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NOTE:
This new update replaces the previous update of Feb 29. Note that while the overall accuracy of the track has not increased, the new update places the centre of the path about 1/4 track width to the east of the previous update. Coromandel and Tauranga may now be close to the edge of the asteroid's shadow.
Please also note that this track should NOT be taken as absolute. This is important! In the first plot below the blue lines indicate the suspected size of the asteroid, while the red lines indicate the possible error in the track. Note that all sites from about Taihape in the south to Whakatane in the north have the potential to see this event. For this reason it remains very important that observers across the entire region attempt to observe. Furthermore, if the asteroid is ellipsoidal (as is highly likely) then even if the centre of the track below is spot on, observers outside the track on either side may still see an event depending on the orientation of the asteroid.
THE UPDATED PATH
Note: The duration given at the top of the map below is the interval during which the occultation shadow sweeps across the Earth. The approximate event time for various locations along the track is as follows:
Napier/Hastings: 08:59:00 UT (9:59:00 pm NZDT) Taupo, Rotorua: 08:59:10 UT Hamiton, Tauranga: 08:59:16 UT Auckland: 08:59:27 UT Whangarei: 08:59:31 UT
On 2004 Mar 20 UT, the 53 km diameter asteroid (509) Iolanda will occult a 10.4 mag star in the constellation Sextans 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 2.9 mag to 13.2 mag (the magnitude of the asteroid) for at most 4.1 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
... .. .. 2 0 0 .. .. .. .. .. .. ... .. .. ... .. .. 135 58 31 ... .. ..
136 9 32 1 0 0 9 6 0 30 99 -1 136 42 39 135 35 59 137 36 6 ... .. ..
137 45 26 0 0 0 9 5 50 31 98 -2 138 17 26 137 13 4 139 9 8 136 19 8
Latitude Latitude Latitude Latitude
138 0 0 - 0 9 22 9 5 49 31 98 -3 0 11 15 - 0 30 5 0 44 51 - 1 4 17
139 0 0 - 0 48 41 9 5 42 33 98 -4 - 0 27 53 - 1 9 35 0 6 1 - 1 44 5
140 0 0 - 1 29 9 9 5 35 34 97 -5 - 1 8 10 - 1 50 15 - 0 33 58 - 2 25 5
141 0 0 - 2 10 48 9 5 28 35 97 -6 - 1 49 37 - 2 32 6 - 1 15 7 - 3 7 16
142 0 0 - 2 53 38 9 5 21 36 96 -6 - 2 32 15 - 3 15 8 - 1 57 25 - 3 50 38
143 0 0 - 3 37 39 9 5 14 37 96 -7 - 3 16 3 - 3 59 21 - 2 40 53 - 4 35 13
144 0 0 - 4 22 51 9 5 6 38 95 -8 - 4 1 3 - 4 44 47 - 3 25 32 - 5 21 1
145 0 0 - 5 9 16 9 4 58 39 95 -9 - 4 47 14 - 5 31 25 - 4 11 22 - 6 8 1
146 0 0 - 5 56 52 9 4 50 40 94 -10 - 5 34 36 - 6 19 15 - 4 58 22 - 6 56 15
