Simons Observatory

A 6 m Large Aperture Telescope and several 0.42 m Small Aperture Telescopes at 5,200 m on Cerro Toco, with tens of thousands of transition-edge-sensor bolometersbolometerA detector that measures incoming power through the heating of an absorber. Transition-edge sensors, held at the edge of a superconducting transition, are the standard for CMB and submillimetre cameras. in six bands from 27 to 280 GHz. The small telescopes target primordial B-modesB-modesThe curl-like component of CMB polarisation. On degree scales, primordial gravitational waves from inflation would produce it; its amplitude is quoted as the tensor-to-scalar ratio r. at degree scales; the large one maps temperature and polarisationpolarimetryMeasuring the polarisation of incoming radiation. It encodes magnetic-field geometry, scattering and emission mechanisms; in the CMB it separates E- and B-mode patterns. at arcminute resolution for CMBcosmic microwave backgroundThermal radiation released 380,000 years after the Big Bang, now at 2.7255 K and peaking near 160 GHz. Its temperature and polarisation anisotropies, at the 10⁻⁵ level, constrain the content and geometry of the Universe. lensing, the Sunyaev–Zel'dovich effect and the neutrinoneutrinoA nearly massless, neutral particle that interacts only weakly, so it escapes dense sources and crosses the Universe undeflected. High-energy astrophysical neutrinos point back to where cosmic rays are accelerated. massarcsecond1/3600 of a degree (″). A milliarcsecond (mas) is 10⁻³″ and a microarcsecond (µas) 10⁻⁶″. Atmospheric seeing limits ground telescopes to about 0.5–1″ without adaptive optics. sum.

Operator

Simons Observatory collaboration

Site

Cerro Toco, Chile

Passband

27 GHz – 280 GHz

First light

2024