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Updated: 2013 May 13, 23:07 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 2013 Jun 12 UT, the 216 km diameter asteroid (375) Ursula will occult a 13.4 mag star in the constellation Hydra for observers along a wide path across central Queensland, western New South Wales and western Victoria.
In the case of an occultation, the combined light of the asteroid and the star will drop by only 0.5 mag to 12.7 mag (the magnitude of the asteroid) for at most 53.4 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.
Occultation of 2UCAC 21546285 by 375 Ursula on 2013 Jun 12
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
143 26 3 -44 41 33 11 53 44 60 300 -52 141 55 6 -44 31 15 144 58 26 -44 51 0 141 8 21 -44 25 34 145 47 3 -44 55 34
143 22 5 -43 21 35 11 54 19 60 297 -53 141 53 13 -43 11 23 144 52 18 -43 30 56 141 7 32 -43 5 46 145 39 46 -43 35 27
143 19 10 -42 2 4 11 54 55 61 295 -53 141 52 14 -41 52 0 144 47 23 -42 11 20 141 7 32 -41 46 27 145 33 47 -42 15 49
143 17 13 -40 42 59 11 55 31 61 293 -54 141 52 5 -40 33 2 144 43 36 -40 52 8 141 8 18 -40 27 34 145 29 2 -40 56 35
143 16 12 -39 24 16 11 56 7 62 290 -54 141 52 43 -39 14 26 144 40 53 -39 33 19 141 9 46 -39 9 2 145 25 25 -39 37 43
143 16 3 -38 5 52 11 56 42 62 288 -55 141 54 6 -37 56 10 144 39 10 -38 14 49 141 11 56 -37 50 50 145 22 51 -38 19 9
143 16 44 -36 47 44 11 57 18 62 285 -55 141 56 12 -36 38 10 144 38 23 -36 56 34 141 14 46 -36 32 54 145 21 18 -37 0 52
143 18 13 -35 29 50 11 57 54 62 283 -55 141 59 0 -35 20 23 144 38 31 -35 38 34 141 18 14 -35 15 11 145 20 42 -35 42 48
143 20 28 -34 12 7 11 58 30 62 280 -56 142 2 28 -34 2 47 144 39 30 -34 20 44 141 22 19 -33 57 40 145 21 2 -34 24 55
143 23 27 -32 54 32 11 59 5 62 278 -56 142 6 36 -32 45 20 144 41 20 -33 3 2 141 27 1 -32 40 17 145 22 15 -33 7 9
143 27 11 -31 37 3 11 59 41 62 275 -57 142 11 23 -31 27 58 144 43 59 -31 45 25 141 32 20 -31 22 59 145 24 19 -31 49 29
143 31 38 -30 19 36 12 0 17 62 273 -57 142 16 48 -30 10 40 144 47 26 -30 27 52 141 38 16 -30 5 45 145 27 15 -30 31 52
143 36 48 -29 2 11 12 0 52 62 270 -57 142 22 52 -28 53 22 144 51 41 -29 10 18 141 44 48 -28 48 31 145 31 0 -29 14 15
143 42 41 -27 44 42 12 1 28 62 267 -57 142 29 35 -27 36 2 144 56 43 -27 52 42 141 51 56 -27 31 15 145 35 35 -27 56 35
143 49 17 -26 27 9 12 2 4 62 265 -58 142 36 58 -26 18 37 145 2 32 -26 35 1 141 59 42 -26 13 55 145 41 0 -26 38 50
143 56 37 -25 9 29 12 2 40 61 262 -58 142 45 0 -25 1 5 145 9 9 -25 17 13 142 8 6 -24 56 27 145 47 14 -25 20 58
144 4 42 -23 51 38 12 3 15 61 260 -58 142 53 43 -23 43 22 145 16 34 -23 59 14 142 17 9 -23 38 49 145 54 19 -24 2 54
144 13 32 -22 33 34 12 3 51 60 258 -58 143 3 8 -22 25 27 145 24 48 -22 41 1 142 26 53 -22 20 58 146 2 14 -22 44 37
144 23 8 -21 15 14 12 4 27 60 256 -58 143 13 17 -21 7 16 145 33 53 -21 22 32 142 37 18 -21 2 52 146 11 2 -21 26 4
144 33 33 -19 56 36 12 5 3 59 254 -58 143 24 11 -19 48 47 145 43 49 -20 3 44 142 48 26 -19 44 27 146 20 43 -20 7 11
144 44 48 -18 37 35 12 5 38 58 252 -58 143 35 51 -18 29 55 145 54 39 -18 44 34 143 0 20 -18 25 41 146 31 20 -18 47 55
144 56 56 -17 18 9 12 6 14 58 250 -58 143 48 20 -17 10 39 146 6 24 -17 24 58 143 13 0 -17 6 30 146 42 54 -17 28 14
145 9 58 -15 58 14 12 6 50 57 248 -58 144 1 41 -15 50 54 146 19 8 -16 4 52 143 26 31 -15 46 50 146 55 27 -16 8 2
145 23 57 -14 37 46 12 7 25 56 246 -58 144 15 56 -14 30 38 146 32 52 -14 44 13 143 40 55 -14 26 39 147 9 4 -14 47 18
145 38 58 -13 16 42 12 8 1 55 244 -58 144 31 9 -13 9 45 146 47 41 -13 22 58 143 56 14 -13 5 52 147 23 47 -13 25 56
145 55 3 -11 54 58 12 8 37 54 243 -58 144 47 23 -11 48 13 147 3 38 -12 1 1 144 12 33 -11 44 26 147 39 40 -12 3 52
146 12 18 -10 32 29 12 9 13 53 241 -57 145 4 43 -10 25 56 147 20 48 -10 38 18 144 29 56 -10 22 16 147 56 48 -10 41 2
Uncertainty in time = +/- 14 secs
Prediction of 2013 May 14.0
Use these links for further information:
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[Observing Details]
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