AVX not Tracking

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Joined: Fri Jan 25, 2019 3:38 am
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Re: AVX not Tracking

Post by W7AY » Tue May 26, 2020 5:54 am

>> However, the object moves significantly when guiding is enabled. How do I troubleshoot guiding?

OK, there are multiple aspects when autoguiding.

First, when autoguiding, there is Tracking Speed. This is the "natural" rate that your mount moves (typically sidereal rate for the stars). You can for example set guide pulse duration to something infinitesimally small (i.e., practically no correction pulses) and see if at least your mount is tracking correctly, Go to Guide Settings and set Max DEC Duration (the current name in 1.4.4 Beta) and Max RA Duration to zero or 1 (I don't know what the smallest number can be, you can keep trying various values). For good measure, you can also set the DEC Mode (just above the Guide graph, to Off and both DEC and RA aggressiveness to 0.

If tracking is now tracking the stars mostly correctly (with a very slow drift, like what we see during drift alignment), then tracking at sidereal rate is working correctly. If not, that is your problem.

Additionally, check to make sure your tracking rate in the hand controller is set to 1x.

Lets say tracking is correct. But guiding causes the stars to move too rapidly, check your guide rate. This is usually set for 0.5x sidereal. Some mounts prefer a larger correction (like 1x sidereal). Basically, as long as you apply a guide pulse (either with ST-4 or with a mount protocol command), the mount will move in the desired direction at a rate of 0.5x sidereal.

PHD2 looks at the error in terms of number of pixels it needs to correct, and then applies a pulse of proper duration. For example, if the MAX Duration is set to 2000ms , then PHD2 is allowed to send a pulse as long as 2000ms, moving at the guide rate. So, if guide rate is 0.5x sidereal rate and you apply 2000ms pulse, then the mount would move 1 sidereal second. This is a huge number when converted to your pixel scale -- typically, the correction pulses are shorter than the MAX.

Speaking of which, be sure to double check that your guide scope focal length is correct, because it affects this pixel scale.

(You can temporarily use the guide scope and camera as your main camera, set the now main camera focal length to 0 and let plate solve find the true focal length for you.)

Remember to turn the MAX DEC and RA durations back to 1 to 2 seconds, and turn DEC Mode back to Auto.

For mounts that track well, the DEC and RA aggressiveness can be kept low (basically just let PHD2 gently nudge the RA and DEC axis gently. If you see wild positive and negative swings in the guide graph, your aggressiveness is set too high.

Finally, does your mount have a way to disable the ST4 port? The reason I ask is that if there is a short in the ST4 connector, your mount would think that someone is making a constant call for adjustment. Shine a light into your ST4 port to see if the pins in the RJ11 connector are in a neat row and not shorting one another out.

Sorry I can't be of any more help. I don't have your mount and not used to its idiosyncrasies. For the past 15 years, I have only used Takahashi and RainbowAstro mounts.

Good luck,

Posts: 6
Joined: Mon May 25, 2020 10:06 pm

Re: AVX not Tracking

Post by astroGrandpa » Fri Jun 12, 2020 3:20 pm

I have a CGEM II and ASIAIR Pro. not using Safari though. after AIR Preview Goto my target, then switch to guiding, my guide stars usually jump around at first, back and forth on the screen, or wonder downward. If I then disconnect the mount in AIR, then reconnect then go back to guiding everything is stable. very strange but I've seemed to found a fix.

Posts: 6
Joined: Wed Jan 15, 2020 10:12 pm

Re: AVX not Tracking

Post by HeliAv8r » Fri Jun 12, 2020 9:35 pm

Thanks for the tip. I'll give that a try if need be. However, I think I found my answer the other night. It is rather weird but in the app there is an option to enable centering of the target after a go to. I had that on when I was having issues. I turned it off the other night and my guiding issues went away.


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