The Small-Sized Telescopes (SSTs) will outnumber all the other telescopes with 70 planned to be spread out over several square kilometers in the southern hemisphere array only. This is because very high-energy gamma-ray showers produce a large amount of Cherenkov light over a large area, and the SST’s smaller mirror is sensitive to the highest energy gamma rays (between a few TeV and 300 TeV). The SSTs’ wide coverage and high sensitivity improve CTA’s chances of detecting the highest energy gamma rays.
Three different SST implementations were proposed for the final SST design. A harmonization process was initiated in 2018 and, in its June 2019 meeting and following the CTAO Management proposal, the Council decided that “the CTA-SST design should be based on the ASTRI/CHEC design (pictured below), taking into account the experience gained from all designs.”