An ensemble of masers orbit the center of an edge-on spiral galaxy at a particular radius, and are observed at a wavelength of 1.855x10-1 m on the side of the galaxy approaching us, and at 1.863x10-1 m on the side receding from us. What is the orbital speed at the radius at which the masers orbit? Astronomers observed these masers over an interval of one year.
What distance does a single maser move during that year? Give your answer in kilometers and in AU. During this period, a maser moving across the line of sight moved through an angle of only 0.000015 arcsec. Calculate the distance to the galaxy.