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Updated: 2017 JUN 23, 22:06 UT
Event Rank : 99
(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 Aug 22 UT, the 75 km diameter asteroid (25) Phocaea will occult a 12.1 mag star in the constellation Vulpecula for observers along a path beginning over Darwin. The path then moves south-west and into WA passing near Esperance.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.16 mag to 10.10 mag (the magnitude of the asteroid) for at most 10.5 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, inparticular 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
114 24 11 -45 0 0 12 26 59 14 32 -30 113 50 59 114 57 14 113 33 39 115 14 21 -0.11
115 11 52 -44 0 0 12 26 55 15 31 -30 114 39 27 115 44 9 114 22 31 116 0 53 -0.11
115 57 33 -43 0 0 12 26 50 16 31 -31 115 25 51 116 29 7 115 9 19 116 45 29 -0.11
116 41 24 -42 0 0 12 26 45 18 30 -32 116 10 22 117 12 17 115 54 11 117 28 18 -0.11
117 23 31 -41 0 0 12 26 40 19 30 -33 116 53 8 117 53 48 116 37 17 118 9 30 -0.11
118 4 5 -40 0 0 12 26 34 20 29 -33 117 34 17 118 33 46 117 18 45 118 49 10 -0.11
118 43 10 -39 0 0 12 26 28 21 29 -34 118 13 56 119 12 18 117 58 41 119 27 25 -0.11
119 20 54 -38 0 0 12 26 22 22 29 -35 118 52 11 119 49 31 118 37 13 120 4 22 -0.11
119 57 22 -37 0 0 12 26 15 23 28 -35 119 29 8 120 25 30 119 14 26 120 40 6 -0.11
120 32 39 -36 0 0 12 26 8 24 28 -36 120 4 53 121 0 20 119 50 25 121 14 42 -0.11
121 6 50 -35 0 0 12 26 1 25 28 -37 120 39 30 121 34 5 120 25 16 121 48 13 -0.11
121 39 59 -34 0 0 12 25 54 26 27 -37 121 13 4 122 6 50 120 59 3 122 20 46 -0.11
122 12 11 -33 0 0 12 25 46 27 27 -38 121 45 39 122 38 38 121 31 50 122 52 22 -0.11
122 43 28 -32 0 0 12 25 38 29 27 -39 122 17 18 123 9 34 122 3 40 123 23 7 -0.11
123 13 54 -31 0 0 12 25 30 30 27 -39 122 48 5 123 39 40 122 34 38 123 53 2 -0.11
123 43 33 -30 0 0 12 25 22 31 27 -40 123 18 4 124 8 59 123 4 47 124 22 12 -0.11
124 12 27 -29 0 0 12 25 13 32 26 -40 123 47 16 124 37 35 123 34 9 124 50 38 -0.10
124 40 39 -28 0 0 12 25 4 33 26 -41 124 15 45 125 5 29 124 2 47 125 18 23 -0.10
125 8 11 -27 0 0 12 24 55 34 26 -41 124 43 34 125 32 45 124 30 44 125 45 31 -0.10
125 35 5 -26 0 0 12 24 46 35 26 -42 125 10 44 125 59 24 124 58 3 126 12 2 -0.10
126 1 25 -25 0 0 12 24 36 36 26 -42 125 37 18 126 25 29 125 24 44 126 37 59 -0.10
126 27 11 -24 0 0 12 24 26 37 26 -43 126 3 18 126 51 1 125 50 51 127 3 24 -0.10
126 52 25 -23 0 0 12 24 16 38 26 -43 126 28 45 127 16 3 126 16 26 127 28 19 -0.11
127 17 10 -22 0 0 12 24 6 39 26 -44 126 53 42 127 40 35 126 41 30 127 52 45 -0.11
127 41 27 -21 0 0 12 23 55 40 26 -44 127 18 11 128 4 40 127 6 4 128 16 44 -0.11
128 5 17 -20 0 0 12 23 45 41 26 -44 127 42 12 128 28 20 127 30 11 128 40 18 -0.11
128 28 42 -19 0 0 12 23 34 42 26 -45 128 5 47 128 51 35 127 53 52 129 3 28 -0.11
128 51 43 -18 0 0 12 23 23 43 26 -45 128 28 58 129 14 26 128 17 8 129 26 14 -0.11
129 14 22 -17 0 0 12 23 11 44 26 -46 128 51 46 129 36 56 128 40 0 129 48 40 -0.11
129 36 40 -16 0 0 12 23 0 45 26 -46 129 14 12 129 59 5 129 2 31 130 10 44 -0.11
129 58 37 -15 0 0 12 22 48 46 26 -46 129 36 17 130 20 55 129 24 40 130 32 30 -0.11
130 20 15 -14 0 0 12 22 36 47 26 -46 129 58 3 130 42 26 129 46 30 130 53 57 -0.11
130 41 35 -13 0 0 12 22 24 48 26 -47 130 19 30 131 3 39 130 8 0 131 15 7 -0.11
131 2 38 -12 0 0 12 22 12 49 26 -47 130 40 39 131 24 35 130 29 13 131 36 0 -0.11
131 23 25 -11 0 0 12 22 0 50 26 -47 131 1 31 131 45 16 130 50 8 131 56 38 -0.11
131 43 56 -10 0 0 12 21 47 51 27 -47 131 22 8 132 5 42 131 10 47 132 17 1 -0.11
132 4 12 - 9 0 0 12 21 34 52 27 -47 131 42 29 132 25 54 131 31 11 132 37 10 -0.11
132 24 15 - 8 0 0 12 21 21 53 27 -48 132 2 37 132 45 52 131 51 21 132 57 7 -0.11
132 44 5 - 7 0 0 12 21 8 54 27 -48 132 22 30 133 5 38 132 11 17 133 16 50 -0.11
133 3 42 - 6 0 0 12 20 55 55 28 -48 132 42 11 133 25 12 132 30 59 133 36 22 -0.11
Uncertainty in time = +/- 3 secs
Prediction of 2017 Jun 23.0
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