Radial component of the relative proper motion (μ_r) as a function of distance from the center of Berkeley 59. The red points and error bars show the values of μ_r in 2′ bins, calculated as the weighted mean and standard deviation, respectively. A distance of 1009 pc was assumed for the top and right axes. Positive values of μ_r indicate expansion. The black line shows a linear fit to the red points inside the radius of 18′ and has a slope of 0.022 ± 0.003 mas yr⁻¹ arcmin⁻¹ and an intercept of 0.013 ± 0.028 mas yr⁻¹.