NGC/IC Project Restoration Effort

===== NGC 5866 is perhaps Messier 102. That is one of the objects found by Mechain (in 1781 in this case), and included by Messier in his 1781 list that appeared in the 1784 Connaissance des temps. For M 102, however, Messier did not have time to visually verify the object, so his "work" on it is limited to its appearance in his list, and to a penciled-in position in his own copy of his published list. That position is "14.40" and "56", i.e. 14h 40m, +56d. There is no equinox given, but -- given the precision -- we can assume it to be 1780 without too much error. For comparison, the accurate position for N5866 precesses back to 15 00.5, +56 37 for 1780. For M 101 (= NGC 5457, which see), my own currently hesitant choice for the actual M 102, the precessed accurate position is 13 55.4, +55 25. It's clear that neither galaxy fits the written-in position in Messier's list very well. But given the precision of Messier's penciled note, this obviously cannot be a strong argument one way or another. However, other evidence in favor of NGC 5866 has been presented. Some of this has been collected in a Web document by Hartmut Frommert on the SEDS site: http://www.seds.org/messier/m/m102d.html To summarize Hartmut's case (as of 2006) for NGC 5866: Messier's working maps were laid out in grids of five degrees in both RA and Dec. This makes it possible that the written-in position was hastily read off his map with a 20 minute and 1 degree error for "15.00" and "57"; this would make the object NGC 5866. My main objection to this is that errors in both coordinates is unlikely. Not impossible, obviously, just unlikely. More recently (see the September 2015 "Sky and Telescope"), Michael Covington makes (my opinion) a somewhat stronger case for NGC 5866 being M 102. I refer you to that article for the details (all of which I have repeated here, though not as gracefully, I'm afraid). I've also come across a note credited to Solon I Bailey about M 102 in Shapley and Davis's Messier list in PASP 29, 177, 1917. Bailey's note makes one of the arguments for NGC 5866 being M 102. He gives Messier's description of the field -- taken, I believe, from Mechain -- in the original French (this is word-for-word the same as the description that appears for M 102 in the Connaissance des Temps for 1784). Here is a translation by me: Nebula between the stars [omicron] Bootis and [iota] Draconis; it is very faint; near it is a star of the sixth magnitude. Bailey goes on: By a star chart, or the sky, you will see that, taken as it stands, no object could well be selected for M 102, since [omicron] Bootis is too far from [iota] Draconis. If, however, [omicron] is a misprint for [theta], it becomes intelligible, and M 102 is perhaps N.G.C. 5866, altho [sic] in Norton's Atlas it is apparently identified as N.G.C. 5879. On our photographs, however, N.G.C. 5866 appears to be the brightest object in this region. Finally, Shapley and Davis comment The visual observations of these neighboring nebulae by the Herschels show NGC 5866 much the brighter, and its identity with M 102 can be accepted as quite probable. (For the record, with V_T = 9.9, NGC 5866 is well within the range of the other Messier objects, so could have been picked up by Mechain.) Arguing against the NGC 5866 hypothesis is Steve O'Meara in his "Eye on the Sky" column for the March 2005 issue of "Sky and Telescope". He shows that Messier's incorrect position is about as far east of theta Bootis as M 101 is west. It is possible then that Messier made a simple plotting mistake, flipped the offset from theta Bootis, and therefore wrote down the incorrect position for Mechain's object. I think it is worth pointing out here that the same kind of mistake may possibly account for Messier's poor position for M 47 (= NGC 2478, which see), though I remain skeptical about that for other reasons. The case for M 102 being M 101 is simply made in a letter that Mechain wrote in 1783 to the editor of the Berliner Jahrbuch. I've copied it into the note for M 101 (= NGC 5457, which see). That argument assumes other errors and mistakes, so skepticism is in order for that, too. However, in the end, I think we need to attach higher weight to Mechain's own words. He, after all, discovered the galaxy, whichever one it may be. So, I am still of the opinion that M 102 is probably identical to M 101, though note that an almost equally strong case for its being NGC 5866 can be made. Whatever happened, we really do need to see Mechain's original observation from his log book and/or other observing records -- if these still exist. If not, we will never know for sure just which of the two galaxies Messier 102 really is. On a different puzzle, see NGC 5826 where Swift has confused NGC 5866 with another galaxy, and NGC 5867 where N5866 helps in the identity of that object.

===== NGC 5866 24" (7/6/13): at 200x appeared extremely bright, large, very elongated 3:1 NW-SE, spindle shaped, well concentrated with a blazing oval core. A very thin, low contrast dust lane bisects the galaxy and is most evident along the central bulging core. The outer halo is much fainter and extends ~3.25'x1.25'. A mag 11.3 star is just off the NW flank, 1.6' from center and a mag 12.2 star is off the SW side 1.4' from center. At 322x, NGC 5867 was picked up 1.0' SSE of the mag 12.2 star as a very faint 8" glow, held continuously with averted vision. 17.5" (6/6/86): very bright, fairly large, elongated 2:1 NW-SE, 3.0'x1.5', bulging bright core. This galaxy has a high surface brightness and a mottled surface. Just a hint of the razor-thin dust lane prominent on photographs is visible. A mag 11.5 star is at the NW end 1.6' from the center and a slightly fainter mag 12 star is 1.5' SW. Located 10' NE of mag 7.5 SAO 29401. 13" (6/4/83): very bright, impressive, large bright core, two stars off the NW and SW edges. A mag 7 star is 10' SW. 8": fairly bright, brighter central bulge, fainter extension.