I've been trying this for 3 hours and I'm getting nowhere. These are the graphs I made for Hydrogen Intensity vs Frequency for a radio telescope that transits the sun and galactic arms of the galaxy. http://img220.imageshack.us/img220/5904/helpgraphia6.jpg http://img139.imageshack.us/img139/8038/graph1nr8.jpg http://img139.imageshack.us/img139/4486/graph2pp2.jpg I need to find the rotation speed of the earth and the galactic arms. So I know I need to measure the doppler shift ...but my problem is, I don't know which spikes correspond to what. What spikes are from the sun or local space and which are from the galactic arms. Anybody please help?