|
|
Updated: 2018 APR 27, 22:48 UT
Event Rank : 84
(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 2018 May 16 UT, the 50.5 km diameter asteroid (446) Aeternitas will occult a 12.4 mag star in the constellation Leo for observers along a path across the north of the South Island of New Zealand from roughly Dunedin to Queenstown.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.97 mag to 12.75 mag (the combined magnitude of the asteroid and the close companion star) for at most 4.9 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, astrometry for the asteroid kindly provided by Bill Owen, astrometry for the asteroid kindly provided by the IAU Minor Planet Center.
This work has made use of data from the European Space Agency (ESA) mission Gaia (http://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, http://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
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 Alt
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4 Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
171 19 17 -52 0 0 7 29 38 21 4 -24 170 52 28 171 46 3 170 26 30 172 11 51 0.64
171 1 43 -51 0 0 7 29 33 22 5 -24 170 35 27 171 27 56 170 10 1 171 53 12 0.64
170 43 50 -50 0 0 7 29 28 23 5 -23 170 18 4 171 9 32 169 53 9 171 34 18 0.64
170 25 38 -49 0 0 7 29 23 24 5 -23 170 0 22 170 50 51 169 35 55 171 15 9 0.64
170 7 8 -48 0 0 7 29 18 25 6 -23 169 42 19 170 31 54 169 18 19 170 55 45 0.64
169 48 20 -47 0 0 7 29 12 26 6 -23 169 23 57 170 12 40 169 0 22 170 36 6 0.64
169 29 14 -46 0 0 7 29 6 27 6 -22 169 5 16 169 53 10 168 42 4 170 16 12 0.64
169 9 51 -45 0 0 7 29 0 28 7 -22 168 46 15 169 33 23 168 23 26 169 56 4 0.64
168 50 10 -44 0 0 7 28 54 29 7 -22 168 26 56 169 13 21 168 4 27 169 35 40 0.64
168 30 11 -43 0 0 7 28 47 30 8 -21 168 7 18 168 53 1 167 45 9 169 15 2 0.64
168 9 55 -42 0 0 7 28 40 30 8 -21 167 47 21 168 32 26 167 25 30 168 54 7 0.64
167 49 20 -41 0 0 7 28 33 31 9 -20 167 27 4 168 11 33 167 5 31 168 32 58 0.64
167 28 28 -40 0 0 7 28 26 32 9 -20 167 6 29 167 50 24 166 45 13 168 11 32 0.64
167 7 17 -39 0 0 7 28 19 33 10 -20 166 45 34 167 28 57 166 24 33 167 49 50 0.64
166 45 48 -38 0 0 7 28 11 34 10 -19 166 24 20 167 7 13 166 3 34 167 27 51 0.64
166 24 0 -37 0 0 7 28 4 35 11 -19 166 2 46 166 45 11 165 42 13 167 5 35 0.64
166 1 52 -36 0 0 7 27 56 36 12 -18 165 40 52 166 22 50 165 20 32 166 43 1 0.64
Uncertainty in time = +/- 2 secs
Prediction of 2018 Apr 27.0
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]