Barnards Galaxy (NGC 6822)

NGC 6822
NGC 6822: Image taken with the 2.2 meter MPG/ESO telescope of the ESO Observatory on La Silla in Chile [275]


This irregular dwarf galaxy was discovered on 17 August 1884 by American astronomer Edward Emerson Barnard using the 6 inch Cook refractor at Vanderbilt Observatory in Nashville, Tennessee. Barnard's galaxy was recorded as NGC 6822 by Dreyer in his «New General Catalogue of Nebulae and Clusters of Stars», published in 1888. Due to a series of confusions with later observations by Herbert Howe and Max Wolf, who used larger telescopes and did not see the galaxy as a whole, the same object was included in Dreyer's later «Index Catalogue» with the designations IC 1380 for a single H-II region and IC 4895 for the whole group of H-II regions in the galaxy. [313, 314, 315]

In 1925 Edwin Hubble published a study about NGC 6822 as a remote stellar system lying outside our galaxy. He identified ten H-II regions, which he designated with roman letters: Hubble I through X (IC 1308). [618]

Hubble-X (IC 1308)
Hubble-X (IC 1308): Image taken with Hubble Space Telescope. © ESA/Hubble & NASA [276]

Physical Properties

Like our Milky Way and the Andromeda galaxy, NGC 6822 belongs to the Local Group. At a distance of about 1.6 million light-years, it is closer than the Andromeda galaxy, but measures just 8000 light-years in diameter. Numerous H-II regions heated by young hot stars are evidence of active star formation. The stellar population is comparable to that of the Magellanic Clouds. The image in Fig. 1 was taken with four different filters (B, V, R, and Hα) and measures 34' x 35'. [4, 196, 274, 275]

Fig. 2 shows a Hubble Space Telescope image of the H-II region of the active star-forming region Hubble-X (IC 1308). This glowing cloud of gas is about 110 light-years across and hosts several thousand newly formed stars at its center. Hubble-X is many times larger and brighter than the Orion Nebula, which is about the size of the small, poorly resolved nebula below. [276]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Name RA Dec Type bMag vMag B-V SB Dim PA z D(z) MD Dreyer Description Identification, Remarks
NGC 6822 19 44 56.6 -14 48 23 Gx (IBm) 9.3 8.7 0.6 14.4 15.4 × 14.2 5 -0.000190 0.500 vF, L, E, dif IC 4895; MCG -2-50-6; DDO 209; IRAS 19421-1455; Barnard's galaxy
IC 1308 19 45 05.2 -14 43 17 GxyP 14.0 0.6 0.500 eF, eS, lE, gbM, 6822 p 12s LBN 83; part of N 6822
IC 4895 19 44 56.6 -14 48 23 dup 9.3 8.7 0.6 14.4 15.4 × 14.2 5 -0.000190 0.500 Group of neb, 25' diam NGC 6822; MCG -2-50-6; DDO 209; IRAS 19421-1455; Barnard's galaxy

Finder Chart

Neighboring dwarf galaxy NGC 6822 is in the constellation Sagittarius, actually closer to Capricornus. It is slightly west of midpoint between α12 Capricorni and υ Sagittarii. It is best seen from May to September. The apparent size of the dwarf galaxy and the low surface brightness assume a dark southern sky.

Finder Chart Barnards Galaxy (NGC 6822)
Barnards Galaxy (NGC 6822) in constellation Sagittarius. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

400 mm Aperture: In the 21 mm Tele Vue Ethos (85x), only a large, diffuse hint of the dwarf galaxy NGC 6822 can be seen with indirect vision, barely brighter than the sky background. With O-III filter Hubble X (IC 1308) is not visible. — 400 mm f/4.5 Taurus Dobsonian, Gurnigel, 19. 8. 2023, Bernd Nies

Objects Within a Radius of 15°