Channel maps of hydrogen RRL, equivalent to H174α at 1237.626 MHz, made from the stacked data cube with a beam size of $4_{.}^{\mathrm{\prime }}7$ (shown in the bottom left as a circle in each channel), which is integrated over a 5 km s⁻¹ range. The central velocity is given at the top-left corner on each map. The RMS noise (σ) is ~0.001 Jy beam⁻¹ km s⁻¹. The contour levels are 5, 10, 20, 40, 80, 120, and 160σ.