Zygotest

My Orion Optics UK 8" f/6 Newton arrived this evening. (need I say the sky is cloudy!?).
Anyway I got a Zygotest with it at wavelength 632,8nm. The figures goes like this:Strehl:0,982, PV Wavefront:0,139 Wave, rms:0,021 Wave,
AstMag: 0,029 Wave.
Comments, please. I will be able to tell when I can test myself, but it would be nice to know what all this figures means. The only figure Iam familiar with is Strehl and it seems quite good.
I bought the scope at 1/6 Lambda.
Thanks for help.

Magnus

That should be an excellent mirror.

PV = 0.139 is the Peak-to-Valley which is the largest
error on the mirror. As the name implies its the
range from the highest point to the lowest point,
as compared to a perfect mirror, measured in wavelengths
and on the wavefront. Their number seems to be for
red light, so for green light its about 0.160 waves.
So its better than their spec of 1/6 wave = 0.167.

RMS is the Root-Mean-Square error. This is a sort
of indicator of the average for the entire mirror.
It is closely related to Strehl, and the number is
excellent. 0.021 wave in red light is about
0.024 wave in green light. Still excellent.

"AstMag" must be the peak to valley astigmatism.
Apparently they give a number for it, even though
it is likely included in the PV value. The number
seems excellent.

Altogether an excellent mirror.