Courtney Seligman

The position precesses to RA 09 41 47.9, Dec +12 26 01 (whence the position above), but there is nothing there. It is generally assumed that Swift actually observed Javelle's IC 555, and simply made an error of 10 arcmin in its declination. However, aside from the fact that this would still put Swift's position well to the southwest of IC 555, the descriptions of the two objects are completely different.

So it seems far more likely that Swift observed a different, fainter galaxy (in which case he would still have had to make a large error in its position), or mistook a faint stellar object for a nebula (which, given his description of the object seems by far the most likely, but since there are no obvious stellar matches near his position, is still not at all certain).

Which if any of the possibilities might be correct is a mystery, as there is no reasonable alteration of Swift's position that fits any of them; so the best description of IC 554 appears to be, as noted above, "lost or nonexistent".

― Courtney Seligman, Celestial Atlas

Harold Corwin

IC 554 = IC 555. Though there is a fainter galaxy near the nominal position for IC 555 (at 09 40 12.3 +12 36 44, B1950.0), it is more likely that Swift saw the same brighter object that Javelle did and made a 10 arcmin error in the declination.

― IC Notes by Harold Corwin

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

A complete list of credits and sources can be found on the about page