South Pole Telescope (SPT)

The South Pole Telescope (SPT) is a ten-meter diameter telescope operating at the National Science Foundation South Pole research station (image above by Daniel Luong-Van). The telescope is designed to conduct large-area millimeter and sub-millimeter wavelength surveys of faint, low-contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background (CMB). A description of the receivers used on the SPT is given below.


From 2008 to 2011, the SPT-SZ receiver carried out a 2500 square-degree survey of the southern sky at high galactic latitude. The instrument had spectral bands centered at 95, 150, and 220 GHz, with 1 arcminute resolution at 150 GHz. Science highlights include:

  • Measurements of primary CMB anisotropy in the TT power spectrum (Story et al. 2013)
  • Measurements of secondary CMB anisotropy - the thermal and kinematic Sunyaev Zel'dovich effects (tSZ and kSZ)
    and foreground anisotropy - the cosmic infrared background (CIB) and radio sources (George et al. 2015)
  • The reconstruction of the CMB lensing potential and its power spectrum (van Engelen et al. 2012)
  • A catalog of tSZ-selected galaxy clusters (Bleem et al 2015) and cosmological constraints (Benson et al. 2013)
  • A catalog of high-redshift, strongly-lensed, star-forming galaxies (Vieira et al. 2013)


From 2012 through 2016, the SPT was equipped with the polarization-sensitive SPTpol receiver, configured to observe in two spectral bands centered at 95 and 150 GHz, with 1 arcminute resolution at 150 GHz. The primary survey conducted with SPTpol was a "wedding-cake" survey of a 500 square-degree region of the southern sky at high Galactic latitudes, with a deeper survey of 100 square degrees within that region. An extended, shallower survey of a further ~2800 square degrees was conducted during the Austral summers. Science highlights include:

  • The CMB lensing potential measurement and cosmological parameters from the 500 square-degree survey (Wu et al. and Bianchini et al.)
  • Searching for Anisotropic Cosmic Birefringence with Polarization Data from SPTpol (Bianchini et al.)
  • Measurements of primary CMB anisotropy in the TE and EE power spectra from the 500 square-degree survey (Henning et al.)
  • Measurements of the B-mode spectrum from the 500 square-degree survey (Sayre et al.)
  • Measurement of the Secondary Cosmic Microwave Background Anisotropies from the SPT-SZ + SPTpol Surveys (Reichardt et al.)


In January 2017, the SPT-3G receiver was installed on the SPT. SPT-3G represents nearly an order-of-magnitude upgrade from SPTpol in instantaneous sensitivity, owing primarily to the increase in detector number (from ~1,500 to ~16,000) enabled by reconfigured optics and trichroic, dual-polarization detector pixels. SPT-3G is configured to observe in three spectral bands centered at 95, 150, and 220 GHz, with 1 arcminute resolution at 150 GHz. Since 2018, SPT-3G has been used primarily to survey a 1500-square-degree region of low-foreground sky (an area that coincides with the BICEP-3 / BICEP Array field and includes the 500-square-degree SPTpol and BICEP-Keck fields), with a target depth of 2-3 uK-arcmin in temperature at 95 and 150 GHz. As with SPTpol, an extended survey is being conducted (over ~2500 square degrees with target noise levels of <~10 uK-arcmin) during the Austral summers.

Further details on SPT may be found at

A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Andrew F. Ptak
LAMBDA Director: Dr. Thomas M. Essinger-Hileman
NASA Official: Dr. Thomas M. Essinger-Hileman
Web Curator: Mr. Michael R. Greason