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SUN
Namibia is hardly an ideal location for observing the
sun. Considering that only 2-3 hours after sunrise the ground is already very
hot it is almost impossible to make useful observations of the sun.
Nevertheless, from time to time conditions are good and we are able to
take great pictures of the sun - at least when the focal length is small. More
importantly, African sunsets are something very special.
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Sometimes, the seeing is very friendly to you.
On October 17, 2014 a huge sunspot group (NOAA-AR 2192) rotated on the Earth-faced side of the Sun. Within the next days, it developed
to one of the largest regions of activity within the last decades
On October 24, 2014 we could capture some good images of the group which reached a diameter of about 130.000 km. The telescope used was the Zeiss APQ with a Baader Herschel prism of the first generation. |
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The image on the left shows the extension of the group compared to the whole solar disk. (Zeiss APQ prime focus, f=1.200mm),
Baader Herschel prism and Canon EOS 60 D). The image in the middle shows a comparison with the Earth (same image data as below) and the image on the right shows the Baader Herschel prism with Celestron SkyRis 445M
camera. To enlarge the images click on the previews.
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NOAA - AR 2192 image data October 24, 2014, 14:20
UT
left: Zeiss APQ prime focus with Baader Herschel prism, Baader IR
Passfilter and Celestron SkyRis 445M camera. 144 of 1.200 frames,
exposure time of the single frames 1/4.000 second. Processed with AviStack and
Photoshop CS 2
right: as above with Baader Q-Turett Barlowlinsenelement, focal length ca. 1.900
mm and longer exposure time. To enlarge the images click on the previews. |
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Test image with a Celestron Aptina AR0132AT CMOS monochrome
We also compared the SkyRis 445M camera with the Celestron Aptina camera. The Aptine camera contains the same sensor but the transfer rate to the PC is about as twice as fast (60 frames/s Aptina vs. 30 frames/s SkyRis). Conclusion: same image quality in a much shorter acquisition time.
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| The image on the right side was captured on October 25 (14:45 UT) and shows the extended group NOAA - AR 2192 in comparison with the solar limb. Taken with the Celestron
Aptina. The seeing was not as good as during the day before. To enlarge the images click on the previews. |
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| All Images and all Content are © by Franz Hofmann
+ Wolfgang Paech |
