NGC 684

NGC 684
NGC 684 (SDSS)
Observation data (J2000.0 epoch)
Constellation	Triangulum
Right ascension	01h 50m 14.0407s [1]
Declination	+27° 38′ 44.472″ [1]
Redshift	0.011798 [1]
Heliocentric radial velocity	3537 ± 1 km/s [1]
Distance	135.03 ± 3.13  Mly (41.400 ± 0.960  Mpc) [1]
Group or cluster	NGC 684 group (LGG 32)
Apparent magnitude  (V)	12.50 [2]
Apparent magnitude  (B)	13.30 [2]
Characteristics
Type	Sb edge-on [1]
Size	~137,500  ly (42.15  kpc) (estimated) [1]
Apparent size  (V)	3.2′ × 0.6′ [1]
Other designations
IRAS 01474+2724, IC 165, UGC 1292, MCG +04-05-017, PGC 6759, CGCG 482-022 [1]

NGC 684 is a spiral galaxy approximately 135 million light-years away from Earth in the constellation of Triangulum. ^[1] It was discovered by William Herschel on October 26, 1786. ^[3] Edward Swift, Lewis' son, found this galaxy again on 18 Jan 1890 while "searching for Swift's Comet." and it was reported as a new object in list IX-6. ^[3]

NGC 684 Group

NGC 684 is the largest member of a group of galaxies named after it (also known as LGG 32), which includes the galaxies NGC 670 and IC 1731. ^[4]

Supernovae

Two supernovae have been observed in NGC 684:

• SN 2021ass (type II, mag. 18.1122) was discovered by the Zwicky Transient Facility on 18 January 2021. ^[5]
• SN 2025aml (type II, mag. 18.1168) was discovered by the Zwicky Transient Facility on 31 January 2025. ^[6]

See also

• Spiral galaxy
• List of NGC objects (1–1000)
• Triangulum (constellation)

References

1. "Results for object NGC 0684". NASA/IPAC Extragalactic Database. NASA and Caltech . Retrieved 4 December 2017.
2. "Revised NGC Data for NGC 684". spider.seds.org. Retrieved December 9, 2017.
3. "Data for NGC 684". www.astronomy-mall.com. Retrieved December 9, 2017.
4. Garcia, A. M. (1993). "General study of group membership. II. Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100: 47. Bibcode:1993A&AS..100...47G.
5. "SN 2021ass". Transient Name Server. IAU . Retrieved 4 September 2024.
6. "SN 2025aml". Transient Name Server. IAU . Retrieved 31 January 2025.

External links

• Media related to NGC 684 at Wikimedia Commons
• NGC 684 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
• SEDS