Rubin Auxiliary Telescope (AuxTel)

The 1.2-meter Rubin Auxiliary Telescope (AuxTel) sits on a hilltop a short distance from the main facility. The AuxTel was originally named Calypso, and it was located at NSF Kitt Peak National Observatory near Tucson, Arizona. After it was acquired from astrophysicist Edgar O. Smith, the telescope was removed from Kitt Peak, refurbished at Rubin headquarters by ACE Manufacturing, and sent to Chile.

The AuxTel improves the accuracy of Rubin Observatory data by measuring atmospheric transmission — how much light passes directly through Earth’s atmosphere in a given area, as opposed to being absorbed or scattered by the different molecules and particles in the air. Atmospheric elements that affect the transmission of light coming from space change constantly, and include molecules like water, oxygen, and ozone, as well as aerosols like sea salt, dust, ash from volcanoes, and smoke from forest fires. The AuxTel determines and records how all those molecules and airborne particles in the atmosphere affect the light captured in Rubin Observatory images.