New IRAM 30 m observations throughout the Orion ISF. From left to right: (a) Spitzer IRAC-1 emission map (Megeath et al. 2012); (b) HCN (J = 1–0), (c) HNC (J = 1–0), and (d) H41α line intensity (also known as total integrated intensity) maps (this work). We note that both HCN and HNC intensity maps are presented in logarithmic scales because of the wide dynamic range in emission that these two species show. The different OMC 1-4 clouds, together with the different clusters and nebulosities, are indicated in the IRAC-1 image. For guidance, the extension of the ONC, M43, and NGC1977 regions (green dotted circles), as well the position of the Trapezium and NU Ori stars (white stars) plus the Orion BN source (yellow star), are also indicated in the different IRAM 30 m maps.