Re: PointXP Analysis explained

Dan Gray

Hi Ralf,
Sensitivity is basically an indicator to see how much data the terms have to work with.  Set the limit to 20,000, the turn on all terms.  This will allow PXP to turn on terms it normally wouldn't have enough information to use.
You RMS will go down, but it will be GarbageIn  GarbageOut.
But that allows you to see what's going on.  The default limit is 300.  Personally I like to see it under 100.  Yours is 280, so there's probably terms that should be turned off.
Theta is always the secondary axis (declination or altitude)  Phi is always the Primary Axis (rt asc/Azimuth).
You can see the errors of Phi vs Phi, and Theta vs Theta, and every other combination, including zenith distance.  Keep in mind, if it's an alt/az scope, theta and zenith are almost the same.

Axis Alignment error is your altitude and azimuth error of an equatorial scope.  If you look on the "features" tab of sitechExe, near the top, it will say "Move Down 00:00:00" (or Up), "Move Right 00:00:00" (or Left) (Birds Eye View).
That's how far you need to move your mount to polar align.

Hope that helps,


On Mon, May 18, 2020 at 1:53 PM Ralf <radinkel123@...> wrote:
Hello experts,
pointxp works great, gives a lot of details, but I have no idea what all the analysis tells me.
E.g. what does "Sensitivity mean" (I have 280)
Pointing error RMS 12,8" (for a completely selfemade mount quite good?)
Axis Alignment Error: does this refer to polaralignment?
What tells me the Grafical Error Analysis? Theta, Phi
I know its quite a theoretical question, but I'd like to understand the things behind (almost a litle bit...)

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