Harold Corwin

IC 3807 may be NGC 4705. It is the only galaxy within several degrees of Swift's position that comes close to matching his description: "eeF, L, eE; 7m * nr s little f." However, the star is northeast, not south-southeast as Swift implies. If so, this just another of his mistakes in noting relative positions. At least Swift's RA matches the NGC galaxy, though the declination is about 48 arcminutes off.

I looked for another galaxy at a declination digit (10 and 20 degrees south) and sign (+3 rather than -3) away from his nominal position -- nothing at all. I have not yet checked at digit errors in RA hours, but there is certainly nothing at +- 1 minute, +- 10, or +- 20 minutes of time.

My feeling is that this is another case like IC 3166/3180 (which see): the NGC galaxy is probably Swift's object, but we have only circumstanstial evidence of the match. With the position so far off, and the direction of the star being different from Swift's description, I am not very comfortable with the hypothesis. But it is the only one we have, so I am going to reluctantly equate the two numbers, though with appropriate question marks.

The magnitude of the star is V = 9.22, by the way, and it is 4.85 arcmin from NGC 4705. If this is Swift's object, the star would have been well within his field radius of 16 arcmin, and the magnitude is at least in the ballpark for a rough estimate. Another note: there are no stars brighter than about 11 or 12 within 15 arcminutes of Swift's nominal position.

― 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