Overview of the giant molecular filament GMF38a. Top panel: ¹³CO (GRS, Jackson et al. 2006) integrated intensity contours in the range v_LSR = 50−60 km s⁻¹ overlaid on integrated H I emission in the same velocity range. The black ellipses show the “off-positions” whose spectra are shown in Fig. 5 and the black “×” signs mark positions whose spectra are show in Fig. 6. Bottom panel: same ¹³CO integrated intensity contours overlaid on 1.4 GHz continuum emission from the THOR survey (Wang et al. 2018). The contours in the top panel indicate integrated ¹³CO emission levels of 5, 10, 20, and 30 K km s⁻¹. The contours in the bottom panel indicate integrated ¹³CO emission levels of 5 K km s⁻¹ for reference. The dashed box in the top panel outlines the region that is discussed in the following sections and shown in Figs. 7, 9, 11, 14, and 19.