NGC 1566 is the brightest member of a nearby group of galaxies
in Dorado and is at a distance of about 50 million light years.
Apart from its beautifully symmetrical, tightly-wound spiral arms,
the galaxy is of interest because it has a very luminous nucleus
which has many of the characteristics of a quasar, though it is
much less energetic. Galaxies of this type are known as Seyfert
galaxies, after Carl Seyfert who first recognised their peculiar
nature in 1943. The active region at the centre of NGC 1566 has
recently been found to vary on a timescale of less than a month,
which indicates that it is extremely compact. Spectra show that hot
gas near the tiny nucleus is moving at an abnormally high velocity,
suggesting that it may be in orbit around a massive black hole at
the heart of NGC 1566.
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