NGC 3972 along with NGC 3977 are listed together as Holm304 in Erik Holmberg'sA Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.[8] This grouping is purely optical, as NGC 3977 is about four times farther away than NGC 3972.[9]
NGC 3972 is a radio galaxy, i.e. a galaxy with giant regions of radio emission extending well beyond its visible structure.[10]
SN 2011by (type Ia, mag. 14.2) was discovered by Zhangwei Jin and Xing Gao in China, on 27 April 2011.[11][12] It was ten days short of maximum, and positioned at an offset 5.3″ east and 19.1″ north of the galactic nucleus.[13]
^Holmberg, Erik (1937). "A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems". Annals of the Observatory of Lund. 6: 1. Bibcode:1937AnLun...6....1H.
^"SN2011by". Transient Name Server. IAU. Retrieved 4 September 2024.
^Boyd, David (September 2011). "SN 2011BY - A Type 1A Supernova in NGC 3972 Discovered before maximum". British Astronomical Association Variable Star Section Circular. 149 (149): 10–12. Bibcode:2011BAAVC.149...10B.
^"SN2021acna". Transient Name Server. IAU. Retrieved 4 September 2024.