The Copeland Septet (also Copeland's Septet, Hickson Compact Group 57) is a group of galaxies in the constellation Leo that includes NGC 3748, NGC 3754, NGC 3750, NGC 3751, NGC 3745, NGC 3753 and NGC 3746.[5][6] The group was discovered by British astronomer Ralph Copeland in 1874. The location of Copeland's Septet is right ascension 11h 37m 50s / declination +21° 59′ (2000.0), about three degrees northwest of third magnitude star 93 Leonis.
 A group of galaxies nicknamed the Copeland Septet, in the constellation of Leo.[1] | |
| Observation data (Epoch J2000) | |
|---|---|
| Constellation(s) | Leo |
| Right ascension | 11h 37m 50.5s[2] |
| Declination | +21° 59′ 06″[2] |
| Brightest member | NGC 3753[3] |
| Redshift | 0.0304[4] |
| Distance | 132 Mpc (431 Mly) h−1 67.3[3] |
| Binding mass | (6.1±1.0)×1014 h−1 50.00[4] M☉ |
| X-ray luminosity | 1041.98 erg·s−1[4] |
| Other designations | |
| HCG 57 | |
The redshift of the brightest member, NGC 3753 places Copelands Septet as a part of the Coma Supercluster.[7]
See also
- Wild's Triplet
- Zwicky's Triplet
- Robert's Quartet
- Stephan's Quintet and NGC 7331 Group (also known as the Deer Lick Group located about half a degree northeast of Stephan's Quintet)
- Seyfert's Sextet
References
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