The Solar Eclipse 1999 From Hungary
EurAstro Team Szeged I (Manfred Rudolf, Alfred Jakoblich, Franz Michlmayer, Carmen Ortega)
Processed images
Structural Details of the Solar Corona
It is normally not possible to get structures of the inner and outer corona onto one single
picture because the photographic film cannot cope with the enormous brightness range of the corona.
On pictures with short exposure times, details of the inner corona may be seen but the outer and less brighter corona
will not be recorded. On the other hand, on exposures which show details of the outer corona, the interior parts of
the corona are hopelessly overexposed. However, by combining images each showing different details of the corona,
some structural features of the corona can be revealed.
The following picture is a composite of eight individual images. The individual images are obtained with
a focal length of 1400 mm and exposure times from 1/250 sec to 2 secs. In the composite image many coronal features
such as streamers and loops can be seen.
How to obtain such pictures:
First, you need a series of corona pictures each made with a different
exposure time and showing different structural features of the corona:
Then, from each of these pictures a blurred image is made:
Each blurred image is subtracted from the corresponding original. The brightness information is mostly cancelled out.
Images are obtained which contain the differences between the sharp and blurred images.
The differential images are added to form a mask which contains structural information of the inner and outer parts of the corona:
This mask with the structural information is superimposed to the original picture:
to form the final image:
The tools for such processing are found in commercial image processing programs, e.g. Photoshop.
Relative size of the Sun and the Moon:
Compare the relative sizes of the lunar disk and the Sun on eclipse day:
On the composite below an image of the partially eclipsed Sun has been copied
onto an image of the lunar disc covering the Sun during totality. It can be
seen that the Moon appears slightly larger than the Sun:
a small portion of the moon remains uncovered, and causes a black ring around the
image of the Sun.
The individual pictures of the totally eclipsed Sun and of the partially
eclipsed Sun for the above composite. Both pictures have been obtained with
a 1000 mm telephoto lens and a 1.4x teleconverter.
Eclipse Sequence:
This picture is a composite of several individual images of the eclipse.
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