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Updated: 2009 MAR 18, 17:43 UT
Event Rank : 63
(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 Apr 03 UT, the 126 km diameter asteroid (469) Argentina will occult a 12.6 mag star in the constellation Scorpius for observers along a wide, somewhat uncertain path across central Western Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.6 mag to 13.9 mag (the magnitude of the asteroid) for at most 12.7 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 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
112 56 23 -17 2 33 15 33 55 11 126 -72 114 52 44 -17 52 42 110 36 39 -15 53 52 118 3 45 -19 2 9 ... .. .. .. .. ..
115 23 53 -19 39 56 15 34 6 14 125 -72 117 1 11 -20 14 32 113 36 26 -18 57 8 119 50 29 -21 5 44 109 12 38 -16 49 54
117 17 51 -21 50 51 15 34 18 17 124 -71 118 45 23 -22 17 6 115 44 6 -21 19 27 121 21 55 -22 57 1 112 15 42 -19 56 57
118 53 6 -23 46 50 15 34 30 19 123 -70 120 14 39 -24 7 42 117 27 7 -23 22 14 122 42 47 -24 39 45 114 23 20 -22 20 27
120 16 1 -25 32 54 15 34 42 21 122 -69 121 33 34 -25 49 56 118 55 2 -25 12 57 123 55 50 -26 16 5 116 5 33 -24 23 48
121 30 3 -27 11 48 15 34 54 23 121 -68 122 44 46 -27 25 55 120 12 30 -26 55 16 125 2 50 -27 47 25 117 32 18 -26 14 52
122 37 17 -28 45 12 15 35 5 25 120 -66 123 49 58 -28 56 59 121 22 12 -28 31 19 126 4 56 -29 14 43 118 48 26 -27 57 25
123 39 8 -30 14 12 15 35 17 26 120 -65 124 50 19 -30 24 6 122 25 50 -30 2 28 127 3 3 -30 38 40 119 56 39 -29 33 40
124 36 35 -31 39 38 15 35 29 28 119 -64 125 46 41 -31 47 56 123 24 34 -31 29 41 127 57 47 -31 59 48 120 58 43 -31 5 0
125 30 21 -33 2 3 15 35 41 29 118 -63 126 39 41 -33 8 59 124 19 16 -32 53 37 128 49 40 -33 18 31 121 55 48 -32 32 21
126 20 59 -34 21 56 15 35 53 30 117 -61 127 29 48 -34 27 40 125 10 32 -34 14 48 129 39 4 -34 35 9 122 48 45 -33 56 27
127 8 54 -35 39 38 15 36 4 31 116 -60 128 17 26 -35 44 19 125 58 51 -35 33 37 130 26 18 -35 49 57 123 38 12 -35 17 48
127 54 28 -36 55 25 15 36 16 33 115 -59 129 2 51 -36 59 10 126 44 37 -36 50 25 131 11 39 -37 3 8 124 24 37 -36 36 48
Uncertainty in time = +/- 16 secs
Prediction of 2009 Mar 19.0
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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