Upper panel: distance uncertainty distributions for the bulge–bar (orange) and RPM (cyan) samples defined in Sects. 4.1 and 4.2, respectively. Also shown are stars with parallax uncertainties smaller than 20% (magenta) and stars with calibrated ASPCAP parameters (green). Lower panel: extinction uncertainty distribution for the bulge–bar (orange) and RPM (cyan) samples. Also shown are stars for which all photometric bands are available (magenta). This illustrates that the secondary and tertiary peaks at larger extinction uncertainties seen in our samples are due to stars for which the optical band is not available (see discussion in Queiroz et al. 2020).