This is a question that I hear almost daily[...]
The low noise of The Imaging Source astronomy cameras is thanks to a number of aspects. The ones listed below are the most important:
The Imaging Source deploys industrial-grade components in their industrial and astronomy cameras. Unlike USB web cameras, where the price is a very important factor (and thus quality gets put in second place), in industry the stability, longevity and quality of components on the PCBs is decisive. With the exception of the exposure time, the cameras in the astronomy line are identical to their industrial brothers.
Low operational temperature
The Imaging Source astronomy cameras run at a low temperature. Unlike many industrial cameras that run so hot that touching them can result in burning of the skin, The Imaging Source cameras are only slightly warm when they are touched. Hence, there is little thermal noise. Furthermore, thanks to their robust aluminum and zinc casing, any heat that is produced is dissipated efficiently.
Non-compressed CCD signal
The signal from the CCD is not compressed. Noise is not only a result of heat, but also of compression. As The Imaging Source astronomy cameras do not compress the signal from the CCD, the cameras do not induce any additional noise.
Highly optimized analog-to-digital SP
The analog to digital signal processing (CCD outputs an analog signal) is highly optimized, thanks to the firmware developed by The Imaging Source.