(a) OB1 stars in S205. The green star symbols mark those within S205, and the blue star symbol is a trace-back target whose trajectory is shown in Appendix A Figure A5(b). The big circles are the same as those in Figure 1. (b) PSR B0355+54 and its trace-back trajectory (dashed line). Solid red circle: current position; open red circle: position 0.56 Myr ago (spin-down age of PSR B0355+54; J. H. Taylor & R. N. Manchester 1975). White shading indicates the trajectory uncertainty due to proper motion uncertainty.