Re: AP1100 autoguiding

Christopher Erickson

I think "compensate" is a better word, but yes.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii

On Thu, May 19, 2022 at 3:26 PM Ted Mickle via <> wrote:

I understand that AP is/was working on an update to the hand controller software that could be used with the CP4 that would correct for orthogonality error - is this correct?


On May 2, 2022, at 20:44, Howard Hedlund <howard@...> wrote:

Hi Christophe,

Congratulations on acquiring the 1100GTO.  You will love it!

Pointing errors can have several sources:
  • The most common cause of pointing errors is polar misalignment.
  • If the RAPAS was not properly calibrated, it may not give good results.  If it was calibrated incorrectly, it will certainly fail to give good pointing.
  • Orthogonality affects pointing, especially nearer to the pole.  Orthogonality problems show themselves most strongly after a meridian flip.
  • Pointing problems are almost never the fault of the mount.
As Oliv points out, one of the first things to determine is whether your drift is in RA, Dec or in both axes.  You can easily determine which direction on the chip is RA by stopping tracking for a short while in the middle of an image.  The streak that results will be in the direction of RA.

You will need to either create a good PE curve or autoguide.  If you received the copy of PEMPro that came with the mount, you can both cure the periodic error and fix the polar alignment at the same time.

You may or may not need to remesh the gears.  This can be quite easily tested using the instructions in our website's technical support section. 

Contact me at Astro-Physics for further assistance.


Join to automatically receive all group messages.