Copeland Septet

{{Short description|Group of galaxies in the constellation Leo}}

{{Infobox galaxy cluster

| name =

| image = Copeland_Septet_group_of_galaxies.jpg

| alt =

| caption = A group of galaxies nicknamed the Copeland Septet, in the constellation of Leo.{{cite web|title=Giant Map of the Sky Sets Stage for Ambitious DESI Survey|url=https://noirlab.edu/public/news/noirlab2103/|access-date=3 February 2021}}

| credit =

| epoch = J2000

| constellation = Leo

| ra = {{RA|11|37|50.5}}

| dec = {{DEC|+21|59|06}}

| brightest_member = NGC 3753

| member_no =

| parent =

| major_axis_mpc =

| minor_axis_mpc =

| richness =

| bmtype =

| velocity_dispersion =

| redshift = 0.0304

| distance = {{convert|132|Mpc|Mly|0|abbr=on|lk=on}} {{hub|67.3}}

| temperature =

| mass = {{val|6.1|1.0|e=14}} {{hub|50.00}}

| luminosity = {{val|e=41.98|u=erg·s⁻¹}}

| flux =

| notes =

| other_names = HCG 57

| names =

| references =

}}

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.{{cite web |title=NAME COPELAND SEPTET |url=http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=NAME+COPELAND+SEPTET&bibdisplay=none |accessdate=12 October 2018}}{{cite book |last1=Bakich |first1=Michael E. |title=1,001 Celestial Wonders to See Before You Die: The Best Sky Objects for Star Gazers |date=July 10, 2010 |publisher=Springer Science & Business Media |isbn=9781441917775 |page=72 |url=https://books.google.com/books?id=ofVGAAAAQBAJ&dq=copeland%27s+septet+galaxies&pg=PA72 |accessdate=12 October 2018}} The group was discovered by British astronomer Ralph Copeland in 1874. The location of Copeland's Septet is right ascension {{RA|11|37|50}} / declination {{DEC|+21|59}} (2000.0), about three degrees northwest of third magnitude star 93 Leonis.

The redshift of the brightest member, NGC 3753 places Copelands Septet as a part of the Coma Supercluster.{{Cite journal |last=Jaffe |first=W. |last2=Gavazzi |first2=G. |date=1986-02-01 |title=Radio continuum survey of the coma/A1367 supercluster. II. 1.5 GHz observations of 396 CGCG galaxies. |url=https://ui.adsabs.harvard.edu/abs/1986AJ.....91..204J |journal=The Astronomical Journal |volume=91 |pages=204–216 |doi=10.1086/114001 |issn=0004-6256}}