Each row shows a different type of CRIRES⁺ raw frame acquired with its three science detectors, all taken in the wavelength setting Y1029. Bad pixels have been masked. Starting from the top, the rows show: a flat-field exposure (Flat), a wavelength calibration frame with the uranium–neon lamp (UNe), a wavelength calibration frame taken with the Fabry–Perot etalon (FPET), a stellar spectrum (Spec), and a stellar spectrum taken with the spectropolarimeter unit in the optical path – resulting in two spectra with opposite polarization being recorded (Pol). We note in passing that on detector 2, an internal reflection (Littrow ghost) produces a faint, diagonal strip.