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Updated: 2009 JUL 08, 13:47 UT
Event Rank : 67
(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 Jul 22 UT, the 41 km diameter asteroid (686) Gersuind will occult a 12.5 mag star in the constellation Pegasus for observers along a path grazing the extreme south of New Zealand and running along the east coast of Queensland.
In the case of an occultation, the combined light of the asteroid and the star will drop by only 0.6 mag to 12.1 mag (the magnitude of the asteroid) for at most 6.3 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 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
167 15 38 -47 0 0 14 13 30 29 358 -59 167 37 42 166 53 32 168 16 54 166 14 8
166 34 41 -46 0 0 14 13 41 30 359 -60 166 56 24 166 12 56 167 35 1 165 34 8
165 53 49 -45 0 0 14 13 53 31 360 -61 166 15 13 165 32 22 166 53 15 164 54 9
165 12 59 -44 0 0 14 14 4 32 0 -62 165 34 5 164 51 50 166 11 36 164 14 8
164 32 9 -43 0 0 14 14 16 33 1 -63 164 52 59 164 11 18 165 29 59 163 34 5
163 51 18 -42 0 0 14 14 29 34 2 -64 164 11 52 163 30 42 164 48 24 162 53 57
163 10 22 -41 0 0 14 14 41 35 3 -65 163 30 42 162 50 1 164 6 48 162 13 42
162 29 21 -40 0 0 14 14 54 36 3 -67 162 49 26 162 9 13 163 25 8 161 33 19
161 48 12 -39 0 0 14 15 8 37 4 -68 162 8 5 161 28 17 162 43 23 160 52 45
161 6 53 -38 0 0 14 15 22 37 5 -69 161 26 34 160 47 10 162 1 32 160 12 0
160 25 24 -37 0 0 14 15 36 38 6 -70 160 44 53 160 5 52 161 19 31 159 31 1
159 43 41 -36 0 0 14 15 50 39 7 -71 160 3 1 159 24 19 160 37 20 158 49 47
159 1 44 -35 0 0 14 16 5 40 8 -72 159 20 54 158 42 32 159 54 56 158 8 16
158 19 30 -34 0 0 14 16 20 41 9 -73 158 38 31 158 0 27 159 12 18 157 26 26
157 36 59 -33 0 0 14 16 36 42 9 -74 157 55 52 157 18 3 158 29 24 156 44 17
156 54 8 -32 0 0 14 16 51 43 10 -75 157 12 54 156 35 19 157 46 12 156 1 46
156 10 55 -31 0 0 14 17 8 44 12 -76 156 29 35 155 52 14 157 2 41 155 18 52
155 27 20 -30 0 0 14 17 24 45 13 -78 155 45 53 155 8 44 156 18 50 154 35 32
154 43 20 -29 0 0 14 17 41 46 14 -79 155 1 48 154 24 50 155 34 35 153 51 47
153 58 54 -28 0 0 14 17 58 46 15 -80 154 17 17 153 40 28 154 49 56 153 7 33
153 13 59 -27 0 0 14 18 15 47 16 -81 153 32 19 152 55 37 154 4 50 152 22 49
152 28 35 -26 0 0 14 18 33 48 17 -82 152 46 51 152 10 16 153 19 16 151 37 34
151 42 38 -25 0 0 14 18 51 49 19 -83 152 0 52 151 24 22 152 33 13 150 51 44
150 56 8 -24 0 0 14 19 10 49 20 -84 151 14 20 150 37 54 151 46 37 150 5 19
150 9 3 -23 0 0 14 19 28 50 21 -85 150 27 13 149 50 49 150 59 27 149 18 17
149 21 19 -22 0 0 14 19 47 51 23 -87 149 39 29 149 3 6 150 11 42 148 30 34
148 32 55 -21 0 0 14 20 7 51 24 -87 148 51 5 148 14 43 149 23 18 147 42 10
147 43 49 -20 0 0 14 20 26 52 26 -88 148 2 0 147 25 36 148 34 13 146 53 2
146 53 58 -19 0 0 14 20 46 53 28 -88 147 12 10 146 35 43 147 44 26 146 3 6
146 3 20 -18 0 0 14 21 6 53 29 -87 146 21 34 145 45 3 146 53 54 145 12 22
145 11 52 -17 0 0 14 21 27 54 31 -86 145 30 9 144 53 32 146 2 33 144 20 45
144 19 31 -16 0 0 14 21 47 54 33 -85 144 37 51 144 1 7 145 10 22 143 28 13
143 26 14 -15 0 0 14 22 8 55 35 -84 143 44 39 143 7 45 144 17 17 142 34 43
142 31 58 -14 0 0 14 22 30 55 37 -83 142 50 28 142 13 24 143 23 15 141 40 11
141 36 39 -13 0 0 14 22 51 55 39 -82 141 55 15 141 17 58 142 28 13 140 44 34
140 40 13 -12 0 0 14 23 13 55 41 -80 140 58 57 140 21 25 141 32 7 139 47 48
139 42 37 -11 0 0 14 23 35 56 43 -79 140 1 29 139 23 41 140 34 53 138 49 48
138 43 45 -10 0 0 14 23 58 56 45 -78 139 2 46 138 24 40 139 36 27 137 50 30
Uncertainty in time = +/- 6 secs
Prediction of 2009 Jul 8.0
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