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NGC 6421 (14,672 of 18,816)

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NGC 6421

NGC 6421, ESO 393-22, h 3702, GC 4324

RA: 17h 45m 44.1s
Dec: −33° 41′ 34″

Con: Scorpius
Ch: MSA:1438, U2:377, SA:22

Ref: NGC/IC

(reference key)

Type: star cloud

Mag: B=?, V=?

Size: 45′
PA: ?

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

NGC 6421 is a brighter patch in the Milky Way that matches JH's description and sketch pretty well. His position is pretty good, too. Note, however, that the NGC description (taken from GC) is wrong. The correct description, from the CGH Observations, should read something like "Cl, vL, r, connected to Milky Way." I suspect that the NGC description was copied by mistake from the CGH entry for h3702 = N6416.

There is also a prime symbol missing from the 3702 in the JH column in the NGC. Neither this object nor N6415 were numbered in the CGH Observations, and JH does not have a note for either in GC indicating why he entered them there. Dreyer copied the entries unchanged into NGC, also without notes.

Historical observations

NGC/IC Dreyer (1888, 1895, 1908)

Recorded in the NGC as "Cl, vL, pRi, stars 8..12" The NGC assigns h3702 to both NGC 6416 and NGC 6421.

John Herschel

In the Cape Observations, John Herschel recorded h3702 and an anonymous object on different occasions. The latter object's coordinates correspond with the recorded position for NGC 6421 in Dreyer's NGC. Herschel sketched it, calling it "a most remarkable, well insulated, semi-nebulous milky way patch of a branching rounded figure, within the limits of the field, quite insulated on the preceding, north and following side, and only connected on the southern side by a narrow isthmus with a brnach of the milky way, which runs meriodionally to a great extent. It forms a VI class cluster of the utmost tenuity, barely resolvable, not resolved. See fig 1, plate V."

Plate 5 Fig 1

Published comments

SAC database

The SAC database comments: "hotly debated, large cluster between M6 & M7"

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a nonexistent object. Their coded description reads NF S.

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