Fig. 1. Map of the Ophiuchi dark cloud observation fields. 2^o diameter ROSAT   PSPC field of view, and its central studied by Casanova et al. (1995); 40´ diameter ROSAT   HRI fields of view and YLW15 area published in Grosso et al. (1997); ASCA   GIS field of view from Koyama et al. (1994) and Kamata et al. (1997); ISOCAM survey field (central programme observations by Nordh et al.; see Abergel et al. 1996). The background image of the Ophiuchi star forming region is taken from the first Digitized Sky Survey, contrast was enhanced with Gaussian histogram specification (Canzian 1997). Regions of high visual extinction are clearly visible. DCO⁺(J=2-1) contours from Loren et al. (1990) show for reference the location of dense cores A, F.