Green line and red line composite image

This color composite image is made of the green line Fe XIV image and red line Fe X image. The exact color for the human vision is preserved and the image corresponds with the view through a hypothetical filter which would transmit light in both mentioned lines simultaneously. The green areas represent the active, dense and hot coronal structures with the temperature about 1.8 mil. K, on the contrary the red areas are of about one million Kelvin cooler areas. The big difference between the red and the green line image is perfectly visible on this negative images pair (red line image is left, green line image is right). The difference is so significant that I had serious problems in images alignment. My standard method using Fourier transform based phase correlation failed on coronal features completely and I was forced to use the lunar edge for alignment. Fortunately, it was a correct solution because the images were taken simultaneously using two identical telescopes.
The extremely high dynamic range film Fomapan N30 (ISO 800) played a very important role. It enabled to manage the extreme brightness ratio by means of only one single image. Only the best nowadays scanners are able to take full advantage of this fantastic film produced a quarter century ago.

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 X and Fe XIV emission but some amount of continuum as well.
OrientationThe image must be rotated approx. 53° anti-clockwise to achieve the 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