Colour-magnitude diagram (CMD) of NGC 3201 and selected stars for spectroscopic observations. Panel a: Photometry from pre-images as described in the text. No calibration or de-reddening process was done, except by a zero point offset to match the calibrated CMD from panel b. Targets for spectroscopic observations were selected from this CMD and are shown as orange circles. Panel b: Same as (a) but using photometry from Kravtsov et al. (2009) that is calibrated and corrected by differential reddening. The selected targets are identified and reveal an outlier from the RGB region that should be excluded from our analysis. Moreover, RGB stars are colour-coded. Panel c: Luminosity function of all stars from (b) indicating the over density of the horizontal branch. Panel d: Luminosity function only of RGB stars from (b) indicating the over density of the RGB bump.