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Updated: 2008 JUL 22, 23:11 UT
Event Rank : 10
(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 Aug 03 UT, the 13 km diameter asteroid (6670) Wallach will occult a 10.4 mag star in the constellation Sagittarius for observers along a narrow and highly uncertain north-to-south path beginning near Rockhampton in Queensland. The path then passes near Dubbo, just west of Canberra and east of Melbourne, and later near Hobart.
In the case of an occultation, the combined light of the asteroid and the star will drop by 3.7 mag to 14.1 mag (the magnitude of the asteroid) for at most 1.3 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 Limit1 Path Limit2 Error Limit1 Error Limit2
E. Longitude Latitude U.T. Alt Az Alt
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' " o ' " o ' " o ' " o ' "
Longitude Latitude Longitude Latitude Longitude Latitude Longitude Latitude
151 27 22 -19 37 59 14 55 45 56 262 -77 151 31 41 -19 38 38 151 23 2 -19 37 20 152 28 42 -19 46 52 150 26 50 -19 28 40
151 2 40 -20 50 58 14 55 58 57 264 -77 151 7 1 -20 51 38 150 58 19 -20 50 19 152 4 21 -20 59 59 150 1 46 -20 41 32
150 38 46 -22 3 48 14 56 12 57 266 -77 150 43 9 -22 4 27 150 34 23 -22 3 8 151 40 52 -22 12 56 149 37 29 -21 54 13
150 15 39 -23 16 29 14 56 25 58 268 -76 150 20 4 -23 17 9 150 11 15 -23 15 48 151 18 12 -23 25 45 149 13 55 -23 6 46
149 53 18 -24 29 5 14 56 39 58 270 -76 149 57 45 -24 29 46 149 48 52 -24 28 24 150 56 21 -24 38 29 148 51 5 -24 19 15
149 31 42 -25 41 38 14 56 52 58 272 -76 149 36 12 -25 42 19 149 27 13 -25 40 56 150 35 18 -25 51 9 148 28 56 -25 31 40
149 10 50 -26 54 9 14 57 6 58 274 -75 149 15 22 -26 54 51 149 6 19 -26 53 27 150 15 3 -27 3 48 148 7 29 -26 44 4
148 50 42 -28 6 42 14 57 19 59 276 -75 148 55 17 -28 7 25 148 46 7 -28 6 0 149 55 34 -28 16 29 147 46 42 -27 56 30
148 31 17 -29 19 19 14 57 33 59 278 -74 148 35 55 -29 20 2 148 26 39 -29 18 36 149 36 52 -29 29 13 147 26 35 -29 8 59
148 12 35 -30 32 2 14 57 46 59 280 -73 148 17 16 -30 32 45 148 7 54 -30 31 18 149 18 56 -30 42 3 147 7 8 -30 21 34
147 54 37 -31 44 52 14 58 0 59 282 -72 147 59 21 -31 45 36 147 49 53 -31 44 8 149 1 48 -31 55 0 146 48 21 -31 34 16
147 37 23 -32 57 53 14 58 14 59 284 -72 147 42 11 -32 58 37 147 32 35 -32 57 8 148 45 28 -33 8 8 146 30 14 -32 47 9
147 20 53 -34 11 6 14 58 27 58 287 -71 147 25 46 -34 11 51 147 16 1 -34 10 21 148 29 58 -34 21 29 146 12 48 -34 0 15
147 5 10 -35 24 34 14 58 41 58 289 -70 147 10 7 -35 25 20 147 0 13 -35 23 48 148 15 17 -35 35 4 145 56 3 -35 13 35
146 50 13 -36 38 20 14 58 54 58 291 -69 146 55 15 -36 39 6 146 45 12 -36 37 33 148 1 29 -36 48 57 145 40 0 -36 27 13
146 36 6 -37 52 25 14 59 8 58 293 -68 146 41 13 -37 53 12 146 31 0 -37 51 38 147 48 35 -38 3 10 145 24 41 -37 41 10
146 22 50 -39 6 52 14 59 21 57 295 -67 146 28 2 -39 7 40 146 17 38 -39 6 5 147 36 39 -39 17 45 145 10 8 -38 55 30
146 10 27 -40 21 45 14 59 35 57 297 -65 146 15 46 -40 22 33 146 5 9 -40 20 57 147 25 42 -40 32 45 144 56 23 -40 10 14
145 59 2 -41 37 5 14 59 48 56 298 -64 146 4 26 -41 37 54 145 53 37 -41 36 17 147 15 49 -41 48 13 144 43 27 -41 25 26
145 48 37 -42 52 56 15 0 2 56 300 -63 145 54 9 -42 53 45 145 43 5 -42 52 7 147 7 5 -43 4 11 144 31 25 -42 41 9
145 39 17 -44 9 21 15 0 15 55 302 -62 145 44 56 -44 10 11 145 33 38 -44 8 31 146 59 34 -44 20 43 144 20 20 -43 57 25
145 31 8 -45 26 23 15 0 29 54 304 -61 145 36 55 -45 27 13 145 25 20 -45 25 32 146 53 23 -45 37 52 144 10 16 -45 14 19
145 24 15 -46 44 5 15 0 42 54 305 -60 145 30 12 -46 44 56 145 18 19 -46 43 14 146 48 40 -46 55 42 144 1 19 -46 31 52
145 18 48 -48 2 31 15 0 56 53 307 -58 145 24 54 -48 3 22 145 12 41 -48 1 40 146 45 34 -48 14 15 143 53 36 -47 50 10
145 14 53 -49 21 45 15 1 10 52 308 -57 145 21 11 -49 22 37 145 8 36 -49 20 53 146 44 15 -49 33 36 143 47 13 -49 9 15
145 12 44 -50 41 51 15 1 23 51 309 -56 145 19 13 -50 42 43 145 6 15 -50 40 58 146 44 55 -50 53 49 143 42 19 -50 29 13
145 12 32 -52 2 53 15 1 37 50 310 -55 145 19 14 -52 3 46 145 5 50 -52 2 0 146 47 51 -52 14 58 143 39 7 -51 50 7
145 14 33 -53 24 57 15 1 50 50 312 -53 145 21 30 -53 25 50 145 7 37 -53 24 3 146 53 21 -53 37 8 143 37 49 -53 12 2
145 19 8 -54 48 7 15 2 4 49 313 -52 145 26 21 -54 49 1 145 11 55 -54 47 13 147 1 48 -55 0 23 143 38 41 -54 35 4
145 26 40 -56 12 29 15 2 17 47 314 -50 145 34 11 -56 13 24 145 19 9 -56 11 35 147 13 40 -56 24 50 143 42 5 -55 59 19
Uncertainty in time = +/- 8 secs
[Prediction of 2008 Jul 22.0]
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[Observing Details]
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