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Updated: 2015 AUG 20, 06:36 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 2015 Sep 23 UT, the 122 km diameter asteroid (68) Leto will occult a 11.7 mag star in the constellation Sagittarius for observers along a broad path across Australia, from Cooktown across western Queensland, and including eastern South Australia, western New South Wales and western Victoria, to Portland (and just off the western Tasmania coast).
In the case of an occultation, the combined light of the asteroid and the star will drop by 0.4 mag to 10.8 mag (the magnitude of the asteroid) for at most 21.4 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
144 18 33 -46 11 1 15 31 12 33 258 -41 142 55 2 -46 24 49 145 43 37 -45 55 50 142 8 53 -46 31 59 146 31 59 -45 46 42
143 52 40 -45 24 28 15 31 28 33 258 -42 142 30 21 -45 38 0 145 16 32 -45 9 36 141 44 53 -45 45 2 146 4 13 -45 0 39
143 28 50 -44 37 39 15 31 44 33 258 -42 142 7 40 -44 50 56 144 51 34 -44 23 2 141 22 50 -44 57 50 145 38 36 -44 14 15
143 6 58 -43 50 32 15 32 0 33 257 -43 141 46 52 -44 3 37 144 28 37 -43 36 9 141 2 38 -44 10 24 145 15 4 -43 27 30
142 46 59 -43 3 8 15 32 16 33 257 -44 141 27 53 -43 16 2 144 7 37 -42 48 58 140 44 13 -43 22 43 144 53 30 -42 40 25
142 28 47 -42 15 28 15 32 32 33 257 -45 141 10 38 -42 28 13 143 48 29 -42 1 27 140 27 29 -42 34 49 144 33 50 -41 53 1
142 12 19 -41 27 31 15 32 47 33 256 -46 140 55 2 -41 40 8 143 31 8 -41 13 39 140 12 24 -41 46 41 144 15 59 -41 5 17
141 57 30 -40 39 18 15 33 3 33 256 -46 140 41 3 -40 51 49 143 15 30 -40 25 32 139 58 52 -40 58 18 143 59 54 -40 17 14
141 44 17 -39 50 47 15 33 19 33 255 -47 140 28 36 -40 3 14 143 1 32 -39 37 6 139 46 51 -40 9 41 143 45 31 -39 28 51
141 32 38 -39 1 59 15 33 35 33 255 -48 140 17 39 -39 14 23 142 49 11 -38 48 21 139 36 18 -39 20 49 143 32 47 -38 40 8
141 22 29 -38 12 54 15 33 51 33 254 -49 140 8 9 -38 25 16 142 38 24 -37 59 17 139 27 10 -38 31 41 143 21 39 -37 51 4
141 13 49 -37 23 30 15 34 7 33 254 -50 140 0 4 -37 35 52 142 29 9 -37 9 52 139 19 25 -37 42 17 143 12 5 -37 1 40
141 6 34 -36 33 47 15 34 22 32 253 -50 139 53 22 -36 46 11 142 21 23 -36 20 7 139 13 2 -36 52 37 143 4 2 -36 11 54
141 0 45 -35 43 44 15 34 38 32 253 -51 139 48 1 -35 56 11 142 15 6 -35 30 1 139 7 58 -36 2 39 142 57 31 -35 21 45
140 56 19 -34 53 20 15 34 54 32 253 -52 139 44 1 -35 5 52 142 10 16 -34 39 32 139 4 12 -35 12 22 142 52 28 -34 31 13
140 53 15 -34 2 34 15 35 10 32 252 -53 139 41 19 -34 15 13 142 6 52 -33 48 39 139 1 43 -34 21 47 142 48 54 -33 40 16
140 51 34 -33 11 26 15 35 26 31 251 -53 139 39 56 -33 24 12 142 4 55 -32 57 22 139 0 31 -33 30 50 142 46 48 -32 48 53
140 51 14 -32 19 53 15 35 41 31 251 -54 139 39 51 -32 32 49 142 4 22 -32 5 38 139 0 35 -32 39 32 142 46 9 -31 57 2
140 52 17 -31 27 54 15 35 57 31 250 -55 139 41 5 -31 41 2 142 5 16 -31 13 26 139 1 56 -31 47 51 142 47 0 -31 4 42
