Comparison between our new T_K(HCN/HNC) temperature estimates and the ¹²CO (1–0) excitation temperatures (Nakamura et al. 2012; Shimajiri et al. 2014) in all positions throughout the ISF outside the ONC nebula Orion HII nebula (i.e., I(H41α) ≤ 1.0 K km s⁻¹; grey dots). The solid line indicates the linear correlation between these two temperatures estimates = T_K(HCN/HNC). Although they are positively correlated (see density contours in blue), we note that the temperature estimates are systematically higher than the corresponding T_K(HCN/HNC) values at the same position. For illustrative purposes we display the (HCN/HNC)+15 K line denotedby a dashed red line in our plot.