Thank you Bandersnatch!! That is exactly what I was looking for. So does that mean we have no real way of measuring these velocities when the galaxy is "face on?"
I am intrigued by how these values infer dark matter, and have a hard time accepting that theory rather than some error in...
Can someone point me to a resource that describes, or describe, how the orbital speed of stars within galaxies are observed and measured?
I'm struggling with how these values can be attained with any confidence in their accuracy.