NGC/IC Project Restoration Effort

===== NGC 3684 may be H II 160. Wolfgang Steinicke has recently (2013) suggested that WH's sweeps over this area only partially overlapped, so that he (WH) could not have seen N3686 in the second of them (sweep 198 on 17 April 1784). Therefore, Dreyer's suggestion that N3686 = III 28 is also H II 160, is probably incorrect. The equivalence with N3686 makes sense, however, given that the reduced position from WH's observation is just 1 minute of time more and at the same declination -- within the errors -- as the position for N3686. The difference for N3684 is half a minute of time, and 10 minutes of arc. A mistaken reading of a single minute of time seems more likely than errors in both RA and Dec, but the two errors are what Wolfgang is suggesting. Looking at CH's fair copies of the sweeps, I do not see information that can help determine the path of the telescope on the sky, so cannot reproduce Wolfgang's argument. The information may be in other of the Herschel Archive files that I haven't examined yet. In particular, there is a large section with CH's work on her brother's observations that may be quite helpful in circumstances like these. I have, however, re-reduced the observation of WH's nebula with all three stars that he observed in the sweep (81, 85, and 90 Leonis), and the positions are coincident to within WH's known errors. The problem therefore is certainly in the observation of the nebula itself. I also see in the fair copy that the nebula is the only one for which the time is recorded with minutes and seconds rather than minutes and decimals. Was there something special about this observation that WH has not told us? His full description, by the way, reads, "cL, R, brightest in the M, but the brightness goes off very gradually." This description could apply to either galaxy. A not-so-by-the-way: There is no problem with the NGC identifications of these two objects. JH adopted his own pretty good positions for them in GC, and Dreyer adopted very similar positions for the NGC. Only the WH number, II 160, may be wrong on the galaxies.

===== NGC 3684 13.1" (1/18/85): moderately bright, slightly elongated NW-SE, broad concentration. Second of three on a line with NGC 3681 14' SW and NGC 3686 14' NE. Also, NGC 3691 lies 15' SE.