Green line Fe XIV 530.3 nm image

This image was taken through green narrow-band filter on the wavelength of the most intense coronal spectral line. This prominent spectral line was discovered by Harkness and Young during the total solar eclipse of August 7, 1869 and for the following 70 years this line was frightening generations of astronomers because they were not able to identify the element responsible for the line. The name Coroniun for this hypothetical element was used as an expression of despair. Finally the puzzle was solved by Grotrian and Edlen in 1939. Coronium was found to be Fe XIV, i.e. 13× ionized iron. This made evident that there must be extremely high temperatures in the solar corona. The problem of coronal heating has not been fully solved yet.
The hot structures of about 1.8 mil. K are revealed by observing the Fe XIV emission line at 530.3 nm. These structures are even better visible in the B&W negative image. The green color of the image presented on this page is exactly computed and represents for the human vision exactly the same color as the light of 530.3 nm wavelength.
The image was taken on Fomapan N30 film (produced by Foma, Czechoslovakia), on that time the best existing high speed (ISO 800) and high dynamic range B&W negative film.

Date31. 07. 1981
Time2nd contact 02:59:11 UT, 3rd contact 03:00:58 UT
Total eclipse duration 1 min 58 s
PlaceBratsk, Siberia, Russia
CoordinateE 101° 21' 40'', N 55° 58' 48'', altitude 410 m
ConditionsDense cirrus clouds
OpticsTwo identical refractors of 130 mm diameter, 1950 mm focal length on one paralactic mount equipped with polarizer and narrow-band filters 530.3 nm (0.2 nm half-width) resp. 637.4 nm (0.3 nm half-width) of B-13 type fy. Baird Atomic.
FilmFomapan N30 (6×6 cm format)
Exposure25 s
ProcessingRed line and green line image were aligned by means of phase correlation on Moon (images were taken simultaneously) and processed by means of Corona software.
Image processing by Miloslav Druckmüller
ScannerEpson Perfection V750 PRO
SoftwareSofo ACC 6.0 with Match II module, Corona 4.0
NoteThis image contains not only Fe XIV emission but some amount of continuum as well.
OrientationThe image must be rotated approx. 53° anti-clockwise to the achieve standard orientation i. e. North up and East left.
Copyright© 1981 Július Sýkora, © 2007 Miloslav Druckmüller

Miloslav Druckmüller
Institute of Mathematics, Faculty of Mechanical Engineering
Brno University of Technology, Czech Republic
Page last update: 27.11.2019