|
|
Updated: 2015 Mar 18, 18:41 UT
Event Rank : 98
(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 2015 Apr 28 UT, the 106 km diameter asteroid (23) Thalia will occult a 10.6 mag star in the constellation Auriga for observers along a path across Queensland, passing over Mount Isa, Brisbane and Toowoomba.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.3 mag to 11.5 mag (the magnitude of the asteroid) for at most 3.0 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, 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 2422-00001-1 by 23 Thalia on 2015 Apr 28
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
157 2 4 -30 0 0 8 35 56 17 322 -21 155 36 12 158 26 6 154 36 41 159 22 18
155 17 37 -29 0 0 8 35 54 18 323 -20 153 50 12 156 43 3 152 49 30 157 40 5
153 30 0 -28 0 0 8 35 51 20 324 -18 152 0 41 154 57 5 150 58 33 155 55 8
151 38 42 -27 0 0 8 35 48 22 325 -16 150 7 8 153 7 46 149 3 17 154 7 3
149 43 9 -26 0 0 8 35 44 24 326 -14 148 8 52 151 14 37 147 2 58 152 15 21
147 42 40 -25 0 0 8 35 40 26 327 -12 146 5 6 149 16 59 144 56 40 150 19 28
146 0 0 -24 11 0 8 35 37 27 329 -11 -24 57 36 -23 25 8 -25 29 42 -22 54 20
145 0 0 -23 43 18 8 35 35 28 329 -10 -24 29 37 -22 57 41 -25 1 33 -22 27 2
144 0 0 -23 16 17 8 35 32 29 330 -9 -24 2 21 -22 30 55 -24 34 5 -22 0 26
143 0 0 -22 49 58 8 35 30 30 331 -8 -23 35 47 -22 4 50 -24 7 21 -21 34 31
142 0 0 -22 24 22 8 35 28 31 331 -7 -23 9 56 -21 39 28 -23 41 19 -21 9 18
141 0 0 -21 59 28 8 35 25 31 332 -6 -22 44 48 -21 14 48 -23 16 2 -20 44 46
140 0 0 -21 35 18 8 35 23 32 333 -5 -22 20 24 -20 50 50 -22 51 28 -20 20 58
Uncertainty in time = +/- 1 secs
Prediction of 2015 Mar 19.0
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]