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Updated: 2009 SEP 07, 00:49 UT
Event Rank : 36
(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 2009 Oct 09 UT, the 29 km diameter asteroid (706) Hirundo will occult a 11.1 mag star in the constellation Aquarius for observers along a somewhat uncertain path running across eastern Australia, beginning near Sydney and leaving near Cape York.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.6 mag to 13.6 mag (the magnitude of the asteroid) for at most 10.9 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
152 48 57 -37 10 48 8 48 25 49 40 -10 152 37 45 -37 14 17 153 0 8 -37 7 19 151 56 24 -37 27 3 153 40 44 -36 54 33
152 25 5 -35 49 40 8 49 15 50 42 -11 152 14 6 -35 53 6 152 36 2 -35 46 14 151 33 36 -36 5 40 153 15 50 -35 33 40
152 0 17 -34 29 42 8 50 6 51 43 -11 151 49 31 -34 33 5 152 11 2 -34 26 19 151 9 47 -34 45 27 152 50 6 -34 13 57
151 34 39 -33 10 49 8 50 56 52 44 -11 151 24 3 -33 14 9 151 45 13 -33 7 29 150 45 2 -33 26 21 152 23 36 -32 55 17
151 8 12 -31 52 56 8 51 47 52 46 -11 150 57 47 -31 56 14 151 18 36 -31 49 39 150 19 24 -32 8 16 151 56 22 -31 37 37
150 41 0 -30 35 59 8 52 37 53 47 -11 150 30 44 -30 39 14 150 51 14 -30 32 44 149 52 57 -30 51 7 151 28 27 -30 20 51
150 13 4 -29 19 53 8 53 27 54 49 -11 150 2 57 -29 23 5 150 23 10 -29 16 40 149 25 42 -29 34 50 150 59 52 -29 4 55
149 44 27 -28 4 33 8 54 18 54 51 -11 149 34 28 -28 7 44 149 54 24 -28 1 23 148 57 43 -28 19 21 150 30 38 -27 49 46
149 15 9 -26 49 58 8 55 8 55 52 -11 149 5 17 -26 53 6 149 24 59 -26 46 50 148 28 59 -27 4 36 150 0 46 -26 35 19
148 45 12 -25 36 3 8 55 59 55 54 -11 148 35 27 -25 39 9 148 54 55 -25 32 56 147 59 34 -25 50 32 149 30 18 -25 21 33
148 14 35 -24 22 45 8 56 49 56 56 -11 148 4 57 -24 25 50 148 24 12 -24 19 40 147 29 27 -24 37 6 148 59 13 -24 8 23
147 43 20 -23 10 1 8 57 40 56 58 -11 147 33 47 -23 13 5 147 52 52 -23 6 58 146 58 39 -23 24 15 148 27 33 -22 55 47
147 11 27 -21 57 49 8 58 30 57 60 -11 147 1 59 -22 0 51 147 20 54 -21 54 48 146 27 10 -22 11 56 147 55 16 -21 43 42
146 38 56 -20 46 6 8 59 21 57 62 -11 146 29 33 -20 49 7 146 48 17 -20 43 6 145 55 1 -21 0 6 147 22 22 -20 32 6
146 5 46 -19 34 50 9 0 11 57 64 -11 145 56 27 -19 37 49 146 15 3 -19 31 51 145 22 11 -19 48 43 146 48 53 -19 20 55
145 31 57 -18 23 58 9 1 1 58 66 -11 145 22 42 -18 26 55 145 41 10 -18 21 0 144 48 41 -18 37 45 146 14 46 -18 10 9
144 57 28 -17 13 27 9 1 52 58 68 -11 144 48 17 -17 16 24 145 6 38 -17 10 31 144 14 29 -17 27 10 145 40 1 -16 59 44
144 22 20 -16 3 17 9 2 42 58 70 -11 144 13 12 -16 6 12 144 31 27 -16 0 21 143 39 35 -16 16 54 145 4 38 -15 49 38
143 46 30 -14 53 24 9 3 33 58 72 -11 143 37 24 -14 56 19 143 55 34 -14 50 30 143 3 59 -15 6 57 144 28 36 -14 39 50
143 9 58 -13 43 47 9 4 23 58 74 -10 143 0 55 -13 46 41 143 18 59 -13 40 54 142 27 38 -13 57 16 143 51 52 -13 30 18
142 32 42 -12 34 24 9 5 14 58 76 -10 142 23 41 -12 37 17 142 41 41 -12 31 32 141 50 32 -12 47 49 143 14 27 -12 20 59
141 54 41 -11 25 13 9 6 4 58 78 -10 141 45 42 -11 28 5 142 3 39 -11 22 21 141 12 40 -11 38 34 142 36 18 -11 11 51
141 15 53 -10 16 13 9 6 55 57 80 -10 141 6 56 -10 19 4 141 24 50 -10 13 21 140 33 59 -10 29 30 141 57 23 -10 2 54
Uncertainty in time = +/- 20 secs
Prediction of 2009 Sep 7.0
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