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Updated: 2008 FEB 15, 00:33 UT
Event Rank : 9
(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 Mar 31 UT, the 12 km diameter asteroid (5851) 1991 DM1 will occult a 9.9 mag star in the constellation Virgo for observers along a narrow path of significant uncertainty across New Zealand near Gisbourne.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.7 mag to 15.6 mag (the magnitude of the asteroid) for at most 1.1 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
179 0 48 -41 0 0 11 10 33 36 50 -51 179 7 52 178 53 43 -179 8 59 177 7 46
178 39 26 -40 0 0 11 10 43 36 50 -52 178 46 26 178 32 25 -179 31 28 176 47 33
178 16 47 -39 0 0 11 10 53 37 51 -53 178 23 43 178 9 50 -179 55 9 176 25 56
177 52 52 -38 0 0 11 11 3 37 52 -54 177 59 44 177 45 58 179 40 1 176 2 57
177 27 41 -37 0 0 11 11 14 37 53 -54 177 34 31 177 20 51 179 14 1 175 38 37
177 1 17 -36 0 0 11 11 25 38 54 -55 177 8 3 176 54 29 178 46 52 175 12 57
176 33 38 -35 0 0 11 11 35 38 55 -56 176 40 22 176 26 53 178 18 34 174 45 57
176 4 45 -34 0 0 11 11 46 38 56 -57 176 11 27 175 58 3 177 49 8 174 17 36
175 34 38 -33 0 0 11 11 58 39 57 -57 175 41 19 175 27 57 177 18 33 173 47 56
175 3 17 -32 0 0 11 12 9 39 58 -58 175 9 56 174 56 37 176 46 48 173 16 56
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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