Re: #APCC - V1.9 Tracking Error #APCC

Roland Christen

The target will move a few hundred pixels over the coarse of the night.
Did the target move in RA or Dec?


-----Original Message-----
From: roozbeh_bid <rbidshahri@...>
Sent: Fri, Aug 20, 2021 2:10 pm
Subject: [ap-gto] #APCC - V1.9 Tracking Error

I'm very happy that V1.9 now works with NINA and ASTAP.
Model building was very straightforward and quick.

For some reason, my unguided exposures have trailing stars. 
The target will move a few hundred pixels over the coarse of the night.

Using the AP1100CP4, no encoders, CDK12 OTA, pier bolted to concrete floor in a remote dome (backyard).  1700mm focal length,  0.92 arcsec/pixel (bin2)

I've double checked every bolt from the concrete to the focuser. The system is very rigid, mirror is bonded to permanent cell. Payload is about 70lbs. 
I also pointed near zenith to eliminate any potential sag with the same inconsistent results.

Periodic Error:
Unlikely as the image is constantly moving in on direction. I checked the mount with Pempro last year with a native error of 3" peak to peak. It was about 1" with PEC on.

Using NINA and ASTAP with "high precision slews" = on
1st attempt with points every 12 degrees
2nd attempt with very fine 6 degrees apart  184 points (I only have half the sky visible)
Environmental sensor, pressure for local weather station.
Its using a sensor on the telescope which was reading RH a bit higher (92 to 99%) than the weather station value of 82%

It seems when I turn Dec-arc tracking on it gets worse.
I tied refraction correction on - off.
Both on both off
Some subs much worse than others, but moves in the same direction generally.

Here is a folder with some 300s test subs, log file, appm files. I have named them with dec arc and refraction correction on or off

Any help would be much appreciated as I've been trying to solve this for days non-stop.



Roland Christen

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