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Updated: 2010 JAN 11, 04:53 UT
Event Rank : 100
(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 2010 Feb 27 UT, the 222 km diameter asteroid (532) Herculina will occult a 6.2 mag star in the constellation Coma Berenices for observers along a wide south-to-north path across Western Australia from between Balladonia and Madura, to Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.8 mag to 8.9 mag (the magnitude of the asteroid) for at most 23.6 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: .
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
128 32 0 -37 0 0 19 4 39 25 334 -24 129 58 12 127 6 16 130 12 3 126 52 36
127 51 17 -36 0 0 19 4 45 26 334 -25 129 16 11 126 26 50 129 29 48 126 13 22
127 11 30 -35 0 0 19 4 51 27 335 -26 128 35 8 125 48 15 128 48 34 125 34 58
126 32 33 -34 0 0 19 4 57 28 335 -27 127 55 2 125 10 27 128 8 16 124 57 20
125 54 24 -33 0 0 19 5 3 29 336 -28 127 15 46 124 33 22 127 28 49 124 20 26
125 16 58 -32 0 0 19 5 10 30 336 -29 126 37 18 123 56 57 126 50 11 123 44 11
124 40 14 -31 0 0 19 5 17 31 336 -30 125 59 34 123 21 10 126 12 18 123 8 32
124 4 7 -30 0 0 19 5 24 32 337 -31 125 22 32 122 45 57 125 35 6 122 33 28
123 28 35 -29 0 0 19 5 31 34 337 -32 124 46 8 122 11 16 124 58 34 121 58 55
122 53 36 -28 0 0 19 5 38 35 337 -33 124 10 19 121 37 5 124 22 37 121 24 52
122 19 7 -27 0 0 19 5 46 36 338 -34 123 35 3 121 3 22 123 47 14 120 51 15
121 45 6 -26 0 0 19 5 53 37 338 -35 123 0 18 120 30 3 123 12 21 120 18 4
121 11 30 -25 0 0 19 6 1 38 338 -35 122 26 1 119 57 8 122 37 58 119 45 15
120 38 19 -24 0 0 19 6 10 39 338 -36 121 52 11 119 24 34 122 4 1 119 12 47
120 5 29 -23 0 0 19 6 18 40 339 -37 121 18 45 118 52 20 121 30 29 118 40 39
119 32 59 -22 0 0 19 6 26 41 339 -38 120 45 41 118 20 24 120 57 19 118 8 48
119 0 48 -21 0 0 19 6 35 42 339 -39 120 12 57 117 48 44 120 24 30 117 37 12
118 28 53 -20 0 0 19 6 44 43 339 -40 119 40 32 117 17 18 119 52 1 117 5 52
117 57 13 -19 0 0 19 6 53 45 340 -41 119 8 25 116 46 6 119 19 49 116 34 44
117 25 48 -18 0 0 19 7 2 46 340 -42 118 36 33 116 15 6 118 47 52 116 3 47
Uncertainty in time = +/- 3 secs
Prediction of 2010 Jan 10.0
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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