NGC/IC Project Restoration Effort

===== NGC 4055 = NGC 4061, NGC 4057 = NGC 4065, and NGC 4059 = NGC 4070. John Herschel found these three nebulae during his Sweep 423 on 29 April 1832. They have not been positively identified in any published catalogue since, though Reinmuth and PGC have made suggestions. Here is the story. Steve Gottlieb started the case by noting that Reinmuth's identifications were unlikely. Bob Erdmann followed up with the suggestion that these might be identical to some of the galaxies in the NGC 4065 group 0.8 deg south. Then, Brent Archinal suggested a check of the other objects seen by Herschel in the same sweep. Here is what is in his 1833 catalog credited to Sweep 423 (there may be one or two others lurking in the list, but I haven't found them in two reasonably careful searches. My comments are in square brackets): NGC h RA (1830) NPD Desc 3937 1003 11 43 56 68 25.1 vF, S, R 4032 1049 11 51 49 68 58.2 pB, R, gbM, 40" [N.B. Seen in 5 other sweeps where the brightness ranges from "B" to "eF"; the positions agree] 4055 1062 11 55 00: 68+- pB 4057 1063 11 55 04: 68+- pB 4059 1064 11 55 08: 68+- pB. On merid[ian] with two more [I presume the other two are N4055 and N4057] 4066 1068 11 55 26 68 41.9 No description [Seen in 3 other sweeps; the positions agree. Those descriptions are "Not vF. Another seen", "pB", and "The third of 5"] 4095 1079 11 57 13 68 28.1 eF [seen in one other sweep; position agrees, but no description] 4098 1082 11 57 22 68 25.5 No description [two other sweeps: positions agree; "vF, R, bM" and "No description"] Looking at this table, I was struck by a couple of things. First, the north polar distances of the three questionable objects have been assigned the same number of degrees as the other five objects. This suggests to me that the minutes of NPD should be similar to the others -- say 68 30 to 68 50 -- since Herschel's sweeps were pretty limited in declination. This would make the NPD's roughly equivalent to the other bright objects in the core of the NGC 4065 group where the NPD's range from 68 38 to 68 53. Second, the descriptions suggest that the objects are not faint, and that they are aligned pretty closely along the same meridian of RA. The NGC 4065 group has four bright objects: N4061, N4065, N4066, and N4070. Since Sir John saw N4066 during the sweep in question, this leaves N4061, N4065, and N4070 as the possible candidates. Interestingly, his more exact positions for N4055, 57, and 59 given in GC (from "a most careful consideration of all the observations and records in the sweeping books" [note in GC], and copied into NGC by Dreyer) are roughly coincident with these three galaxies if a systematic offset of about -0.88 degrees in Dec and +20 seconds in RA is applied. Putting all this together, Occam's Razor (the simplest hypothesis that fits the facts) suggests that NGC 4055 = NGC 4061 NGC 4057 = NGC 4065 NGC 4059 = NGC 4070 I'm not sure about this, of course. But this is certainly a reasonable solution to the problem. There is more discussion of the identities in the group under NGC 4056 and NGC 4069.

===== NGC 4055 See observing notes for NGC 4061.