Harold Corwin

IC 1234 is a star -- though it does not match Bigourdan's description very well. He says (roughly translated by me; pardon my French!): "Object of doubtful appearance, which could be formed from stars 13.5 with a little nebulosity; it is completely imperceptible and a little elongated toward the position indicated for NGC 6262."

He has two observations of it on the night of 5 Sept 1888. They do not agree very well, with differences of 0.95 seconds in RA, and 12.7 arcsec in Dec. Nevertheless, the mean of the two leads us unambiguously to the star.

Earlier I wrote:

I should note that the identity of Bigourdan's comparison star is not quite secure. He places it -6 seconds and -7 arcmin from BD +57 1713; there is no star there. However, there are several stars scattered around including a noticeably brighter one 3 arcmin to the south. The identity of I1234 rests on our accepting this as Bigourdan's comparison star for his two measurements.

This is wrong. There is a roughly 2 arcminute error in the BD declination of BD +57 1713. Once that is taken into account, Bigourdan's offsets lead us directly to his comparison star. As it happens, I got the right one when I went over the field years ago, so there is no problem with accepting the identity.

Or is there? Using the same comparison star, Bigourdan measured the position of NGC 6262 (which see for its own story). But that turns out to be another of his "fausse images", though two stars near the position he measured are actually on the sky where he says they are.

Given that, I am now wondering if IC 1234 might not be simply another eyepiece illusion. The star is within Bigourdan's rather large measurement errors (see above), but it is quite faint. Could he have actually seen it?

Whatever happened, colons are now on the identification of the star.

― IC Notes by Harold Corwin

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