Need to recallibrate at the start of each session and after flip

[franco...@gmail.com]

Hi, I've started having an issue with my guiding during my last few imaging sessions. I'm using NINA to control my setup, and the issue is that every time I start running a sequence, guiding won't work on RA and I will start getting a huge RA drift and the error message on PHD "Your Max RA duration setting is preventing PHD from making adequate corrections...". The image will start drifting away quite fast and guide pulses don't seem to work. It's honestly as if the guide pulses in RA were going the opposite way because the image will drift way faster than if corrections were just not enough. 

This issue will be immediately resolved by forcing a re-calibration and will get very good guiding (in the 0.4-0.8 RMS range) with no issues after re-callibrating.

Then after the meridian flip I'll get exactly the same issue, which will be perfectly resolved with a new callibration.

Here are my guide logs from last night:

https://openphdguiding.org/logs/dl/PHD2_logs_oQGj.zip

My setup is a 90mm refractor on a ioptron cem40 mount, evoguide scope and qhy462C guidecam. Everything is run on NINA and this is a permanent setup so Polar Align is pretty spot on and mount is nowhere near it's weight limit.

Honestly like I said it looks like if those RA pulses were in the opposite direction, pushing it farther and farther away instead of bringing the guide star closer.

I'm attaching a 180s exposure to show the amount of drift which is much greater than if it were just PA drift due to RA not being able to make large enough corrections.

Also, I'd just like to reiterate that the issue will be absolutely resolved after a normal re-callibration and I'll get very good guiding, so I wouldn't think there's a physical issue with the mount.

Anyways, any help will be greatly appreciated!!

[Brian Valente]

Hi Franco

What software are you using to connect your mount?

your pier side is not being reported, so PHD cannot adjust the calibration based on pier side. My guess is you calibrated on one side and then your target was on the other. The best solution would be to resolve this so the pier side is reported

Then one calibration works across the entire sky

As a separate observation, your Dec calibration is 2x RA, If you ran the guiding assistant (which I recommend you do) you will probably get a warning on this. something worth looking into

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[wave...@talktalk.net]

Hello Franco,

I suspect the location you're calibrating at is causing issues.

You should be pointing near the intersection of the celestial equator and your meridian.

You appear to be on your horizon at -73.1°

Cheers,

- Jack

[franco...@gmail.com]

Thanks Brian! I am using Ioptron Commander 8.0. Should the "report side of pier" be an option to enable in ioptron commander? Or is it a PHD2 setting? I did run the "Calibrate meridian flip" option in PHD2 but I think that is just for DEC commands, right? In a broader question, does side of pier affect the direction of guide pulses in relation to drift? Anyways, yes, I'm pretty sure its some sort of config issue because there's no real problem with my guiding once I re-callibrate. 

Regarding "your Dec calibration is 2x RA" not sure what setting this is? I do run the guiding assistant every once in a while, I'll normally do it when I notice my guiding isn't really as good as it should be, so I'll just run it and most of the time I'll accept all the suggestions, but I can look into this setting specifically and adjust accordingly, just not sure where to find it?

Thanks for all your help!

[Brian Valente]

>>> I am using Ioptron Commander 8.0. Should the "report side of pier" be an option to enable in ioptron commander? 

Yes, side of pier is something reported by your telescope software (Ioptron Commander in this case). you should look into how to enable that or make sure it's active. 

>>>I did run the "Calibrate meridian flip" option in PHD2 but I think that is just for DEC commands, right? 

Without knowing the side of pier, it won't work. so start there

>>>In a broader question, does side of pier affect the direction of guide pulses in relation to drift? A

not in relation to drift, in relation to the side of pier and therefore the direction of the guide pulses. If you calibrate for each target, you don't need side of pier because you are calibrating whichever side the target is one.

>>>Regarding "your Dec calibration is 2x RA" not sure what setting this is?

that's not a setting, that's the result of some setting. Jack mentioned you calibrating at the horizon, which possibly could explain that. You should be calibrating near DEC=0. That may address this

>>> I do run the guiding assistant every once in a while, I'll normally do it when I notice my guiding isn't really as good as it should be

Consider running it every night, even if just for a few minutes. It will accurately measure your night's seeing conditions and give you appropriate min moves

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/6ca27313-181f-40dd-8f72-0d66c36d010fn%40googlegroups.com.

[franco...@gmail.com]

Thank you Brian! I've managed to solve the issue. Turns out the culprit was a setting in NINA which is "Use telescope side of pier" under meridian flip settings. This was turned off (must have accidentaly switched it because I wasn't having this issue and then it randomly started) so PHD2 wasn't getting this info. Just as an FYI, ioptron commander (at least v8) does not have a "report side of pier" setting to turn or on off, so I guess it always reports it and I mistakenly switched that off in NINA which is the go-between the mount and PHD2.

Thank you Brian and Jack for all your help!

PS: Still need to figure out the 2x RA dec calibration, although after resolving the issue and making a fresh calibration at the meridian and equator intersection I got very good guiding both before and after the flip.