Two-dimensional map of the Galactic interstellar dust in the Orion region (Planck 353 GHz optical depth, color scale at bottom right). Superimposed are the SDSS/APOGEE target stars contained in the field of view. The black and white coding of the markers follows the ratio between the 15 273 Å DIB strength and the extinction of the target light in the visible, with white (resp. black) indicative of a high (resp. low) ratio. Towards the cores of the clouds (in red) there is a spectacular decrease of the DIB/extinction ratio. At the cloud periphery, and also outside the clouds that are visible in the Planck image, the ratio is enhanced, reflecting the so-called “skin effect”.