Data:

All at least 10 curves with 64 points each. All during decent seeing and with high PID data not used (tossed out, not one of the 10 component curves).

No Filter:

RightSlope =0.051096
LeftSlope =-0.051099

Red Filter:

RightSlope =0.051747
LeftSlope =-0.051742

Lum Filter:

RightSlope =0.051406
LeftSlope =-0.051386

Green Filter:

RightSlope =0.051929
LeftSlope =-0.051945

Blue Filter:

RightSlope =0.051774
LeftSlope =-0.051788

Ha Filter:

RightSlope =0.051476
LeftSlope =-0.051460


If the theory is right and "all curves with the same mirrors/lenses are the same", then the 5th digit has to be just noise as they are widely different. But if THAT is the case then why are the right and left slopes the same to the 5th digit in nearly every case?

BTW, this is a 14.5 inch f9 RCOS with an AOL/SBIG 11000M. AOL was, of course, not operating during the curve gathering. It does have one refractive element other than the AOL and that is the RCOS flattener.

If one were to ask my theory, I would say that the flattener is not quite perfectly apochromatic.

Which leads back to the original question - what digit is significant?