Prism calibrates AO-8 but won't guide with it

[OregonAstronomer]

Hello all,
I have a situation here I'm hoping somebody can help me figure out. I'm trying to use Prism with an SBIG ST-2000 with internal guide chip equipped with an AO-8 adaptive optics guider. Both the mount and the AO-8 calibrate properly. When guiding, however, Prism does not appear to be using the AO-8. When I use CCDSoft or Maxim I can hear the rapid clicking of the tip-tilt lens as either of those programs guide with the AO-8, and as I decrease the guide exposure time, the tracking improves. When using Prism, I never hear any clicking, and as I decrease the exposure time, tracking deteriorates, I assume because Prism is trying to move the mount (Losmandy G-11) faster than it was designed to. I have Prism set to not use ASCOM pulse guiding because I have a cable connecting the camera to the mount, and "Use AO-7 or AO-L" is checked (there is no AO-8 option) under Camera Settings. Is there something else I'm missing?
Thanks so much,
Arnie

[Cyril Cavadore]

Difficult to say without screen copies of the guiding setup...

[OregonAstronomer]

Hi,
Here are all the screenshots I can think of. Please let me know if you need anything else.
Thanks so much,
Arnie

[millermk32]

I'm just starting to setup using PRISM with my SBIG STT8300 with AO-8. Did you ever get this issue resolved?

[OregonAstronomer]

Hi,
I never heard back from anybody after posting the screenshots and I have never been able to get Prism to guide using the AO-8. Please let me know if you are successful in doing so. Maybe it will help me figure something out.
Thanks!

[millermk32]

Thanks for the reply. I would hope that Hamza would take a few minutes to help us users that have an AO-8 be able to utilize this valuable part of our imaging equipment. It would be nice to have specifics on the settings for using the AO-8 plus any strategies that he used in the design of the program. I have not been able to use it to date either. At this point, I may have to go back to using MaximDL which handles it quite well.

Hamza....help, please.

[Hamza Touhami]

Hello. Let’s communicate in private about a way to help you and then update the forum with a resolution.

Email coming shortly.

[alr10]

Similar conxerns with AO-X. Can't get an image with stars, just a noise screen.

[millermk32]

I've been imaging the past few nights since I've had best weather conditions in a long time. I an using my STT-8300/FW8G-STT/AO-8 combination with marginal results. The sky conditions were great with seeing around 2.0". Last night I imaged for 6 hours which resulted in only 2 hours of usable images due to difficulty with guiding with the AO-8. I had to have the guide exposures of 3 seconds to get these results. This compares to using Maxim DL where I routinely can do 0.5 seconds (or less) which utilizes the full capability of the adaptive optics. I have recently done side by side comparisons of Prism and Maxim DL (same target, same sky conditions) and the results were significantly different. I can only speculate that Maxim DL has a way to make the sensitivity of the guide chip to be much more than what Prism does. I really like most of the Prism features, but it's very frustrating using my system with the marginal guiding results. If you'd like to converse via email offline, you can reach me at merrel@reagan.com. Good luck and hoping for continued clear skies. Merrel

[alr10]

Hi. Similar responses from Prism Support- silence. I have the SBIG 16200, self-guided filter wheel and AO-X. I have painstakingly workes my way through to having Prism recognize both the main chip and the guide chip in the filter wheel, and even managed to get an excellent calibration sqiare. The AO calibration however doesn't look as good. My problem though is the autoguider will start but then stop as soon as I start the imaging. It is probably a bis somewhere that I checked or should uncheck, but I have never received any response to any of my posts to support so I thought I'd just piggy-back the question onto an existing similar thread.
Al.

[rottielover]

@Hamza Touhami might be able to help you out. I don't know a thing about AO setups. Have you tried getting on one of the hangout sessions? (the live google hangout's where you can share your screen?)

[alr10]

@Hamza Touhami might be able to help you out. I don't know a thing about AO setups. Have you tried getting on one of the hangout sessions? (the live google hangout's where you can share your screen?)

Thanks. I'm clueless about navigating to this hangout place but I'll try to figure it out.
-Al

[Hamza Touhami]

Hi. Similar responses from Prism Support- silence.

I do not appreciate this comment and it is not welcome here.

[Hamza Touhami]

we are working on a resolution and sometimes not having access to this equipment neither getting support from the hardware manufacturer is a grave hurdle to overcome.

We are ALWAYS trying to respond as fast as we can. We CANNOT help if some folks expect the impossible, we have provided our clients with a staggering amount of videos tutorials, written tutorials and even LIVE HANGOUTS where I spend my own time answering your questions using your own gear in your own backyards. Where in the industry is done? right...nowhere else.

[alr10]

I apologize.

