NGC/IC Project Restoration Effort

===== NGC 2026. WH's position, reduced by me using the Hipparcos position for the nominal comparison star (54 Ori), is 36 seconds of time preceding the NGC position. The NGC position is more nearly correct -- so where does it come from? Not Auwers; his reduction agrees precisely with my reduction with the Hipparcos data. The answer is in CH's fair copy of WH's sweeps. There, in Sweep 329 on 5 Dec 1784, the offset from 54 Ori is given as 11m 19s preceding, 15 arcmin south. The offset published in PT from which I and Auwers worked reads 11m 53s preceding the star, and again 15 arcmin south. The difference, 34 seconds of time with a minus sign, corresponds to a notation made in the log book just below the recorded time of the observation of the star, not the cluster. The same minus 34 seconds is noted for the next star in the Sweep, 62 Ori, and for one star preceding, 102 Tauri, as well (two other stars, 105 and 106 Tauri, have notations of "-12"). Yet the cluster was "moved" 34 seconds further away from the star for its offset in the big PT paper. It's clear that this is the source of the error. Now we have only to work out why WH applied the "correction". Toward that goal, I have been looking through CH's fair copy. I found this comment following the short sweep 350 on 21 December 1784: It appears now plainly that my late improvements in RA and PD have so far succeeded that I now should use the places of the stars reduced to the present time; but having registered all my Sweeps in the time and PD of Flamsteed, I shall use them both till I may have leisure to alter my register of Sweeps. The greatest inaccuracy now remaining in owing to the clock not having a compound pendulum, but I shall endevour also to keep an account of its errors, which I have found have formerly been very considerable. His comment "alter the register" may well be relevant. CH began her reduction of WH's positions in 1799 and used not just Flamsteed's, Mayer's, and La Caille's stars, but those in recently published catalogues by Wollaston and Bode. Thus, the positions and reductions were worked over after they had been published. And it was these newer reductions that were adopted by JH for his working lists, the GC, and ultimately for the NGC. WH mentions the clock, too, with its "very considerable" errors. I suspect that the 34 second discrepancy comes from this source, though am still puzzled by the fact that he included the 34 second difference in the published offset for NGC 2026. I would have guessed that this came to light during CH's much later reduction of the positions. What is clear is that WH, just over a year into his systematic sweeps with the 20-foot telescope, was still experimenting and adjusting his observing procedures. Not only did CH's post-publication reduction of the positions take into account new star positions not available at the time of observation, but WH himself was still learning the best way to conduct his sweeps and gather his data.

===== NGC 2026 17.5" (2/14/99): At 220x, ~30 stars in a 6' region including three mag 9-9.5 stars (mag 8.7 SAO 77440 and mag 9.3 SAO 77448). Most of the stars are mag 11-13. The group lacks any concentration and appears to be an asterism with the three brighter stars drawing attention to the group. However, there is a small arc of a half a dozen mag 13 stars that includes SAO 77448 at the SE corner and a nice clump of mag 13 stars is just south of the mag 9.5 star at the north end of the group. Listed as nonexistent in the RNGC.