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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 Aug 21 UT, the 40 km diameter asteroid (332) Siri will occult a 10.8 mag star in the constellation Sagittarius for observers along a path across New Zealand.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.8 mag to 13.6 mag (the magnitude of the asteroid) for at most 22.7 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
... .. .. -12 0 0 .. .. .. .. .. .. ... .. .. ... .. .. 139 0 32 ... .. ..
139 28 27 -13 0 0 8 37 37 47 116 -1 139 47 13 139 9 42 140 22 30 138 34 25
140 50 28 -14 0 0 8 36 27 48 115 -2 141 9 19 140 31 38 141 44 45 139 56 13
Latitude Latitude Latitude Latitude
141 0 0 -14 6 58 8 36 19 48 115 -2 -13 53 12 -14 20 44 -13 27 23 -14 46 39
142 0 0 -14 50 42 8 35 27 49 115 -3 -14 36 56 -15 4 29 -14 11 6 -15 30 25
143 0 0 -15 34 19 8 34 34 50 114 -4 -15 20 33 -15 48 6 -14 54 42 -16 14 4
144 0 0 -16 17 47 8 33 41 51 113 -5 -16 4 0 -16 31 34 -15 38 9 -16 57 33
145 0 0 -17 1 5 8 32 48 52 113 -6 -16 47 18 -17 14 53 -16 21 26 -17 40 52
146 0 0 -17 44 13 8 31 54 53 112 -7 -17 30 26 -17 58 1 -17 4 33 -18 24 1
147 0 0 -18 27 10 8 31 0 54 111 -7 -18 13 22 -18 40 58 -17 47 29 -19 6 58
148 0 0 -19 9 54 8 30 5 55 110 -8 -18 56 7 -19 23 43 -18 30 13 -19 49 44
149 0 0 -19 52 26 8 29 10 56 109 -9 -19 38 38 -20 6 15 -19 12 45 -20 32 16
150 0 0 -20 34 44 8 28 15 57 109 -10 -20 20 56 -20 48 33 -19 55 3 -21 14 35
151 0 0 -21 16 48 8 27 19 58 108 -11 -21 3 0 -21 30 37 -20 37 6 -21 56 39
152 0 0 -21 58 37 8 26 23 59 107 -12 -21 44 49 -22 12 26 -21 18 55 -22 38 28
153 0 0 -22 40 10 8 25 28 60 105 -12 -22 26 22 -22 53 59 -22 0 28 -23 20 1
154 0 0 -23 21 27 8 24 32 60 104 -13 -23 7 39 -23 35 16 -22 41 45 -24 1 17
155 0 0 -24 2 26 8 23 35 61 103 -14 -23 48 39 -24 16 15 -23 22 45 -24 42 17
156 0 0 -24 43 8 8 22 39 62 102 -15 -24 29 21 -24 56 57 -24 3 28 -25 22 58
157 0 0 -25 23 32 8 21 43 63 101 -15 -25 9 44 -25 37 20 -24 43 52 -26 3 21
158 0 0 -26 3 36 8 20 47 64 99 -16 -25 49 49 -26 17 25 -25 23 57 -26 43 25
159 0 0 -26 43 21 8 19 50 64 98 -17 -26 29 35 -26 57 9 -26 3 43 -27 23 9
160 0 0 -27 22 46 8 18 54 65 96 -18 -27 9 0 -27 36 34 -26 43 10 -28 2 33
161 0 0 -28 1 51 8 17 58 66 94 -18 -27 48 5 -28 15 38 -27 22 15 -28 41 37
162 0 0 -28 40 34 8 17 2 67 93 -19 -28 26 48 -28 54 21 -28 1 0 -29 20 18
163 0 0 -29 18 55 8 16 6 67 91 -20 -29 5 10 -29 32 41 -28 39 23 -29 58 38
164 0 0 -29 56 54 8 15 10 68 89 -21 -29 43 10 -30 10 40 -29 17 24 -30 36 36
165 0 0 -30 34 31 8 14 14 69 87 -21 -30 20 47 -30 48 16 -29 55 2 -31 14 11
166 0 0 -31 11 45 8 13 19 69 85 -22 -30 58 1 -31 25 29 -30 32 17 -31 51 22
167 0 0 -31 48 34 8 12 24 70 83 -23 -31 34 52 -32 2 18 -31 9 10 -32 28 10
168 0 0 -32 25 0 8 11 29 70 80 -23 -32 11 19 -32 38 43 -31 45 38 -33 4 34
169 0 0 -33 1 2 8 10 34 71 78 -24 -32 47 21 -33 14 44 -32 21 42 -33 40 33
170 0 0 -33 36 39 8 9 39 71 75 -25 -33 22 59 -33 50 20 -32 57 22 -34 16 7
171 0 0 -34 11 51 8 8 45 72 73 -25 -33 58 12 -34 25 31 -33 32 36 -34 51 16
172 0 0 -34 46 37 8 7 51 72 70 -26 -34 32 59 -35 0 16 -34 7 26 -35 26 0
173 0 0 -35 20 58 8 6 58 73 67 -26 -35 7 21 -35 34 36 -34 41 50 -36 0 17
174 0 0 -35 54 52 8 6 5 73 64 -27 -35 41 17 -36 8 29 -35 15 47 -36 34 8
175 0 0 -36 28 21 8 5 12 73 61 -28 -36 14 46 -36 41 56 -35 49 19 -37 7 33
176 0 0 -37 1 22 8 4 19 73 58 -28 -36 47 49 -37 14 57 -36 22 25 -37 40 31
177 0 0 -37 33 57 8 3 27 74 54 -29 -37 20 26 -37 47 30 -36 55 3 -38 13 2
178 0 0 -38 6 5 8 2 36 74 51 -29 -37 52 35 -38 19 37 -37 27 15 -38 45 6
179 0 0 -38 37 46 8 1 45 74 48 -30 -38 24 17 -38 51 16 -37 59 0 -39 16 43
180 0 0 -39 8 59 8 0 54 74 45 -30 -38 55 32 -39 22 28 -38 30 18 -39 47 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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