X-ray observations of the Ophiuchus, PKS 0745-191 and Cygnus-A clusters of galaxies.

The authors report observations of the X-ray emission from three bright clusters of galaxies at low Galactic latitudes; the Ophiuchus, PKS 0745-191 and Cygnus-A clusters. Temperatures and iron abundances are determined from EXOSAT spectral data. Images of the Ophiuchus cluster show it to have a high central density and a cooling flow. The authors confirm measurements of a high gas density around PKS 0745-191 and show that the X-ray emission is centred on the radio galaxy. The PKS 0745-191 cluster is the most distant object for which an abundance has been measured from X-ray spectra. The spectrum of Cygnus-A contains a highly absorbed power-law component that the authors identify with the nucleus of the radio source.