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Updated: 2018 Aug 30, 16:53 UT
Event Rank : 80
(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 Oct 26 UT, the 44 km diameter asteroid (1456) Saldanha will occult a 10.5 mag star in the constellation Andromeda for observers along a slightly uncertain path beginning near Geelong during evening twilight then running across central and northern Victoria and southern and eastern New South Wales, passing over Melbourne, Albury-Wodonga and Port Macquarie.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.19 mag to 14.62 mag (the magnitude of the asteroid) for at most 4.6 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.
Occultation of TYC 1739-01436-1 by 1456 Saldanha on 2018 Oct 26
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
137 14 24 -43 0 0 10 1 41 9 46 -7 136 48 41 137 40 3 136 21 17 138 7 11 0.26
138 46 46 -42 0 0 10 1 38 10 45 -8 138 21 44 139 11 44 137 55 4 139 38 10 0.27
140 16 1 -41 0 0 10 1 34 12 44 -10 139 51 35 140 40 22 139 25 36 141 6 9 0.28
141 42 26 -40 0 0 10 1 30 13 43 -11 141 18 35 142 6 14 140 53 13 142 31 26 0.28
143 6 19 -39 0 0 10 1 26 15 42 -12 142 43 0 143 29 36 142 18 11 143 54 15 0.28
144 27 54 -38 0 0 10 1 21 16 42 -14 144 5 3 144 50 42 143 40 45 145 14 52 0.29
145 47 23 -37 0 0 10 1 16 18 41 -15 145 24 59 146 9 46 145 1 9 146 33 28 0.29
147 4 59 -36 0 0 10 1 11 19 40 -17 146 42 58 147 26 57 146 19 35 147 50 14 0.29
148 20 50 -35 0 0 10 1 5 20 39 -18 147 59 13 148 42 26 147 36 13 149 5 20 0.29
149 35 8 -34 0 0 10 0 59 22 38 -19 149 13 51 149 56 23 148 51 14 150 18 56 0.30
150 48 0 -33 0 0 10 0 52 23 38 -21 150 27 2 151 8 56 150 4 45 151 31 9 0.30
151 59 34 -32 0 0 10 0 45 25 37 -22 151 38 54 152 20 13 151 16 56 152 42 7 0.30
153 9 57 -31 0 0 10 0 38 26 36 -23 152 49 34 153 30 20 152 27 54 153 51 57 0.30
154 19 17 -30 0 0 10 0 31 27 36 -25 153 59 8 154 39 25 153 37 45 155 0 46 0.30
155 27 39 -29 0 0 10 0 23 29 35 -26 155 7 44 155 47 33 154 46 36 156 8 40 0.30
Uncertainty in time = +/- 5 secs
Prediction of 2018 Aug 30.0
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