First light for Simons Observatory's large aperture telescope

The Simons Observatory (SO has reached a significant milestone with the successful installation of its Large Aperture Telescope (LAT).  

Located at the summit of Cerro Toco in the Chilean Atacama Desert, the LAT joins three Small Aperture Telescopes (SATs) already in operation. These instruments are designed to measure the polarization of the cosmic microwave background (CMB) with the unprecedented precision at all scales, providing crucial insights into the physics of the early universe and on the processes governing the formation of cosmic structures such as the presence of massive neutrinos and dark energy. In February 2025, the LAT achieved its "first light" by capturing an image of Mars, signaling that the telescope's design and functionality are on track. This accomplishment marks the start of the observatory's full scientific operations. The LAT's successful integration is a result of eight years of effort by SO researchers and engineers. 

Members of the IAS cosmology team are involved in the analysis and reduction of the LAT data, in the scientific exploitation of its measurements of the gravitational lensing effects on CMB polarization as well as in their combination with data of the ESA Euclid mission.

Further progress and breakthroughs of the Simons Observatory can be monitored on its new website: https://simonsobservatory.org

News @ INSU & IN2P3 :  https://www.in2p3.cnrs.fr/fr/cnrsinfo/le-grand-telescope-du-simons-obser...

contact: Giulio Fabbian