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Updated: 2012 Apr 18, 22:16 UT
Event Rank : 34
(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 2012 Apr 25 UT, the 31 km diameter asteroid (872) Holda will occult a 12.3 mag star in the constellation Serpens for observers along a significant uncertainty path across New Zealand, passing over Blenheim and near Wellington.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.9 mag to 14.0 mag (the magnitude of the asteroid) for at most 7.0 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.
Occultation of TYC 5670-00275-1 by 872 Holda on 2012 Apr 25
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
174 57 28 -43 4 17 14 21 32 58 33 -50 174 45 40 -43 7 30 175 9 14 -43 1 3 173 58 38 -43 20 11 175 55 32 -42 48 11
174 26 5 -41 40 36 14 22 5 59 35 -51 174 14 32 -41 43 46 174 37 35 -41 37 25 173 28 31 -41 56 14 175 22 54 -41 24 47
173 54 44 -40 17 50 14 22 39 60 37 -52 173 43 25 -40 20 57 174 6 0 -40 14 43 172 58 21 -40 33 13 174 50 24 -40 2 17
173 23 23 -38 55 56 14 23 12 61 39 -53 173 12 18 -38 59 0 173 34 27 -38 52 52 172 28 6 -39 11 5 174 18 1 -38 40 38
172 52 2 -37 34 49 14 23 46 62 41 -54 172 41 8 -37 37 50 173 2 54 -37 31 47 171 57 45 -37 49 44 173 45 41 -37 19 44
172 20 38 -36 14 24 14 24 20 63 43 -55 172 9 55 -36 17 23 172 31 19 -36 11 25 171 27 17 -36 29 6 173 13 23 -35 59 32
171 49 9 -34 54 38 14 24 53 64 46 -56 171 38 37 -34 57 34 171 59 40 -34 51 41 170 56 40 -35 9 8 172 41 5 -34 39 58
Uncertainty in time = +/- 15 secs
Prediction of 2012 Apr 19.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
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[Asteroid Occultation Results]
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