Animations in Gnuplot can be built using “do for []{…}”; Set a circle in the centre: set object circle at …;

#example_1
plot 'file' every I:J:K:L:M:N 
plot 'file' every 2		# Plot every 2 lines
plot 'file' every ::3	        # Plot starting from the 3rd line
plot 'file' every ::3::15	# Plot lines 3-15
 
#example_2
do for [t=0:50] {
  outfile = sprintf('animation/bessel%03.0f.png',t)
  set output outfile
  splot u*sin(v),u*cos(v),bessel(u,t/50.0) w pm3d ls 1
  pause 0.02
}