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The science payload - the instrument package - of each satellite (Figure below) consists of a five -lens telescope with an aperture of 3 cm and an interline CCD detector from Kodak, aKAI 11002-M, with 11M pixels (see Table below, for specifications). The optical elements are housed inside the optical cell and are held in place by spacers. The photometer has a resolution of about 30 arcseconds per pixel and a field-of-view of 24 degrees. The mechanical design for the blue and for the red instrument is nearly identically optimized for the respective wavelength range.
Figure: BRITE-Constellation Telescope and Baffle.
The structure in front of the telescope, the baffle, is needed to reduce direct light infall from the bright Earth (Earthshine) and other bright sources such as the Sun and the Moon, alltogether called straylight.
Figure: CCD architecture.
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Kodak KA11002-M CCD
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Imager size
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37.25 x 25.70mm
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# of pixels
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4008 x 2672
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Pixel size
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9.0 µm x 9.0 µm
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Peak quantum efficiency
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50%
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Saturation Signal
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60000 e-
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Dark current
Read out current
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4 e-/s/pixel
13 e-/pixel
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Power consumption
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1 Watt
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Table: Detector specifications.
This detector was selected based on its low dark current for temperatures at or below +20C. This low thermal noise does not require the device to be cooled for good performance and the device consumes only a modest amount of power.
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