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Solar Eclipse 2015 - Error analysis |
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4c Error analysis Errors always will occur in measurements. If I can provide error limits for my quantitative measurements, I can improve the quality assess of the values. My values are taken from the image sequence. Here the following sources of error can be named: Time error, haziness, image blur, glare, halos and distortion errors of the lens. Time errors usually occur as a constant shift of camera-time against CET, caused e.g. by battery replacement. To determine a possible error of time I produced two black images at fixed moments. They were caught by the radio-controlled clock signal (DCF77). It came out, that my camera-time ran fast 2 minutes and 32 seconds in relation to CET. Blurred or shaky images were prevented by the pre-programmed trigger lock of autofocus. Due to the lack of tracking, my object (the sun) was displayed scattered on the CCD camera sensor. An other unfavorable effect was the case, that Sun was imaged at relatively small size. Unfortunately, I only can estimate a distortion error by the lens. In fact, it is clear, that distortion increases towards edges. As mentioned above (3. experiences and results) I made a change of location around 11:00 o'clock. Thus, my reference altered in determining the Sun's center. Therefore error bars at Fig. 41 can not be compared with those from times before 11:00 o'clock. The biggest mistakes in my image sequence result from glare and halos at the edges of the sun. Only ten images remained for the eclipse episode after an extensive selection of my image sequence and a subsequent image processing in shutter speed. By using the arithmetic average of maximum and minimum area ratio of the images in my sequence the solar-occultation-error was found between 4.6 % and 8.5 %. The large standard error of 16.6 % for the coordinates of Moon's center results from the cumulative error propagation of Sun's center. Again, I missed a unique reference, due to distributed sun images on the camera sensor. A reference would be given automatically by tracking. The tilt of the lunar orbital plane relative to the ecliptic is within the calculated error range. Read more at: 5. More to Explore and get a better understanding of eclipses. Back to top Back to evaluating the image sequence Back to directory | |
| Copyright by Hans Joachim Ilgen since 1950 | |