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Updated: 2010 MAY 26, 22:29 UT
Event Rank : 73
(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 Jun 26 UT, the 54 km diameter asteroid (925) Alphonsina will occult a 11.5 mag star in the constellation Scorpius for observers along a path passing near Invercargill in New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.3 mag to 12.4 mag (the magnitude of the asteroid) for at most 3.9 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
167 52 54 -54 20 24 6 14 57 34 115 -14 167 11 24 -54 12 39 168 34 13 -54 27 48 166 6 21 -53 59 50 169 38 20 -54 38 40
167 55 12 -53 26 0 6 15 4 34 115 -13 167 14 21 -53 18 13 168 35 52 -53 33 27 166 10 16 -53 5 20 169 38 57 -53 44 23
167 55 25 -52 31 3 6 15 11 34 116 -13 167 15 10 -52 23 12 168 35 29 -52 38 33 166 11 58 -52 10 13 169 37 37 -52 49 35
167 53 38 -51 35 31 6 15 17 33 116 -13 167 13 55 -51 27 34 168 33 9 -51 43 6 166 11 33 -51 14 27 169 34 24 -51 54 15
167 49 54 -50 39 22 6 15 24 33 117 -12 167 10 41 -50 31 19 168 28 54 -50 47 3 166 9 4 -50 18 1 169 29 20 -50 58 22
167 44 15 -49 42 33 6 15 31 32 117 -12 167 5 29 -49 34 22 168 22 48 -49 50 22 166 4 33 -49 20 52 169 22 30 -50 1 52
167 36 44 -48 45 2 6 15 38 32 118 -12 166 58 22 -48 36 42 168 14 52 -48 53 0 165 58 2 -48 22 57 169 13 54 -49 4 44
167 27 22 -47 46 46 6 15 45 31 118 -11 166 49 21 -47 38 15 168 5 8 -47 54 55 165 49 33 -47 24 12 169 3 34 -48 6 54
167 16 9 -46 47 42 6 15 52 31 119 -11 166 38 27 -46 38 58 167 53 36 -46 56 3 165 39 5 -46 24 34 168 51 31 -47 8 20
167 3 5 -45 47 45 6 15 59 30 120 -10 166 25 38 -45 38 46 167 40 16 -45 56 20 165 26 39 -45 23 58 168 37 44 -46 8 58
166 48 9 -44 46 50 6 16 6 29 120 -10 166 10 54 -44 37 35 167 25 7 -44 55 41 165 12 11 -44 22 19 168 22 13 -45 8 43
166 31 18 -43 44 53 6 16 13 29 121 -9 165 54 12 -43 35 19 167 8 6 -43 54 2 164 55 39 -43 19 31 168 4 55 -44 7 31
166 12 29 -42 41 47 6 16 20 28 122 -8 165 35 27 -42 31 51 166 49 11 -42 51 17 164 37 0 -42 15 27 167 45 48 -43 5 16
165 51 37 -41 37 25 6 16 27 27 122 -8 165 14 36 -41 27 5 166 28 16 -41 47 19 164 16 6 -41 9 59 167 24 47 -42 1 53
165 28 35 -40 31 39 6 16 34 26 123 -7 164 51 30 -40 20 50 166 5 17 -40 42 0 163 52 50 -40 2 56 167 1 48 -40 57 13
165 3 16 -39 24 19 6 16 41 26 123 -6 164 26 2 -39 12 57 165 40 5 -39 35 10 163 27 3 -38 54 8 166 36 44 -39 51 8
164 35 29 -38 15 12 6 16 47 25 124 -5 163 58 0 -38 3 12 165 12 32 -38 26 39 162 58 31 -37 43 18 166 9 26 -38 43 28
164 5 1 -37 4 3 6 16 54 24 125 -5 163 27 8 -36 51 19 164 42 23 -37 16 12 162 26 56 -36 30 10 165 39 43 -37 34 1
163 31 34 -35 50 35 6 17 1 23 125 -4 162 53 9 -35 36 59 164 9 24 -36 3 32 161 51 58 -35 14 20 165 7 21 -36 22 31
162 54 45 -34 34 24 6 17 8 21 126 -3 162 15 36 -34 19 45 163 33 13 -34 48 19 161 13 5 -33 55 17 164 32 2 -35 8 40
Uncertainty in time = +/- 4 secs
Prediction of 2010 May 27.0
Use these links for further information:
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[Observing Details]
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