B_∥ in Orion-A. Blue (red) circles show magnetic fields toward (away from) us. The size of the circles indicates the magnitude of magnetic field. Sources numbered in bold white indicate the sources used for this study. Points 3, 4, 6, 7, 8, 12, 15, 17, 18, 19, 29, 31, 32, and 34 in this figure have errors less than 100%. Points 4, 6, 12, 15, 17, 18, and 29 are considered in this study.