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Updated: 2008 APR 09, 17:20 UT
Event Rank : 3
(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 May 14 UT, the 11 km diameter asteroid (7778) Markrobinson will occult a 10.2 mag star in the constellation Ophiuchus for observers along a very narrow but highly uncertain path beginning near Mt Gambier in South Australia during morning twilight. The path moves north west into Western Australia passing near Broome and Derby as it leaves the continent.
In the case of an occultation, the combined light of the asteroid and the star will drop by 4.7 mag to 14.9 mag (the magnitude of the asteroid) for at most 1.0 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
119 26 12 - 8 0 0 21 22 34 47 270 -11 119 30 20 119 22 4 122 39 51 116 22 15
119 42 23 - 9 0 0 21 22 24 47 271 -11 119 46 32 119 38 13 122 57 19 116 37 20
119 59 39 -10 0 0 21 22 14 47 272 -11 120 3 51 119 55 28 123 16 2 116 53 23
120 18 3 -11 0 0 21 22 3 47 273 -11 120 22 17 120 13 50 123 36 2 117 10 27
120 37 38 -12 0 0 21 21 53 46 274 -11 120 41 54 120 33 23 123 57 22 117 28 33
120 58 25 -13 0 0 21 21 42 46 275 -11 121 2 43 120 54 8 124 20 5 117 47 43
121 20 27 -14 0 0 21 21 32 46 276 -11 121 24 48 121 16 7 124 44 13 118 7 59
121 43 47 -15 0 0 21 21 22 45 277 -11 121 48 10 121 39 24 125 9 51 118 29 24
122 8 28 -16 0 0 21 21 11 45 278 -11 122 12 54 122 4 2 125 37 2 118 52 1
122 34 34 -17 0 0 21 21 1 44 278 -11 122 39 3 122 30 5 126 5 52 119 15 51
123 2 8 -18 0 0 21 20 51 44 279 -11 123 6 41 122 57 36 126 36 25 119 40 59
123 31 16 -19 0 0 21 20 40 43 280 -11 123 35 52 123 26 39 127 8 46 120 7 27
124 2 1 -20 0 0 21 20 30 42 280 -11 124 6 42 123 57 20 127 43 2 120 35 20
Latitude Latitude Latitude Latitude
125 0 0 -21 44 58 21 20 12 41 282 -10 -21 36 38 -21 53 16 -14 37 21 -27 32 59
126 0 0 -23 23 56 21 19 56 40 282 -10 -23 16 6 -23 31 44 -16 48 4 -28 54 24
127 0 0 -24 54 36 21 19 40 39 283 -10 -24 47 11 -25 2 0 -18 44 5 -30 10 1
128 0 0 -26 18 8 21 19 26 38 284 -9 -26 11 3 -26 25 11 -20 28 27 -31 20 28
129 0 0 -27 35 26 21 19 14 37 284 -9 -27 28 39 -27 42 11 -22 3 16 -32 26 16
130 0 0 -28 47 13 21 19 2 36 284 -8 -28 40 42 -28 53 42 -23 30 3 -33 27 52
131 0 0 -29 54 5 21 18 51 34 284 -8 -29 47 48 -30 0 20 -24 49 54 -34 25 37
132 0 0 -30 56 31 21 18 40 33 284 -7 -30 50 27 -31 2 34 -26 3 43 -35 19 52
133 0 0 -31 54 56 21 18 31 32 284 -7 -31 49 3 -32 0 48 -27 12 12 -36 10 52
134 0 0 -32 49 41 21 18 22 31 284 -6 -32 43 58 -32 55 23 -28 15 56 -36 58 54
135 0 0 -33 41 4 21 18 14 30 284 -6 -33 35 31 -33 46 37 -29 15 23 -37 44 8
136 0 0 -34 29 21 21 18 6 29 284 -5 -34 23 56 -34 34 46 -30 10 56 -38 26 48
137 0 0 -35 14 46 21 17 58 28 284 -5 -35 9 28 -35 20 3 -31 2 56 -39 7 3
138 0 0 -35 57 30 21 17 52 27 283 -4 -35 52 19 -36 2 40 -31 51 40 -39 45 2
139 0 0 -36 37 44 21 17 45 27 283 -4 -36 32 40 -36 42 48 -32 37 23 -40 20 54
140 0 0 -37 15 38 21 17 39 26 283 -3 -37 10 40 -37 20 36 -33 20 18 -40 54 45
141 0 0 -37 51 21 21 17 33 25 282 -3 -37 46 28 -37 56 13 -34 0 36 -41 26 43
142 0 0 -38 24 59 21 17 28 24 282 -2 -38 20 11 -38 29 47 -34 38 29 -41 56 53
143 0 0 -38 56 40 21 17 23 23 281 -2 -38 51 57 -39 1 23 -35 14 4 -42 25 21
144 0 0 -39 26 30 21 17 18 22 281 -1 -39 21 51 -39 31 9 -35 47 29 -42 52 11
145 0 0 -39 54 34 21 17 13 21 280 -1 -39 49 59 -39 59 9 -36 18 53 -43 17 29
146 0 0 -40 20 58 21 17 9 21 280 0 -40 16 27 -40 25 29 -36 48 21 -43 41 18
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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