Harold Corwin

IC 1279 = IC 1281. Swift found this galaxy twice, first on 18 Oct 1887, then on 28 May 1896. Dreyer suspected the identity and queried it in IC1; Howe looked at the field (see MNRAS 61, 29, 1900) and found only one "vF, pS" object (Howe's micrometric position is within a few arcseconds of the modern ones). Dreyer correctly took this to confirm the identity of Swift's two objects, and reported it in an IC2 note.

Coincidentally, Swift's positions (copied correctly into the IC) fall near two of its galaxies, CGCG 1809.5+3559 and CGCG 1809.8+3558, the second actually a pair. So, Zwicky and Herzog assigned the two numbers to what they thought were the appropriate galaxies; the rest of us have, unfortunately, followed these mistaken identities for nearly half a century.

I noticed the problem in October 2013 because Swift's description of his "second" nebula (IC 1279) reads, "eeF, S, cE; semicircle of sev sts nr f." I was curious -- could Swift have seen both galaxies in the CGCG pair? They are not only aligned north-south, but their major axes are also aligned. Perhaps Swift saw both, and mistook it for a single object.

But there is no "semicircle" of stars following (east) of the pair. Widening the DSS field to look for these stars, I found them preceding (west), following IC 1279. Looking at Swift's description for that, I read "eeeF, pS, R; in a semicircle of st.; eee diff." That clinched the identity that Dreyer had suggested and Howe had confirmed.

By the way, Swift's position for IC 1279 is about 10 seconds of time too small in RA (18 09 21, +36 01.2; B1950.0), while his position for IC 1281 (18 09 51, +36 00.7; B1950.0) is about 20 seconds of time too large in RA. His declinations for both observations are within two arcminutes of the galaxy. Compare them, too, with the CGCG positions, and you'll see why Zwicky and Herzog assigned the IC numbers as they did.

― IC Notes by Harold Corwin

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

A complete list of credits and sources can be found on the about page