NGC 6166

NGC 6166 is a supermassive, type cD galaxy, with several smaller galaxies within its envelope.

Suspected to have formed through a number of galaxy collisions, NGC 6166 has a large number of globular clusters (estimated as between 6,200 and 22,000 in 1996) orbiting the galaxy. A 2016 study, however, gave an even higher number (around 39,000) suggesting also that the halo of this galaxy blends smoothly with the intra-cluster medium. Because of that, the galaxy has the richest globular cluster system known. The galaxy harbors a supermassive black hole at its center with a mass of 28.4 billion ^+2.7
_−1.8 M_☉, nearly 30 billion M_☉ based on dynamical modelling.

NGC 6166 is known to host an active nucleus, classified as an FR I source, which powers two symmetric parsec-scale radio jets and radio lobes. These are caused by the infall of gas into its center due to a cooling flow that deposits 200 solar masses of gas every year there.

It has been proposed that a number of O-type stars may be present in the center of NGC 6166.

Two supernovae have been observed in NGC 6166:

• SN 2009eu (Type Ia, mag. 19.5) was discovered by Lick Observatory Supernova Search (LOSS) on 21 May 2009.
• PSN J16283836+3932552 (Type Ia-91bg, mag. 19.5) was discovered by R. Gagliano, D. Post, Jack Newton, and Tim Puckett on 15 May 2015.