NGC 867 has long been considered to be the same object as NGC 875, discovered by d'Arrest over 80 years later. However, Herschel's position for the object listed as NGC 867 was very poor, and Corwin has recently suggested that depending upon a possible misidentification of the star Herschel used to measure the position, the object could be IC 225. With more than a century of tradition behind the identification with NGC 875, it seems reasonable to accept that; but it now appears that what Herschel actually observed is essentially unknown. Because of that, any discussion of the physical nature of the objects which might or might not be NGC 869 is best covered at the linked entries.

Per Dreyer, NGC 869 (= Hipparchus, 1860 RA 02 09 15, NPD 33 29.9) is "a remarkable object, cluster, most very large, very rich, stars from 7th to 14th magnitude". (Since Hipparchus couldn't have studied the cluster in such detail, the description is by (or contemporaneous to) Dreyer.) The position precesses to RA 02 19 03.4, Dec +57 09 05, about 1 arcmin north of the "current" position of the cluster, but well within its extended outline, and in any event the millennia of naked-eye observations would establish the identity. The designation of the star clusters has evolved over the last few hundred years. The last and greatest naked-eye observer, Tycho Brahe, measured a single position for the "nebulous star" which is the double cluster, and Johann Bayer designated that as χ Persei. The title "h Persei" was presumably assigned to some faint star in the same neighborhood at a later date. However, in about the 1840's it became common usage to designate the brighter western cluster as h, the fainter eastern one as χ, and that usage has stuck ever since. The point at which the stellar nature of the cluster was first noticed is not as clear, but it must have been known before 1654, when Hodierna listed the pair as #3 in his catalog of nebulous objects which were resolved into stars by a telescope. Recent studies of the two clusters have somewhat revised previous estimates of their nature. Previously, it was thought that they are about 7000 light years away, but more recent estimates are around 10000 light years. Similarly, earlier estimates of their ages, based on the hottest, brightest stars still on the Main Sequence, have been substantially revised upward (primarily because of a large number of B-emission stars, which make it difficult to determine the "turn-off" point), from around 5 million years to around 12 to 14 million years for h Persei, and from around 3 million years to about 10 million years for χ. Other estimates of the cluster characteristics remain as they were: They are separated by only a few hundred light years, and probably originated in the same star-forming region. Each cluster contains more than 300 blue white supergiants (very hot, very bright upper Main Sequence stars), which give off substantial amounts of UV and X-radiation as well as visible light, and since fainter stars are generally far more numerous than bright ones, the total membership of each cluster (including fainter stars) must measure in the thousands or even tens of thousands. Although hundreds of times younger than the Sun, the hottest, brightest stars in these clusters are near the end of their lives, and the most massive ones have already turned into red giants, the last stage of stellar "life". These red giants are particularly obvious in the eastern cluster, as seen in the images below. Each cluster is approaching us at a little over 20 km/sec, but the proper motions and space velocity are probably unknown.

See the discussion of NGC 867 concerning the possible (probable?) identity of the two NGC objects. Given the uncertain identification of NGC 867, for the purposes of this tabulation d'Arrest is treated as the actual discoverer.

Per Dreyer, NGC 884 (= Hipparchus, 1860 RA 02 12 35, NPD 33 32.0) is "most remarkable object, cluster, very large, very rich, ruby star in middle". (Since Hipparachus couldn't possibly have studied the cluster in such detail, the description is probably taken from John Herschel's GC 521.) The position precesses to RA 02 22 26.6, Dec +57 06 36, about 21.6sE and 1'12"S = 5.5 arcmin south of the "current" position of the center of the cluster, but dead center on the "ruby star" stated as being in the middle of the cluster, so the identification is certain (and in any event, the millennia of naked-eye observations would establish the identity). See NGC 869, or h Per, for a detailed discussion of the clusters.

NGC 891 is about 100 thousand light years across, and 30 million light years away. Edge-on to our line of sight, it shows dramatic dust lanes bisecting its disk, while numerous tendrils of dust extend for hundreds of light years above and below the plane of the disk. (Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT, apod020703; Copyright CFHT).