Calibrated colour–magnitude (left) and free-reddening parameter-magnitude (right) diagrams for Masgomas-1. The red segmented arrow in the left panel shows A_KS = 3.00. Main sequence and supergiant sequence, shown in black, are located without reddening at the distance determined in this study (3.53 kpc). In the right panel the red segmented lines show the limit for the Q_IR parameter used in the systematic search. The expected Q_IR and K_S magnitude for the dwarf and giant sequences located at the distance determined in this study (3.53 kpc) are also shown in black. In both diagrams the positions of the spectroscopically observed stars are marked with blue (multi-object spectroscopy) and red numbers (long-slit spectroscopy). We marked the stars located in the central regions of both diagrams with blue circles and amplified the regions in the upper squares, where the observed stars are marked with blue numbers. We used visual magnitudes and intrinsic colours from Cox (2000) for deriving the dwarf, giant, and supergiant sequences.