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NGC 757
NGC 757
History and Accurate Positions for the NGC/IC Objects (Corwin 2004)
NGC 757 = NGC 731. Both N757 and NGC 763 (which see) were found by Ormond Stone with the Leander McCormick 26-inch, presumeably on the same night, though he doesn't give us the dates in the discovery paper. He has, however, left us a sketch of N763 labeled "Drawn Jany 11.0 1886, sketched Jany 4.5 1885" where the "1885" pretty clearly should be 1886 (there are a couple of other sketches from early 1886 where the dates are given correctly).
In any event, this is the western of two relatively bright galaxies in the area, found by WH early in 1785 (the other, as I noted, is NGC 755 = NGC 763). Taking Stone's poor positions into account, the true position difference of the two galaxies pretty well matches the difference in Stone's positions for his two nebulae. In addition, his descriptions match the galaxies very well, particularly his estimated magnitudes and diameters (N757: m = 11.0, D = 0.4 arcmin, gbMN; N763: m = 13.0, D = 1.6 x 0.4 arcmin, PA = 65 deg, gbMN).
Even though WH's relative positions are good (though his declinations are about 4 arcmin too far north), JH had trouble with these two objects. Though he claims his Slough observation is for one of his father's objects, and his Cape observation is for the other, neither of his positions is very good. I suspect that both observations refer to the brighter western galaxy, N731. Peters got things sorted out when he micrometrically remeasured the galaxies' positions (see his second Copernicus article and his discussion in AN 2365). Dreyer adopted Peters's good positions for the NGC.
Finally, my identification of both N757 and N763 with NGC 755 in the early versions of ESGC is wrong.
Published comments
Helwan Obs. Bulletin No 22 (1921)
No nebula here. Exposure 60 minutes.
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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Favourite lists
Lacaille's catalogue
The Messier objects
Dunlop's catalogue
The Bennett objects
The Caldwell list
Named DSOs
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