Corona in visible light and SOHO EIT 19.5nm/30.4nm - composed image

Total solar eclipse gives us a unique opportunity to observe the solar corona but the phenomenon is extremely short and rare. During the eclipse we are able to obtain a very high quality image of the solar corona, unfortunately only from one single direction and therefore it is very difficult to understand the 3D coronal structure. Images like the one on this page may improve our understanding of the coronal features spatial distribution. In order to visualize the part of corona hidden by the Moon in the understandable way I created a pseudocolor image from a pair of SOHO EIT images. The hot corona is displayed on the 19.5 nm image and I colored it using the blue-white color near to the appearance of the solar corona during the eclipse on the blue sky. The lower and colder gas layer displayed on the 30.4 nm image I colored using the orange hue. I obtained the image in which the transparent holes in corona are orange. The dense parts of hot corona are of the blue-white color, which corresponds the appearance in visible light. The red color denotes chromosphere and prominences visible during the eclipse. These features are missing in polar regions because my observing place was nearly on the eclipse central line and for the whole eclipse they were obscured by the Moon.
The image illustrates that even with very simple and cheep amateur equipment (about 400 USD) it is possible to obtain valuable scientific data and that improvement of mathematical processing may be more effective than improvement of used technical means.
Click on the image or on the following reference to display the higher resolution image version (1.7 MB, PNG format).

Date11. 08. 1999
TimeSecond contact 10:50:37 UT, third contact 10:53:00 UT
SOHO EIT images 11:08:16 UT, 12:02:16 UT
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, 10.5/1084 mm
CameraSoligor SR-300MD
Resolution4.76 arc sec / pixel (higher resolution image version)
FilmFujicolor Superia 800
ProcessingComposition of 21 images processed by means of Corona 3.0 merged to SOHO EIT images.
Image processing by Miloslav Druckmüller
ScannerNikon Super Coolscan 4000 ED (4000 dpi resolution, RGB, 3 × 16 bit/pixel, 16× multisample)
SoftwareSofo ACC 6.0 with Match II module, Corona 3.0
NoteSOHO EIT images file names efz19990811.110816, efz19990811.120216
OrientationThe image must be rotated 16.7° clockwise to achieve the standard orientation i.e. North top, East left
Copyright© 1999 ESA/NASA © 2004 Miloslav Druckmüller


Miloslav Druckmüller
Institute of Mathematics, Faculty of Mechanical Engineering
Brno University of Technology, Czech Republic
Page last update: 19.3.2007