Figure 2.

H i brightness temperature, T_B, as a function of Doppler velocity with respect to the local standard of rest, V_LSR, for the line of sight at $l={172}_{\cdot }^{{}_{°}}5$, $b={70}_{\cdot }^{{}_{°}}5$. The upper panel illustrates how the preliminary velocity boundaries (dotted vertical lines) are adjusted to fall at the nearest minima or inflection points of the T_B profile (dashed vertical lines). The bottom panel illustrates the fitting procedure to correct the N (H i) column densities for spillover from one region to the next: in red Gaussian functions associated with peaks of the IV component, in green the Gaussian function associated with the peak of the low-velocity (local) component, in blue the total (no peaks were detected in this direction for the high-velocity component).