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A 1.11 second occultation was recorded by John Broughton, using CCD Drift scan technique.
View the Occult prediction.
View the Occult prediction.
Observers: 1 J Broughton,Reedy Creek, QLD, Aus 2(P) Prediction 1-April
Discussion:
The circle above is plotted at the expected 147 km diameter of Dione. With only one chord it is not possible to determine whether John was north or south of the central line of the event. However, assuming the prediction was approximately correct it would suggest that the chord might lie close to the southern portion of the asteroid.
The figures below show the drift-scan image of the occultation
Observational Data:
Observation details for MP (106 ) Dione By Star UCAC2 21161679 On 2008-06-03 at 19:23:00.0 _______________________________ Observer Location Longitude +153:23:52.8 Latitude -28:06:30.3 Altitude 66 m Datum WGS84 Telescope SCT Aperture 25 cm Seeing Steady Clear Timing Tape Recorder + time signal + shutter Drift scan Disappearance 19:23:04.46 Reappearance 19:23:05.57 Comments: : A clearly positive result from a magnitude 12.5 occultation. The measured duration of 1.11 is remarkably short (9%) compared with the maximum duration of 12 seconds. Supporting a grazing occultation scenario where the star passed within 1km of the edge of Dione is the fact that the event occurred only 5 seconds later than prediction. On the other hand, if the occultation was caused by a Dione satellite, then the best guess for its diameter is 17km, which represents a body 27% longer than the length of this random chord. I should also mention that the apparent second gap in the trail on the right is actually the end of the trail and beginning of another.