Harold Corwin

Bigourdan's first observation of this is an asterism of about a dozen faint field stars covering an area of around 1.7 x 1.0 arcmin. Bigourdan himself suspected that the object might consist of stars "at the extreme limit of visibility," and notes that it was difficult to measure. In fact, his first two measurements on 20 Sept 1884 are quite discordant, being more than 20 arcsec apart.

His third measurement twelve years later on 29 Oct 1896 is not even of the same clump of stars, but is a smaller and fainter asterism of four stars over three arcmin away. Though I've given positions for both in the table, I've taken the first set of stars as the IC object as that is the one published in Bigourdan's Comptes rendus list that Dreyer incorporated into the first IC.

Reinmuth could not find the object on the Heidelberg plates that he examined, so questioned if it might be the same as NGC 6892. It isn't; NGC 6892 is a different clump of four stars. Bigourdan's measurements under the NGC number refer to the right asterism. Since he found and measured I1312 on two of the same nights as NGC 6892, the objects must be different.

Looking for this again in March 2018, I don't even see the first clump of a dozen stars I noted many years ago. This may well be one of Bigourdan's "fausse images".

― IC Notes by Harold Corwin

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