| NGC 3021 | |
| Type: | SA(rs)bc, 4.0 |
| Appmag V: | 10.88 |
| Appmag B: | 12.54 |
| Absmag V: | −21.25 |
NGC 3021 is a spiral galaxy in the northern constellation of Leo Minor. It is about 93 million light-years away from Earth, and is receding with a heliocentric radial velocity of . This galaxy was discovered December 7, 1785 by Anglo-German astronomer William Herschel. The morphological classification of NGC 3021 is SA(rs)bc, which indicates a spiral galaxy with no central bar (SA), an incomplete inner ring structure (rs), and moderate to loosely wound spiral arms (bc).
The galaxy contains many Cepheid variable stars. These stars have been used to measure the distances of galaxies. This galaxy was also used to help refine the measurement of the Hubble constant.[1]
On November 1, 1995, S. Pesci and P. Mazza in Milan, Italy reported the discovery of a supernova in the NGC 3021 galaxy. G. M. Hurst in England confirmed the finding, estimating the magnitude at 13.2. Designated SN 1995al, it was offset west and south of the galactic nucleus. The spectrum matched a type Ia supernova and was found to be similar to SN 1981b near maximum. On 18 February 2023, a second supernova appeared in this galaxy: SN 2023bvj (Type II, mag. 17).[2]