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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 25 UT, the 34 km diameter asteroid (418) Alemannia will occult a 10.7 mag star in the constellation Sagittarius for observers along a path across Australia.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.6 mag to 14.3 mag (the magnitude of the asteroid) for at most 7.8 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
179 7 16 17 0 0 17 36 36 47 207 -2 179 20 9 178 54 24 179 55 40 178 18 51
178 14 25 16 0 0 17 36 9 48 206 -3 178 27 14 178 1 36 179 2 35 177 26 13
177 21 48 15 0 0 17 35 42 49 205 -4 177 34 33 177 9 2 178 9 45 176 33 47
176 29 21 14 0 0 17 35 14 51 205 -5 176 42 3 176 16 37 177 17 8 175 41 29
175 37 1 13 0 0 17 34 45 52 204 -7 175 49 41 175 24 19 176 24 39 174 49 17
174 44 44 12 0 0 17 34 15 53 203 -8 174 57 23 174 32 4 175 32 17 173 57 6
173 52 28 11 0 0 17 33 46 55 202 -9 174 5 6 173 39 49 174 39 56 173 4 53
173 0 8 10 0 0 17 33 15 56 201 -10 173 12 45 172 47 30 173 47 33 172 12 36
172 7 41 9 0 0 17 32 44 57 200 -11 172 20 19 171 55 4 172 55 6 171 20 9
171 15 5 8 0 0 17 32 12 59 199 -13 171 27 42 171 2 26 172 2 31 170 27 30
170 22 14 7 0 0 17 31 40 60 198 -14 170 34 53 170 9 34 171 9 43 169 34 35
169 29 5 6 0 0 17 31 7 61 196 -15 169 41 45 169 16 24 170 16 40 168 41 20
168 35 35 5 0 0 17 30 34 62 195 -16 168 48 18 168 22 52 169 23 18 167 47 42
167 41 40 4 0 0 17 30 0 63 193 -18 167 54 25 167 28 54 168 29 32 166 53 36
166 47 15 3 0 0 17 29 25 65 191 -19 167 0 3 166 34 26 167 35 19 165 58 58
165 52 16 2 0 0 17 28 50 66 190 -20 166 5 8 165 39 23 166 40 34 165 3 44
164 56 39 1 0 0 17 28 15 67 187 -22 165 9 36 164 43 41 165 45 14 164 7 49
164 0 19 0 0 0 17 27 38 68 185 -23 164 13 21 163 47 16 164 49 13 163 11 8
163 3 11 - 1 0 0 17 27 2 69 182 -24 163 16 19 162 50 2 163 52 26 162 13 37
Latitude Latitude Latitude Latitude
162 0 0 - 2 5 17 17 26 21 70 179 -26 - 2 18 51 - 1 51 41 - 2 56 13 - 1 14 3
161 0 0 - 3 6 11 17 25 43 71 176 -27 - 3 19 39 - 2 52 42 - 3 56 43 - 2 15 22
160 0 0 - 4 5 58 17 25 4 72 172 -28 - 4 19 20 - 3 52 36 - 4 56 5 - 3 15 35
159 0 0 - 5 4 36 17 24 26 73 168 -30 - 5 17 51 - 4 51 21 - 5 54 17 - 4 14 39
158 0 0 - 6 2 2 17 23 48 73 164 -31 - 6 15 9 - 5 48 54 - 6 51 17 - 5 12 31
157 0 0 - 6 58 14 17 23 10 74 159 -32 - 7 11 14 - 6 45 13 - 7 47 2 - 6 9 10
156 0 0 - 7 53 11 17 22 33 74 154 -34 - 8 6 4 - 7 40 16 - 8 41 32 - 7 4 33
155 0 0 - 8 46 51 17 21 56 75 149 -35 - 8 59 37 - 8 34 3 - 9 34 45 - 7 58 40
154 0 0 - 9 39 13 17 21 19 75 144 -36 - 9 51 52 - 9 26 33 -10 26 41 - 8 51 29
153 0 0 -10 30 16 17 20 43 75 139 -37 -10 42 48 -10 17 43 -11 17 18 - 9 42 59
152 0 0 -11 20 1 17 20 7 74 134 -39 -11 32 25 -11 7 35 -12 6 36 -10 33 11
151 0 0 -12 8 26 17 19 32 74 130 -40 -12 20 44 -11 56 7 -12 54 35 -11 22 2
150 0 0 -12 55 32 17 18 57 74 126 -41 -13 7 43 -12 43 20 -13 41 15 -12 9 34
149 0 0 -13 41 18 17 18 23 73 122 -42 -13 53 22 -13 29 13 -14 26 36 -12 55 47
