Harold Corwin

IC 2131 = IC 422. This is one of the galaxies that actually gives us a bit of insight into Dreyer's working methods. In the introduction to IC2, he makes no mention of any correspondence with Lewis Swift -- yet that must have happened in this case (see also I2129 = I2130 for another instance of Swift's published data, the description in that instance, not agreeing with the IC2 data).

The position for IC 2131 given in all of Swift's original papers is 05 29 53, -17 17.8 (precessed to B1950.0 from B1900), a bit off the galaxy to the southwest. Yet the IC2 carries the position 05 30 03, -17 15.4, very close to the actual position, and very close Javelle's micrometrically measured position given in IC1 for I422. So, Dreyer obviously had some additional input from Swift on this object.

Along with other evidence in the IC itself (e.g. the many unpublished IC nebulae credited to Barnard), this suggests that Dreyer had an extensive correspondence with the astronomers working in the field of nebulae. If this correspondence still exists, it may be another source of data that we can use to help debug the IC's.

About this object: there is no question about the identity. The positions and descriptions are too similar. Again, I'm faintly surprised that neither Dreyer nor Swift caught the identity.

Given the frequency of such positional coincidences (see e.g. IC 2123 = IC 412 and IC 2124 = IC 413), I am beginning to wonder if IC2 was a bit of a chore for Dreyer, taken on not out of any lingering love for cataloguing new nebulae, but simply from a sense of duty. This is just a suspicion at the moment. I suspect that Dreyer's correspondence -- if it still exists -- might offer more clues.

― IC Notes by Harold Corwin

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