Guiding Assistant for capturing seeing conditions

[Georg Albrecht]

Hi,

I have a general question with regards to running the Guiding Assistant to capture seeing conditions beginning of the night. After running GA a minimum 120sec and accepting those suggestions, does PHD2 run the entire night with those values or does it still make some changes during the night? And would it be better to let it run longer as 120 sec is the bare minimum to get values?
I am curious as I am pretty sure conditions are changing during the night.

The other question is the location to run GA. As per what I mostly read here, the recommendation is to point the scope at the same location the Calibration Assistant does best it's work (Declination 0 | Meridian <15). Is that the common understanding?

Thank you, Georg

[Brian Valente]

Georg

Generally speaking, the guiding assistant measures conditions and recommends minimum move settings based on those conditions. Min moves are fixed, they do not change throughout the night. 120 seconds is fine: you want enough time for settling, and then enough time so there are enough samples.

RUnning the guiding assistant immediately following the calibration assistant is fine. You can run it elsewhere, but as a general guideline, the same location as calibration assistant (intersection of meridian and celestial equator) is safe.

Brian

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Brian Valente

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[Georg Albrecht]

Thank you Brian for your quick response.

I am actually writing a NINA external script to add to the advanced sequencer. It moves the mount to the calibration assistant location and runs the Guiding Assistant automatically for x time, captures the suggested values and then homes the mount, waiting for the imaging session to start. I was doing this manually every night before imaging and got lazy...

Cheers and thank you, Georg

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[Don Miller]

Hello

I'm wondering about doing the assistant, but also handling changes in seeing. I typically start guiding at 95F (35C) and it's  not good. On a good night it settles down after about 45 minutes. I could start an hour after astronomical, but I want see the startup  before bed. And sometimes I get decent captures early. But the perpetual question is always it it poor conditions or a problem.  So I would like to formalize the evaluation  of seeing as much as possible for review later.

Out of curiosity I would like to run guiding assistant after the meridian flip, but I'm not sure its worth the time.

Don

[Brian Valente]

Don

I'm not sure what is your question?

I think you may be complicating it more than necessary, and I'm not sure constantly tuning min moves through the night would actually produce results that are meaningfully better.

The guiding assistant run establishes the min move based on the seeing conditions it's evaluating. It's certainly possible/probable that you can run the guiding assistant at other times of the night, and you will get different answer for min move. There's no way to tell if the new ga results are transient (clouds, wind, etc.), or actual sustained better/worse seeing conditions. If the GA runs when it happens to be a wind gust, do you really want to increase your min move for the rest of the night based on that? 

Guiding has been around for a long time, and there hasn't really been a need for constantly tweaking the min move. I suggest reviewing your guidelogs over time, judge for yourself what is the average seeing, and set your min moves there. You might have slightly different values for summer vs winter.

A meridian flip won't change seeing conditions since you are pointed at roughly the same point in the sky. GA measures seeing based on Dec without guide pulses, so even if your RA is mechanically poor and cause issues, it would not change the min move result.

Brian

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[Georg Albrecht]

Hi Don

I have similar conditions (SoCal desert) with hot starts. One of the last nights started out at 39°C. I placed the script in my NINA sequence to run after I have PA addressed which is about mids into Nautical darkness. Although I think|know|guess|believe seeing is changing over the night, guiding seems to be relatively even (0.5-0.7) throughout the imaging session with the applied GA values from early night. My rig is well tuned and I don't use GA in this case for gear evaluation. I might do a manual run with GA once a month if even, to check backlash etc.. This rig has a wide field scope on it (250mm). 

Mid of this month, I will take my large scope out (1000mm) and start imaging including using the same script. Here I expect things to be more "volatile". I have been using GA this way for 2-3 years and just wanted the option to not have to handle several tools manually to get the results. 

Depending on your sequence management, you probably could set the script to run at a later time. However I do not see how this could be implemented directly after a Meridian flip. The MF is not bound to an exact time. Also this script follows PHD2 guidelines where to run GA and I suspect from your description, you would run GA at the pointing location of your rig after MF? I might be wrong with my assumption. The script puts the rig at DEC 0 - Meridian 5 west although that can be modified, if needed. It produces a log and shows implemented Min-Mo values.

The package is on GitHub available. You can reach out via my email for more info or if the moderators allow me to place the link here, I am happy to share it publicly. The product is still in constant development as I am working on a solution to integrate it into NINA's safety protocol so it can hopefully be used in an observatory environment although I personally don't need that. 

Cheers and clear skies, Georg

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