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OCCULTATION OF TYC 4972-01341-1 BY (503) EVELYN
2007 JANUARY 06


A 0.90 second occultation was recorded by John Broughton, at Reedy Creek, Australia, using CCD Drift Field technique.

View the updated prediction.

Observers:
  1    J Broughton, Reedy Creek, Australia

Evelyn Occultation

Discussion:

The circle above is plotted at the expected 82km diameter of Evelyn. With only one chord it is not possible to determine whether John was north or south of the central line of the event. The observation was shorter than the predicted maximum which implies he was near one side. The predicted path was very close to his site.

The figures below show the drift-scan image of the occultation together with data as analysed by John's Scanalyser software.

Evelyn occultation - 2007 January 06

TELESCOPE DETAILS:
Aperture (cm)                    : 25.4
Focal length (cm)                : 169
Type (e.g. SCT; Newtonian)       : SCT
Magnification                    : CCD drift-scan at 5 pps, 50'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)    : Good
Star Image Stability (Delete two): Fair
Other Conditions:                  
     (Wind, Clouds, Lights, etc.): Gibbous moon
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       : 13
                                          | Estimated  |
                           Universal Time | Reaction   | Accuracy, Remarks
                              h  m  s     | Time (sec) | 
Started Observing          : 16:09:23.15       n/a       0.01
Disappearance At           : 16:09:43.46       n/a       0.06
Reappearance At            : 16:09:44.36       n/a       0.06
Stopped Observing          : 16:10:03.48       n/a       0.01
Duration                   :        0.90   

ADDITIONAL COMMENTS:  
Rigorously timed CCD drift-scan measured in Scanalyzer:
http://www.users.bigpond.com/reedycrk/driftscantiming.htm

This event was observed from inside the house with the 10" SCT
pointed though an open window. I did a pre-point by an altitude offset
from a prominent star. The next update of my coordinating software
will include such an altazimuth alignment option and finder chart.

The drift-scan showed a positive event of only 0.9 second;
easily the shortest I have ever recorded.  To accurately measure
the short duration, it was necessary to do some image manipulation. 
First I removed the adjacent trail by pasting background over it.
Then I made a version where 20 pixels of background was pasted
over the R and another where background was pasted over the D.
D and R could then be measured accurately in Scanalyser from
trail profiles of the separate images.


Return to 2007 occultation results



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