Corona Brightness Isolines

Adaptive filters enable to visualize coronal structures invisible on original unprocessed image but they cause loss of information about absolute image brightness. This information itself is not of big value if the image is only observed on computer screen because the human vision has very poor ability to estimate absolute brightness as it was explained before. This information can be added to the image in the way easily understandable for human vision by constructing of brightness isolines. It makes possible to study the corona shape from the point of brightness distribution.
Click on the image or on the following reference to display the higher resolution image version (2.2 MB, PNG format).

Date21. 06. 2001
TimeSecond contact 12:36:34 UT, third contact 12:41:10 UT
Total eclipse duration 4 min 36 s
PlaceAngola, near Sumbe (Ngunza)
CoordinateS 11° 07' 29'', E 13° 55' 51'', Alt. 168 m
ConditionsExcellent, clear sky
OpticsMertz - II, 1875/100 mm (VOD Turnov), siderostat off-axis configuration
CameraPENTAX 67 II, 6 × 7.5 cm format
Resolution4.434 arc sec / pixel - full resolution version
FilmKodak Ektachrome 100 S Professional
ProcessingSum of 8 images enhanced by means of adaptive kernel convolution with isolines.
Image processing by Miloslav Druckmüller
ScannerNikon LS 8000 (4000dpi resolution, RGB, 3 × 16 bit/pixel)
SoftwareSofo ACC 5.0 Scientific Image Analyzer with Match II Module (isolines creation and final image processing)
Corona 2.0 Analyzer (coronal structure enhancement)
PhaseCorr 2.0 Analyzer (rotation estimation - registration of images)
OrientationImage must be rotated -9.47° (clockwise) to achieve the standard orientation (N top, E left)
Copyright© 2001 Úpice Observatory, © 2003 Miloslav Druckmüller


Miloslav Druckmüller
Institute of Mathematics, Faculty of Mechanical Engineering
Brno University of Technology, Czech Republic
Page last update: 29.9.2007