147 0 0 - 6 45 41 9 4 41 41 93 -11 - 6 23 11 - 7 8 18 - 5 46 34 - 7 45 43
148 0 0 - 7 35 42 9 4 33 42 93 -12 - 7 12 57 - 7 58 34 - 6 35 57 - 8 36 24
149 0 0 - 8 26 55 9 4 24 43 92 -13 - 8 3 55 - 8 50 3 - 7 26 31 - 9 28 18
150 0 0 - 9 19 21 9 4 14 44 91 -14 - 8 56 6 - 9 42 45 - 8 18 16 -10 21 27
151 0 0 -10 12 59 9 4 5 45 90 -15 - 9 49 28 -10 36 39 - 9 11 12 -11 15 49
152 0 0 -11 7 49 9 3 55 46 89 -16 -10 44 1 -11 31 46 -10 5 20 -12 11 24
153 0 0 -12 3 51 9 3 45 47 87 -17 -11 39 46 -12 28 5 -11 0 37 -13 8 12
154 0 0 -13 1 3 9 3 35 47 86 -18 -12 36 41 -13 25 36 -11 57 5 -14 6 13
155 0 0 -13 59 27 9 3 25 48 85 -18 -13 34 47 -14 24 18 -12 54 42 -15 5 26
156 0 0 -14 59 0 9 3 14 49 83 -19 -14 34 2 -15 24 10 -13 53 27 -16 5 50
157 0 0 -15 59 42 9 3 3 50 82 -20 -15 34 25 -16 25 11 -14 53 20 -17 7 24
158 0 0 -17 1 32 9 2 52 51 80 -21 -16 35 55 -17 27 21 -15 54 19 -18 10 8
159 0 0 -18 4 29 9 2 41 51 78 -22 -17 38 32 -18 30 38 -16 56 24 -19 14 0
160 0 0 -19 8 31 9 2 30 52 77 -22 -18 42 14 -19 35 1 -17 59 33 -20 18 59
161 0 0 -20 13 37 9 2 18 53 75 -23 -19 46 58 -20 40 29 -19 3 45 -21 25 3
162 0 0 -21 19 44 9 2 6 53 73 -24 -20 52 44 -21 46 58 -20 8 56 -22 32 10
163 0 0 -22 26 51 9 1 54 54 70 -24 -21 59 29 -22 54 28 -21 15 7 -23 40 18
164 0 0 -23 34 56 9 1 42 54 68 -25 -23 7 11 -24 2 55 -22 22 13 -24 49 25
165 0 0 -24 43 55 9 1 30 54 66 -26 -24 15 48 -25 12 19 -23 30 14 -25 59 28
166 0 0 -25 53 47 9 1 18 55 63 -26 -25 25 16 -26 22 34 -24 39 5 -27 10 25
167 0 0 -27 4 28 9 1 5 55 61 -27 -26 35 33 -27 33 40 -25 48 45 -28 22 13
168 0 0 -28 15 55 9 0 53 55 58 -27 -27 46 36 -28 45 31 -26 59 9 -29 34 47
169 0 0 -29 28 3 9 0 40 55 56 -28 -28 58 20 -29 58 6 -28 10 15 -30 48 5
170 0 0 -30 40 51 9 0 28 55 53 -28 -30 10 43 -31 11 19 -29 21 59 -32 2 2
171 0 0 -31 54 12 9 0 15 55 51 -29 -31 23 39 -32 25 6 -30 34 16 -33 16 34
172 0 0 -33 8 4 9 0 3 55 48 -29 -32 37 5 -33 39 24 -31 47 2 -34 31 37
173 0 0 -34 22 20 8 59 50 54 46 -29 -33 50 56 -34 54 6 -33 0 13 -35 47 5
174 0 0 -35 36 55 8 59 38 54 43 -29 -35 5 6 -36 9 8 -34 13 44 -37 2 53
175 0 0 -36 51 46 8 59 26 54 41 -30 -36 19 31 -37 24 25 -35 27 30 -38 18 55
176 0 0 -38 6 45 8 59 13 53 38 -30 -37 34 5 -38 39 50 -36 41 24 -39 35 6
177 0 0 -39 21 47 8 59 1 53 36 -30 -38 48 42 -39 55 18 -37 55 22 -40 51 19
178 0 0 -40 36 45 8 58 49 52 34 -30 -40 3 16 -41 10 42 -39 9 18 -42 7 28
179 0 0 -41 51 34 8 58 38 51 31 -30 -41 17 41 -42 25 56 -40 23 5 -43 23 26
180 0 0 -43 6 6 8 58 26 51 29 -30 -42 31 49 -43 40 53 -41 36 38 -44 39 5
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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