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Type: galaxy, Sc
Mag: B=12.4, V=?
Size: 2.454′ x 2.454′
Synonyms: H VI-041
Discovered in 1797 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "round, resolvable, about 3' diameter, vgbM. I suppose it to be a cluster of stars extremely compressed. 300 power confirms the supposition, and shews a few of the stars; it must be immensely rich."
Hinks, A. R. (1911) On the galactic distribution of gaseous nebulae and of star clusters. MNRAS, 71(8), 693-701.
p 697: The only difficulty in discussing the distribution of globular clusters arises from the fact that some of the objects described in the NGC as globular clusters are really spiral nebulae. Prof Bohlin has called attention to this .. and gives as an instance: NGC 628 = M74, which is described by Rosse, and photographed by Roberts (vol ii,. p 67) and by Keeler (Crossley, plate 4) as a fine spiral, though in the NGC it is described as a globular cluster.
Two other instances are NGC 6221 and NGC 6412, both of which are really spirals."
Listed as No. 38 in Arp's "Atlas of Peculiar Galaxies" (Astrophysical Journal Supplement, vol. 14, 1966.) He remarks "small ring in arm on north side, part of large ring on east side shows in hydrogen-alpha only."
Charlier, C V L (1931) "Stellar clusters and related celestial phaenomena", Lund Annals 2, 14, No. 19. Charlier examined prints from the Franklink-Adams atlas; "Table 6 gives a list of those objects in Bailey's catalogue for which the globular character is uncertain or not probable..."
NGC 6412 Remarks: "Not found by Bailey."
(Sulentic and Tifft 1973) notes that this is a 12.5 mag galaxy. Their coded description reads SC,R,STELNUC,DKLNS PD,KNOTTY.
Sandage, A. & Tammann, G. A. (1975) Steps toward the Hubble constant. V - The Hubble constant from nearby galaxies and the regularity of the local velocity field. ApJ, 196, 313-328. [1975ApJ...196..313S]
(Astrophysical Journal, 196, 313-328) includes this galaxy in the NGC 6643 Group. Members include NGC 6217, NGC 6340, NGC 6412, NGC 6643 & NGC 6654.
G. de Vaucouleurs ("Galaxies and the Universe", Chapter 14 - Nearby Groups of Galaxies) notes that the five brightest members of the NGC 6643 group are NGC 6643, NGC 6217, NGC 6340, NGC 6412 & NGC 6654. NGC 6503 is a foreground member, and NGC 6621 is a background member.
de Vaucouleurs, G. (1975) Nearby groups of galaxies. In: Kuiper, G. (ed) Stars and Stellar Systems. Volume 9: Galaxies and the Universe. Chapter 14, p557.
Foreground NGC 6503; background NGC 6621.
Brightest members: 6643 ( B(0) = 11.97), 6217 ( B(0) = 12.17), 6340 ( B(0) = 12.21), 6412 ( B(0) = 12.62), 6654 ( B(0) = 12.80).
POSS: m11 * 2' SE; m9 * ~4'.2 S; m9.5 ~7'.5 SSW. these three form string
~7' long in 30cm obs. m14 * 1'.0 SSW on edge of neb.
15cm - nope.
- mod br @ 50x N of m8 *. has m13.5 * just off SW edge. m11.5 * SE. diam
of circ gx sl lgr than sep of these two *s, or about 2'. wk even concen
to sub*ar nuc. BS, 29Jun1992, Anderson Mesa.
25cm - vf glow N of m8 *, just NW of m10 *. other f *s nrby. 1' diam w/o cen
condens. 190x best.
30cm - f, fairly losfcbr. N of a 6' string of three m10-11 *s in pa30.
threshold * on S edge, 1' from cen. sl smooth concen. 2' diam, circ.
The Messier objects
The Bennett objects
The Caldwell list
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