Copeland's Septet, Leo
Latest Images
Solar system
Calibrate monitor

  Copeland's Septet (Hickson 57)

Hickson 57 is a compact group of eight galaxies in the Constellation of Leo that are interacting and possibly merging. The group is also known as Arp 320 and VV 282. This group was first named "The Septet" by Ralph Copeland (1837-1905), while employed as an observer under Lord Rosse, Earl of Parsonstown, Ireland. He probably first observed the group while using the 72-Inch "Leviathan of Parsonstown" at Birr Castle. This speculum mirror telescope, built by Lord Rosse, enabled Copeland to observe this cluster with relative ease. This can be seen in the NGC descriptions he provided for members of this cluster. His original NGC descriptions for this group were pB (pretty bright) for members NGC 3745, 3746, 3748, 3750, and 3753. His original description for NGC 3751 was F (faint), while his original description for NGC 3754 was vF (very faint). Ralph Copeland later went on to take spectral measurements of the supernova S Andromeda in 1885, travel overseas to view the conjunction of Venus with the sun, and once visited the famous 19th century optician, Alvan Clark, in the United States. He also served as Astronomer Royal of Scotland between 1889-1905.

Dr. Paul Hickson included this group as Number 57 in his "Atlas of Compact Groups of Galaxies". Hickson notes for No. 57: "...... Redshifts have been measured for 7 members, and are all found to be accordant. The small compact galaxy NGC 3754 interacting with the bright spiral NGC 3753 is a radio and infrared source."

Barred Spiral Galaxy NGC 3746 (Hickson 57b) was the host galaxy for Supernova 2005ba. This galaxy was also the host for Supernova 2002ar, a Type Ia that reached a maximum magnitude of 16.5. A rough distance estimate to NGC 3746 and SN 2005ba is 480 million light years.

Comparison Image

  Location J65, Celbridge Observatory
  Date/Time (UTC) 24 May 2006, 22:20
  Optics 200mm SCT, F6.3 reducer
  Filters None
  Imager Meade DSI-C
  Mount Astro-physics 1200GTO
  Exposure details 44 images * 60 seconds
  Software MaximDL, Photoshop 7
© David McDonald 2012 Updated 10 June 2012