140 54 41 -30 35 27 15 36 13 30 250 -55 139 43 37 -30 48 49 142 7 36 -30 20 44 139 4 33 -30 55 45 142 49 19 -30 11 51
140 58 30 -29 42 31 15 36 29 30 249 -56 139 47 28 -29 56 8 142 11 25 -29 27 30 139 8 28 -30 3 13 142 53 9 -29 18 27
141 3 43 -28 49 3 15 36 45 29 249 -57 139 52 40 -29 2 58 142 16 43 -28 33 42 139 13 40 -29 10 12 142 58 32 -28 24 27
141 10 22 -27 55 1 15 37 1 29 248 -57 139 59 14 -28 9 17 142 23 33 -27 39 18 139 20 13 -28 16 41 143 5 30 -27 29 48
141 18 31 -27 0 23 15 37 16 28 248 -58 140 7 13 -27 15 2 142 31 57 -26 44 13 139 28 7 -27 22 37 143 14 6 -26 34 27
141 28 13 -26 5 5 15 37 32 28 247 -59 140 16 38 -26 20 9 142 42 1 -25 48 26 139 37 25 -26 27 58 143 24 24 -25 38 22
141 39 30 -25 9 3 15 37 48 27 247 -59 140 27 33 -25 24 37 142 53 47 -24 51 51 139 48 11 -25 32 41 143 36 30 -24 41 26
141 52 28 -24 12 15 15 38 4 27 246 -60 140 40 3 -24 28 22 143 7 21 -23 54 25 140 0 27 -24 36 42 143 50 29 -23 43 37
142 7 13 -23 14 35 15 38 20 26 246 -61 140 54 11 -23 31 19 143 22 51 -22 56 3 140 14 19 -23 39 58 144 6 28 -22 44 48
142 23 50 -22 15 58 15 38 36 25 245 -61 141 10 4 -22 33 24 143 40 23 -21 56 37 140 29 51 -22 42 25 144 24 37 -21 44 52
142 42 30 -21 16 18 15 38 51 25 245 -62 141 27 49 -21 34 32 144 0 9 -20 56 2 140 47 10 -21 43 57 144 45 8 -20 43 41
143 3 20 -20 15 28 15 39 7 24 244 -62 141 47 34 -20 34 36 144 22 21 -19 54 8 141 6 24 -20 44 28 145 8 13 -19 41 7
143 26 35 -19 13 19 15 39 23 23 244 -62 142 9 30 -19 33 30 144 47 13 -18 50 46 141 27 42 -19 43 53 145 34 10 -18 36 57
143 52 30 -18 9 41 15 39 39 22 243 -63 142 33 49 -18 31 4 145 15 6 -17 45 42 141 51 15 -18 42 3 146 3 22 -17 30 56
144 21 23 -17 4 21 15 39 55 21 243 -63 143 0 48 -17 27 8 145 46 24 -16 38 40 142 17 19 -17 38 48 146 36 18 -16 22 47
144 53 41 -15 57 3 15 40 11 20 243 -63 143 30 45 -16 21 29 146 21 40 -15 29 19 142 46 10 -16 33 57 147 13 37 -15 12 4
145 29 56 -14 47 25 15 40 26 19 242 -63 144 4 6 -15 13 50 147 1 39 -14 17 11 143 18 10 -15 27 15 147 56 11 -13 58 13
146 10 52 -13 34 59 15 40 42 18 242 -63 144 41 25 -14 3 51 147 47 22 -13 1 36 143 53 48 -14 18 24 148 45 20 -12 40 26
146 57 32 -12 19 7 15 40 58 17 241 -63 145 23 26 -12 51 2 148 40 23 -11 41 39 144 33 44 -13 6 59 149 43 3 -11 17 30
147 51 26 -10 58 51 15 41 14 15 241 -63 146 11 12 -11 34 44 149 43 7 -10 15 49 145 18 48 -11 52 27 150 52 42 - 9 47 20
148 55 1 - 9 32 44 15 41 30 13 240 -62 147 6 16 -10 14 0 150 59 54 - 8 41 27 146 10 15 -10 34 3 152 20 52 - 8 5 57
150 12 33 - 7 58 8 15 41 46 11 240 -61 148 11 4 - 8 47 20 152 39 59 - 6 52 58 147 10 0 - 9 10 34 154 24 38 - 6 3 2
151 52 59 - 6 9 36 15 42 1 9 240 -60 149 29 54 - 7 12 7 155 12 57 - 4 32 32 148 21 10 - 7 40 8 ... .. .. .. .. ..
Uncertainty in time = +/- 7 secs
Prediction of 2015 Aug 20.0
Use these links for further information:
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[Using the Predictions]
[Observing Details]
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