Doppler Tracking with Multiple Spectral Windows on the GBT

The GBT allows multiple spectral windows to be observed simultaneously, a very useful feature for spectral line studies. But with the present LO/IF system, all windows are not equal. These inequalities can be ignored for Galactic objects, with velocities less than a few hundred km/sec, but for much larger velocities, one must understand the complications.

The Basics

So how about some specific examples !