|
|
Updated: 2008 APR 08, 23:47 UT
Event Rank : 99
(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 Apr 14 UT, the 216 km diameter asteroid (375) Ursula will occult a 8.3 mag star in the constellation Scorpius for observers along a path that may graze the eastern coast of New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.2 mag to 12.5 mag (the magnitude of the asteroid) for at most 29.5 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: .
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
-179 12 54 -39 28 7 13 10 13 62 111 -56 -177 55 1 -39 53 36 179 29 23 -39 1 33 -177 19 7 -40 4 57 178 53 41 -38 48 57
179 59 38 -40 39 15 13 10 33 62 109 -55 -178 41 20 -41 5 12 178 40 51 -40 12 11 -178 4 54 -41 16 46 178 4 40 -39 59 22
179 9 29 -41 49 47 13 10 53 62 107 -55 -179 30 20 -42 16 15 177 49 34 -41 22 12 -178 53 20 -42 28 3 177 12 54 -41 9 8
178 16 25 -42 59 43 13 11 12 62 105 -54 179 37 50 -43 26 45 176 55 21 -42 31 34 -179 44 36 -43 38 48 176 18 10 -42 18 13
177 20 15 -44 9 3 13 11 32 62 103 -53 178 42 55 -44 36 41 175 57 58 -43 40 16 179 21 5 -44 49 1 175 20 15 -43 26 38
176 20 41 -45 17 44 13 11 52 61 101 -52 177 44 39 -45 46 2 174 57 11 -44 48 17 178 23 26 -45 58 40 174 18 56 -44 34 20
175 17 30 -46 25 45 13 12 12 61 100 -52 176 42 48 -46 54 46 173 52 44 -45 55 34 177 22 13 -47 7 44 173 13 55 -45 41 17
174 10 22 -47 33 4 13 12 31 60 98 -51 175 37 2 -48 2 51 172 44 20 -47 2 5 176 17 7 -48 16 10 172 4 57 -46 47 26
Uncertainty in time = +/- 7 secs
[Prediction of 2008 Apr 8.0]
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]