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NGC 6847 (15,936 of 18,816)

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NGC 6847

NGC 6847, LBN 151, Sh 2-97, LBN 066.74+00.86, II 202, GC 4527

RA: 19h 56m 37.7s
Dec: +30° 12′ 46″

Con: Cygnus
Ch: MSA:1172, U2:119, SA:8

Ref: NGC/IC, SIMBAD, DAML02

(reference key)

Type: open cluster

Mag: B=14.72, V=13.06

Size: 30′
PA: ?

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

NGC 6847 may be the cluster and HII region 1 degree north and 30 seconds west of WH's single position. There is certainly nothing near his place, and these objects may well be the ones he saw. They are immersed in a fairly large star cloud in the Milky Way, which might have led to WH's comments about the surround area. His full description, given by Dreyer in the Collected Papers of 1912, reads, "A resolvable nebulous patch; there are great numbers of them in this neighborhood like forming nebulae; but this is the strongest of them; they are evidently congeries of small stars."

Another possibility is raised by Dreyer's note in the NGC, "Not noticed by d'A, who has 2 observations of GC 5947 = m 403 [= NGC 6842, a planetary]." Is N6842 the object that WH saw? It is just 2 minutes of time preceding and 3 arcmin south of his position. There may be enough stars around the nebula to lead to WH's description, but I suspect not.

Two other possibilities are nearby on the POSS prints. First is a clump of stars about 20 arcmin north of WH's position. The second is another clump about 55 arcmin south. Neither of these, however, has "great numbers" of similar clumps nearby.

Dreyer notes that Bigourdan found no nebulosity at WH's place, though he searched the area four times. His one micrometric observation (I haven't reduced it) probably points at a double or multiple star. There are many of them around.

Finally, using the POSS1 overlays, I thought that this might be identical to " NGC 6846 " (which see). However, the overlay copies RNGC's 2 degree error in the declination for N6846 so that it lands on top of the cluster and HII region I noted at the beginning of this story. N6846 is not these objects, though as I said, N6847 might just be.

Historical observations

William Herschel (c.1784)

Synonyms: H II-202

Discovered in 1784 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "A resolvable nebulous patch of stars." In the Notes, Dreyer quotes from the Register: "Sweep 239, July 17, 1784. 'A resolvable nebulous patch; there are great numbers of them in this neighbourhood like forming nebulae, but this is the strongest of them; they are evidently congeries of small stars.' According to Bigourdan, there is no second class nebula here; a region rich in stars, but if there is any nebulosity about it, it is very diffused (4 obs.)." in the Notes to the NGC, Dreyer comments that it was not noticed by d'Arrest.

Published comments

Sulentic & Tifft (1973)

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

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