Re: Tracking and guiding with and without encoders - Part2


Ray Gralak
 

Hi Chad,

You showed images of a mount with "40 arc seconds PE." Assuming you ran a valid test it only demonstrates that
PEC improves guiding if your mount has 40" PE. I fully expect it would. That doesn't begin to address whether
PEC improves guiding on an AP mount with less than +/- 3" P-P smooth native PE.
As I said previously I have run many tests, including many at 5 arc-sec Peak-Peak that showed up to 10% improvement in FWHM.

These logs will be very difficult to draw any conclusions from since I had zero intention of making them clear and
intelligible. What I can tell you is:

PEM was enabled near the end of the night on one of the two mounts. I believe it was enabled on the file that ends
in 201308 but I don't remember for sure. Total RMS stayed right around Total RMS for the other mount which had
PEM disabled. I also didn't notice a change from when PEM was off vs. on.
As I suspected the RA data is dominated by drift and mostly overshadows the periodic error. It's no wonder that you didn't notice much difference.

Are you using APCC Pro? If you are I think there is something wrong with the data model you are using. You should have little residual drift in RA and Dec.

I will try and do a proper test tonight. If there's improvement, that's what I'll report. I hope there is.
If your mount still has that a lot of RA drift then any improvement will be diminished. Also, you must do the tests on the same mount because each mount may have different levels of drift. Drift will affect the RMS error, sometimes more so than periodic error.

So, please do your tests with the same mount. I will be able to isolate and analyze the drift and periodic error in the logs to determine exactly what is contributing to your RMS error.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Tuesday, September 17, 2019 3:10 PM
To: ap-gto@yahoogroups.com
Subject: RE: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Ray,
You showed images of a mount with "40 arc seconds PE." Assuming you ran a valid test it only demonstrates that
PEC improves guiding if your mount has 40" PE. I fully expect it would. That doesn't begin to address whether
PEC improves guiding on an AP mount with less than +/- 3" P-P smooth native PE.

Regarding guide logs... here's a copy of the email I just sent you - with guide logs from both mounts on Sep. 4
attached. I can't imagine they'll be helpful - it's just one of the times I've enabled PEM and noticed no difference. I
can also provide you PEMPro logs from that same evening if such a thing exists. I plan to do a proper and much
longer test when the weather cooperates - possibly tonight.

--Email below---

Ray,
There was a lot going on this particular evening ... creating new PEC curves in PEMPro, running guiding assistant,
testing various PHD2 settings, testing PEM on/off, etc.

These logs will be very difficult to draw any conclusions from since I had zero intention of making them clear and
intelligible. What I can tell you is:

PEM was enabled near the end of the night on one of the two mounts. I believe it was enabled on the file that ends
in 201308 but I don't remember for sure. Total RMS stayed right around Total RMS for the other mount which had
PEM disabled. I also didn't notice a change from when PEM was off vs. on.

I will try and do a proper test tonight. If there's improvement, that's what I'll report. I hope there is.

Chad


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