John Herschel discovered NGC 1531 = h2620 on 19 Oct 1835 and recorded "faint, round, brighter in the middle, 60". The preceding of two [with NGC 1532]." His position (measured on 3 sweeps) is accurate.

300/350mm - 13.1" (12/22/84): moderately bright, small, slightly elongated. Forms a close pair with larger and brighter NGC 1532 1.6' SE.

900/1200mm - 48" (10/22/11): very bright, moderately large, oval ~2:1 NW-SE, 1.2'x0.7', well concentrated with a very bright core. Forms a beautiful pair with the stunning edge-on NGC 1532 and situated just 1.7' NW of the core of the larger galaxy. In addition, the major axis of NGC 1531 is angled directly perpendicular to the core of NGC 1532. Several stars surround the galaxy.

Notes by Steve Gottlieb