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Updated: 2017 May 19, 18:59 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 2017 Jul 11 UT, the 283 km diameter asteroid (511) Davida will occult a 10.1 mag star in the constellation Sagittarius for observers along a wide path across south-eastern Australia, passing over all of Victoria and south-eastern New South Wales east of a line running approximately from Port Macquarie to Mount Gambier, including all of Sydney, Canberra and Melbourne. Note that morning twilight and low elevation will interfere, in particular, for locations near the northern end of the path.
In the case of an occultation, the combined light of the asteroid and the star will drop by 1.49 mag to 11.30 mag (the magnitude of the asteroid) for at most 17.7 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 6890-02714-1 by 511 Davida on 2017 Jul 11
Centre Star Star Sun Path Limit1 Path Limit2 Error Limit1 Error Limit2 Alt
E. Longitude Latitude U.T. Alt Az Alt Crn
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
149 10 7 -35 29 14 20 44 6 10 249 -6 ... .. .. .. .. .. 143 16 54 -36 28 17 ... .. .. .. .. .. 142 46 52 -36 31 46 1.35
146 59 16 -36 54 28 20 44 12 13 250 -8 155 3 55 -34 56 22 141 38 44 -37 37 19 156 24 50 -34 29 47 141 10 33 -37 39 50 1.42
145 8 9 -38 10 47 20 44 18 14 252 -10 151 49 9 -36 52 7 140 9 10 -38 42 26 152 41 41 -36 38 33 139 42 19 -38 44 12 1.45
143 29 53 -39 21 16 20 44 24 16 253 -11 149 28 22 -38 23 31 138 46 12 -39 44 31 150 11 40 -38 14 17 138 20 23 -39 45 41 1.47
142 0 50 -40 27 34 20 44 29 17 254 -13 147 32 39 -39 43 34 137 28 30 -40 44 12 148 11 7 -39 36 42 137 3 28 -40 44 52 1.48
140 38 47 -41 30 43 20 44 35 19 255 -14 145 52 15 -40 56 43 136 15 5 -41 41 55 146 27 41 -40 51 24 135 50 40 -41 42 9 1.49
139 22 16 -42 31 23 20 44 41 20 256 -15 144 22 25 -42 5 6 135 5 17 -42 37 59 144 55 48 -42 0 55 134 41 20 -42 37 52 1.50
138 10 17 -43 30 0 20 44 47 21 257 -16 143 0 29 -43 9 58 133 58 30 -43 32 40 143 32 22 -43 6 38 133 34 57 -43 32 13 1.50
137 2 5 -44 26 57 20 44 53 22 258 -17 141 44 42 -44 12 7 132 54 21 -44 26 9 142 15 29 -44 9 28 132 31 5 -44 25 25 1.51
Uncertainty in time = +/- 1 secs
Prediction of 2017 May 19.0
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