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Updated: 2012 NOV 29, 22:59 UT
Event Rank : 36
(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 2012 Dec 09 UT, the 21 km diameter asteroid (918) Itha will occult a 9.8 mag star in the constellation Auriga for observers along a path across Australia from (aproximately) Cairns across northern Queensland, Northern Territory and Western Australia to Moora, possibly including Perth, at low elevation.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.1 mag to 14.9 mag (the magnitude of the asteroid) for at most 1.7 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 Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
110 41 45 -34 0 0 14 53 59 8 29 -29 110 24 58 110 58 38 109 23 40 112 1 58
111 47 15 -33 0 0 14 53 56 9 29 -30 111 30 16 112 4 20 110 28 18 113 8 27
112 55 29 -32 0 0 14 53 52 11 28 -31 112 38 16 113 12 48 111 35 29 114 17 53
114 6 42 -31 0 0 14 53 48 12 27 -33 113 49 12 114 24 19 112 45 26 115 30 33
115 21 11 -30 0 0 14 53 43 13 27 -34 115 3 21 115 39 8 113 58 25 116 46 45
116 39 16 -29 0 0 14 53 37 15 26 -35 116 21 2 116 57 39 115 14 44 118 6 54
118 1 23 -28 0 0 14 53 31 16 25 -37 117 42 40 118 20 14 116 34 43 119 31 27
119 28 0 -27 0 0 14 53 23 18 24 -38 119 8 43 119 47 27 117 58 49 121 1 0
120 59 46 -26 0 0 14 53 15 19 23 -39 120 39 49 121 19 56 119 27 34 122 36 19
122 37 29 -25 0 0 14 53 5 21 22 -41 122 16 41 122 58 30 121 1 36 124 18 23
124 22 11 -24 0 0 14 52 55 22 21 -42 124 0 22 124 44 16 122 41 48 126 8 31
126 15 17 -23 0 0 14 52 42 24 20 -43 125 52 10 126 38 43 124 29 16 128 8 33
128 18 46 -22 0 0 14 52 29 25 18 -45 127 53 59 128 43 58 126 25 32 130 21 12
Latitude Latitude Latitude Latitude
129 0 0 -21 41 13 14 52 24 26 18 -45 -21 29 45 -21 52 44 -20 47 54 -22 35 57
130 0 0 -21 14 58 14 52 17 26 17 -46 -21 3 37 -21 26 23 -20 22 10 -22 9 9
131 0 0 -20 50 0 14 52 10 27 16 -46 -20 38 46 -21 1 18 -19 57 41 -21 43 40
132 0 0 -20 26 18 14 52 2 28 16 -47 -20 15 10 -20 37 30 -19 34 26 -21 19 29
133 0 0 -20 3 50 14 51 55 28 15 -47 -19 52 47 -20 14 57 -19 12 24 -20 56 34
134 0 0 -19 42 36 14 51 48 29 14 -47 -19 31 38 -19 53 37 -18 51 33 -20 34 54
135 0 0 -19 22 35 14 51 40 29 13 -48 -19 11 42 -19 33 31 -18 31 54 -20 14 29
136 0 0 -19 3 45 14 51 32 30 13 -48 -18 52 57 -19 14 37 -18 13 25 -19 55 17
137 0 0 -18 46 7 14 51 25 30 12 -48 -18 35 22 -18 56 54 -17 56 5 -19 37 19
138 0 0 -18 29 39 14 51 17 31 11 -49 -18 18 58 -18 40 22 -17 39 54 -19 20 32
139 0 0 -18 14 20 14 51 9 31 10 -49 -18 3 43 -18 25 0 -17 24 52 -19 4 56
140 0 0 -18 0 11 14 51 1 32 9 -49 -17 49 37 -18 10 47 -17 10 57 -18 50 30
141 0 0 -17 47 10 14 50 53 32 9 -49 -17 36 39 -17 57 43 -16 58 10 -18 37 15
142 0 0 -17 35 17 14 50 45 32 8 -49 -17 24 48 -17 45 48 -16 46 29 -18 25 9
143 0 0 -17 24 31 14 50 37 33 7 -49 -17 14 5 -17 35 0 -16 35 55 -18 14 12
144 0 0 -17 14 53 14 50 29 33 6 -49 -17 4 29 -17 25 19 -16 26 26 -18 4 23
145 0 0 -17 6 21 14 50 21 33 5 -49 -16 55 59 -17 16 45 -16 18 3 -17 55 42
146 0 0 -16 58 55 14 50 13 33 4 -49 -16 48 35 -17 9 18 -16 10 45 -17 48 8
147 0 0 -16 52 36 14 50 5 33 3 -49 -16 42 17 -17 2 57 -16 4 32 -17 41 42
148 0 0 -16 47 22 14 49 56 34 3 -49 -16 37 5 -16 57 42 -15 59 23 -17 36 23
149 0 0 -16 43 14 14 49 48 34 2 -48 -16 32 57 -16 53 33 -15 55 19 -17 32 10
150 0 0 -16 40 11 14 49 40 34 1 -48 -16 29 55 -16 50 30 -15 52 20 -17 29 4
151 0 0 -16 38 14 14 49 32 34 360 -48 -16 27 59 -16 48 32 -15 50 24 -17 27 5
152 0 0 -16 37 22 14 49 24 34 359 -48 -16 27 7 -16 47 40 -15 49 33 -17 26 12
153 0 0 -16 37 35 14 49 15 34 358 -47 -16 27 20 -16 47 53 -15 49 46 -17 26 26
Uncertainty in time = +/- 4 secs
Prediction of 2012 Dec 3.0
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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