How could I calculate the distance from galactic center (Kpc) when I have position-velocity diagram and the central point is at the x axis (position or offset) of about 2.5 arcsec?

Question

How could I calculate  the distance from galactic center (Kpc) when I have position-velocity diagram and the central point is at the x axis (position or offset) of about 2.5 arcsec?

amilapsn · Answer

can you explain the question a little bit?

anonymous · Answer

my question is when I get the image which shows the velocity(Km/sec) Vs. offset (arcsec), how can I calculate true or actual distance where the central point on x axis is at 2.5 arcsec ?