Overview

The most frequently used TEXES instrument mode is “hi-med”, a high-resolution cross-dispersed (by the medium-resolution echelle) mode achieving a resolving power R≈λ/δλ~100,000, 0.5% spectral coverage with an ~0.4 x 3″ slit (varying with wavelength). “Hi-lo” mode is a high-resolution cross-dispersed (by low-resolution grating) mode achieving R≈100,000, 0.25 µm spectral coverage, and a very short 0.4″ x 1″ slit. Medium resolution long-slit mode (“med”) achieves R ≈ 15,000, 0.5% spectral coverage, and utilizes an 0.4″ x 16″ slit. Low resolution long slit mode (“low”) achieves δλ ≈ 0.004 µm, 0.25 µm coverage, with a ~0.4″ x 16″ slit. Additionally, two more modes (source acquisition imaging and pupil imaging) are available, though these modes are not used for science observations.