Ttics

The set ttics command places tics around the perimeter of a polar plot. This is the border if set border polar is enabled, otherwise the outermost circle of the polar grid drawn at the rightmost ticmark along the r axis. See set grid (p. ), set rtics (p. ). The angular position is always labeled in degrees. The full perimeter can be labeled regardless of the current trange setting. The desired range of the tic labels should be given as shown below. Additional properties of the tic marks can be set. See xtics (p. ).

    set ttics -180, 30, 180
    set ttics add ("Theta = 0" 0)
    set ttics font ":Italic" rotate