NGC 3261

Lore & Background

NGC 3261 was discovered by John Herschel on March 15, 1836. It has a low surface brightness bar with a bright nucleus, and at the end of the bar lies a nearly complete inner pseudoring formed by the spiral arm. From this ring emanate two diffuse spiral arms that can be traced for more than half a revolution; the east arm is better defined than the west arm but becomes diffuse at about two-thirds of its length. The spiral pattern is between a grand design galaxy and a multiple arms pattern, with at least ten spiral fragments visible.

The galaxy is the main member of the NGC 3261 Group (also known as LGG 198), which according to Garcia also includes NGC 3256 and NGC 3256C. Four companion galaxies are visible south of NGC 3261, two of them lying close to it. NGC 3261 lies about 9 degrees south of the Antlia Cluster, which lies at a similar redshift.

Two supernovae have been observed in NGC 3261. SN 1997Z was discovered on 10 February 1997 by R. Martin, A. Williams, and S. Woodings, Perth Observatory, at an apparent magnitude of 15.5, and was identified as a Type II supernova several months post maximum. SN 2008fw was discovered on 19 September 2008 at an apparent magnitude of 14.3, lying 52" west and 30" south of the galaxy center; spectral analysis showed it was a Type Ia supernova near maximum light.

Reader's Guide

NGC 3261 is significant as the main member of the NGC 3261 Group, a small galaxy cluster that includes NGC 3256 and NGC 3256C. Its barred spiral structure, with a low surface brightness bar, bright nucleus, and nearly complete inner pseudoring, places it in an intermediate category between grand design and multiple-arm spiral galaxies, exhibiting at least ten spiral fragments. The galaxy's proximity to the Antlia Cluster at a similar redshift provides context for studying galaxy interactions and group dynamics. The two recorded supernovae—SN 1997Z, a Type II event discovered several months after maximum, and SN 2008fw, a Type Ia supernova near maximum light—offer data points for stellar evolution and distance measurements. The presence of four companion galaxies south of NGC 3261, two of which lie close, suggests ongoing gravitational interactions that may influence its spiral structure and star formation. Its discovery by John Herschel in 1836 adds historical depth to its study.