 A group of galaxies nicknamed the Copeland Septet, in the constellation of Leo.[1] | |
| Observation data (EpochJ2000) | |
|---|---|
| Constellation | 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)×1014h−1 50.00[4] M☉ |
| X-rayluminosity | 1041.98 erg·s−1[4] |
| Other designations | |
| HCG 57 | |
TheCopeland Septet (also Copeland's Septet, Hickson Compact Group 57) is agroup of galaxies in the constellation Leo that includesNGC 3748,NGC 3754,NGC 3750,NGC 3751,NGC 3745,NGC 3753 andNGC 3746.[5][6] The group was discovered by British astronomerRalph Copeland in 1874. The location of Copeland's Septet isright ascension11h 37m 50s /declination +21° 59′ (2000.0), about three degrees northwest of third magnitude star93 Leonis.
The redshift of the brightest member,NGC 3753 places Copelands Septet as a part of theComa Supercluster.[7]
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