Harold Corwin

IC 1487 = NGC 7649. Swift's position for NGC 7649 falls close to the brightest galaxy in the cluster Abell 2593, so there is no mistaking that identity. However, his position for IC 1487, which he found two years later, is very close to a fainter galaxy in the cluster. Just an arcminute or so to the southeast of this object is the second brightest cluster member, a double galaxy taken by Herbert Howe as IC 1487. He clearly described the two stars close to it, but makes no mention of the fainter galaxy at Swift's position.

Swift's description of IC 1487, however, says, "8 m * f, F * nr nf" (he goes on to say "not [GC] 4659" = NGC 7653, some distance away from the cluster, so that turns out to be irrelevant to the discussion). Keeping in mind Swift's 32-arcmin field, his two stars are easy to pick out. They point to NGC 7649 as the most likely candidate as Swift's second object.

There is the possibility that Howe's galaxy is in fact Swift's object, but that would require that Swift's "F * nr nf" actually be a "F * nr np." While there are a lot of errors of this sort in Swift's lists (e.g. NGC 6039, which see), it's easier to accept his observation at face value and think that he simply picked up the brightest cluster galaxy a second time. (He, in fact, has rediscovered galaxies in several instances; see, for example, IC 1270 = NGC 6488, and NGC 6497 = NGC 6498; and for a particularly striking example, the bright southern pair IC 5003 = IC 5029 = IC 5039 = IC 5046 and IC 5007 = IC 5030 = IC 5041 = IC 5047.)

― IC Notes by Harold Corwin

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