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Updated: 2008 JAN 07, 00:48 UT
Event Rank : 13
(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 2008 Feb 10 UT, the 28 km diameter asteroid (16785) 1997 AL1 will occult a 9.6 mag star in the constellation Gemini for observers along a path across Papua New Guinea.
In the case of an occultation, the combined light of the asteroid and the star will drop by 7.0 mag to 16.6 mag (the magnitude of the asteroid) for at most 3.0 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, 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
122 24 26 -13 0 0 15 0 30 43 328 -58 122 4 45 122 44 16 118 56 50 126 10 59
123 54 8 -12 0 0 15 0 9 43 326 -60 123 33 49 124 14 38 120 20 23 127 49 16
125 28 43 -11 0 0 14 59 48 43 324 -61 125 7 39 125 50 0 121 47 48 129 34 5
127 8 55 -10 0 0 14 59 27 43 322 -63 126 46 56 127 31 8 123 19 33 131 26 42
128 55 40 - 9 0 0 14 59 4 43 320 -65 128 32 36 129 19 1 124 56 13 133 28 50
130 50 14 - 8 0 0 14 58 40 42 318 -66 130 25 49 131 14 59 126 38 36 135 43 0
132 54 21 - 7 0 0 14 58 14 42 316 -68 132 28 15 133 20 52 128 27 38 138 13 7
Latitude Latitude Latitude Latitude
133 0 0 - 6 57 23 14 58 13 42 316 -68 - 6 45 15 - 7 9 35 - 4 47 7 - 9 13 42
134 0 0 - 6 30 19 14 58 1 41 315 -69 - 6 18 16 - 6 42 25 - 4 21 1 - 8 45 31
135 0 0 - 6 4 25 14 57 49 41 314 -69 - 5 52 27 - 6 16 26 - 3 56 1 - 8 18 34
136 0 0 - 5 39 40 14 57 38 41 313 -70 - 5 27 48 - 5 51 36 - 3 32 8 - 7 52 50
137 0 0 - 5 16 4 14 57 26 40 312 -70 - 5 4 16 - 5 27 55 - 3 9 21 - 7 28 18
138 0 0 - 4 53 36 14 57 15 40 311 -71 - 4 41 52 - 5 5 22 - 2 47 39 - 7 4 57
139 0 0 - 4 32 14 14 57 4 39 310 -71 - 4 20 35 - 4 43 56 - 2 27 1 - 6 42 46
140 0 0 - 4 12 0 14 56 53 39 310 -71 - 4 0 24 - 4 23 37 - 2 7 27 - 6 21 46
141 0 0 - 3 52 51 14 56 42 38 309 -72 - 3 41 19 - 4 4 25 - 1 48 56 - 6 1 54
142 0 0 - 3 34 47 14 56 31 38 308 -72 - 3 23 19 - 3 46 18 - 1 31 28 - 5 43 10
143 0 0 - 3 17 48 14 56 21 37 307 -72 - 3 6 23 - 3 29 16 - 1 15 3 - 5 25 34
144 0 0 - 3 1 54 14 56 10 36 307 -72 - 2 50 32 - 3 13 19 - 0 59 39 - 5 9 5
145 0 0 - 2 47 4 14 56 0 36 306 -72 - 2 35 44 - 2 58 25 - 0 45 17 - 4 53 43
146 0 0 - 2 33 17 14 55 51 35 306 -72 - 2 22 0 - 2 44 36 - 0 31 56 - 4 39 27
147 0 0 - 2 20 33 14 55 41 35 305 -72 - 2 9 18 - 2 31 50 - 0 19 35 - 4 26 16
148 0 0 - 2 8 52 14 55 31 34 305 -72 - 1 57 39 - 2 20 7 - 0 8 16 - 4 14 11
149 0 0 - 1 58 13 14 55 22 33 304 -71 - 1 47 3 - 2 9 26 0 2 4 - 4 3 11
150 0 0 - 1 48 37 14 55 13 32 304 -71 - 1 37 28 - 1 59 49 0 11 23 - 3 53 16
151 0 0 - 1 40 3 14 55 4 32 303 -70 - 1 28 55 - 1 51 13 0 19 42 - 3 44 26
152 0 0 - 1 32 31 14 54 55 31 303 -70 - 1 21 24 - 1 43 40 0 27 2 - 3 36 40
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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