Harold Corwin

IC 2998 may be one of the galaxies in the NGC 4092 group -- but this isn't likely as Bigourdan has good measurements of all the others (though he lists NGC 4095 under the number "4098"). He has just one "observation" of IC 2998, and it consists only of a scanty description. He gives no offsets, not even estimated ones. The comparison "star" he lists is NGC 4099 with its NGC position. His note says only: "Object seen only once, then lost from view, the sky having become a little worse. One of d'A's new nebulae could be identical to one of H's. All the nebulae in the group are pretty insignificant except for GC 2714 [NGC 4099] which is pretty well seen."

The CR paper, from which Dreyer correctly copied the IC position, has 11 58 46, 68 28 as the 1860.0 position (with NPD rather than declination which Bigourdan later adopted for his big tables). The CR description is "vF nebula, neighboring but distinct from the nebulae in the area listed in NGC." In his tables of new nebulae, the 1900.0 position becomes 12 00 59, +21 11 with the brief comment "Only glimpsed."

Precessing these positions to a common equinox shows immediately that they are about 10 arcmin apart, with the later position being just over an arcmin northeast of NGC 4098 = NGC 4099 (which see for its own problems). Bigourdan has no discussion of how he derived the two different positions, so we have no way of knowing which to accept. I've put them both in my position list -- no guessing here!

In fact, it does not matter which position we go to -- there is no nebula at either one. I think that this, like IC 2997, is probably an illusory "nebula" picked up in a moment of fatigue, or while pushing too hard against the limit of the telescope.

― IC Notes by Harold Corwin

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