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Updated: 2011 Aug 23, 17:30 UT
Event Rank : 97
(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 2011 Oct 19 UT, the 89 km diameter asteroid (109) Felicitas will occult a 11.6 mag star in the constellation Auriga for observers along a path running up the western coast of New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.0 mag to 12.1 mag (the magnitude of the asteroid) for at most 8.8 seconds. Note the low elevation of the target star.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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.
Occultation of TYC 2424-01063-1 by 109 Felicitas on 2011 Oct 19
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 47 54 -47 0 0 15 59 49 8 15 -17 168 50 56 166 45 37 169 39 21 165 58 45
168 28 54 -46 0 0 15 59 52 9 14 -17 169 31 14 167 27 18 170 19 9 166 40 57
169 10 49 -45 0 0 15 59 55 10 14 -17 170 12 33 168 9 50 171 0 0 167 23 58
169 53 41 -44 0 0 15 59 59 11 13 -17 170 54 53 168 53 15 171 41 56 168 7 48
170 37 31 -43 0 0 16 0 3 12 13 -18 171 38 15 169 37 34 172 24 57 168 52 29
171 22 22 -42 0 0 16 0 8 13 12 -18 172 22 41 170 22 49 173 9 6 169 38 4
172 8 14 -41 0 0 16 0 13 15 11 -18 173 8 14 171 9 3 173 54 24 170 24 34
172 55 11 -40 0 0 16 0 18 16 11 -18 173 54 55 171 56 17 174 40 54 171 12 1
173 43 16 -39 0 0 16 0 24 17 10 -18 174 42 48 172 44 34 175 28 39 172 0 28
174 32 31 -38 0 0 16 0 31 18 9 -17 175 31 56 173 33 57 176 17 42 172 49 59
175 22 59 -37 0 0 16 0 38 19 9 -17 176 22 21 174 24 30 177 8 6 173 40 37
176 14 45 -36 0 0 16 0 45 20 8 -17 177 14 9 175 16 17 177 59 57 174 32 24
177 7 54 -35 0 0 16 0 53 21 7 -17 178 7 24 176 9 21 178 53 18 175 25 27
Uncertainty in time = +/- 5 secs
Prediction of 2011 Aug 23.0
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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