Harold Corwin

IC 346 has three observations, one by Frank Muller (on 21 Oct 1887, called number 171 in the first volume of Leander McCormick Publications), the second by Ormond Stone (on 21 Sept 1889 -- though I suggest another year below -- called 151 in the same list), and a final one by Lewis Swift (on 5 Oct 1896, number 60 in his 11th list in AN 3517). Dreyer put number 151 into the 1st IC as IC 346, but somehow missed number 171. In the Notes to IC2, he says this about IC 346: "The place and description should be 03h 35m 26s, 108d 43.0', eF, pL, E 80d, dif (my mistake). Is no doubt identical with Sw. XI. 60: 03h 35m 13s, 108d 39.8'."

Dreyer is certainly right about the equality of Swift's and Muller's nebulae. The position and description from both of their observations is also correct, while there is nothing at Stone's position. I'm puzzled, though, by Dreyer's parenthetical comment, "my mistake". How did he know he made a mistake? Perhaps Stone or Muller wrote to him? A search of his correspondence, if it still exists, could clear this up.

But this also leaves us with the question of Stone's observation. There is certainly nothing near his place, and I wonder if the date of his observation is correctly given in the list. The printed date is "[18]89.724"; I have a suspicion, based on Stone's use of the same comparison star that he claimed to have used for the missing IC 339 (which see), that the date might be "87.724", the same night he observed IC 339. If this speculation is true, then Stone may have used the same misidentified comparison star for both observations.

Ignoring the date for the moment, I searched the area in and around the NGC 1407 group for a star-galaxy pair that Stone might have seen. If his data for number 151 refer to IC 345 (rather than IC 346), then his comparison star could well be UCAC4 359-004084. The declination difference would be about 10 arcseconds too small with this star, but that may be within the realm of Stone's usual errors.

Summing up, we will take Dreyer at his IC2 word and assign the number IC 346 to Muller and Swift's galaxy. That leaves us with Stone's observation reported in IC1; I've called this "IC 346.1" in the big table where I suggest again that it just might be IC 345 measured with the misidentified comparison star.

Also see IC 2090 for another missing object where IC 346 plays a small role.

Finally, I thank Courtney Seligman for bringing this to my attention in March of 2013. Courtney suggests that the star nearest Stone's position for number 151 might be the object intended. In its favor, this suggestion agrees with Stone's estimated magnitude ("14.") and size ("0.1" arcmin). So, while this is certainly a possibility, I'm still skeptical that this is will prove correct because the position is far enough off the star to make the identity doubtful -- Stone claims twelve comparisons in RA and four in declination; he should have done better with that many observations. (The star's proper motion is small, too -- 2.0 milliarcseconds per year in RA, and -6.7 mas/yr in Dec. These would contribute very little to an offset (0.22 and 0.74 arcsec) between the modern position precessed back to Stone's observation epoch, and Stone's own position reduced from the modern data for his comparison star). However, it is as good a suggestion as any, so I've listed the star in the table. Please read Courtney's analysis of the situation, too, at http://cseligman.com/text/atlas/ic3.htm#ic346 . He may be able to convince you where he has only suggested a possible solution to me.

Whatever happened, there are question marks galore for this observation of Stone's.

― IC Notes by Harold Corwin

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

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