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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 the time for your location)
On 2004 Apr 23 UT, the 80 km diameter asteroid (850) Altona will occult a 11.9 mag star in the constellation Leo for observers along a path across Australia, passing close to both MELBOURNE and CANBERRA.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.0 mag to 14.8 mag (the magnitude of the asteroid) for at most 19.9 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Ron Stone, 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
... .. .. -64 0 0 .. .. .. .. .. .. ... .. .. 150 52 3 ... .. .. 152 42 55
150 2 14 -63 0 0 8 58 0 1 15 -18 148 39 18 151 23 22 146 44 59 153 9 32
150 31 37 -62 0 0 8 57 58 2 14 -18 149 12 10 151 49 26 147 22 52 153 31 23
150 56 0 -61 0 0 8 57 56 3 14 -19 149 39 41 152 10 51 147 54 49 153 49 0
151 15 59 -60 0 0 8 57 54 4 14 -19 150 2 28 152 28 8 148 21 35 154 2 52
151 32 1 -59 0 0 8 57 50 5 14 -19 150 21 2 152 41 44 148 43 44 154 13 20
151 44 29 -58 0 0 8 57 45 6 13 -20 150 35 48 152 52 0 149 1 45 154 20 45
151 53 46 -57 0 0 8 57 40 7 13 -20 150 47 10 152 59 15 149 16 3 154 25 24
152 0 6 -56 0 0 8 57 34 8 13 -20 150 55 26 153 3 45 149 26 59 154 27 32
152 3 47 -55 0 0 8 57 26 9 13 -20 151 0 51 153 5 44 149 34 51 154 27 19
152 5 1 -54 0 0 8 57 19 10 13 -20 151 3 41 153 5 25 149 39 54 154 24 59
152 3 58 -53 0 0 8 57 10 11 13 -20 151 4 7 153 2 57 149 42 22 154 20 40
152 0 50 -52 0 0 8 57 0 12 14 -20 151 2 19 152 58 29 149 42 27 154 14 29
151 55 43 -51 0 0 8 56 50 13 14 -20 150 58 26 152 52 10 149 40 18 154 6 35
151 48 45 -50 0 0 8 56 39 14 14 -20 150 52 38 152 44 5 149 36 3 153 57 4
151 40 4 -49 0 0 8 56 27 15 14 -20 150 44 59 152 34 22 149 29 51 153 46 0
151 29 43 -48 0 0 8 56 14 16 14 -20 150 35 36 152 23 5 149 21 48 153 33 29
151 17 49 -47 0 0 8 56 1 17 15 -20 150 24 34 152 10 18 149 11 59 153 19 34
151 4 24 -46 0 0 8 55 46 17 15 -20 150 11 58 151 56 6 149 0 29 153 4 19
150 49 33 -45 0 0 8 55 31 18 15 -20 149 57 51 151 40 31 148 47 23 152 47 47
150 33 18 -44 0 0 8 55 15 19 16 -19 149 42 16 151 23 36 148 32 43 152 30 0
150 15 41 -43 0 0 8 54 58 20 16 -19 149 25 16 151 5 24 148 16 32 152 10 59
149 56 45 -42 0 0 8 54 41 21 17 -19 149 6 53 150 45 55 147 58 53 151 50 48
149 36 31 -41 0 0 8 54 22 22 17 -18 148 47 8 150 25 12 147 39 48 151 29 26
149 15 0 -40 0 0 8 54 3 23 18 -18 148 26 3 150 3 16 147 19 17 151 6 55
148 52 12 -39 0 0 8 53 43 24 18 -18 148 3 37 149 40 6 146 57 21 150 43 14
148 28 9 -38 0 0 8 53 22 24 19 -17 147 39 53 149 15 42 146 34 2 150 18 25
148 2 48 -37 0 0 8 53 0 25 20 -17 147 14 48 148 50 6 146 9 18 149 52 27
147 36 11 -36 0 0 8 52 37 26 20 -16 146 48 24 148 23 16 145 43 9 149 25 19
147 8 16 -35 0 0 8 52 13 27 21 -16 146 20 38 147 55 11 145 15 34 148 57 0
146 39 2 -34 0 0 8 51 49 28 22 -15 145 51 29 147 25 51 144 46 32 148 27 30
146 8 27 -33 0 0 8 51 23 28 23 -15 145 20 56 146 55 12 144 16 0 147 56 45
145 36 28 -32 0 0 8 50 57 29 23 -14 144 48 56 146 23 14 143 43 57 147 24 46
145 3 3 -31 0 0 8 50 30 30 24 -13 144 15 27 145 49 53 143 10 18 146 51 28
144 28 9 -30 0 0 8 50 2 30 25 -13 143 40 24 145 15 6 142 35 0 146 16 49
143 51 42 -29 0 0 8 49 32 31 26 -12 143 3 43 144 38 50 141 57 59 145 40 46
143 13 38 -28 0 0 8 49 2 32 27 -11 142 25 21 144 1 1 141 19 9 145 3 14
142 33 50 -27 0 0 8 48 31 32 28 -10 141 45 11 143 21 33 140 38 24 144 24 10
141 52 13 -26 0 0 8 47 59 33 29 -9 141 3 6 142 40 22 139 55 37 143 43 28
141 8 40 -25 0 0 8 47 26 33 30 -8 140 18 59 141 57 19 139 10 40 143 1 2
140 23 3 -24 0 0 8 46 51 34 32 -7 139 32 41 141 12 18 138 23 21 142 16 45
139 35 11 -23 0 0 8 46 16 34 33 -6 138 44 2 140 25 10 137 33 29 141 30 28
138 44 54 -22 0 0 8 45 39 34 34 -5 137 52 49 139 35 44 136 40 50 140 42 4
137 51 58 -21 0 0 8 45 1 34 35 -4 136 58 46 138 43 48 135 45 7 139 51 20
136 56 7 -20 0 0 8 44 21 35 37 -3 136 1 37 137 49 8 134 45 58 138 58 4
135 57 1 -19 0 0 8 43 41 35 38 -2 135 0 59 136 51 26 ... .. .. 138 2 0
134 54 18 -18 0 0 8 42 58 35 40 0 ... .. .. 135 50 20 ... .. .. 137 2 52
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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