The SL-200 is divided into three units along the optical axis of the tube for the convenience of use and to provide a possibility of replacing the beam (spectral) splitting filter and CCD photo detecting device on the board of SM.
The three units are: the block of mirror light filter – BOM1, the bock of photo detecting device – BOM2 and the basic block of solar limbograph including pointing and control systems – BOM3. BOM1 and BOM2 are installed on BOM3 by the means of joint pins and are fastened by reusable locks.
Each group of photo detecting blocks works independently and is driven by its own control system CS1, CS2, CS3.
Each group of photo detecting blocks has its own (common for each group) electronic shutter with adjustable integration time.
Photometric quality control system: the software periodically checks the quantity and coordinates of defective pixels in the CCD array, dark voltage values and sensitivity coefficients.
Thermal stabilization of the invar tube and optical units of BOM:
The experiment is conducted in two-day uninterrupted series consisting of subsequent sessions of coordinate and photometric measurements of the shape and diameter of the Sun and also of its separate regions during the adjacent circuits.
The quantity of the above two-day series is at least 6 per month. The quantity of sessions is up to 6 per day,
duration of a session is defined by the possibility of solar observations and is up to 30 minutes (see the mission profile of the sessions of solar observations and power consumption).
The whole mass of the BOM is 64 kg, of the BE (internal sub block with a computer inside the airtight compartment) – 15 kg, of the external sub block with a microprocessor – 7 kg. Dimensions of the BOM – 1090x490x550 mm, of the BE (internal sub block with a computer) – 180x400x270 mm and of the external sub block with a microprocessor – 200x200x80 mm.