Guiding Spikes

MrAstro

Hi,

For the 1st time I faced this issue with AM5.. Which is18 months old.
About 27 huge spikes (more than 30") in guiding in 3 hours period.. a simple image from PHD2 viewer is attached.
They are random but almost the same value and they only appeared after meridian flip..
Before the meridian I had Zero spikes in 1 hour period.
I lost 2 frames 120" each due to bad stars ( not a big deal) but I wish to catch up if I can do something before things go worst.
Main: SW100 telescope, ASI2600mc pro, Guider: WO50mm with asi290mini
I used 5kg counter weight, I already use it before with no issue.

I checked :
1- No any cable snag or drag
2- No strong winds
3- Good seeing
The only thing I suspected is Cold weather,
Although temp. was around 8C, but this is the only thing which consider a new thing for my AM5, Can be??
PHD2 log link is here:
https://www.dropbox.com/scl/fi/xm56yod425884l2mstj0y/PHD2_GuideLog_2024-02-02_185142-flaming-star-nebula.txt?rlkey=das80we8opmpydd5c12gnxy4p&dl=0

Any Hints ?

Kevin_A

What are you using to guide with? Asiair or phd2? If it is asiair, use the new TestFlight beta release which has an additional setting under the mount for heavier setups in the cold and this version puts the minmo back to 0.1px. It also uses a better multistar selection algo. Try that first and post your settings for max dur, agg, exp length etc.

MrAstro

I use PHD2, Max duration=500, agg.Ra=50 Dec=45, Exp=1sec.
I tried to manipulate these settings but no luck..
Before meridian flip these settings were work fine: RMS 06-08 but immediately after flip those spikes appeared.

Kevin_A

MrAstro have you tried manual guide re calibration after the flip to see if guiding is better? Are you using latest ascom driver? Bump up the minmo a bit to 1.0px and also try 1.5px as some mounts have issues with oscillation after flips and after dithers when set too low.

MrAstro

Thanks Kevin,
I don't know what is "manual guide"
I will try to re calibrate after the flip..
Yes latest ascom driver is installed .

regarding minmo, you mean bump up to 1.5px OR 0.15px as these values are too small.
If you mean 0.1px and 0.15px I already tried and spikes didn't stop.
If you mean 1.0px I will try as I never do.

Thank you again for your usual support 🙂

Kevin_A

MrAstro sorry… typo, I meant 0.1 to 0.15px but looking again at the guiding graph, that is not normal and it does not look like a setting issue or mechanical either. I would say it looks more electrical or data related signal interruption. I would replace the guide camera usb cable, mount usb cable and verify constant voltage to the mount as it could be a bad power supply or cable.
Your graph looks like it just drops out thus both axis are simultaneously affected. A bad cable or connector would do that.

MrAstro

Kevin_A
Your analysis looks logic to me..
I will replace both camera and mount cables..
Regarding power, I thinks it would stop tracking if its interrupted .
Next imaging session I will see if those spikes appeared in one side only of the pier or both sides,
If appeared in both side it means cables, power or data..
What if spikes appear only in one side? What does it mean?

Kevin_A

MrAstro can you post the log with dithering showing and maybe a smaller segment showing a shorter 20minute period with spikes. It is too zoomed out to see any telltale signs.
Regarding power or data signal… it could be so rapid that on data it does not stop guiding enough to set off phd alarms and power below 11.5 volts may do strange things too. The meridian flip could just put a cable in a bad position. Make sure you are using all the latest ascom drivers and go from there. It is just a matter of elimination.

MrAstro

1- A new ZWO ASCOM 6.5.23 is released, I installed it just now, All other drivers are up to date, So, drivers issue are not in the suspected list.
2- I eliminated the power issue for now, as I used a reliable regulator that gives steady 13.5v.
3- You can see PHD2 log here:

phd2-guidelog-2024-02-02-185142-flaming-star-nebula.txt

870kB

MrAstro

A new strong suspected came on the line 🙂
These spikes are start to appear in the new PHD2 version (2.6.13)..
I was using the previous version with no issue.
I only noticed that when decided to read the PHD2 log file carefully, and in the 1st row it stated " PHD2 version 2.6.13"
I will do nothing with cables or changing anything, And I will roll back to previous version and check.