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Updated: 2011 JUL 21, 22:48 UT
Event Rank : 68
(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 2011 Aug 28 UT, the 111 km diameter asteroid (545) Messalina will occult a 13.3 mag star in the constellation Sagittarius for observers along a south-to-north path across WA centred from Esperance to Kalgoorlie to near Port Hedland.
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.7 mag to 13.2 mag (the magnitude of the asteroid) for at most 19.5 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, 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
122 16 54 -40 52 14 11 31 35 73 59 -25 121 36 3 -40 52 50 122 57 39 -40 51 26 120 24 42 -40 53 25 124 8 17 -40 49 35
122 11 30 -39 27 8 11 32 2 74 63 -25 121 31 29 -39 27 44 122 51 24 -39 26 20 120 21 38 -39 28 20 124 0 34 -39 24 29
122 5 21 -38 2 17 11 32 29 74 68 -26 121 26 8 -38 2 54 122 44 27 -38 1 29 120 17 39 -38 3 30 123 52 16 -37 59 39
121 58 30 -36 37 38 11 32 57 75 73 -26 121 20 1 -36 38 15 122 36 53 -36 36 51 120 12 49 -36 38 52 123 43 26 -36 35 2
121 51 1 -35 13 9 11 33 24 75 78 -26 121 13 13 -35 13 46 122 28 43 -35 12 22 120 7 12 -35 14 23 123 34 6 -35 10 34
121 42 55 -33 48 46 11 33 51 75 83 -26 121 5 45 -33 49 22 122 20 0 -33 47 59 120 0 51 -33 49 59 123 24 17 -33 46 12
121 34 14 -32 24 25 11 34 19 75 89 -26 120 57 39 -32 25 1 122 10 43 -32 23 39 119 53 47 -32 25 38 123 14 0 -32 21 54
121 25 0 -31 0 5 11 34 46 75 94 -26 120 48 58 -31 0 40 122 0 56 -30 59 20 119 46 2 -31 1 16 123 3 16 -30 57 36
121 15 13 -29 35 41 11 35 14 75 100 -26 120 39 41 -29 36 16 121 50 39 -29 34 57 119 37 39 -29 36 51 122 52 6 -29 33 16
121 4 55 -28 11 12 11 35 41 75 105 -26 120 29 51 -28 11 45 121 39 53 -28 10 28 119 28 39 -28 12 19 122 40 31 -28 8 49
120 54 6 -26 46 32 11 36 8 74 110 -26 120 19 29 -26 47 5 121 28 37 -26 45 50 119 19 2 -26 47 37 122 28 30 -26 44 13
120 42 47 -25 21 41 11 36 36 74 114 -26 120 8 34 -25 22 12 121 16 54 -25 21 0 119 8 50 -25 22 43 122 16 4 -25 19 25
120 30 58 -23 56 34 11 37 3 73 118 -26 119 57 8 -23 57 4 121 4 43 -23 55 54 118 58 4 -23 57 32 122 3 14 -23 54 22
120 18 39 -22 31 7 11 37 30 72 122 -26 119 45 10 -22 31 36 120 52 3 -22 30 29 118 46 42 -22 32 2 121 49 58 -22 29 0
120 5 51 -21 5 19 11 37 58 72 126 -26 119 32 41 -21 5 46 120 38 56 -21 4 42 118 34 47 -21 6 9 121 36 18 -21 3 16
119 52 33 -19 39 4 11 38 25 71 129 -26 119 19 40 -19 39 29 120 25 20 -19 38 29 118 22 16 -19 39 49 121 22 11 -19 37 6
119 38 44 -18 12 19 11 38 53 70 132 -26 119 6 7 -18 12 42 120 11 15 -18 11 47 118 9 11 -18 12 59 121 7 38 -18 10 27
119 24 23 -16 45 1 11 39 20 69 134 -26 118 52 2 -16 45 22 119 56 40 -16 44 30 117 55 31 -16 45 35 120 52 38 -16 43 14
119 9 31 -15 17 5 11 39 47 67 137 -25 118 37 22 -15 17 23 119 41 34 -15 16 36 117 41 14 -15 17 33 120 37 10 -15 15 24
118 54 5 -13 48 26 11 40 15 66 139 -25 118 22 8 -13 48 42 119 25 57 -13 48 0 117 26 20 -13 48 47 120 21 12 -13 46 52
118 38 5 -12 19 0 11 40 42 65 141 -25 118 6 18 -12 19 14 119 9 47 -12 18 37 117 10 47 -12 19 14 120 4 44 -12 17 33
118 21 29 -10 48 43 11 41 10 64 142 -25 117 49 50 -10 48 53 118 53 2 -10 48 22 116 54 34 -10 48 48 119 47 44 -10 47 23
118 4 14 - 9 17 27 11 41 37 62 144 -24 117 32 43 - 9 17 35 118 35 40 - 9 17 10 116 37 39 - 9 17 24 119 30 9 - 9 16 16
117 46 19 - 7 45 8 11 42 4 61 145 -24 117 14 54 - 7 45 12 118 17 39 - 7 44 54 116 20 0 - 7 44 55 119 11 58 - 7 44 6
117 27 41 - 6 11 39 11 42 32 60 147 -23 116 56 20 - 6 11 40 117 58 57 - 6 11 29 116 1 33 - 6 11 16 118 53 8 - 6 10 47
Uncertainty in time = +/- 17 secs
Prediction of 2011 Jul 22.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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