The Radio Galaxy Cygnus "A"

The Radio Galaxy  Cygnus A

The faint 18th magnitude glow at the centre of this image is in fact 
the second brightest radio source in the entire sky. The image is a
4x40 second exposure with 50 cm f/4 Newtonian and SX CCD.

The optical counterpart of the radio emmission of Cygnus A was identified
in 1951 by the 200" Palomar telescope as a close pair of faint galaxies.
The radio emmitting region appearing in the lower inset image appears as
two huge lobes some twenty times as large as the visible object at 160 Kly
in length.

Cygnus A lies at a distance of 600 million light years. it is now believed
to be an active galaxy rather than two galaxies in collision.

Also shown are comparison images from the Digital Sky Survey (top right)
and HST image bottom left showing the galaxy resolved into a close pair.

Cygnus A is a real power house - its energy is equivalent to ten billion
Crab Nebulae (a single exploded star at a distance of 6000 light years).

D. Strange
Worth Hill Observatory
Dorset U.K.