|
|
Updated: 2005 MAR 16, 04:04 UT
Event Rank : 22
(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 2005 Apr 12 UT, the 103 km diameter asteroid (1208) Troilus will occult a 11.4 mag star in the constellation Ursa Major for observers along a path across Canada, Alaska, Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 5.6 mag to 17.0 mag (the magnitude of the asteroid) for at most 6.6 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, 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 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
... .. .. -36 0 0 .. .. .. .. .. .. ... .. .. ... .. .. ... .. .. 144 11 24
140 19 27 -35 0 0 9 26 22 1 22 -15 139 42 29 140 56 21 ... .. .. 144 38 27
140 49 19 -34 0 0 9 26 22 2 22 -15 140 12 50 141 25 44 136 31 20 145 5 5
141 18 37 -33 0 0 9 26 21 3 22 -15 140 42 36 141 54 37 137 3 56 145 31 20
141 47 26 -32 0 0 9 26 21 4 22 -16 141 11 50 142 22 59 137 35 51 145 57 14
142 15 45 -31 0 0 9 26 20 5 21 -16 141 40 34 142 50 55 138 7 6 146 22 49
142 43 39 -30 0 0 9 26 20 6 21 -17 142 8 50 143 18 25 138 37 46 146 48 6
143 11 7 -29 0 0 9 26 19 7 21 -17 142 36 41 143 45 33 139 7 53 147 13 8
143 38 14 -28 0 0 9 26 18 8 21 -17 143 4 7 144 12 19 139 37 28 147 37 55
144 4 59 -27 0 0 9 26 17 9 20 -18 143 31 12 144 38 45 140 6 34 148 2 29
144 31 26 -26 0 0 9 26 15 10 20 -18 143 57 57 145 4 54 140 35 13 148 26 52
144 57 35 -25 0 0 9 26 14 11 20 -18 144 24 23 145 30 46 141 3 27 148 51 4
145 23 28 -24 0 0 9 26 12 13 20 -19 144 50 33 145 56 23 141 31 18 149 15 7
145 49 6 -23 0 0 9 26 11 14 20 -19 145 16 26 146 21 46 141 58 47 149 39 1
146 14 31 -22 0 0 9 26 9 15 20 -20 145 42 6 146 46 57 142 25 57 150 2 49
146 39 45 -21 0 0 9 26 7 16 19 -20 146 7 32 147 11 57 142 52 48 150 26 32
147 4 47 -20 0 0 9 26 5 17 19 -20 146 32 48 147 36 47 143 19 22 150 50 9
147 29 40 -19 0 0 9 26 2 18 19 -21 146 57 52 148 1 28 143 45 41 151 13 43
147 54 25 -18 0 0 9 26 0 19 19 -21 147 22 48 148 26 2 144 11 45 151 37 14
148 19 3 -17 0 0 9 25 58 20 19 -21 147 47 36 148 50 30 144 37 37 152 0 43
148 43 34 -16 0 0 9 25 55 21 19 -22 148 12 17 149 14 52 145 3 17 152 24 12
149 8 0 -15 0 0 9 25 52 22 19 -22 148 36 51 149 39 10 145 28 47 152 47 40
149 32 23 -14 0 0 9 25 49 23 18 -22 149 1 22 150 3 24 145 54 7 153 11 10
149 56 42 -13 0 0 9 25 46 24 18 -22 149 25 48 150 27 36 146 19 19 153 34 41
150 20 59 -12 0 0 9 25 43 25 18 -23 149 50 12 150 51 47 146 44 25 153 58 15
150 45 15 -11 0 0 9 25 40 26 18 -23 150 14 33 151 15 57 147 9 24 154 21 53
151 9 30 -10 0 0 9 25 36 27 18 -23 150 38 54 151 40 8 147 34 18 154 45 36
151 33 47 - 9 0 0 9 25 33 28 18 -24 151 3 15 152 4 20 147 59 8 155 9 24
151 58 5 - 8 0 0 9 25 29 30 18 -24 151 27 37 152 28 34 148 23 55 155 33 18
152 22 25 - 7 0 0 9 25 25 31 18 -24 151 52 1 152 52 52 148 48 40 155 57 19
152 46 50 - 6 0 0 9 25 21 32 18 -24 152 16 27 153 17 13 149 13 24 156 21 29
153 11 18 - 5 0 0 9 25 17 33 18 -25 152 40 57 153 41 40 149 38 8 156 45 47
153 35 51 - 4 0 0 9 25 13 34 18 -25 153 5 32 154 6 12 150 2 53 157 10 15
154 0 31 - 3 0 0 9 25 9 35 17 -25 153 30 13 154 30 52 150 27 39 157 34 53
154 25 18 - 2 0 0 9 25 4 36 17 -25 153 54 59 154 55 39 150 52 27 157 59 44
154 50 13 - 1 0 0 9 25 0 37 17 -26 154 19 53 155 20 34 151 17 20 158 24 47
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
[Top of Page][Return to Home Page]