NGC 1275 is the brightest galaxy in the preseus cluster and it, is a strong radio source. It was by far the most distant of the twelve galaxies originally listed as Seyfert galaxies. Since the Perseus cluster is rich in elliptical galaxies it has been suggested that NGC 1275 might, be an active, elliptical galaxy and not a spiral galaxy like all the other Seyferts, but this is not the case . However NGC 1275 is clearly not, a normal spiral galaxy. It has a bright central part, several kiloparsecs in diameter, outside which are found broad, extended structures as well as absorbing clouds. There are also numerous filamentary structures due to ejected gas.

Spectroscopic studies of the nuclear gas in NGC1275 show lines with widths corresponding to velocities of several thousand kilometres per second. Immediately outside the nucleus, gas is present moving with a velocity of approximately 3000kms-1 relative to the centre of the galaxy. Direct photographs taken in the light of the H? line centred on each velocity system have been taken by American astronomers . They clearly show the remark¬able extent of the filamentary structure which was presumably generated by an enormous explosion in the centre of the galaxy. In some respects the filamentary structure is reminiscent of that of the Crab Nebula, The optical continuum from the nucleus of NGC 1275 has a considerable non-thermal component which is polarized in the ultra violet.

The radio structure of NGC 1275 is complex; it has a number of discrete components with sizes ranging from nearly 100 kpc down to 0.1 pc. The compact core is variable at radio wavelengths.

The activity in the Perseus cluster is not restricted to NGC 1275: there is evidence that the influence of this dominant Seyfert galaxy emanates throughout the cluster. For example, a large, low-brightness halo of radio emission extends through the cluster. The other bright galaxy in the cluster, NGC 1265, has a most unusual radio structure , with the appearance of a galaxy moving through space trailing radio-emitting clouds out behind it. Astronomers are not agreed as to the reason for this structure but it is known that NGC 1265 has a considerable velocity (2500 km s-1) relative to the cluster as a whole. Probably the radio blobs are indeed being shed by NGC 1265 as it travels through the extremely tenuous intergalactic medium in the cluster. It is not clear whether NGC 1275 is itself a radio galaxy or whether the radio emission is generated by the motion of the galaxy through the intergalactic medium in the cluster. The Perseus cluster is also a strong X-ray source and there are another two much weaker radio-trail sources in the cluster.

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