[millermk32]

Since I last posted on this AO topic, I've done some additional research using the French version of the Prism help (using Google translate). I now have a better understanding on the operating strategy Prism employs to manage AO guiding. Over the past several nights, I've had a lot of success using my AO-8 setup utilizing 0.5 second guiding exposures (probably could have gone to a shorter exposure if I had of wanted to). The guider settings that made this work were utilizing full frame guiding and Global Image for shift computation method. The system was quite stable resulting in average tracking errors of ~.05 pixels throughout the several nights. Pretty amazing given my previous experience. The only thing that would make it better would be a delay in beginning the main CCD capturing until the AO mirror returns to its correct position. The way I understand that Prism handles the AO is that it centers the mirror for each exposure and will take a few seconds to zero in on the mirror correct position. There is a setting for Capture delay but it's only for the moving the mount and in most cases using the AO that is not necessary for a well polar aligned scope. So a settling delay for the AO mirror would be a big help. I'm very excited about this breakthrough for me as this makes the total automated observation process literally trouble free, requiring little or no attention to the night's observation session.

[Cyril Cavadore]

The only thing that would make it better would be a delay in beginning the main CCD capturing until the AO mirror returns to its correct position.

Correct position ? is home position ?

The way I understand that Prism handles the AO is that it centers the mirror for each exposure and will take a few seconds to zero in on the mirror correct position. There is a setting for Capture delay but it's only for the moving the mount and in most cases using the AO that is not necessary for a well polar aligned scope. So a settling delay for the AO mirror would be a big help. I'm very excited about this breakthrough for me as this makes the total automated observation process literally trouble free, requiring little or no attention to the night's observation session.

The guide loop has an
InitAOTipTilt; procedure
and you want me to add a delay ?
How much ?

I do not have any AO device here, so testing myself is complicated.

Rgds,

[millermk32]

Cyril,

Thanks for responding to my posting concerning the use of my AO-8. I'll answer your two questions:

1. Correct position meaning where it centers the guide star and not the the home position.

2. Before I switched to Prism I was using MaximDL, and I used a 20 second delay to have the AO mirror settle back to the correct guiding position. I took a screen shot of last night's guiding chart, and you can see it take about that amount of time to return to the centerline after a download. Note that the attached

graph shows a spike for the image download at about 286.06 minutes and return to stable guiding at about 286.36 minutes......so about 0.3 minutes or close to 20 seconds. If you could make it a variable for the user to input , that would be great, if it's easier, a 20 second delay would do the job.

Thanks again for your help in this important matter.

Merrel

[Cyril Cavadore]

This is happening when an image completes and another is going to start ?
I do not understand this spike … do you dither ?
In the end I do not know where to put this delay.

[millermk32]

Cyril,

Thanks so much for your time in helping solve this issue for us AO users. I hope that I can do a better job in explaining what I need.

First to answer your questions: The spike was after the image completes and starts the next one. Also, I use the automatic DEC correction feature which doesn't allow dithering.

Based on my experience, the way I understand how the AO works is that the mirror corrects for minor fluctuations in seeing and drift of the telescope at very high speed and short exposures for the guiding CCD camera ( I previously used exposures as low as a 0.2 seconds). The other feature of the AO is that once the mirror deflection reaches the limits that you set for correction by the mirror, the mount is engaged to bring the guide star back into the control range of the mirror. Usually, that adjustment is only a small fraction of a second. For a well polar aligned telescope, this doesn't happen too frequently. So in net, there are two portions to AO guiding.... the mirror (for fine adjustments) for most of the time and the mount (bumps as MaximDL calls it) for more crude adjustments to accomplish high resolution guiding.

The chart that I posted is the correction of the mirror and the spike shown is when the guider is engaged at the beginning of the exposure. The program tells the guider to stop to download the main CCD image and after that is complete, the guider starts again (and within about a second the main CCD starts) and in the case of the AO-8, the mirror then returns to the correct guide position (where it was prior to the download). Note that the entire graph for the night shows that the mount almost never moves and the mirror makes the guiding corrections. The posted graph is only a small portion of the automated session that I did. Again, over the course of the imaging session the AO-8 mirror compensates for the minor amount of drift caused by polar misalignment and rarely does the mount have to move to compensate.

So, what I'd like is to have the program start the AO-8 mount and mirror about 20 seconds before the main CCD is engaged. You do have a setting to accomplish something similar for a standard guider that you call capture delay. I have experimented with that but that delay is for only the mount portion of the guiding and once the delay that I set is reached, the AO mirror then was engaged to bring the guide star back to the correct position. They are two different functions.

I hope this makes sense and if there are other AO users out there that could maybe explain it better than me, please join in.

Please let me know if I can provide you with some other information.

Thanks again for your help.

Merrel

[Cyril Cavadore]

May be a video capture would be nice, than 1000 words...
Since I do not the hardware here, I do not dare to change things that could worsen the issue...