Different reduction stages of a spectrum from a 4.4 seconds exposure on a single CCD. Left: Raw spectrum. Y is in ADU (analogue-to-digital units), X is in samples (one sample is 1 AL × 10 AC pixels), the biasNU effect is visible as an offset after sample 820. The Ca II triplet lines are indicated by red lines. Right: Spectrum calibrated in wavelength, normalised to the pseudo-continuum, and samples on the leading/trailing edges are discarded. The wavelength range of the calibrated spectra is [846–870] nm. The atmospheric parameters that have been determined by DetermineAP (Sect. 6.5) and associated with the star are T_eff = 6000 K, logg = 3.5, and [Fe/H] = 0. The internal magnitude is = 10.2 (Sect. 6.3), and the S∕N ~ 9.