NGC/IC Project Restoration Effort

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NGC863

 

Basic Information


Location and Magnitude


Right Ascension: 2:14:33.5
Declination: -0:45:58
Constellation: CET
Visual Magnitude: 12.9

Historic Information


Discoverer: Herschel W.
Year of discovery: 1785
Discovery aperture: 18.7

Observational


Summary description: vF, R, bM, stellar
Sub-type: Sa

Corwin's Notes

===== NGC 863 = NGC 866 = NGC 885 and company. The problem here is what to do with the five observations reported by Lewis Swift in his fifth "catalogue" of nebulae, published in Astronomische Nachrichten No. 2763 (Vol. 116, page 33, 1886). All five received NGC numbers: 856, 859, 866, 868, and 885. So, in addition to NGC 863, found by William Herschel (H III 260), there are six numbers in the area and but only three fairly bright galaxies. NGC 863 itself is no problem. The NGC position, from JH's observations, is very good (there is a 30 second error in WH's RA; see Dreyer's note in his edition of WH's Scientific Papers). It obviously pins down the brightest of the galaxies in the area (which, by the way, is Markarian 590). Another of the galaxies is very nearly as bright (Mark 590 and this second galaxy are listed at m_p = 14.0 and 14.4, respectively, in the CGCG), and I'm a bit surprised that the Herschels did not see it. These two are obviously the two brightest that Swift found on the night of 3 October 1886 (N859 and N866, numbers 23 and 24, respectively, in his AN list). The relative positions that he gives them are correct -- "np of 2" and "sf of 2." The declinations are not too bad, but the RA's are out. The third object that he found that night is NGC 868; the position is not too bad, and the description (what there is of it: "eF, pS, R") is appropriate. Swift returned to the area on 31 October of the same year, finding two more objects. The first of these, NGC 856 (the 22nd object in Swift's list), has a good position, and the description ("eF, S, lE, F * close") is again appropriate. The star was measured by both Bigourdan and Howe, and is about a minute of arc east and slightly north of the galaxy. The second object, NGC 885 (number 27), has -- if my conjecture is correct -- the largest positional error of any of Swift's five objects here: five minutes of time in RA. Swift's declination is good. What I believe happened on this night is that Swift simply rediscovered the two brightest galaxies. So, NGC 859 = NGC 856 and NGC 885 = NGC 863. His descriptions of the brightnesses of the two objects, though, is systematically fainter -- "eF" vs. "pF" for the fainter of the two, and "vF" vs. "pF" for the brighter -- than on his earlier night's observations. This suggests to me that the sky was not as good on this second night as on the first, or that Swift was then simply noting nebulae as fainter. The right ascension problem for NGC 885 is, I believe, one of Swift's large random errors that are littered throughout his lists. For example, in the same list, NGC 1689 (found 22 October 1886) is also five minutes out, being = NGC 1667. Another example: NGC 1037, also in the same list, has as a part of its description "[GC] 581 in field." This means that GC 581 = NGC 1032 must be within 16 arcminutes of Swift's object (Swift was using an eyepiece that had a field diameter of 33 arcmin), but his declination for NGC 1037 is 2 deg 49.7 arcmin different from NGC 1032's declination! In summary, then, I think that my original assignments of the NGC numbers are probably correct, though we do not have the evidence to be absolutely sure. The observations reported by Herbert Howe in M.N. 68, 356, 1898, and 69, 29, 1900, support my position: he could not find NGC 859, NGC 866, and NGC 885, though he reports observing NGC 856, NGC 863, and NGC 868. Bigourdan also has observations of only three objects here, though he assigns a different number to the faintest: NGC 859 rather than NGC 868. I've yet to sort out his data completely, however.

Steve's Notes

===== NGC 863 17.5" (12/4/93): fairly faint, very small, round, fairly concentrated, very small bright core, stellar nucleus. NGC 856 is 14' WNW and NGC 868 21' ENE.