NGC 5394/5, Heron Galaxy

NGC 5394/5
NGC 5394/5: Pair of galaxies in Canes Venatici; 500 mm Cassegrain f/7.2; SBIG STL11K; 420-60-60-60 min LRGB; Bernese Highlands; © 2014 Radek Chromik

History

The pair of galaxies NGC 5394/5 was discovered on May 16, 1787 by the German-British astronomer William Herschel with his self-made 18.7 inch f/12.8 reflecting telescope in Bath, England. He cataloged it as I 190 and I 191. He noted: «Two. The south considerably bright, considerably large. The north pretty bright, small. Distance 1.5'.» The same night he discovered NGC 5380 (II 698). [464]

His son John found NGC 5378 with his 18.3 inch telescope 11 March 1831. The small galaxy IC 4356 was discovered on 19 June 1897 by the French astronomer Stephane Javelle using the 76 cm refractor telescope at the Observatoire de Nice. [196, 277]

Heron
Heron: The namesake for this pair of galaxies; © Bernd Nies

The pair of galaxies NGC 5394/5 is listed as VV 48 in the «Atlas and Catalogue of Interacting Galaxies» [432] published by B. A. Vorontsov-Velyaminov in 1959. In Halton Arp's 1966 «Atlas of Peculiar Galaxies», the two interacting galaxies below Arp 84 are found as an example of a galaxy with a large companion of high surface brightness. [199]

Because of the appearance of this unusual pair of galaxies, which resembles a heron standing in wait, it was nicknamed the «Heron Galaxy».

NGC 5394/5
NGC 5394/5: Image taken with the Gemini 8-meter telescope on Maunakea [507]

Physical Properties

NGC 5395 is a Seyfert Type II spiral galaxy. It is interacting with the smaller companion NGC 5354 which shows two open tidal arms and also starburst activity in its center region. This could be the result of a past collision, which was shown with model calculations. Distances to the galaxy pair NGC 5394/5 range from 50 Mpc to 54 Mpc (163 bis 178 million light-years). The larger galaxy (NGC 5395) is 140'000 light-years across and the smaller one (NGC 5394) is 90'000 light-years across. [145, 506, 507]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 537813 56 50.5+37 48 00SBR2.7 x 2.213.4301790
NGC 538013 56 56.7+37 36 33L1.9 x 1.913.23178
NGC 539413 58 33.7+37 27 18SB M1.7 x .813.73427
NGC 539513 58 38.2+37 25 32C M2.7 x 1.312.53488167
IC 435613 58 44.5+37 30 26C x 16.2

Finder Chart

Although the pair of galaxies are in the constellation Canes Venatici, it is better to use the constellation Bootes for finding. Extend the line connecting the two stars Nekkar (β Boötis) and Seginus (γ Boötis) by the same amount and set the outermost Telrad circle north of it at right angles. The best observation time is January to July, when the constellation is at its highest at night.

Chart NGC 5395
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

320 mm Aperture: The galaxy pair NGC 5394/5 is said to represent a gray heron. Only it was upside down or astronomically correct. The two parts of the galaxy could be seen well, with the smaller galaxy only revealing the bright core. The beak or the fine spiral arm was not visible. — 12.5" f/4.5 Ninja-Dobsonian, Glaubenberg, 25. 3. 2022, Eduard von Bergen

400 mm Aperture: At low magnification (21 mm Tele Vue Ethos, 85x) the galaxy pair NGC 5394/5 can be easily missed as it appears dimmer than the DSS overview map suggests. It reveals itself here only as an elongated, irregular nebula. At higher magnification (9 mm Nagler, 200x) the pair of galaxies becomes more visible. From the head of the heron (galaxy NGC 5394), however, only the core area can be seen. No spirals. This requires much more aperture. — Taurus T400 f/4.5 Dobsonian, Glaubenberg, 25. March 2022, 22:50 CET, SQM-L 21.1, Bernd Nies

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)
145SIMBAD astronomical database; simbad.u-strasbg.fr/simbad
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
196Celestial Atlas by Curtney Seligman; cseligman.com/text/atlas.htm (2020-12-28)
199Atlas Of Peculiar Galaxies, Halton Arp; ned.ipac.caltech.edu/level5/Arp/Arp_contents.html (2020-12-28)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; klima-luft.de/steinicke (2021-02-17)
432«The Atlas and Catalogue of Interacting Galaxies» B.A. Vorontsov-Velyaminov (Moscow 1959); ned.ipac.caltech.edu/level5/VV_Cat/frames.html (2021-09-25)
464«Catalogue of a second thousand of new nebulae and clusters of stars; with a few introductory remarks on the construction of the heavens» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1789; DOI:10.1098/rstl.1789.0021
506«The Interacting Galaxies NGC 5394/5395: A Post-Ocular Galaxy and Its Ring/Spiral Companion» Michele Kaufman, Elias Brinks, Bruce G. Elmegreen, Debra Meloy Elmegreen, Mario Klarić, Curtis Struck, Magnus Thomasson, and Stuart Vogel; The Astronomical Journal, Volume 118, Number 4, 1999; DOI:10.1086/301030
507noirlab1912 — Photo Release: A Galactic Dance; noirlab.edu/public/news/noirlab1912 (2022-03-29)