Re: Needing re-do the PE after updating 1200 cp3 L chip to V chip.


Roland Christen
 


Might even be able to do this with a camera targeted on Polaris, to eliminate the complications of  tracking,
The whole idea of generating a PE curve is to measure tracking, so if you aim the camera at the pole, you won't get any data. But not to worry, PEMPro automatically sends your mount to the celestial equator, where the tracking rate of a star is almost exactly sidereal. Any departure measured by PEMPro is then the PE.

Rolando


-----Original Message-----
From: 'Joseph Zeglinski' J.Zeglinski@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 3, 2018 1:16 pm
Subject: Re: [ap-gto] Needing re-do the PE after updating 1200 cp3 L chip to V chip.



Hi,
 
    I suspect you may dread being out there in the cold winter night, capturing raw data for the curve. Luckily, sampling 6 to 8 raw data cycles will take over an hour anyway,  and once started, doesn’t require your presence at the mount – good time for an indoor coffee break. Later, even the PEC analysis and final curve fitting can be leisurely done indoors as well, then just upload the result into the CPx  mount controller.
 
    Programs that calculate the PEC wave pattern on the gear train teeth variations, need “some kind” of reference.
A bouncing star is ideal because it is simple. I suppose it might be theoretically possible, but impractical –  to do the PEC curve generation in daylight, or even in the house, using a commonly available “simulated star” or compare successive frames of a room scene (or a precisely printed target), for their shifting. But it would be less precise and require much more computer resource. Might even be able to do this with a camera targeted on Polaris, to eliminate the complications of  tracking, PA, cross winds, and drift from the process – but not a present capability in any PEC generating software I know of.
 
    So, PEC generation can only be done with a camera centered on a reference star.
 
    Luckily, PemPro doesn’t require a perfect polar alignment to do this part of the job – it compensates internally for many things, including an arbitrarily CCD rotation, although a reasonably close CCD rotational alignment with the axes, and a good initial mount polar alignment would probably help it producing a slightly more accurate curve. But such detail isn’t really necessary, since normal “seeing conditions” could affect guiding more, in spite of a good PEC curve. But, everything helps.
 
    PEC is only needed for imaging and not for visual use with the mount, since visual use won’t see minor position variations. Since you will be doing it soon anyway, just be patient and leave the PEC curve generation for that first night out there under the stars with your CCD. PemPro makes it easy and indeed fun to do.
 
Joe 


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