Harold Corwin

Steve Gottlieb emailed a note in July 2017 asking about this number. Steve says of the galaxy that usually carries the IC number, "Even in my 24-inch, this was a faint galaxy (V ~15), and I really doubt that it could have been picked up by Bigourdan."

Bigourdan says of this (my translation), "An object [of magnitude] 13.4-13.5 whose existence is certain and which could be a mixture of small stars and nebulosity." He saw this on just one night (6 September 1891) and estimated its position with respect to NGC 6338 as +28 seconds and -5 arcminutes 30 arcseconds. As with IC 4649 = IC 1252 (which see), some kind of bookkeeping error led him to include it in two of his lists of new nebulae: It is Big 430 = Big 541. I wondered if this might be a duplicate observation of IC 4649, but Bigourdan saw both objects on that same night in September 1891.

His estimated position is somewhat north of the galaxy usually taken as IC 4650, NPM1G +57.0229 = 2MASX J17154740+5718066. This, like IC 1252, is a member of the tight group around NGC 6338 -- but unlike IC 1252, the position is in an empty part of the sky. However, there are about a dozen faint stars -- centered at roughly 17 15 50, +57 17.7 -- scattered around the NPM1G galaxy, covering an area of roughly 3.2 by 1.8 arcminutes. The NPM1G galaxy is in the northern part of this asterism, and there are two fainter galaxies to the south, neither of which would be visible in Bigourdan's 30-cm refractor. Unfortunately, Bigourdan gives us no idea of the size of his object, so I am reluctant to assign the IC number to the asterism as his "novae" are usually much smaller.

Steve has suggested that one or the other of the two stars 0.7-0.8 arcminutes north of NPM1G +57.0229 might be the object that Bigourdan picked up. While I think this is unlikely because of the faintness of the stars (both are around V = 16), we still note it as a possibility.

For consistency with the few modern catalogues which list it, I will keep the IC number on the NPM1G galaxy, though with a query. This one, lacking a micrometric observation from its discoverer, is still a bit of a mystery.

― 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