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Updated: 2008 OCT 31, 00:50 UT
Event Rank : 79
(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 2008 Dec 09 UT, the 82 km diameter asteroid (122) Gerda will occult a 10.4 mag star in the constellation Virgo for observers along a path passing over the South Island New Zealand in morning twilight at low alitutde. The path is centred near Invercargill with the 1-sigma area extending north to Wanaka.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.6 mag to 14.0 mag (the magnitude of the asteroid) for at most 2.3 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 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
155 25 3 -42 12 44 15 52 43 5 99 -17 159 16 52 -42 24 20 ... .. .. .. .. .. 163 4 48 -42 23 44 ... .. .. .. .. ..
159 7 44 -43 11 36 15 52 45 8 96 -15 162 0 39 -43 12 33 155 9 52 -42 59 18 165 14 48 -43 5 37 ... .. .. .. .. ..
161 49 50 -43 59 47 15 52 47 10 94 -13 164 16 11 -43 55 46 158 51 49 -43 58 20 167 9 48 -43 44 51 152 3 26 -43 28 25
164 4 20 -44 43 6 15 52 50 12 92 -11 166 14 45 -44 36 0 161 33 25 -44 46 43 168 54 18 -44 22 14 156 58 3 -44 40 41
166 2 9 -45 23 29 15 52 52 13 91 -10 168 1 46 -45 14 12 163 47 29 -45 30 16 170 30 57 -44 58 14 159 59 17 -45 32 59
167 48 33 -46 1 52 15 52 54 14 89 -9 169 40 16 -45 50 55 165 44 56 -46 10 54 172 1 28 -45 33 10 162 23 19 -46 18 45
169 26 32 -46 38 48 15 52 56 15 88 -7 171 12 13 -46 26 29 167 31 0 -46 49 32 173 27 3 -46 7 14 164 26 54 -47 0 55
170 58 2 -47 14 36 15 52 59 16 87 -6 172 38 54 -47 1 9 169 8 40 -47 26 44 174 48 34 -46 40 37 166 17 9 -47 40 46
172 24 20 -47 49 30 15 53 1 17 85 -5 174 1 19 -47 35 6 170 39 52 -48 2 48 176 6 40 -47 13 25 167 57 50 -48 18 58
173 46 23 -48 23 42 15 53 3 18 84 -4 175 20 9 -48 8 26 172 5 53 -48 38 0 177 21 52 -47 45 44 169 31 18 -48 55 55
175 4 53 -48 57 18 15 53 5 19 83 -3 176 35 57 -48 41 16 173 27 39 -49 12 29 178 34 36 -48 17 38 170 59 3 -49 31 55
176 20 23 -49 30 25 15 53 7 20 82 -2 177 49 9 -49 13 41 174 45 52 -49 46 24 179 45 10 -48 49 11 172 22 11 -50 7 9
177 33 18 -50 3 8 15 53 10 20 81 -1 179 0 8 -49 45 44 176 1 6 -50 19 50 -179 6 9 -49 20 26 173 41 28 -50 41 46
178 44 0 -50 35 29 15 53 12 21 80 0 -179 50 51 -50 17 29 177 13 46 -50 52 52 -177 59 7 -49 51 25 174 57 33 -51 15 53
Uncertainty in time = +/- 2 secs
[Prediction of 2008 Oct 31.0]
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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