148 0 0 -14 25 46 17 17 49 73 118 -43 -14 37 43 -14 13 48 -15 10 39 -13 40 40
147 0 0 -15 8 55 17 17 16 72 115 -45 -15 20 46 -14 57 4 -15 53 23 -14 24 14
146 0 0 -15 50 47 17 16 43 71 112 -46 -16 2 31 -15 39 1 -16 34 51 -15 6 30
145 0 0 -16 31 21 17 16 11 70 109 -47 -16 42 59 -16 19 42 -17 15 1 -15 47 28
144 0 0 -17 10 39 17 15 40 70 107 -48 -17 22 11 -16 59 6 -17 53 56 -16 27 9
143 0 0 -17 48 41 17 15 9 69 105 -49 -18 0 7 -17 37 15 -18 31 36 -17 5 35
142 0 0 -18 25 29 17 14 38 68 103 -50 -18 36 49 -18 14 8 -19 8 2 -17 42 45
141 0 0 -19 1 3 17 14 8 67 101 -51 -19 12 18 -18 49 48 -19 43 15 -18 18 41
140 0 0 -19 35 25 17 13 39 66 100 -52 -19 46 34 -19 24 16 -20 17 16 -18 53 23
139 0 0 -20 8 36 17 13 10 65 99 -53 -20 19 39 -19 57 31 -20 50 6 -19 26 54
138 0 0 -20 40 36 17 12 42 64 98 -54 -20 51 34 -20 29 37 -21 21 47 -19 59 14
137 0 0 -21 11 26 17 12 15 63 97 -55 -21 22 20 -21 0 33 -21 52 18 -20 30 24
136 0 0 -21 41 9 17 11 48 62 96 -56 -21 51 57 -21 30 20 -22 21 43 -21 0 25
135 0 0 -22 9 45 17 11 21 61 96 -57 -22 20 29 -21 59 1 -22 50 1 -21 29 19
134 0 0 -22 37 15 17 10 55 60 95 -58 -22 47 54 -22 26 35 -23 17 14 -21 57 6
133 0 0 -23 3 40 17 10 30 59 95 -59 -23 14 15 -22 53 5 -23 43 23 -22 23 48
132 0 0 -23 29 2 17 10 5 58 94 -60 -23 39 32 -23 18 31 -24 8 29 -22 49 25
131 0 0 -23 53 21 17 9 41 57 94 -61 -24 3 47 -23 42 54 -24 32 33 -23 14 0
130 0 0 -24 16 38 17 9 17 56 94 -62 -24 27 1 -24 6 15 -24 55 36 -23 37 32
129 0 0 -24 38 56 17 8 53 55 93 -62 -24 49 14 -24 28 36 -25 17 39 -24 0 3
128 0 0 -25 0 13 17 8 30 54 93 -63 -25 10 29 -24 49 57 -25 38 43 -24 21 35
127 0 0 -25 20 33 17 8 8 53 93 -64 -25 30 44 -25 10 20 -25 58 50 -24 42 7
126 0 0 -25 39 54 17 7 46 52 93 -65 -25 50 3 -25 29 45 -26 18 0 -25 1 41
125 0 0 -25 58 20 17 7 25 51 93 -66 -26 8 25 -25 48 14 -26 36 13 -25 20 18
124 0 0 -26 15 49 17 7 4 50 93 -66 -26 25 52 -26 5 46 -26 53 32 -25 37 59
123 0 0 -26 32 24 17 6 43 50 93 -67 -26 42 24 -26 22 24 -27 9 56 -25 54 44
122 0 0 -26 48 5 17 6 23 49 93 -68 -26 58 2 -26 38 7 -27 25 27 -26 10 35
121 0 0 -27 2 53 17 6 3 48 94 -68 -27 12 47 -26 52 58 -27 40 5 -26 25 32
120 0 0 -27 16 48 17 5 44 47 94 -69 -27 26 40 -27 6 55 -27 53 52 -26 39 37
119 0 0 -27 29 52 17 5 25 46 94 -70 -27 39 42 -27 20 1 -28 6 47 -26 52 49
118 0 0 -27 42 4 17 5 7 45 94 -70 -27 51 52 -27 32 16 -28 18 52 -27 5 9
117 0 0 -27 53 27 17 4 49 44 94 -71 -28 3 12 -27 43 40 -28 30 7 -27 16 39
116 0 0 -28 3 59 17 4 31 43 95 -71 -28 13 43 -27 54 15 -28 40 33 -27 27 18
115 0 0 -28 13 43 17 4 14 42 95 -72 -28 23 25 -28 4 0 -28 50 10 -27 37 8
114 0 0 -28 22 38 17 3 57 41 95 -72 -28 32 18 -28 12 56 -28 58 59 -27 46 9
113 0 0 -28 30 45 17 3 41 40 96 -73 -28 40 24 -28 21 5 -29 7 1 -27 54 22
112 0 0 -28 38 4 17 3 25 39 96 -73 -28 47 42 -28 28 25 -29 14 15 -28 1 46
111 0 0 -28 44 36 17 3 9 38 96 -73 -28 54 13 -28 34 59 -29 20 43 -28 8 23
110 0 0 -28 50 22 17 2 54 37 97 -74 -28 59 58 -28 40 46 -29 26 25 -28 14 13
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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