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CG5 autoguiding issues

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#1 Anand I

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Posted 26 August 2009 - 12:54 PM

First night out trying to autoguide with a st-2000 and a cg5. Calibration repeatedly failed because the software was not getting any movement out of the mount in the y-plus and y-minus directions. x-plus and x-minus worked just fine. This happened with both ccdops and ccdsoft.

I tried increasing the duration of y motion up to 15 seconds (x was 5s). Still no movement.

Any ideas about what's happening? If this is an equipment fault, is there a way to tell if its the camera or the mount?

-Anand

PS - The mount is definitely at weight limit with a c9.25 and imaging gear. But the goto and manual slewing work fine, so I know at least the motors work.

#2 HaleBopper

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Posted 26 August 2009 - 03:05 PM

Are you trying to image too close to the pole? I also had this problem when trying to image in Draco. The star would not move much and the calibration failed. I even had this problem while trying to get a guide star tp pass calibration around M8 in Sag.

You can always try calibrating in a part of the sky where the calibration passes and then move to your target. Just make sure you're not too far away.

Here is a link to PhD troubleshooting:

http://www.stark-lab...torials:phd:faq

Here is a quote from that site:

"When imaging near the pole, you can increase the Calibration step and/or to turn off Dec guiding. You can also move away from the pole a bit more and calibrate there and then move back (don’t go too far). Remember, if you recalibrate on the one side of the meridian you must always recalibrate if you move to the other side of the meridian."

#3 rmollise

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Posted 26 August 2009 - 03:46 PM

First night out trying to autoguide with a st-2000 and a cg5. Calibration repeatedly failed because the software was not getting any movement out of the mount in the y-plus and y-minus directions. x-plus and x-minus worked just fine. This happened with both ccdops and ccdsoft.

I tried increasing the duration of y motion up to 15 seconds (x was 5s). Still no movement.

Any ideas about what's happening? If this is an equipment fault, is there a way to tell if its the camera or the mount?

-Anand

PS - The mount is definitely at weight limit with a c9.25 and imaging gear. But the goto and manual slewing work fine, so I know at least the motors work.


What's your setup? Serial? Autoguide port? You need to check connections/software.

My ST2000 autoguides the CG5 like a champ.

#4 dickbill

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Posted 27 August 2009 - 08:37 AM

Anand, I have the same setup, cg5+C9.25, short refractor piggybacked for autoguiding with a DSIc and I use Phd instead of the built in guider in the St-2000.

Here is what happened to me. Phd has a tool to set the corrections pulses. The CG5 has huge backlash, less than 1000 ms pulses (milliseconds and not seconds)would not make the mount move and phD calibration would fail.
Actually PhD says "calibration failed" but can still continue to autoguide with declination off (dec off) if you don't start over.
Obviously, if your polar alignment is so-so, autoguiding without declination correction won't be usefull.

So I set the impulse in phd to 2000 ms ! and it worked, Phd passed the calibration successfully and autoguided with RA AND dec corrections, although results were disapointing but this is because I was Imaging at 1300 mm or longer which is another part of the problem.

In your post you mentioned that you set the duration of the pulses in your st-2000 to 15 seconds (15000 milliseconds !!) or 5 s (5000 ms).
If this is a mistake and you mean 15 ms or 5 ms instead of seconds, then this might not be enough. This has probably something to do with the backlash and you have to use pulses around 1500-2500 ms (or 1.5 to 2.5 seconds) to make your mount reactive to corrections.






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