ANDES, the high resolution spectrograph for the ELT: calibration unit(s)

The instrumentation plan for the ELT foresees the ArmazoNes high Dispersion Echelle Spectrograph (ANDES). The ANDES-project and consortium entered phase B in January 2022 and underwent several (internal and external) revisions by now to ensure that the requirements and eventually the challenging goals can be met by the physical design of the spectrograph.

Among its main scientific goals are the detection of atmospheres of exoplanets and the determination of fundamental physical constants. For this, high radial velocity precision and accuracy are required. Even though the ANDES-spectrograph is designed for maximum intrinsic stability, a calibration and thus a calibration unit is mandatory. To allow for maximum flexibility and modularity the calibration unit is physically split into three calibration units.

We show the design of the calibration units and their individual components, where possible. This includes the electronics, the mechanics, the software supporting and controlling the light guiding and calibration sources.