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Updated: 2011 Jun 08, 00:54 UT
Event Rank : 21
(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 2011 Jul 21 UT, the 37 km diameter asteroid (4768) Hartley will occult a 11.4 mag star in the constellation Pegasus for observers along a path across Western Australia. running from Geraldton to Broome.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.3 mag to 15.7 mag (the magnitude of the asteroid) for at most 2.7 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.
Occultation of TYC 0601-00326-1 by 4768 Hartley on 2011 Jul 21
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
110 58 58 -33 20 51 17 24 46 22 56 -74 110 40 15 -33 20 59 111 17 30 -33 20 46 108 36 45 -33 23 7 113 11 46 -33 21 24
113 13 14 -31 13 33 17 24 56 25 55 -74 112 56 5 -31 13 19 113 30 16 -31 13 48 111 3 48 -31 12 55 115 15 48 -31 16 20
115 5 57 -29 13 54 17 25 7 28 54 -74 114 49 55 -29 13 26 115 21 54 -29 14 23 113 5 24 -29 11 19 117 1 7 -29 18 15
116 42 56 -27 20 10 17 25 18 30 54 -73 116 27 44 -27 19 32 116 58 4 -27 20 49 114 49 0 -27 16 11 118 32 29 -27 25 39
118 7 54 -25 31 12 17 25 28 32 53 -73 117 53 21 -25 30 26 118 22 23 -25 31 59 116 19 5 -25 26 9 119 52 59 -25 37 34
119 23 19 -23 46 12 17 25 39 34 53 -72 119 9 18 -23 45 20 119 37 18 -23 47 5 117 38 37 -23 40 20 121 4 48 -23 53 15
120 31 0 -22 4 33 17 25 49 36 53 -71 120 17 24 -22 3 36 120 44 33 -22 5 31 118 49 39 -21 58 1 122 9 30 -22 12 9
121 32 14 -20 25 47 17 26 0 38 54 -70 121 19 0 -20 24 46 121 45 26 -20 26 49 119 53 41 -20 18 43 123 8 14 -20 33 50
122 28 3 -18 49 32 17 26 11 39 54 -69 122 15 7 -18 48 27 122 40 56 -18 50 37 120 51 52 -18 42 1 124 1 55 -18 57 58
123 19 12 -17 15 29 17 26 21 41 54 -68 123 6 33 -17 14 22 123 31 50 -17 16 38 121 45 2 -17 7 36 124 51 15 -17 24 14
124 6 20 -15 43 24 17 26 32 42 55 -67 123 53 54 -15 42 14 124 18 44 -15 44 35 122 33 53 -15 35 12 125 36 48 -15 52 26
124 49 56 -14 13 4 17 26 43 44 55 -65 124 37 41 -14 11 52 125 2 9 -14 14 17 123 18 59 -14 4 35 126 19 2 -14 22 20
125 30 25 -12 44 18 17 26 53 45 56 -64 125 18 21 -12 43 4 125 42 28 -12 45 32 124 0 46 -12 35 34 126 58 20 -12 53 46
126 8 8 -11 16 56 17 27 4 47 57 -63 125 56 12 -11 15 40 126 20 2 -11 18 12 124 39 36 -11 7 59 127 35 1 -11 26 36
126 43 22 - 9 50 51 17 27 14 48 57 -62 126 31 34 - 9 49 34 126 55 8 - 9 52 8 125 15 48 - 9 41 42 128 9 21 -10 0 40
Uncertainty in time = +/- 12 secs
Prediction of 2011 Jun 8.0
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