A research group led by Prof. Wang Jian from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) proposed a continuous-scanning near-infrared sky brightness monitor (CNISBM). It can measure 2.5 to 5 μm infrared sky brightness based on an InSb detector and a linear variable filter.
Source:
https://phys.org/news/2020-08-continuous-scanning-sky-brightness-m.html