English: This ultra-deep, high-resolution image of the peculiar galaxy Centaurus A (NGC 5128) was created from data collected over ten years (2013–2024) using homebuilt telescopes. The total exposure time is 321 hours, including 126 hours of narrowband H-alpha and O III. The image is entirely starless: every point of light is either part of the Centaurus A system or a distant background galaxy or quasar.

The image reveals numerous unique and scientifically interesting features. The full extent of the H-alpha and O III filaments associated with the relativistic jets is visible, including detailed structure within both the inner and outer regions of the northern (bottom) jet. The southern (top) jet is seen as a faint red patch at the 10 o’clock position, a feature first detected optically by the author in 2013. The complete system of stellar shells surrounding Centaurus A is clearly resolved, from the faint outer shells to the brighter inner ones. A distinct blue arc—likely the remnant of a disrupted dwarf galaxy—is also visible. A total of 1,108 globular clusters are identifiable in this field, and the background contains countless distant galaxies and quasars.

The image is a 2×2 mosaic, with earlier 130-hour data merged into the central region. To create an accurate starless image that removes Milky Way foreground stars while preserving extragalactic sources, GAIA DR3 data were used to identify and remove only true stars. Every remaining point source is therefore either a globular cluster of Centaurus A, a background galaxy, or a quasar.

The full extent of Centaurus A’s halo is revealed, including its concentric stellar shells—remnants of past mergers with smaller galaxies. Simulations of galaxy interactions show that such shells form when merging galactic cores orbit their common centre of mass while their halos are disrupted, sending stars onto eccentric orbits. These stars create outward-propagating density waves that manifest as shell structures until the system eventually settles into a single, larger galaxy.

Centaurus A is the nearest radio galaxy and contains an active galactic nucleus (AGN) powered by a supermassive black hole. Magnetic fields in the accretion disk help collimate oppositely directed jets of relativistic plasma. These jets produce strong synchrotron radiation detectable at radio wavelengths, and large radio lobes extend far beyond the galaxy.

A complex system of reddish H-alpha filaments lies along the northern jet, including a bright inner filament with sprite-like extensions roughly 30,000 light-years from the core, and a larger filament beginning about 65,000 light-years out. Both extend from the core toward the lower right (4 o’clock position). The 126 hours of narrowband data reveal extremely faint structures in these filaments. A small red smudge on the opposite side of the core (10 o’clock position) marks ionised gas associated with the southern jet, first detected optically by the author. The brightness asymmetry between the jets is consistent with relativistic beaming and is a well-known phenomenon also seen in active galaxies such as M87.

Centaurus A lies about 11 million light-years away in the constellation Centaurus. It is the nearest active galaxy and one of the most studied objects in the sky. Its true classification remains debated: it has been described as a lenticular or giant elliptical galaxy. The prominent dark dust lane is the remnant of a recent merger with a spiral galaxy, which likely triggered intense star formation. The resulting young, massive stars give the dust lane region its distinctive blue glow.