The Solar Dome : First light of the CCD camera
This first-light image of the photosphere was taken on Friday March 30 by the new DALSA 1024x1024 CCD camera system under development at the ROB. The 0.17 s raw exposure was taken through a broadband filter centered in the blue-green portion of the visible-light spectrum (530nm, infrared-blocking), at the prime focus of a 150mm f/D 11 Lichtenknecker doublet refractor. It shows numerous active regions present on the solar disk around that date, including the huge sunspot complex of region NOAA9393. The biggest sunspot has 2-3 times the diameter of the Earth and is very dark (less than 10% of the average photospheric brightness). The close-up image of this impressive sunspot group is shown at the intrinsic camera resolution.
The imaging hardware and software will soon be completed. Once the camera will be fully commissioned (May or June 2001), those images will be produced daily (weather permitting!) and made widely available in near real-time. The past observing record for the Uccle Solar Equatorial Table (USET) shows that we may expect more than 230 observing days per year, despite the prevailing maritime climate of Belgium. A second camera will follow in a few months. It will be used for monitoring solar flares in the chromospheric H-alpha line (Lyot filter).
(Instrument design: F. Clette; control software: F. El Hassouni, J. Nutin)
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