NGC/IC Project Restoration Effort

===== NGC 5922 is almost certainly NGC 5923. I had this as a double star for many years following the NGC position which comes from WH. This position is about an arcminute southwest of the wide double, and WH says only "eF, S" on 9 April 1787, where it was the last object in a very productive sweep (No. 725). However, I have just noticed (October 2015) that NGC 5923 does not have a WH number in the NGC. JH is credited as the discoverer -- he recorded it in four different sweeps -- and calls it "vF, R, vgbM, 40[arcsec]", "eF, L, R, 60[arcsec]", and "F, pL, lE, vgbM", with "No description" on the fourth night. Though he makes the size larger, his brightness estimates are not wildly inconsistent with his father's. The galaxy has relatively low-surface- brightness arms, so it is possible that WH saw just the inner region. This might account for the "S" size that he recorded. WH's observations let us derive three different positions, one by simply precessing CH's reduced position (using the 1800 position for HD 128902 which WH calls "244 (B) Bootis of Bode's Cat."), the second by reducing the offsets given in the sweep (43min 31sec following and 2deg 9arcmin south of the star), and a third by reducing the offsets that WH published in his second list of nebulae (these are given relative to the star 20 CVn). All are accordant within WH's usual errors of 2-3 arcminutes, with a mean position about five arcminutes south of the galaxy. JH claims to have seen it, too (also on just a single night, 6 May 1828), but has even less data: "No descr. RA by working list; PD rough." In the sweep, "III 661" is No. 41 and the wire column has a notation that I haven't deciphered yet. The clock reading is "15 18 40" with the chronometer beat at "-9" and the NPD index is "2 43 00"; there is no description. JH's reduced position is "[15 15 43]", "47 44 48::", obviously uncertain. There is nothing at all in that position. The nearest star in JH's sweep is beta Boo at "14 56 40", "-15", wire 2, "3 54 55". Assuming the same wire was used for "III 661", then the position becomes 15 23 25, +41 35.5 (J2000). If wire 1, then the RA is 15 22 42; if the edge of the field, then the RA becomes 15 24 03. There is nothing at any of these positions that JH might have glimpsed, so his "sighting" must have been based on his expectation of seeing something in his father's place and not much else. What about NGC 5923? It is No. 40 in the sweep, and is noted at "15 16 15", "-14", wire 2, "2 38 20", about 2.5 minutes preceding No. 41, and nearly five arcminutes north. JH's reduced position is "15 15 10.3", "47 40 08"; this precesses to 15 21 17, +41 43.0 for J2000, which is within an arcminute of the modern position. Taking the difference and assuming the same wire for the "III 661" data, the offset leads us to a faint double star at 15 23 42.3 +41 38 40 (J2000). Is this the object that JH took for H III 661? (Assuming either wire 1 or the edge of the field leads to empty fields.) The fact that JH put so little effort into the object suggests that he had little confidence in his observation. On the other hand, he put the object in both of his catalogues (his 1833 list, and the GC of 31 years later), so Dreyer followed suit for the NGC. In short, it is difficult to understand how WH might have mistaken a faint, wide double star as a nebula while passing over a much brighter galaxy just a few arcminutes to the north. And JH's observation of an object somewhere near his father's position has almost certainly no basis beyond his desire to find a faint nebula there. So, while the equality of NGC 5922 with NGC 5923 is not assured by the data, I am nevertheless certain enough about it to list it with colons in the big table.

===== NGC 5922 See observation of NGC 5923.