Harold Corwin

Bigourdan's single estimated position from an observation on 11 July 1887 lands not far from an edgewise galaxy. Yet he calls it a star cluster, so there has been some question about the identification. His full description is informative: "Object which, at first sight, could be nebulous, but in which I suspect several stellar points. It is therefore a cluster enveloped in nebulosity; it is vaguely elongated at 90 degrees and is 1 arcmin long by 40 arcsec wide."

Reference to the field shows the galaxy surrounded by three stars. Could one or more of these be Bigourdan's "stellar points"? Perhaps the nucleus of the galaxy also appeared stellar under the conditions prevailing when Bigourdan made his observation.

In any event, there is no problem with the identification. The PA of the galaxy, by the way, is about 95 degrees, close to Bigourdan's estimate.

That was how things stood until I received a fairly surprising email in June of 2014 from Steve Gottlieb -- he pointed out that William Herschel actually mentioned this object. In his observation of NGC 5712, Herschel writes, "It [NGC 5712] is preceded by a S patch of sts which appears almost like this nebula, but more resolved." He calls NGC 5712 itself "vF, S, r"; so the fact that the preceding patch is "more resolved" is significant.

And it agrees with Bigourdan's observation of nearly a century later. Yet the IC object is clearly a galaxy. Its edge looks a bit serrated in the DSS2 images, so it's possible that it is an edgewise late-type galaxy with bright knots included.

In any event, here is another object that was known before the NGC, yet did not receive an NGC number. At least it got picked up for the IC! There is, of course, an entry for this in the "notngc" files.

― IC Notes by Harold Corwin

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