Fig. 1. Map of the analyzed ROSAT PSPC pointings. Each circle is radius. The black circles correspond to pointings containing ONS candidates (see text). The contours of the clouds are from Dame & Thaddeus (1985).
![[FIGURE]](img79.gif)
![[FORMULA]](img77.gif)
radius. The black circles correspond to pointings containing ONS candidates (see text). The contours of the clouds are from Dame & Thaddeus (1985).