Andrew Cooper
Jun 7, 2005    Whipple Obs., Green Valley, AZ (map)
46cm f/4.5 Deep Violet

Large, dim, no distinct core in slightly brighter central region, large dim halo with hints of structure, particularly an arc to the south of the core, NGC4625 is 8' northeast, 11th magnitude star 3.5' south

Harold Corwin

IC 3667 = NGC 4618, and IC 3675 = NGC 4625. I have no idea how these identities came about, aside from a coincidence of oversight by both Max Wolf (in whose 5th Konigstuhl list the IC objects first appear) and Dreyer. The NGC and IC positions are vitually identical in both cases, and Wolf's descriptions -- liberally sprinkled with exclamation points -- leave no doubt as to which objects he saw on his plate (the correct objects are clearly marked on the print of the plate that I've compared to POSS1). Perhaps both astronomers were becoming bored with long lists of faint nebulae by 1904 and just didn't do the careful checking needed.

Whatever the case, there is no doubting the identities. The second has been noted in several galaxy catalogues (RC1, MCG, etc.), but the first has been overlooked. I suspect that the feeling, on seeing an IC number attached to an 11th magnitude galaxy, was one of disbelief; or that the number must belong to a knot in the galaxy (IC 3668 is in fact such a knot, and IC 3669 is the south-southeastern arm). But this is all speculation, with none of the principals now alive to tell us what really happened.

― IC Notes by Harold Corwin

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

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