|
|
Updated: 2015 SEP 28, 04:51 UT
Event Rank : 73
(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 Nov 28 UT, the 119 km diameter asteroid (2241) Alcathous will occult a 12.3 mag star in the constellation Taurus for observers along a wide path across New Zealand centred over Gisborne, with almost all of New Zealand within the 1-sigma uncertainty area.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.6 mag to 15.8 mag (the magnitude of the asteroid) for at most 6.8 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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
157 39 48 -51 0 0 13 19 41 11 12 -18 155 16 41 160 9 18 151 41 20 164 21 43
158 51 22 -50 0 0 13 19 37 12 11 -19 156 28 14 161 21 11 152 53 16 165 34 53
160 5 55 -49 0 0 13 19 33 13 10 -20 157 42 24 162 36 26 154 7 20 166 52 17
161 23 38 -48 0 0 13 19 29 15 9 -21 158 59 22 163 55 20 155 23 44 168 14 16
162 44 49 -47 0 0 13 19 24 16 8 -22 160 19 22 165 18 12 156 42 36 169 41 20
164 9 46 -46 0 0 13 19 18 17 7 -23 161 42 40 166 45 26 158 4 11 171 14 6
165 38 54 -45 0 0 13 19 12 18 5 -23 163 9 36 168 17 32 159 28 43 172 53 21
167 12 41 -44 0 0 13 19 5 19 4 -24 164 40 32 169 55 7 160 56 30 174 40 11
168 51 44 -43 0 0 13 18 58 20 3 -25 166 15 59 171 39 2 162 27 54 176 36 3
170 36 52 -42 0 0 13 18 49 21 1 -26 167 56 31 173 30 21 164 3 20 178 43 4
172 29 4 -41 0 0 13 18 40 22 359 -26 169 42 56 175 30 32 165 43 20 -178 55 32
174 29 44 -40 0 0 13 18 30 23 357 -27 171 36 12 177 41 41 167 28 32 -176 14 27
Latitude Latitude Latitude Latitude
175 0 0 -39 45 41 13 18 28 23 357 -27 -38 21 49 -41 14 47 -36 17 58 -43 49 22
176 0 0 -39 18 7 13 18 23 24 356 -27 -37 55 16 -40 46 2 -35 52 42 -43 18 7
177 0 0 -38 51 40 13 18 18 24 355 -27 -37 29 45 -40 18 28 -35 28 25 -42 48 14
178 0 0 -38 26 19 13 18 13 24 354 -27 -37 5 17 -39 52 4 -35 5 5 -42 19 41
179 0 0 -38 2 4 13 18 7 25 353 -27 -36 41 51 -39 26 50 -34 42 44 -41 52 27
180 0 0 -37 38 52 13 18 2 25 352 -27 -36 19 26 -39 2 44 -34 21 20 -41 26 29
-179 0 0 -37 16 45 13 17 57 25 351 -28 -35 58 2 -38 39 45 -34 0 54 -41 1 47
-178 0 0 -36 55 41 13 17 51 25 350 -27 -35 37 39 -38 17 53 -33 41 24 -40 38 20
Uncertainty in time = +/- 7 secs
Prediction of 2015 Sep 28.0
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]