The SALT HRS spectrograph: final design, instrument capabilities, and operational modes

The high-resolution chelle spectrograph, SALT HRS, is at an advanced stage of construction and will shortly become available to the user community of the Southern African Large Telescope (SALT). This paper presents a commentary on the construction progress to date and gives the instrument's final specification with refined estimates for its performance based on the initial testing of the optics and the science-grade detectors. It also contributes a discussion of how the fibre input optics have been tailored to specific scientific aspirations to give four distinct operational modes. Finally, the use of the instrument is discussed in the context of the most common science cases.