Equivalent widths of the narrow component of the DIB at 5780 Å correlates linearly with our E(B–V) estimates determined in Sect. 3.2 (black squares). The E(B–V) values calculated from our equivalent widths using the relations in Friedman et al. (2011) and Vos et al. (2011) are also shown (gray points and gray stars). The offset of ~0.25 mag between the calculated and our values is probably due to different equivalent measurement procedures. Our procedure includes some of the broad component of the DIB so that we overestimate the equivalent widths.