Spatial and proper motion distribution of eight open clusters. (a): Spatial distribution of open clusters in the Galactic coordinate system. (b): Distribution of proper motions of eight open clusters. (c): Spatial distribution of open clusters in the Galactocentric Cartesian coordinate system on the X − Y plane. The stars with distance correction are shown by color dots, whereas the position of the members without distance correction is shown by grey dots in the background. The direction of the line of sight is shown by the grey arrow. The error bars are depicted in the three diagrams by the grey lines. The data errors in position and proper motion space are much smaller than the scale of the cluster itself. The contribution of errors to cluster search and identification is negligible.