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The CTAO’s “Alpha Configuration” approved for the first construction phase

On summer 2021, the Board of Governmental Representatives (BGR) approved the Cherenkov Telescope Array Observatory’s (CTAO’s) Cost Book and Scientific & Technical Description, fundamental documents towards the establishment of the final legal entity of CTAO as a European Research Infrastructure Consortium (ERIC). In particular, these documents include the configuration of the telescope arrays at the two sites for the first construction phase, named “Alpha Configuration.” This configuration includes 4 Large-Sized Telescopes (LSTs) and 9 Medium-Sized Telescopes (MSTs) for the northern array located on La Palma (Spain), and 14 MSTs and 37 Small-Sized Telescopes (SSTs) for the southern array situated in the Atacama Desert (Chile). The definition of these configurations is the result of a meticulous optimization process for each array’s scientific capabilities, which implies the specialization of the northern array in extragalactic sources (low and medium CTAO’s energy range) and that of the southern array in Galactic targets (medium and high CTAO’s energy range) for the first construction phase.

More information:

Rendering of the CTAO northern telescope array. Credit: Gabriel Pérez Díaz, IAC.

Moreover, new performance plots and the Instrument Response Functions (prod5 IRFs) for this Alpha Configuration are now publicly available on the CTAO website, in FITS and Root format, for three different zenith angles (20-40-60deg), averaged azimuth and dark conditions. Visit