 9 43 150 37 30
151 52 17 -32 0 0 17 29 13 53 350 -39 152 46 6 150 58 34 153 7 39 150 37 7
151 51 10 -31 0 0 17 29 27 54 349 -39 152 44 24 150 58 1 153 5 44 150 36 47
151 50 8 -30 0 0 17 29 41 55 349 -39 152 42 50 150 57 32 153 3 57 150 36 31
151 49 13 -29 0 0 17 29 55 56 349 -39 152 41 24 150 57 7 153 2 19 150 36 18
151 48 24 -28 0 0 17 30 9 57 348 -39 152 40 6 150 56 47 153 0 48 150 36 10
151 47 40 -27 0 0 17 30 24 57 348 -39 152 38 54 150 56 31 152 59 26 150 36 5
151 47 2 -26 0 0 17 30 39 58 347 -39 152 37 50 150 56 20 152 58 11 150 36 4
151 46 30 -25 0 0 17 30 54 59 347 -38 152 36 53 150 56 12 152 57 4 150 36 7
151 46 4 -24 0 0 17 31 9 60 346 -38 152 36 4 150 56 9 152 56 5 150 36 13
151 45 43 -23 0 0 17 31 24 61 346 -38 152 35 21 150 56 11 152 55 13 150 36 24
151 45 28 -22 0 0 17 31 39 62 345 -38 152 34 45 150 56 17 152 54 29 150 36 38
151 45 19 -21 0 0 17 31 54 63 345 -38 152 34 16 150 56 28 152 53 52 150 36 57
151 45 16 -20 0 0 17 32 10 64 344 -38 152 33 54 150 56 43 152 53 23 150 37 20
Uncertainty in time = +/- 5 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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