CEM70 DEC guiding error is big before meridian flip: Page 2

CEM70 DEC guiding error is big before meridian flip

Jake

Ekato Did you notice any difference between meridian flip? My DEC error is still better after meridian flip, although lowering aggression helps both cases.

Ekato

Jake
Got some clear sky to test before and after MF. Using app 8.83, mount CEM70, 2x2Binning.
RA aggression 50%, Dec aggression 20%. Dec mode auto. 2 sec exposure.
Before MF total RMS between 0.2” and 0.4”. (Little bit more wind than other day)
After MF dec started to get very erratic. Let it settle for about 5 min. but did not help. Then I started a recalibration, did not help either. Started to increase dec aggression in 5% steps to 35% but did not make a difference. Next I set dec mode to South and what a difference, guiding went back to the normal range. That brings up a question, does dec in auto send the mount at times in the wrong direction as it goes from way north then goes way south?

Jake

Ekato Same situation here, I am using auto mode for DEC all the time. I notice the difference before and after meridian flipping. For me the results after meridian flipping is better for the Orion target last night. Although 3D balance improves the results, guiding is still better after meridian flip.

Jake

Ekato I also tried to change DEC mode from "auto" to "south" before meridian flip, it improved the results. However, after meridian flip, I found "auto" to be slightly better.

Boutrosbolos

I have the same issue as Ekato !

I described it in detail in my post:
https://bbs.zwoastro.com/d/26282-dec-guiding-instability-after-meridian-flip-with-asiair-star-adventurer-gti

A summary here:
I’m using ASIAIR with a Star Adventurer GTi in the northern hemisphere.
My calibration is done on the eastern side of the meridian, near the celestial equator, with DEC set to Auto.

During calibration I consistently get something that looks unusual compared to the “ideal” pattern:

around 12 steps West and North,

but only 2 steps East and South.

Despite this asymmetry, guiding on the eastern side is excellent — I’m getting around 0.7" total RMS with stable DEC.

The problem starts after the meridian flip.
ASIAIR performs a new calibration, and from that moment DEC begins to ripple heavily, with no convergence or stability. The DEC RMS jumps to around 2", and the graph oscillates continuously.

If I switch DEC guiding to North Only and recalibrate, the rippling stops immediately. Guiding becomes stable again and the error drops back to the previous level, with only occasional spikes that correct themselves.

I’ve already ruled out mechanical issues, temperature effects, balancing, focus, and other obvious causes.

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