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Type: supernova remnant
Mag: B=?, V=?
NGC 7822. I wonder about JH's declination for this. He has only one observation of it, and places it quite definitely 1.5 degrees north of the center of a huge HII region that would match his description pretty well. Here is what he has to say about it:
The central part of what I am positive is an enormously large, but extremely faint nebulosity of a round figure, though I cannot trace its limits. The night exquisite. I swept often across it to be sure, but always recurred to the same place. No doubt but can never be seen but in the best state of air and sky. Diameter 10 arcmin +-.
Dreyer attached two notes to the object, one in NGC itself: "Not seen at Birr Castle in two observations. It is, however, far north of the Zenith, and the speculum may have tilted." In the 2nd IC, he says briefly, "40' diameter, many stars involved (Roberts, MN lxviii, 301)."
Roberts's description, from three 90-minute plates taken in 1901 and 1902, is clearly that of the large nebula south of JH's position. Roberts notes three pretty bright stars involved (BD +66 1675, 1676, and 1679) which make it quite clear that he thought N7822 to be the HII region. I'm puzzled, though, that neither he nor Dreyer mentioned the differing declinations. I also find JH's diameter estimate to be puzzling. Usually, a 10 arcmin diameter would rate a description of "vL", not "eeL".
Also, there is, centered just a few arcmin south of JH's place, a "wing" of the nebula that could possibly be the object that he saw. But it is fainter than the main part of the object. Perhaps the northern part happened to be in the sweep on that "exquisite" night, while the brighter central portion was passed over in another sweep on an average night. Whatever the case, this fainter wing is a possible candidate for N7822, also.
However, I'm going to follow Roberts and Dreyer in adopting the HII region as the object that JH probably described, and assume that his declination represents an error of some sort. So, it gets the colon, while the northern wing gets the question mark. I've put the position for the HII region midway between the latter two BD stars in Roberts's note.
The HII region, by the way, is Cederblad 214B. It is incorrectly listed as a reflection nebula in at least one catalogue, and various pieces of it have ended up with separate numbers in Lynds's catalogue of bright nebulae. See Dixon's "Master List" for a complete list of the various names.
This bright nebula was observed by Sir John Herschel, who described it as "a remarkable object, most extremely faint, most extremely large."
Dreyer notes: "Not seen at Birr Castle in two observations. It is, however, far north of the Zenith, and the speculum may have tilted."
Ced 215 (NGC 7822)
Position (1900): RA 23 59.6, Dec + 68 0
Star: Cl (Mp=6.0:, SpT=A0, ?)
Spectrum of nebula: continuous spectrum (observed)
Classification: Nebulous cluster (milky neb cover the clusters, eg NGC 1976)
Notes: "NGC 7822 = GC 5051 = h 2302. R. The coordinates and the description given by John Herschel must refer to the nebulous cluster containing the HD stars: +68 1423 = HD 225123, and +67 1588 = HD 224825. Compare (630) Pl 20. (114, 304, 631). "
(Astrophysical Journal Supplement, No 105, 1965) in her Catalogue of Bright Nebulae notes that this nebula is moderately bright, more prominent on the red POSS plate and has a maximum size of 20' x 4'.
(Sulentic and Tifft 1973) notes that this is a diffuse nebula.
by Jim Lucyk: Astronomy mag. 11/85 p49, Deep Sky #17 Wi86 p14, Vehrenberg's Atlas of DS Splendors (3ed) p11, Vehrenberg's Atlas of Galactic Neb-1 p1 & 2.
15cm - don't see any convincing neb @ 30x or 50x w/[OIII] or UHC. broad region
of *s centered ~15' SE of triangle of m7-9 *s plotted on U2000. grp is
45' diam, looks like abs hole. BS, 26Oct1992, Anderson Mesa.
The Messier objects
The Bennett objects
The Caldwell list
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