Atmospheric monitoring, mostly[1]. Notably, the picture on Google is wrong, it shows Gemini, which is here: https://www.google.com/maps/place/Gemini+North+Teles

Atmospheric monitoring, mostly[1]. Notably, the picture on Google is wrong, it shows Gemini, which is here: https://www.google.com/maps/place/Gemini+North+Telescope/@19.8223693,-155.4694613,16.36z/data=!4m5!3m4!1s0x7953bd822cbdaedb:0xc4dad786a5b1882f!8m2!3d19.823819!4d-155.4689039?hl=en https://www.google.com/maps/place/Gemini+North+Telescope/@19... [1]https://en.wikipedia.org/wiki/Mauna_Loa_Observatory https://en.wikipedia.org/wiki/Mauna_Loa_Observatory