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A 4.90 second occultation was recorded by John Broughton, Reedy Creek, QLD, Australia, using CCD drift field technique.
View the updated prediction.
Observers: 1 John Broughton, Reedy Creek, QLD, Australia 2 Diana Watson, Whakatane, NZ
Discussion:
The circle above is plotted at the expected 39km diameter of Kriemhild. 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 updated prediction was approximately correct the longer than expected chord of about 52km would suggest that the chord might lie close to the central portion of the asteroid.
The figures below show the drift-scan image of the occultation together and the data as analysed by John's Scanalyser software.
Observational Data:
J Broughton:
TELESCOPE DETAILS:
Aperture (cm) : 50.1
Focal length (cm) : 138
Type (e.g. SCT; Newtonian) : F/2.7 Astrograph
Magnification : CCD drift-scan at 4.2 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) : Poor
Star Image Stability (Delete two): Fair
Other Conditions:
(Wind, Clouds, Lights, etc.): Constantly changing transparency
caused by cirrus cloud.
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 : Increased from 11 to 12 during the scan
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
Started Observing : 10:44:50.05 n/a 0.01
Disappearance At : 10:44:56.10 n/a 0.13
Reappearance At : 10:45:01.00 n/a 0.13
Stopped Observing : 10:45:30.34 n/a 0.01
Duration : 4.90
ADDITIONAL COMMENTS:
Rigorously timed CCD drift-scan measured in Scanalyzer:
http://www.users.bigpond.com/reedycrk/driftscantiming.htm
Due to cirrus cloud, the CCD limiting magnitude was no better than 8
prior to a marked improvement in the final 15 minutes. On the other hand
with an increasing amount of low-level cloud passing over the area where
the scope was pointed, getting a usable image was a very close-run thing
and I had no idea if anything had been recorded until I checked the monitor
shortly after the event.
--------------------------------------------------------------------------------
D Watson
TELESCOPE DETAILS:
Aperture (cm) : 20
Focal length (cm) : 200
Type (e.g. SCT; Newtonian) : Celestron 8
Magnification : 115 times
Observing site name : Whakatane
Longitude (DD MM SS ; East +ve) : 176 51 50.7
Latitude (DD MM SS ; South -ve) : -37 55 18.5
Height above Sealevel (metres) : 2.8 metres
Geodetic Datum (e.g.WGS84,NZ1949): WGS84
Height Datum (if known) :
Sky Transparency (Delete two) : Good
Star Image Stability (Delete two): Good
Other Conditions:
(Wind, Clouds, Lights, etc.): Moonlight and light ground mist.
Time Source (e.g. WWVH, GPS) : WWVH
Recording method (e.g. tape) : tape recorder
Could you see the Asteroid? : Yes
Approx. Limiting Magnitude : 13
| Estimated |
Universal Time | Reaction | Accuracy, Remarks
h m s | Time (sec) |
Started Observing : 10:31:00.0
Star and Object Merged : 10:25:00.0 Very approx. by this minute
Disappearance At :
Estimated Closest Approach :
(if no D/R)
Reappearance At :
Star and Object Separated : 11:00:00.0 well separated, could have been up to
Stopped Observing : 10:49:00.0 5mins after.
ADDITIONAL COMMENTS: The moonlight cut down the good seeing so I was not able to see the minor planet so easily,
only by averted vision. The target area was a close double star.
The minor planet joined the top or north one.
To me it seemed to be passing on the north side of this star, which from the up date,
I thought it should pass south of the star? Perhaps it was the way I was lining things up.
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