Harold Corwin

IC 629 = NGC 3312. This is the identity that Bigourdan published in his big table without comment. So, we can only speculate as to why he thought he had a new nebula when he first went over the field.

Perhaps it was John Herschel's slightly uncertain north polar distance. In his first observation of it on 26 March 1835, he says "... PD only correct to the nearest minute." His polar distance is not, however, marked uncertain. But in his second observation four nights later, he says "No PD taken, a hurried observation, and the wire mistaken ([RA] rectified in reduction)."

Curiously, his single polar distance is two arcminutes south of that in the NGC (which is just an arcminute south of the modern position for the galaxy). No other observers are credited with observing this, so either Dreyer or John Herschel made a mistake in transcribing the NPD into the GC and/or NGC, or John Herschel has other observations that his did not include in his CGH volume.

In any event, Bigourdan's object is certainly the same as John Herschel's and the identity is sure.

― IC Notes by Harold Corwin

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