|
|
Updated: 2009 FEB 06, 00:02 UT
Event Rank : 48
(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 2009 Mar 19 UT, the 40 km diameter asteroid (351) Yrsa will occult a 11.5 mag star in the constellation Libra for observers along a somwhat uncertain south-to-north path over the North Island New Zealand centred between Rotorua and Gisborne.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.1 mag to 13.4 mag (the magnitude of the asteroid) for at most 12.9 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
177 32 55 -48 21 26 13 20 26 38 47 -40 177 10 58 -48 26 8 177 54 42 -48 16 42 176 11 47 -48 38 37 178 51 54 -48 4 6
177 37 55 -46 57 52 13 21 7 39 47 -41 177 16 47 -47 2 30 177 58 54 -46 53 14 176 19 49 -47 14 46 178 54 2 -46 40 51
177 39 34 -45 35 56 13 21 47 40 48 -42 177 19 9 -45 40 30 177 59 51 -45 31 23 176 24 10 -45 52 33 178 53 9 -45 19 12
177 38 18 -44 15 30 13 22 28 41 49 -43 177 18 32 -44 19 58 177 57 57 -44 11 0 176 25 18 -44 31 50 178 49 37 -43 59 2
177 34 29 -42 56 25 13 23 9 42 50 -44 177 15 17 -43 0 49 177 53 34 -42 52 0 176 23 38 -43 12 31 178 43 46 -42 40 13
177 28 24 -41 38 36 13 23 50 43 50 -46 177 9 43 -41 42 56 177 46 58 -41 34 15 176 19 30 -41 54 27 178 35 50 -41 22 38
177 20 16 -40 21 57 13 24 31 44 51 -47 177 2 4 -40 26 14 177 38 22 -40 17 39 176 13 8 -40 37 35 178 26 2 -40 6 12
177 10 19 -39 6 22 13 25 11 45 52 -48 176 52 33 -39 10 36 177 28 0 -39 2 8 176 4 46 -39 21 48 178 14 34 -38 50 51
176 58 42 -37 51 48 13 25 52 46 53 -49 176 41 19 -37 55 58 177 16 0 -37 47 37 175 54 37 -38 7 1 178 1 34 -37 36 28
176 45 35 -36 38 9 13 26 33 46 54 -50 176 28 33 -36 42 16 177 2 31 -36 34 1 175 42 48 -36 53 11 177 47 11 -36 23 0
176 31 3 -35 25 21 13 27 14 47 56 -51 176 14 20 -35 29 25 176 47 40 -35 21 16 175 29 29 -35 40 13 177 31 29 -35 10 24
176 15 13 -34 13 21 13 27 55 47 57 -52 175 58 49 -34 17 23 176 31 33 -34 9 20 175 14 46 -34 28 3 177 14 36 -33 58 34
175 58 10 -33 2 6 13 28 35 48 58 -53 175 42 2 -33 6 5 176 14 14 -32 58 7 174 58 45 -33 16 39 176 56 34 -32 47 28
175 40 0 -31 51 32 13 29 16 49 59 -54 175 24 7 -31 55 29 175 55 48 -31 47 35 174 41 30 -32 5 55 176 37 30 -31 37 3
175 20 44 -30 41 36 13 29 57 49 60 -56 175 5 5 -30 45 30 175 36 19 -30 37 42 174 23 7 -30 55 51 176 17 25 -30 27 16
Uncertainty in time = +/- 22 secs
[Prediction of 2009 Feb 6.0]
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]