|
|
Updated: 2011 May 18, 03:02 UT
Event Rank : 74
(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 Jul 10 UT, the 93 km diameter asteroid (886) Washingtonia will occult a 11.7 mag star in the constellation Virgo for observers along a path across eastern West Australia, during or shortly after twilight.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.1 mag to 14.8 mag (the magnitude of the asteroid) for at most 14.5 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.
Occultation of UCAC2 28028333 by 886 Washingtonia on 2011 Jul 10
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
124 22 51 -14 12 7 9 45 3 74 79 -5 124 49 11 -14 7 9 123 56 28 -14 17 2 125 29 34 -13 59 27 123 15 40 -14 24 31
124 32 45 -15 34 37 9 45 27 74 74 -5 124 59 14 -15 29 38 124 6 12 -15 39 34 125 39 52 -15 21 53 123 25 8 -15 47 6
124 42 17 -16 57 15 9 45 51 74 69 -6 125 8 57 -16 52 14 124 15 33 -17 2 14 125 49 52 -16 44 26 123 34 13 -17 9 50
124 51 29 -18 20 4 9 46 16 74 64 -7 125 18 21 -18 15 1 124 24 33 -18 25 5 125 59 34 -18 7 10 123 42 54 -18 32 44
125 0 22 -19 43 8 9 46 40 73 60 -8 125 27 27 -19 38 2 124 33 12 -19 48 11 126 8 59 -19 30 7 123 51 12 -19 55 53
125 8 56 -21 6 28 9 47 4 73 55 -8 125 36 15 -21 1 20 124 41 31 -21 11 34 126 18 10 -20 53 21 123 59 9 -21 19 20
125 17 12 -22 30 9 9 47 28 72 51 -9 125 44 48 -22 24 58 124 49 32 -22 35 17 126 27 6 -22 16 55 124 6 45 -22 43 8
125 25 12 -23 54 14 9 47 52 71 47 -10 125 53 5 -23 49 0 124 57 15 -23 59 25 126 35 50 -23 40 53 124 14 0 -24 7 20
125 32 56 -25 18 45 9 48 17 70 44 -10 126 1 7 -25 13 29 125 4 39 -25 24 0 126 44 21 -25 5 16 124 20 55 -25 31 59
125 40 25 -26 43 48 9 48 41 70 41 -11 126 8 56 -26 38 28 125 11 47 -26 49 5 126 52 40 -26 30 10 124 27 31 -26 57 9
125 47 38 -28 9 24 9 49 5 69 38 -12 126 16 32 -28 4 1 125 18 38 -28 14 45 127 0 50 -27 55 38 124 33 47 -28 22 55
125 54 37 -29 35 39 9 49 29 68 35 -12 126 23 55 -29 30 12 125 25 13 -29 41 4 127 8 50 -29 21 44 124 39 44 -29 49 19
126 1 22 -31 2 37 9 49 53 66 33 -13 126 31 6 -30 57 6 125 31 32 -31 8 6 127 16 41 -30 48 31 124 45 21 -31 16 27
126 7 54 -32 30 23 9 50 18 65 31 -14 126 38 6 -32 24 47 125 37 34 -32 35 56 127 24 23 -32 16 5 124 50 39 -32 44 23
126 14 11 -33 59 0 9 50 42 64 29 -14 126 44 55 -33 53 20 125 43 21 -34 4 38 127 31 59 -33 44 31 124 55 36 -34 13 12
126 20 16 -35 28 35 9 51 6 63 27 -15 126 51 33 -35 22 49 125 48 51 -35 34 17 127 39 28 -35 13 52 125 0 13 -35 43 0
126 26 6 -36 59 13 9 51 30 62 25 -15 126 58 0 -36 53 22 125 54 4 -37 5 1 127 46 51 -36 44 17 125 4 28 -37 13 51
Uncertainty in time = +/- 12 secs
Prediction of 2011 May 18.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]