South Pole Telescope

The South Pole Telescope (SPT) is a 10-meter millimeter/microwave telescope at South Pole Station, for the purpose of studying the cosmic microwave background (CMB), specifically, the CMB anisotropies. The location's advantages are the dry air and altitude, 2800 meters or 9300 feet, both very useful for the wavelengths of interest. The telescope went into service in March 2007 and has served as a component of the Event Horizon Telescope (EHT). Some past and present instruments:

• SPT-SZ camera - bolometer array (95 GHz, 150 GHz, and 220 GHz, used 2008-2011).
• SPTpol camera - also detects polarization (90 GHz and 150 GHz, used 2012-2016).
• SPT-3G camera - many more sensors (90 GHz, 150 GHz, and 220 GHz, used 2017-).

These frequencies are useful for finding distant galaxy clusters, e.g., using the Sunyaev-Zel'dovich effect (SZ effect).