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Updated: 2018 Jun 12, 23:28 UT
Event Rank : 69
(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 Aug 01 UT, the 31 km diameter asteroid (852) Wladilena will occult a 11.6 mag star in the constellation Triangulum Australe for observers along a somewhat uncertain path across south-eastern Queensland, New South Wales, eastern Victoria and Tasmania, passing over Toowoomba and near Tamworth, Bathurst, Canberra and Lakes Entrance.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.43 mag to 12.69 mag (the magnitude of the asteroid) for at most 5.1 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Hugh Harris, 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.
Occultation of 4U 147-189881 by 852 Wladilena on 2018 Aug 1
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
155 20 28 -18 0 0 12 50 42 31 209 -77 155 30 8 155 10 48 155 44 8 154 56 50 0.28
154 59 14 -19 0 0 12 50 32 32 209 -77 155 8 57 154 49 31 155 23 1 154 35 30 0.28
154 38 5 -20 0 0 12 50 21 33 209 -76 154 47 51 154 28 19 155 1 58 154 14 13 0.28
154 16 58 -21 0 0 12 50 10 35 209 -76 154 26 48 154 7 10 154 41 0 153 52 59 0.28
153 55 54 -22 0 0 12 49 58 36 210 -75 154 5 47 153 46 2 154 20 4 153 31 46 0.28
153 34 51 -23 0 0 12 49 47 37 210 -75 153 44 47 153 24 55 153 59 9 153 10 34 0.28
153 13 48 -24 0 0 12 49 35 38 210 -74 153 23 48 153 3 48 153 38 16 152 49 21 0.28
152 52 44 -25 0 0 12 49 22 39 211 -73 153 2 48 152 42 40 153 17 22 152 28 7 0.28
152 31 37 -26 0 0 12 49 10 40 211 -72 152 41 46 152 21 28 152 56 26 152 6 49 0.28
152 10 27 -27 0 0 12 48 57 41 211 -72 152 20 40 152 0 13 152 35 28 151 45 27 0.27
151 49 12 -28 0 0 12 48 44 42 212 -71 151 59 30 151 38 53 152 14 25 151 24 0 0.27
151 27 51 -29 0 0 12 48 31 43 212 -70 151 38 15 151 17 27 151 53 17 151 2 25 0.27
151 6 22 -30 0 0 12 48 17 44 212 -69 151 16 52 150 55 53 151 32 3 150 40 43 0.27
150 44 45 -31 0 0 12 48 3 45 213 -68 150 55 21 150 34 9 151 10 40 150 18 50 0.27
150 22 57 -32 0 0 12 47 49 46 213 -68 150 33 39 150 12 15 150 49 8 149 56 47 0.27
150 0 58 -33 0 0 12 47 34 47 214 -67 150 11 47 149 50 9 150 27 25 149 34 31 0.27
149 38 45 -34 0 0 12 47 20 48 214 -66 149 49 41 149 27 48 150 5 30 149 12 0 0.27
149 16 16 -35 0 0 12 47 5 49 215 -65 149 27 20 149 5 12 149 43 20 148 49 13 0.26
148 53 31 -36 0 0 12 46 50 50 216 -64 149 4 43 148 42 19 149 20 55 148 26 8 0.26
148 30 27 -37 0 0 12 46 34 51 216 -63 148 41 48 148 19 6 148 58 12 148 2 43 0.26
148 7 2 -38 0 0 12 46 19 52 217 -62 148 18 31 147 55 32 148 35 8 147 38 55 0.26
147 43 13 -39 0 0 12 46 3 53 218 -61 147 54 52 147 31 34 148 11 43 147 14 43 0.26
147 18 59 -40 0 0 12 45 47 54 218 -60 147 30 49 147 7 10 147 47 54 146 50 4 0.26
146 54 17 -41 0 0 12 45 31 55 219 -59 147 6 17 146 42 17 147 23 38 146 24 56 0.26
146 29 4 -42 0 0 12 45 14 56 220 -59 146 41 16 146 16 53 146 58 53 145 59 16 0.26
146 3 18 -43 0 0 12 44 58 57 221 -58 146 15 41 145 50 55 146 33 35 145 33 0 0.25
145 36 55 -44 0 0 12 44 41 58 222 -57 145 49 31 145 24 19 146 7 43 145 6 6 0.25
145 9 51 -45 0 0 12 44 24 59 223 -56 145 22 40 144 57 2 145 41 12 144 38 29 0.25
Uncertainty in time = +/- 6 secs
Prediction of 2018 Jun 12.0
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