Subset of the images used to construct the integrated SED of NGC 23. The new NOT optical observations of the g, r, and Hα+[N ii] bands are shown. The rest of the images were obtained from the public archives of their respective observatories (see Sect. 3 for details). Some images used in the SED are not displayed here because they have morphologies similar to those of the presented images (2MASS J and H, IRAC 4.5 and 5.8 μm, and PACS 100 μm) or because they have a very low angular resolution (SPIRE 350 and 500 μm). All images are shown in a logarithm scale. North is up and east to the left. The white bar in the Hα+[N ii] panel represents 10 kpc at the distance of the object.