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Updated: 2009 FEB 18, 14:42 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 2009 Feb 25 UT, the 126 km diameter asteroid (469) Argentina will occult a 11.5 mag star in the constellation Scorpius for observers along a broad path across the South Island of New Zealand, from Dunedin to Haast, and including all of the southern half of the South Island in the one sigma limit..
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.8 mag to 14.2 mag (the magnitude of the asteroid) for at most 5.1 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
165 55 31 -41 20 46 13 47 16 21 118 -39 167 32 25 -41 34 37 164 14 23 -41 3 31 168 50 55 -41 43 57 162 45 38 -40 45 57
167 20 22 -42 46 54 13 47 21 23 116 -37 168 55 5 -42 57 51 165 41 59 -42 33 1 170 12 5 -43 5 3 164 16 9 -42 18 46
168 40 0 -44 8 43 13 47 25 24 115 -36 170 13 14 -44 17 16 167 3 30 -43 57 34 171 29 13 -44 22 39 165 39 39 -43 45 57
169 55 29 -45 27 0 13 47 30 26 114 -34 171 27 45 -45 33 31 168 20 14 -45 18 9 172 43 5 -45 37 20 166 57 42 -45 8 42
171 7 37 -46 42 22 13 47 34 27 113 -33 172 39 18 -46 47 5 169 33 7 -46 35 29 173 54 18 -46 49 32 168 11 26 -46 27 52
172 17 0 -47 55 14 13 47 39 28 111 -32 173 48 27 -47 58 23 170 42 53 -47 50 5 175 3 19 -47 59 35 169 21 39 -47 44 3
173 24 7 -49 5 57 13 47 43 29 110 -30 174 55 36 -49 7 41 171 50 4 -49 2 20 176 10 33 -49 7 47 170 28 59 -48 57 43
174 29 22 -50 14 49 13 47 48 30 109 -29 176 1 7 -50 15 15 172 55 7 -50 12 36 177 16 20 -50 14 19 171 33 56 -50 9 13
Uncertainty in time = +/- 3 secs
[Prediction of 2009 Feb 18.0]
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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