Re: PHD2 aggressiveness with Absolute Encoders

Roland Christen

If you have absolute encoders it is not necessary to set aggressiveness high. The mount will be tracking at an ideal rate and any error that needs correcting either comes on very slowly, or it happens very fast due to atmospheric instability and so cannot be corrected (chased) anyway. The downside to very low aggressiveness happens when you dither, and it will take longer to bring the guide star back to center. I set mine to 80% on nights of medium seeing and maybe 100% if the seeing is totally pristine and there is no atmospheric instability.

The Min Move is more important when the seeing is not perfect. If you set it too low you will introduce more error into the guiding. Min Move should be set to the level of atmospheric seeing error.


-----Original Message-----
From: pnagy@... [ap-gto]
To: ap-gto
Sent: Sat, May 12, 2018 11:19 am
Subject: [ap-gto] PHD2 aggressiveness with Absolute Encoders

I have A-P1100 with Absolute Encoders (AE) and so far I imaged only once with AE with pretty good success. The RMS error was about 0.35 arcsec and I think it's not bad on the first try with AE. The stars were pretty round and I was happy. The PHD2 RA/Dec aggressiveness was set to 60%. My scope is TEC 140 and camera is QSI660wsg and guide camera is SX Ultrastar and guided with OAG.

My question is should the aggressiveness be set higher for mounts with AE? I have very limited clear nights and I really don't have time for experimentation and would like to just setup and image the next clear night. Do you think I should set PHD2 aggressiveness to 90% for mounts with AE?

You can see my pictures of my equipment at:

Thank you,

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