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A 11.02 second occultation was recorded by John Broughton using CCD drift scan technique, and a miss by Dave Gault using video.
View the updated prediction.
Observers: 1 J Broughton, Reedy Creek, Qld, Australia 2 D Gault, Hawksbury Heights, NSW, Australia 3 Predicted
Discussion:
The circle above is plotted at the expected 97km diameter of Lampetia. With only one chord it is not possible to determine whether John was north or south of the central line of the event. The measured duration was 30% longer than predicted suggesting his chord is fairly central.
The figures below show the drift-scan image of the occultation together with data as analysed by John's Scanalyser software.
Observational Data:
TELESCOPE DETAILS: John Broughton
Aperture (cm) : 50.1
Focal length (cm) : 138
Type (e.g. SCT; Newtonian) : F/2.7 modified newtonian
Magnification : CCD drift-scan at 3.9 pps, 60'FOV
Observing site name : Reedy Creek, Gold Coast
Longitude (East +ve) : +153 23' 49"
Latitude (South -ve) : -28 06' 36"
Height above Sealevel (metres) : 66
Geodetic Datum (e.g.WDD84,NZ1949): AGD66
Sky Transparency (Delete two) : Fair
Star Image Stability (Delete two): Fair
Other Conditions:
(Wind, Clouds, Lights, etc.): Scattered cloud
TIMINGS: (PLEASE REPORT IN UNIVERSAL TIME)
Time Source (e.g. WWV, VNG) : WWVH.
Recording method (e.g. tape) : Tape.
Could you see the Asteroid? : Only combined light monitored.
Approx. Limiting Magnitude : 15
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
COLUMN FORMAT TO USE---> __:__:__._ _._ _________________)
Started Observing : 17:26:02.83 n/a 0.01
Disappearance At : 17:26:10.34 n/a 0.05
Reappearance At : 17:26:21.37 n/a 0.05
Stopped Observing : 17:26:43.17 n/a 0.01
Duration : 11.02
ADDITIONAL COMMENTS:
Rigorously timed CCD drift-scan measured in Scanalyzer:
http://www.users.bigpond.com/reedycrk/driftscantiming.htm
The exposure was limited to 40 seconds due to cloud cover of up to 80%
prior to the event. Fortune was on my side during occultation since
the plot indicates cloud was not a factor excepting a 15% reduction
in transparency 11 seconds after reappearance.
Relative to prediction, the occultation was 7 seconds early,
lasted 30% longer than maximum duration and must have shifted east
a whole pathwidth for an event to have been seen from this site.
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TELESCOPE DETAILS: Dave Gault
Aperture (cm) : 25
Focal length (cm) : 122
Type (e.g. SCT; Newtonian) : EQ Newtonian
Magnification : N/A
Observing site name : Dave's Skyshed
Longitude (DD MM SS ; East +ve) : 150 38 27.8
Latitude (DD MM SS ; South -ve) : -33 39 52.0
Height above Sealevel (metres) : 286
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known) : MSL
Sky Transparency (Delete two) : Good
Star Image Stability (Delete two): Good
Other Conditions:
(Wind, Clouds, Lights, etc.):
TIMINGS: (PLEASE REPORT IN UNIVERSAL TIME)
Time Source (e.g. WWVH, GPS) : GPS-KIWI
Recording method (e.g. tape) : Video
Could you see the Asteroid? : NO
Approx. Limiting Magnitude : 11.8
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
COLUMN FORMAT TO USE---> __:__:__._ _._ _________________)
Started Observing : 17:26:06
Star and Object Merged :
Disappearance At :
Estimated Closest Approach :
(if no D/R)
Reappearance At :
Star and Object Separated :
Stopped Observing : 17:27:38
ADDITIONAL COMMENTS:
Observed by the unattended, prepoint and drift through technique.
I tried for another chord about 10k east of my home and while looking
for a site almost bogged my Van... Grrr. I managed to get it out of
the sand and by the time I got the scope, video and kiwi osd running,
I was 2 minutes too late ... :-(