M102?

[Ganymede12]

My list of Messier objects (printed from Wikipedia ) says that M102 is "Not conclusively identified". Wikipedia says that it is believed to be a re-listed object that was already on the list. Why is it not removed from the list or why wasn't it put on the end?

[michael.h.f.wilkinson]

It is one of the "missing Messiers". Some believe it is a duplicate of M101, others assume NGC 5866 in Draco is M102. I went with the latter identification when I was hunting down the last Messiers.

[Qualia]

That's a great question, Ganymede!

I think it's because historically speaking, folk have believed that M 102 was in fact M 101.

You see, if I've got it sort of right, Messier never saw it, but took a given Méchain's word that it existed. It was lumped on the end of the list for publication along with Méchain's other discoveries, namely, M 101 and M 103. Now, these two were never disputed because description and position were offered (although erroneous) but M 102 was only given a physical description. Already there were suspicions.

Then a few years later, Méchain himself, wrote some letters to some rather renowned academies in Europe and retracted his discovery, saying that he now believed M 102 was in fact M 101. However, although M 102 was now the first 'non-object' in the list, it wasn't exactly obvious to all. Given that the list included sights made by two great observers, humble enough to retract the discovery of M 102, playing by the principle of charity, why then were the descriptions of M101 and M 102, so different? Could it be that Méchain really had discovered M 102?

A little more than a hundred years later, it was argued that if Méchain had ever seen M 102 it was more than likely NGC 5866, but either way, M 102 was never "conclusively identified".

Hope that makes some kind of sense - if I've got the story right, that is.

[Tinker1947]

Stellarium show's M102 as being in Draco, this is the one i have on my list..

[michael.h.f.wilkinson]

Stellarium show's M102 as being in Draco, this is the one i have on my list..

That is NGC 5866. It fits Paul Mechains description quite well. It is a nice side-on galaxy. My C8 showed hints of the dust lane

[Double Kick Drum]

Given its brightness (NGC 5866), I am surprised it was missed (if indeed it was missed). I think it's quite a nice object even for quite small telescopes.

Admittedly optics may have been "a bit wonky" back in the day, which may have hampered my French friends.

.... and given some of my note taking, I am in no position to criticise Messier and company.

I'll get me coat.

[Ganymede12]

Thanks for the info!

Has anyone ever tried to image M102?

[Brent]

12DString also lists NGC 5866 as M102.

Has anyone ever tried to image M102?

Just did a quick search in the Deep Sky Imaging section, found only this one:

http://stargazerslou...866#entry599696

I might have a go when it goes right overhead again.

[DazC]

So what should i do about trying to see all 110 "M's" now then? Should i only be looking for 109?

I'm confused!!!

D.C

[michael.h.f.wilkinson]

I bagged all 110. I just used NGC 5866, as per Messier Club instruction. After all, if you bagged the 110, you have certainly bagged the 109 required by some others. M110 was only added to the official Messier list in 1967, I think mainly to make the number of items a nice round number. Messier did observe it in 1773.

[ronin]

This came up a year or two ago and being half interested I looked around concerning it.

Seems that M102 was "reported" as a duplicate of M101.

There was questions about the recorded position of M102 but the surrounding references appear to match with M102 being NGC 5866.

Messier included M102 with the proviso that no positional confirmation was provided only a description. The information for M102 coming from Mechain.

There seems to have been a bit of a mess. Add in that the original question about it being a duplicate was apparently a letter from Mechain, but some 2 years after the original list was submitted and published, this letter was published by the Berlin Acadamy who were in competition with Messier. It was published twice it seems and the second was translated with a few question concerning the accuracy of the translation in what I suppose were key areas. One of the "additional" bits being added was that the second states Messier was in error, whereas the original does not mention Messier at all. Other bits were added also.

In effect Mechain appears to have decided some 2 years afterwards that M102 was a duplicate report of M101 (Mechain reported M101 as well to Messier). This is strange as the descriptions for M101 and M102 do not match, which they would if they happened to be a duplicate and being reported by the same person.

Another point made is that the Messier catalogue was reported and published via a French acadamy that Mechain was the editor in chief of. The question being why would he bypass that organisation and go to a German group with whom he had no relationship.

The position of NGC5866 match the description of "M102" and the position that seems to have been recorded by Messier in his notes. The original discoverer of M102 being Mechain who worked with Messier.

There are some questions about the position recorded by Messier which appear to be down to differences in writing some of the greek characters - sort of do you write 0 with or without a bar through it, same with the number 7 ?

Additionally it was Mechain that reported concerns with star charts that he had, no reports were of the star charts that Messier had and used.

The area is a bit of a minefield, have a look at Wikipedia M102 and messier.seds.org

Somewhere I have seen other information, that has greater detail, takes longer to search out.

It appears that Mechain reported it to Messier, Messier took the report and published and seemingly later verified it, then Mechain may have had doubts for some reason. One thing that comes out is that Messier never reported it as a duplicate and seemes to have verified M102 later himself and so not M101.