Mapping the Milky Way's Rotation Curve from Archival 21-cm HI Observations

The provided text details a project that utilizes the 21-cm hyperfine spectral line of neutral atomic hydrogen (H I) to map the internal kinematics of the Milky Way. Because radio waves easily pass through the thick interstellar dust lanes that obscure optical light, radio astronomy provides an unobstructed view of the Galactic disk. By analyzing the Doppler shifts of these radio emissions, the project tracks the line-of-sight motion of hydrogen gas clouds to reconstruct how the inner galaxy rotates. The primary objective is to take archival raw data from the HI4PI survey and transform it into a Galactic rotation curve, which plots the orbital speed of cosmic material against its distance from the Galactic center.