SANNA, NicolettaNicolettaSANNAOLIVA, ErnestoErnestoOLIVAORIGLIA, LiviaLiviaORIGLIA2021-02-222021-02-222021http://hdl.handle.net/20.500.12386/30532http://dx.doi.org/10.20371/INAF/TechRep/74The Exposure Time Calculator (ETC) is a tool to predict the performances of an instrument. It is extremely useful during all the phases of a project, from the design to the observations. Here we present a detailed description of the ETC for HIRES@ELT, the high resolution optical- infrared spectrograph for the Extreme Large Telescope.ELETTRONICOenTechnical reporthttp://arcetri.astro.it/~hires/DoCs/etc_description.pdf