Rotation of Earth --Spectroscopy?

Hi. The sharp spike should correspond to the Sun. The only Doppler shift will be due to the speed of the antenna, and this will include any compensation for latitude and season. (At the equator the effect would be more consistent.) The Doppler spread for the galactic arms will be more spread out due to variations in Earth's speed relative to them. Never calculated the speed from shift before but I'm sure the emission line deviates at a known rate.