Image

Outer Corona

The outer corona is very faint. There is a very low contrast between the outer corona and the sky background and it makes the photography rather difficult. It is necessary to increase the contrast of an outer corona image as much as possible and therefore the main problem is the image noise caused by the photographic emulsion graininess. This noise can be reduced by summing of more images. Therefore I used the sum of six different pictures taken with fast telephoto lens Sonnar 2.8/200 mm. It enabled me to obtain relatively good image of outer corona but the middle corona and especially the inner corona were extremely overexposed. There was no chance to improve the image quality in the inner corona by mathematical processing. Fortunately the inner corona was perfectly recorded on the images taken with Maksutov - Cassegrain 10.5/1084 mm telescope (outer corona was out of the viewing field of this telescope) and I used these images for improving the inner corona display. Totally 27 different images (6 taken with Sonnar, 21 taken with Maksutov-Cassegrain) were used for creation of the image you are looking at.
 
Click on the image or on the following reference to display the higher resolution image version (3.1 MB, PNG format).

ImageSe1999n_outcor2.jpg
Date11. 08. 1999
TimeSecond contact 10:50:37 UT, third contact 10:53:00 UT
Total eclipse duration 2 min 23 s
PlaceHungary, 2 km SSE from Németkér village
CoordinateN 46° 41' 36'', E 18° 47' 14''
ConditionsExcellent, clear sky. (Solar altitude 59° above horizon)
OpticsMaksutov - Cassegrain MTO 1000a, 10.5/1084mm and Sonnar 2.8/200mm
Resolution17.3 arc sec / pixel (higher resolution image version)
FilmFujicolor Superia 800 (for MTO), Agfacolor HDC 400 Plus (for Sonnar)
ProcessingAdaptive processed composition of 27 images (6 taken with Sonnar, 21 taken with MTO)
Image processing by Miloslav Druckmüller
ScannerNikon Super Coolscan 4000 ED (4000dpi resolution, 16× multisample)
SoftwareSofo ACC 6.0, Corona 3.0, PhaseCorr 3.0
OrientationThe image must be rotated 11.8° clockwise to achieve the standard orientation i.e. North top, East left
More infoComplete set of processed images and animation including many texts about Sun and solar eclipses was published on multimedia CD: Miloslav Druckmüller, Journey to Solar Eclipse, AION and WOLF RECORDS, 2000
Copyright© 2004 Hana Druckmüllerová and Miloslav Druckmüller

 

Miloslav Druckmüller
Institute of Mathematics, Faculty of Mechanical Engineering
Brno University of Technology, Czech Republic
druckmuller@fme.vutbr.cz
Page last update: 19.3.2007