Hickson 57, Copelands Septet

Hickson 57
Hickson 57: Copelands Septet in Leo; 500 mm Cassegrain 3625 mm f/7.2; SBIG STL11K; 120+40+40+40 min LRGB; Bernese Highlands; © 2011 Radek Chromik

History

This group of galaxies was discovered on February 9, 1874 by the British astronomer Ralph Copeland with Lord Rosse's 72 inch reflecting telescope in Birr Castle. [277]

Physical Properties

The visual magnitudes between 13.6 mag to 15.2 mag challenge larger amateur telescopes from approx. 14 inches to a duel. Especially the weaker galaxies of the seven are not easy to capture. NGC 3745 is one of the most difficult galaxies with 15.2 mag. NGC 3746, NGC 3748, NGC 3750, NGC 3751 and NGC 3753 have visual magnitudes of 14.2 mag, 14.8 mag, 13.9 mag, 13.9 mag and 13.6 mag. The galaxy NGC 3754, which is close to NGC 3753, is another tough nut to crack with 14.3 mag.

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 3746, HICK 57B11 37 43.6+22 00 33SBRM1.1 x .514.89025127
NGC 3745, HICK 57G11 37 44.6+22 01 15L M.4 x .216.19413
NGC 3748, HICK 57E11 37 49.1+22 01 33L M.7 x .415.78989
NGC 3750, HICK 57C11 37 51.7+21 58 26L M.8 x .714.99064
NGC 3753, HICK 57A11 37 53.8+21 58 51S M1.7 x .514.58717120
NGC 3751, HICK 57F11 37 54.0+21 56 10L M.8 x .515.395925
NGC 3754, HICK 57D11 37 55.1+21 59 08S M.4 x .314.79012

Finder Chart

The galaxy septet is located in the constellation Leo. Left behind on the lion, near δ Leonis on the extension of two stars with 4.5 mag and 5.2 mag is the septet.

Leo: Hickson 57
Chart Hickson 57
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

350 mm Aperture: The somewhat distant galaxy NGC 3751 can be easily and reliably recognized with a 14-inch device with averted vision. In the first group of three with NGC 3750/53/54, verifying the faint galaxy NGC 3754 is difficult because it almost merges with the neighboring galaxy NGC 3753. In the second group of three with NGC 3746/45/48 the middle galaxy NGC 3745 with 15.2 mag is at the same time the weakest and most difficult galaxy.

To see all seven galaxies, you need an extremely transparent sky and a larger amateur telescope. With an aperture of 14 inches, the lower limit is certainly exhausted. More aperture makes all galaxies more safely accessible and verifiable. [192]

14" PWO-Dobson, F:4.6 / TV-Nagler 13mm, 123x, 0.67° und TV-Radian 8mm, 200x, 0.3°
Eduard von Bergen, 2005

References

144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); cdsarc.unistra.fr/viz-bin/cat/VII/119 (2021-02-18)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
192Deep-Sky Guide; fernrohr.ch/1d_deep-sky-guide.html (2020-12-25)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)