M101 picture is about 770 pixels across = 40 kpc
    - so, let 800 pixels = 40,000 pc -> 50 pc per pixel

    - XFig units 40,000 kpc = 11505 units -> 3.5 pc per unit

    - Hipparcos: precision 0.003 arcsec, go to about 100 pc
          (use rule that 1/(3*uncert) = dist limit)
          100 pc = 2 pix radius = 30 units

    - VERA: precision 0.000 05 arcsec, go to about
            1 / (0.000 05 * 3) = 6000 pc
          6000 pc = 120 pix radius = 1725 units


          VERA freq 22 GHz so wavelength is 0.0136 m = 13.6 cm


    - VERA resolution   =  70 deg * (0.0136 m / 2,000,000 m) 

                        =  4.76 x 10^(-7) degrees

                        =  0.0017 arcsec