NGC/IC Project Restoration Effort

===== NGC 6331. There is a single observation by WH who says "eF, S. 320 shewed [sic] it better." CH lists two offsets in her fair copy of the sweep, the main one being the one that WH published in his Third Catalogue: 21min 18sec preceding and 1deg 25arcmin south of "4 Cephei of Bode's Cat." which is HD 158996. This star has a high proper motion (+56.6 mas/yr in RA and +207.1 mas/yr); this may have influenced its corrections to WH's observations in the sweep. They are a minute of time and 3 arcminutes off those for the other two stars in the same sweep, so it is not a particularly good reference star. The other star that CH lists is "2 Cephei of Bode's Cat."; this is HD 152303. It is written in an otherwise small space in the sweep in a bit of a cramped hand; I suspect it was added later when CH noticed that "4 Cephei" gave a different correction than the other two stars. In any event, the offsets she gives for the observation are 22 min 55 sec following and 59 arcminutes north of the star. I've reduced WH's observation with respect to both stars, and as you'll see in the position table, his position using HD 152303 is considerably closer to the position provided by Bigourdan, and to the modern positions. There are a couple of unusual aspects of the object that might affect its identification, though the corrected position (and Bigourdan's observation) pretty well pin it down as the brightest object in the cluster Abell 2256. First, the object is a triple system. This might have reduced its visibility a bit, but the blended image seems to have been the only one in the cluster that WH and Bigourdan saw. This is a bit curious as the 2nd and 3rd brightest galaxies are only 0.1 and 0.2 magnitudes fainter, and are just 2 arcminutes to the east. NGC 6331 must have been right at the limit of visibility for both of the keen-eyed observers to miss the companions. In any event, neither of them saw any other galaxies in the cluster.

===== NGC 6331 24" (8/7/13): brightest member of Abell Galaxy Cluster 2256 and first in a 6' string to the east containing a total of 6 galaxies. At 375x appeared fairly faint, fairly small, oval 5:3 NW-SE, ~30"x18", broad concentration, brighter core. This is a very close double system (two nuclei on the SDSS) with a companion on the NW side. A mag 13 star lies 1.8' E and this star is attached on the southwest side of CGCG 355-026. PGC 84834, an extremely faint and small galaxy lies 1.1' E, on line with the mag 13 star. Also in the string is UGC 10726 2.7' ENE, MCG +13-12-019 3.7' ENE, PGC 59471 4.4' SW and MCG +13-12-020 6' E. In addition, PGC 59495 lies 2.4' SW. UGC 10726: faint to fairly faint, irregularly round, ~35" diameter, broad weak concentration. This galaxy and NGC 6331 are the two largest in the cluster. MCG +13-12-019: faint, fairly small, round, 18" diameter. PGC 59471: extremely faint and small, only 6" diameter. MCG +13-12-020: very faint, small, round, 18" diameter, low even surface brightness. A mag 11.3 star is 1.4' E. PGC 59495: very faint, extremely small, round, 10" diameter. 18" (7/5/08): at 280x, appeared fairly faint, fairly small, elongated 2:1 WNW-ESE (a very faint companion at the WNW end may contribute to the impression of elongation), 40"x20", even surface brightness. Brightest in the core of distant AGC 2256 (~800 million light years) with 6 faint companions picked up within 6'. NGC 6331 is the first in a 3.7' curving chain of 5 galaxies extending to the east. A mag 13.9 star lies within this chain 1.7' E. 17.5" (5/14/88): faint, small, elongated NW-SE. A mag 13.5 star is 1.8' E. UGC 10726 lies 2.7' E. This is the brightest galaxy in AGC 2256 galaxy cluster and a triple system in a common halo.