New HMSC v_lsr (this work) and those in Y17. Panels a and b: renewed v_lsr and difference between renewed v_lsr and those in Y17, , respectively. The 90th percentile of for HMSCs located at higher longitude (|l| > 3°) is 3.9 km s⁻¹ , shown as red dashed lines in (b). The red and black dots represent HMSCs with values largerand smaller than 3.9 km s⁻¹ , respectively. The gray region indicates the lower-longitude region, |l| < 3°, where the HMSCs are excluded from following analyses. Orange regions are considered by Ellsworth-Bowers et al. (2015). The four spiral and local arms are shown by different colors and their positions are taken from Urquhart et al. (2018) and its references Taylor & Cordes (1993) and Bronfman et al. (2000). Most of the errors of v_lsr are less than 2 km s⁻¹ and the associated error bars are smaller than the point size in (a).