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Updated: 2015 APR 06, 11:19 UT
Event Rank : 90
(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 2015 May 22 UT, the 99 km diameter asteroid (506) Marion will occult a 11.3 mag star in the constellation Hydra for observers along a path across WA passing near Eucla.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.8 mag to 14.0 mag (the magnitude of the asteroid) for at most 12.5 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, TMO astrometry for the asteroid kindly provided by Bill Owen, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
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 Limit1 Path Limit2 Error Limit1 Error Limit2
E. Longitude Latitude U.T. Alt Az Alt
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
129 23 46 -34 23 48 9 40 11 60 88 -15 128 46 34 -34 26 1 130 0 44 -34 21 25 128 7 39 -34 28 6 130 38 58 -34 18 45
129 11 12 -33 8 21 9 40 28 60 90 -15 128 34 32 -33 10 31 129 47 39 -33 6 0 127 56 9 -33 12 34 130 25 19 -33 3 23
128 57 44 -31 52 52 9 40 46 60 92 -15 128 21 33 -31 54 59 129 33 42 -31 50 34 127 43 42 -31 57 0 130 10 52 -31 48 0
128 43 24 -30 37 20 9 41 3 60 95 -14 128 7 40 -30 39 24 129 18 55 -30 35 4 127 30 18 -30 41 22 129 55 37 -30 32 33
128 28 12 -29 21 41 9 41 21 59 97 -14 127 52 54 -29 23 43 129 3 18 -29 19 29 127 15 57 -29 25 38 129 39 34 -29 17 1
128 12 9 -28 5 54 9 41 38 59 99 -13 127 37 14 -28 7 52 128 46 52 -28 3 45 127 0 42 -28 9 44 129 22 44 -28 1 21
127 55 15 -26 49 56 9 41 56 59 101 -13 127 20 42 -26 51 51 128 29 36 -26 47 50 126 44 32 -26 53 39 129 5 7 -26 45 29
127 37 30 -25 33 44 9 42 14 58 103 -12 127 3 16 -25 35 35 128 11 32 -25 31 42 126 27 27 -25 37 20 128 46 42 -25 29 25
127 18 53 -24 17 16 9 42 31 58 105 -11 126 44 57 -24 19 3 127 52 37 -24 15 18 126 9 26 -24 20 44 128 27 29 -24 13 5
126 59 24 -23 0 28 9 42 49 57 107 -11 126 25 44 -23 2 12 127 32 52 -22 58 35 125 50 30 -23 3 48 128 7 27 -22 56 26
126 39 1 -21 43 19 9 43 6 57 109 -10 126 5 36 -21 44 58 127 12 15 -21 41 30 125 30 37 -21 46 30 127 46 35 -21 39 25
126 17 44 -20 25 44 9 43 24 56 111 -10 125 44 31 -20 27 18 126 50 44 -20 24 0 125 9 46 -20 28 45 127 24 52 -20 22 0
125 55 30 -19 7 41 9 43 42 55 112 -9 125 22 28 -19 9 10 126 28 19 -19 6 1 124 47 55 -19 10 32 127 2 15 -19 4 7
125 32 17 -17 49 6 9 43 59 54 114 -8 124 59 25 -17 50 30 126 4 57 -17 47 32 124 25 1 -17 51 45 126 38 42 -17 45 43
125 8 4 -16 29 55 9 44 17 54 116 -7 124 35 20 -16 31 13 125 40 35 -16 28 27 124 1 4 -16 32 23 126 14 12 -16 26 44
124 42 46 -15 10 5 9 44 34 53 117 -7 124 10 8 -15 11 17 125 15 11 -15 8 43 123 35 58 -15 12 20 125 48 41 -15 7 6
124 16 21 -13 49 31 9 44 52 52 118 -6 123 43 47 -13 50 36 124 48 41 -13 48 15 123 9 42 -13 51 32 125 22 6 -13 46 45
123 48 44 -12 28 8 9 45 9 51 120 -5 123 16 13 -12 29 6 124 21 2 -12 27 0 122 42 10 -12 29 54 124 54 24 -12 25 37
123 19 51 -11 5 52 9 45 27 50 121 -4 122 47 21 -11 6 42 123 52 8 -11 4 51 122 13 19 -11 7 22 124 25 28 -11 3 36
122 49 37 - 9 42 37 9 45 45 49 122 -3 122 17 5 - 9 43 18 123 21 54 - 9 41 44 121 43 1 - 9 43 49 123 55 16 - 9 40 38
122 17 55 - 8 18 16 9 46 2 48 123 -3 121 45 20 - 8 18 48 122 50 15 - 8 17 33 121 11 12 - 8 19 8 123 23 39 - 8 16 35
121 44 38 - 6 52 43 9 46 20 46 124 -2 121 11 57 - 6 53 5 122 17 4 - 6 52 10 120 37 42 - 6 53 14 122 50 33 - 6 51 22
121 9 37 - 5 25 50 9 46 37 45 125 -1 120 36 48 - 5 26 0 121 42 11 - 5 25 28 120 2 23 - 5 25 57 122 15 47 - 5 24 52
Uncertainty in time = +/- 8 secs
Prediction of 2015 Apr 6.0
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