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NGC 6816 (15,864 of 18,816)

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NGC 6816

NGC 6816, ESO 460-30, LEDA 63587, MCG-05-46-006, SGC 194056-2831.3, h 3800, GC 4509

RA: 19h 44m 2.23s
Dec: −28° 24′ 3″

Con: Sagittarius
Ch: MSA:1410, U2:380, SA:22

Ref: SIMBAD

(reference key)

Type: galaxy, S0

Mag: B=?, V=?

Size: 1.621′ x 1.174′
PA: 77°

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 6816. RC3 is indeed wrong on this as it followed ESO and RNGC. SGC got the wrong galaxy, too, and as Steve Gottlieb noted earlier, JH's original description of the position of the star (six arcmin north) is correct.

Looking at GC, I see that the description is exactly the same as in NGC; it does not follow the Cape of Good Hope description. So, the modification of the description is due to John Herschel himself, not Dreyer. JH must have done this to save space, though how he decided to place the star preceding as well as north is a mystery to me. He also apparently mistook the nucleus of ESO 460-G030 for one of the "vS stars" around the bright star 6' north.

Herbert Howe (1898, MN 58, 515) also has a curious observation of this object: "In this is a star of mag 13.5. h noted a '* np.' I saw only a star of mag 14 at an angle of 20 degrees and a distance of 30 arcsec. The sky was dull, so that the nebula was difficult to measure." I see his "star" of mag 13.5; it looks like it is actually a superposed interacting galaxy. Howe also did not publish his position; this means that he found that the original position to be correct to within two arcmin. However, there are no stars 30 arcsec away at PA = 20. There are stars at about this PA, but they are 14 arcsec and 55 arcsec away from the nucleus of the galaxy. I wonder if Howe somehow picked up the wrong object. Well, whatever the case, while there are some unsolved mysteries here, the identification of N6816 is clear.

Historical observations

John Herschel (1847) Cape Observations

Discovered by Sir John Herschel at the Cape of Good Hope with an 18-inch f/13 speculum telescope. He recorded it as "eF, R, vlbM, 40 arcseconds, a star 9m north of it, at 6' distance has what may be easily taken for a nebula attached to it, but it is only a little group of vS stars."

Published comments

Bailey, S.I. (1913)

Bailey, examining a Bruce plate (Harvard Annals, Vol 72, No 2), describes it as "probably a double of triple star, possibly nebulous."

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 16.0 mag galaxy. Their coded description reads E,SLEL,DKPCHS,*NR P.

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