Hi John,

I have had an issue with autoguiding with the setup that does not have a rotator for quite a few months where often (but not always) the guide star is driven away from center with obviously incorrect vectors being applied....this does not happen with my other setup that uses the offaxis guiding with an AOL and a rotator. The autoguiding problem occurs particularly when I image away from the pole and on either side of the meridian. I have not posted here about it previously, because I suspected a problem with CCDSoft. The problem only appeared after I updated from CCDSoft ...188 to ...192 . It has persisted after a further update to 195. I have checked everything mechanically with the mount and I can autoguide very well with CCDSoft alone if I do another calibration at the same part of the sky first. I notice that CCDSoft does not seem to be updating the change in dec when I use TS6 to reposition however. I have tried multiple times to do a recalibration with CCDSoft and I get a good calibration with 4 good looking equal and opposite vectors. I have my camera axis positioned well (about 20 deg) away from the mounts axes. My plate solves are OK. I have tried re-initialising CCDAP of course many times and still the weirdness continues. Sometimes the guiding works as usual with sub pixel errors as the same setup which has not been touched or altered in any way has guided superbly for over a year previously.

If you have any thoughts for further trouble shooting this , I would be very grateful. I have attached a recent log where this sort of guiding weirdness was apparent.
Cheers,
Tim

ccdap20091013_204822.txt (99 KB, 13 downloads)

Hi Tim,

In looking at your log, it appears that the guider is bringing the star back to center after the dither, but it overshoots the first time. Then it corrects and is bringing it back again, but runs out of cycles. It almost acts like there is some backlash that the guiding corrections are having to deal with. As a suggestion, could you try 1. increasing the Max Move parameter to say 1.5, just to see if that movement takes up any backlash quicker, and 2. increase the cycles to give the guider more time to overcome the backlash (if that's what it is). HTH .....

Hi Frank,

Thanks as always.

The problem is that something often , but not always , drives the star in completely the wrong direction.

CCDSoft does not seem to be getting / utilizing the dec or EW info properly.

Yes, there is some backlash, but I can guide perfectly well with the mount with CCDSoft alone and a calibration done at the same part of the sky.
This problem has plagued my setup for about 6 months now.

I might see if I can see what happens with Maxim although I have never used Maxim for image acquisition before and I am sure I will have to spend a fair bit of time sorting through all of the setup issues with it!

Cheers,
Tim

Tim:

I was having a similar problem.

It was solved by calibrating with the camera at about 10 degrees from exact alignment with the X and Y directions of the mount.

I would do an "align camera," which exactly aligns the camera with the X/Y directions of the mount, and then calibrate the guider. It would then guide like the corrections were being applied in the wrong direction.

However, John suggested that I not calibrate with an exact alignment, so I rotated the camera about 10 degrees and did a guider calibration. It solved the problem...suggest you give it a try.

Hi Arlo,

Thanks....I have the camera rotated about 20 degrees from the X Y directions of the mount...I was lead to believe that as long as it was not too close, i.e <10deg, to the mounts direction that all would be Ok...I will keep experimenting.
Regards,
Tim

Hi John,

Thanks very much for fixing the guider problem where there is no rotator in the setup...it seems to be fine now.

Regards,
Tim

You're welcome, Tim. Glad it is working for you.

Hi John,

I spoke too soon.
Last night the issue with the guider being given wrong vectors surfaced again....the guide star is driven in circles with incorrect vectors being applied...this has plaqued me for most of this year now, with the setup that has no rotator...guiding with CCDSoft after a local calibration is fine....I have touched and changed nothing...even imaging the same target as the other night which worked fine....CCDsoft seems to not be given the correct DEC initially...
The mount guides fine with <0.5 pixel errors when CCDAP4 is not in the equation.

Cheers,
Tim

Hi Tim,

Can you post your log file where this happened?

Oops..I thought i had....sorry!
Cheers,
Tim

CCDPLOG20091116.txt (20 KB, 2 downloads)

Hi Guys,

I have a remote session in progress tonight as I type...I note with this current run, that the guiding was a scrambled catastrophe until after the meridian flip and now it is perfect....I will post a log once the run is completed tomottorw at dawn...

Cheers again!

Tim

Hi Tim,

Here's something you might want to check out. Take a look at the plate solve PAs starting at 21:40:53. They are not consistent - 230.1, 85.6, 230.1, and 122.9. Also note the pointing errors. I think there is a problem with the plate solves and that may be what is causing the guiding issue since CCDAP4 doesn't get a correct plate solve to set the vectors up. If the plate solves are working correctly, then your PA for the Sync images should match the PA of your target. If you turn on the tracing function, any errors generated will be logged and the Sync images will be saved. Then you can see if the images plate solve outside of CCDAP4. I think that would be the first place to start. HTH ......

Hi John and Frank,

Thanks for your help. I am very sorry that I have not had a chance to reply or to followup on the troubleshooting of this over the past few days. It is my wife's fault.

She has just given birth to our 4th child a baby girl....She totally unreasonably has expected me to be with her rather than focusing on astrophotography !!

I will be back in touch with this hopefully before too long!

Cheers,
Tim

Hi Tim,

Congratulations on the new addition to the family !!!! When you are ready to get back on this, we'll be here !!!