Plot illustrating the lines in the S, Q, and O branches (purple, blue, and orange, respectively) of the H₂ (1,0) transitions for the DF1 region of the Horsehead. Identifications in italics with a dashed line were not included in final line lists − Q(9) is blended with the H₂ (2,1)Q(2) transition and not extracted independently while Q(12), Q(14), and Q(15) were very weak and not definitively detected. In addition, the O(2) line is blended with H I Br β and not independently extracted.