AOX star fade

Well I guess what you call particularly dim for the use with an AO. From what I can tell those stars were around 9.5-9.7.

 

No sorry, I don't have any SNR measurements. To be fair though I think I am guiding on Alnitak whilst imaging the horse head.

 

I would like to add some more information to help determine the cause of this problem which still seems to exist with the version of MaximDL (V6.12) that I have. I think I have found a work around though. What I do is start up CCDAP 5 and connect all component software including MaximDL. At dark I start the run. Dome opens and then I move the scope to target, take a 1 second image with the main camera and then take a locate image with the AOX. In this case I use 0.5 seconds. I then calibrate the drive and then calibrate the AOX. I then locate again and go the track tab and track the auto selected star. Now I leave the AOX to guide on that star. CCDAP at the appointed time start time of the imaging stops the AOX and tracking and commences a focus run. It does the focus run then returns to the target, selects the guide star after plate solving and then commences guiding. After a delay of 15 seconds the main camera starts and guiding continues without guide star fade occurring. If I leave the guiding idle at the start and let CCDAP do the run as per normal the guide camera will always produce guide star fade and I lose the first sub after each focus run or meridian flip. Is this a sequencing problem in MaximDL? Perhaps MaximDL is not remembering the settings on the calibration and guiding etc? Is this information helpful?

 

It is helpful in that people using ACP have been seeing this and working with SBIG to solve it. I am putting together a package for this and I will include this thread. Thanks.

 

Interesting - here's a recent post that also talks about this http://www.diffractionlimited.com/forum/index.php?threads/ao-x-track-and-locate-bin-settings.2136/

Apparently there are problems with AO-X/guider settings 'sticking'. This could explain what I have been seeing which is that after the 'fade' the guide star re-appears in the track box but is a shadow of its former self (its now much smaller and dimmer). If the binning somehow got changed from 2 to 1 when trying to recover the star that could explain it.

 

Geoff, FYI there's a leading blank and I think a missing : in the link to thread 2136. It comes out with a %20http//xxxxxx (missing : before //) and dies. You can edit that out

Interesting thought on the binning thing. I have a couple of posts on this including this one from a few days ago.

 

I never noticed this AO-X section before, but what is discussed here is also a fault I am experiencing and thought was associated to the timeout fault mentioned in the STXL section. Im surprised how civilised correspondence is within this long standing thread! Im very upset with this camera (STXL11002, AOX, self guide filter wheel)! Ive been trying ACP, being only able to get it to work once I deactivate the AOX.

And regarding SNR value needed to get a lock automatically under ACP = 50! Values of 3-5 were impossible, 8 is when I could stop/start auto guiding manually after the main chip started its exposure, but 50 was the number it worked at automatically under ACP. As you can imagine, hz was slooooow, thus the reason for deactivating the AOX.

Steve Mohr

 

Is there any progress here at all? So far I have found that very bright stars will autoguide without guide star fade. Brightness values around 10000 in the AOX panel seem to auto guide easily and guide star fade does not occur on main camera start. Values around 2000 and below have trouble autoguiding without guide star fade on main camera start. So ultimately this has to be a maxim code problem similar to the small guide star problem several years ago and I wonder what is happening with resolving this problem. I have learnt to get around this problem for now but it would be better if the problem was resolved.

 

I am having this exact same problem with relatively bright stars. Nothing outrageous, but certainly not dim. For the most part, the stars I pick are in the 4000-6000 range. I get the AO guiding, prior to exposing the main chip. I could let it guide forever before exposing the main chip and it will guide perfectly. As soon as I start the imaging process, it freezes for a moment and loses the star. Now, what I don't know is if it's the start of the exposure or the initial movement of the filter wheel that causes the problem. However, when it comes back online, the background is markedly black and the star populates 1/3 of the pixels it did at the start OR it loses the star all together and has to be re-calibrated.

Is there anything I can do?

 

Thanks, Doug.

 

It has been a while since my bad tempered response above [sorry, but this has been a testing number of years], and I acknowledge that Adam has made progress to improving the performance of my camera [STXL11002 with self guide and AOX] with the last driver update. At these driver update times I reinstall the ACP trial again with Maxim to see if I can guide at full speed under Maxim DL with no binning, but still, the guide speed is somehow compromised and a very high ADU number is still necessary for Maxim to lock onto the guide star [currently set at 20,000 ADU in ACP]. However, as mentioned elsewhere, whilst using either binning 2x2 or binning 3x3, the camera works as advertised at ADU 3000, and high speed iterations are possible. I still cannot understand how this can be?

I must defer to TSX for the time being, as the camera seems to work correctly there whilst being controlled by CCDAP5. In the future, I hope to use ACP-Scheduler/ Maxim combination as this looks to provide the best automated imaging solution.

Hopefully the next SBIG w/AO plug-in does the trick!

Regards,
Steve

 

Doug, can you tell me if the latest patch takes care of this? I tried 6.13 but had to revert back to the 6.10 as I could not calibrate the AOX. I confess I did not try the patched version as I was getting very frustrated with not being able to image. Does the patched version take care of calibration and guide star fade issue? Thanks for any information. BTW I cannot seem to find the thread on calibration. I thought it was in this forum, but perhaps I am wrong.

 

Hi Paul,

There have been significant changes made to the AO plugin. You can find the latest update here. I'm waiting for word on how well it performs, but I'm hopeful that it solves the major issues in the original reports. Please give it a try (with V6.13 only) and let me know what you find.

Thanks.

- Owen -