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Updated: 2018 MAY 15, 17:45 UT
Event Rank : 100
(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 Nov 22 UT, the 150.2 km diameter asteroid (95) Arethusa will occult a 11.3 mag star in the constellation Canis Minor for observers along a broad path across south-eastern Australia from south-eastern Queensland from Rockhampton to Mungindi, across New South Wales and across Victoria from Cobram to Melbourne, in early morning twilight.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.63 mag to 12.69 mag (the magnitude of the asteroid) for at most 22.3 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
142 47 27 -44 0 0 17 51 54 34 1 -9 141 44 56 143 50 3 141 20 47 144 14 18 0.38
143 10 50 -43 0 0 17 51 43 35 0 -9 142 9 18 144 12 29 141 45 31 144 36 21 0.38
143 34 8 -42 0 0 17 51 33 36 360 -10 142 33 31 144 34 51 142 10 5 144 58 23 0.38
143 57 21 -41 0 0 17 51 22 37 359 -10 142 57 36 144 57 13 142 34 31 145 20 24 0.38
144 20 31 -40 0 0 17 51 11 38 359 -11 143 21 36 145 19 34 142 58 50 145 42 26 0.38
144 43 39 -39 0 0 17 51 0 39 359 -11 143 45 30 145 41 55 143 23 2 146 4 29 0.38
145 6 46 -38 0 0 17 50 49 40 358 -12 144 9 21 146 4 17 143 47 11 146 26 34 0.38
145 29 52 -37 0 0 17 50 37 41 358 -12 144 33 10 146 26 41 144 11 15 146 48 42 0.38
145 52 59 -36 0 0 17 50 25 42 357 -12 144 56 56 146 49 8 144 35 17 147 10 54 0.38
146 16 7 -35 0 0 17 50 13 43 357 -13 145 20 42 147 11 39 144 59 18 147 33 10 0.38
146 39 17 -34 0 0 17 50 0 44 356 -13 145 44 29 147 34 14 145 23 18 147 55 31 0.38
147 2 31 -33 0 0 17 49 47 45 356 -13 146 8 16 147 56 53 145 47 19 148 17 58 0.38
147 25 48 -32 0 0 17 49 35 46 355 -14 146 32 5 148 19 39 146 11 20 148 40 31 0.38
147 49 10 -31 0 0 17 49 21 47 355 -14 146 55 57 148 42 30 146 35 24 149 3 11 0.38
148 12 36 -30 0 0 17 49 8 48 354 -14 147 19 52 149 5 29 146 59 30 149 25 58 0.38
148 36 9 -29 0 0 17 48 55 49 353 -15 147 43 52 149 28 34 147 23 41 149 48 54 0.37
148 59 48 -28 0 0 17 48 41 50 353 -15 148 7 57 149 51 48 147 47 55 150 11 58 0.37
149 23 35 -27 0 0 17 48 27 51 352 -15 148 32 7 150 15 11 148 12 15 150 35 11 0.37
149 47 29 -26 0 0 17 48 13 52 351 -16 148 56 24 150 38 43 148 36 40 150 58 35 0.37
150 11 32 -25 0 0 17 47 58 53 351 -16 149 20 48 151 2 25 149 1 12 151 22 8 0.37
150 35 44 -24 0 0 17 47 44 54 350 -16 149 45 19 151 26 17 149 25 51 151 45 53 0.37
151 0 5 -23 0 0 17 47 29 55 349 -16 150 9 59 151 50 20 149 50 38 152 9 50 0.37
151 24 37 -22 0 0 17 47 14 55 348 -17 150 34 48 152 14 35 150 15 34 152 33 58 0.37
151 49 20 -21 0 0 17 46 59 56 347 -17 150 59 47 152 39 3 150 40 39 152 58 19 0.37
152 14 15 -20 0 0 17 46 43 57 346 -17 151 24 56 153 3 43 151 5 54 153 22 54 0.37
152 39 21 -19 0 0 17 46 28 58 345 -17 151 50 16 153 28 36 151 31 19 153 47 42 0.37
153 4 41 -18 0 0 17 46 12 59 344 -17 152 15 48 153 53 44 151 56 56 154 12 46 0.37
153 30 14 -17 0 0 17 45 56 60 343 -18 152 41 32 154 19 7 152 22 45 154 38 4 0.37
-107 0 0 .. .. .. .. .. .. .. .. .. 47 1 19 .. .. .. 47 18 40 .. .. .. ....
Uncertainty in time = +/- 5 secs
Prediction of 2018 May 15.0
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