Caldwell 77 (North Up, East Left)
Caldwell 77, also known as NGC 5128, or Centaurus A, is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type (lenticular galaxy or a giant elliptical galaxy) and distance (10–16 million light-years). It is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers.  The center of the galaxy contains a supermassive black hole with a mass equivalent to 55 million solar masses, which ejects a relativistic jet that is responsible for emissions in the X-ray and radio wavelengths. By taking radio observations of the jet separated by a decade, astronomers have determined that the inner parts of the jet are moving at about one half of the speed of light. X-rays are produced farther out as the jet collides with surrounding gases resulting in the creation of highly energetic particles. The X-ray jets of Centaurus A are thousands of light-years long, while the radio jets are over a million light-years long. Like other starburst galaxies, a collision is suspected to be responsible for the intense burst of star formation. Models have suggested that Centaurus A was a large elliptical galaxy which collided and merged with a smaller spiral galaxy. This image comprises 7 x Luminance (60 seconds each) and 4 x Red, Green and Blue (60, 70 and 63 seconds each), 0.5m f/2.9 ASA Astrograph with FLI ML3200 camera at an altitude of 17 degrees on 13 March 2016. The fields of view of the images at the top and bottom are 34’ x 23’ and 18’ x 18’ respectively.
Hills Observatory: 1 January 2013 to 6 May 2018