DEC Guiding issue, post flip

[Behyar Bakhshandeh]

I have a permanent setup at a nearby remote observatory. The setup consists of an FSQ-106N on an AP1200 with CP4 and uses an OAG.

My guiding has been pretty good lately, but over the last few nights it has been acting up after a meridian flip.

On Sunday night, after finishing with my object, I decided to recalibrate since it had been over a month since the last calibration.

It guided well while pointing east, but after the meridian flip around midnight, it started complaining about DEC movement. I figured there might be a cable snag or something similar, so I had someone watch the mount while I simulated the movement during the day. They did not see anything catching.

Last night, I started with a fresh configuration and performed a Calibration Assistant run and a Guiding Assistant run at Dec 0°, pointing east. I was using 5-minute subs, refocusing after every six frames, and dithering after every sub.

Again, guiding was good to start with until the flip. Every now and then it seemed to guide normally again, but by then the object had moved off center.

https://openphdguiding.org/logs/dl/PHD2_logs_keTs.zip

The screenshot shows the first sub after the flip. 

I plan to drive out and check the hardware myself, but I’m wondering if there is anything in the logs that might point to a software or configuration issue.

Thanks,

Behyar

[Brian Valente]

Behyar

It looks to me like your Reverse Dec output option' on the Advanced Dialog guiding tab is set incorrectly. 

If it's enabled, disabled it. or vice versa

You can also test what value is needed using the Calibrate Meridian Flip on the Tools menu

Brian

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Brian 

Brian Valente

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[Behyar Bakhshandeh]

Its been off since I did the MF calibration last year but I'll run it again just to be sure.

The odd thing is that it guided fine the night before using the old calibration.

[Brian Valente]

The logs show this pretty clearly, not sure what or why it changed

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[Behyar Bakhshandeh]

Here is what I tried last night.

I ran the Meridian Flip Calibration, which confirmed that “Reverse Dec Output” should be disabled.
Then I performed a normal calibration at Dec 0, looking east (pier west).
I slewed to a position near the meridian, still looking east.
I started guiding and let it continue past the meridian. It guided fine.
Once it was past the meridian, I stopped guiding and issued a slew command to the same location.
The mount flipped and was now looking west.
I restarted guiding, and it guided fine with no runaways.

Then I started my NINA sequence.
Guiding was fine before the flip.
When NINA performed the meridian flip at 23:42, guiding started to run away again.
I stopped guiding and applied “Flip Calibration Now.”
After that, guiding was fine until the clouds came in.

I guess I should consider enabling “Reverse Dec Output,” despite the Meridian Flip Calibration wizard recommending that it remain disabled?

Last night’s PHD2 logs:
https://openphdguiding.org/logs/dl/PHD2_logs_6r4K.zip

Mount and NINA logs:
https://www.dropbox.com/scl/fi/hujzp9tuzwmte6qyubgiu/AP_ASCOM_2026-09-16_18-34-03.zip?rlkey=s3n9ha0kzbvo8vei8yjmkunkz&st=uhe1zfkd&dl=0

Behyar

[Brian Valente]

That sounds to me like you have something configured in NINA that is causing an issue.

You might try posting this question to the NINA discord

To view this discussion visit https://groups.google.com/d/msgid/open-phd-guiding/2884659f-add7-4290-b1af-6498b94fcdebn%40googlegroups.com.

[Bruce Waddington]

Hi Behyar.  I think your problem likes elsewhere, the reverse-dec option is off and it's working fine so I recommend against tinkering with that.  The problem I see is that when you slew to the east side of the pier, pointing to Dec = 72, it looks like PHD2 is picking up something that looks like a star but isn't.  Your guide stars are normally quite tight with HFD values around 2, but when all these wild excursions occur, the primary star in the list has an HFD value over 3, sometimes as much as 4.  This sounds like an internal reflection is showing up in the field of view in this pointing position.  The next time it happens, please capture several guide camera frames using the Diagnostic logging options on the 'Global' tab of Advanced settings.  You can just choose the option for 'Until this count is reached' and set a value of 5 or so.  Once you've done that, you can then try setting your Max-HFD value to 3.0 and see if it keeps PHD2 from locking on the bogus object.  Once we have the diagnostic log images, we can probably see what it is although you may able to see it in the live image display.

Let us know what you find out.

Bruce

[Behyar Bakhshandeh]

Hi Bruce,

That sounds like a good plan.  I will try that if it stays clear tonight.

Behyar

[Brian Valente]

>>>This sounds like an internal reflection is showing up in the field of view in this pointing position.

Ah yes, this came up recently and I should have thought of this

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[Behyar Bakhshandeh]

Confirmed it was locking on an internal reflection.  

At first it was hard to tell in the star window due to low contrast but it was obvious in the saved FITS file.

Once I set the Max-HFD to 3.0, it selected an actual star and guided well all night. Only lost the star a few time due to passing clouds.

Looking at the FITS file, I have a lot of vertical artifacts that I need to address.

https://openphdguiding.org/logs/dl/PHD2_logs_esjR.zip

Thank you both for your help with this.

Behyar