[sac-forum] Re: Call for Observations - for June, M102, Which one is it?

For June we're going to divert from the normal constellation selection and 
follow a different path.  For this we will study the only outstanding unsolved 
mystery of the Messier Catalog and that is, is M102 a duplicate observation of 
M101 or not, and if not, what are the likely candidates?  The short story is 
there isn't enough information to make a correct decision; at least not with 
the information available.  Our assignment is to go out and observe M101 and a 
number of other galaxies that are thought to be M102 and report your results.  
To start with we must observe M101, a magnificent face on spiral galaxy, which 
Méchain described as,

101. 13h 43m 28s (208d 52' 42") +55d 24' 25"

(March 27, 1781) `Nebula without star, very obscure & pretty large, of 6 or 7 
minutes [of arc] in diameter, between the left hand of Boötes & the tail of the 
great Bear [Ursa Major]. It is difficult to distinguish when one lits the 
[graticule] wires.' (diam. 7')

For the observation of M102, wherever it is, Méchain described M102 as,

 (Méchain) `Nebula between the stars Omicron of Boötes & Iota of the Dragon 
[Draco]: it is very faint; near it is a star of the sixth magnitude.'

(Handwritten position added by Messier in his personal copy: 14h 40m, +56.)

In all of your observations, look for the 6th magnitude star.  Where is it?  
Remember, though, this is a visual observing estimating the magnitude of a 
star.  Could it be off by a magnitude or so?

So much for the introduction now let's move on to the objects for us to study.  
We start with the obvious M101.  The NGC candidates are a selection of the 
brighter galaxies in the area.  The first galaxy takes us into Boötes, is mag 
12.5 NGC5899.  Magnitude 12.8, NGC5908 follows.  The third is magnitude 11.1 
NGC5907 a late type spiral.  Second to last NGC5879 another spiral galaxy at 
magnitude 12.2.  Finally, the last is a popular pick for M102, is magnitude 
10.8 NGC5866, an early spiral.  Some of the above galaxies have other field 
galaxies included.  Just for the observational fun of it, let us know which 
ones you can identify.

Include your opinion of which object you believe is M102 and don't let the 
popular pick sway your selection.

Clear skies,
aj

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