NGC 3521

NGC 3521 is a flocculent^[4] intermediate spiral galaxy located in the constellation Leo. Its velocity with respect to the cosmic microwave background is 1167 ± 26 km/s, which corresponds to a Hubble distance of 56.1 ± 4.1 Mly (17.21 ± 1.26 Mpc).^[1] However, 26 non-redshift measurements give a much closer distance of 37.17 ± 1.83 Mly (11.395 ± 0.56 Mpc).^[5] It was discovered by German-British astronomer William Herschel on 22 February 1784.^[6][7]

NGC 3521 imaged by R Jay GaBany

NGC 3521
NGC 3521 imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
Constellation	Leo
Right ascension	11h 05m 48.581s[1]
Declination	–00° 02′ 09.11″[1]
Redshift	0.002672[1]
Heliocentric radial velocity	801[2] km/s
Distance	37.17 ± 1.83 Mly (11.395 ± 0.56 Mpc)[1]
Apparent magnitude (V)	11.0[1]
Characteristics
Type	SAB(rs)bc[2]
Size	~146,000 ly (44.75 kpc) (estimated)[1]
Apparent size (V)	11.0′ × 5.1′[1]
Notable features	HII LINER
Other designations
Bubble Galaxy[3], IRAS 11032+0014, UGC 6150, MCG +00-28-030, PGC 33550, CGCG 010-074[1]

NGC 3521 has a morphological classification of SAB(rs)bc,^[2] which indicates that it is a spiral galaxy with a trace of a bar structure (SAB), a weak inner ring (rs), and moderate to loosely wound arm structure (bc).^[8] The bar structure is difficult to discern, both because it has a low ellipticity and the galaxy is at a high inclination^[2] of 72.7° to the line of sight.^[4] The relatively bright bulge is nearly 3/4 the size of the bar, which may indicate the former is quite massive.^[2] The nucleus of this galaxy is classified as an HII LINER,^[9] as there is an H II region at the core and the nucleus forms a low-ionization nuclear emission-line region.

NGC 3521 is structurally similar to the Milky Way; additionally, its supermassive black hole has a similar mass to that of the Milky Way, at about 7 million solar masses.^[10]

Supernova

One supernova has been observed in NGC 3521: SN 2024aecx (Type Ic, mag. 14.543) was discovered by ATLAS on 16 December 2024.^[11] Astronomers originally classified it as Type IIb, but spectroscopy suggests this supernova is very similar to SN 1994I.^[11]