Hey all, looking for some feedback on some odd behavior from my asiair a few days ago. I started the night out with no issues, ran EAF, guide star calibration, plate solve and PA just fine (personal time record). Trying to goto M81, the mount started to flip flop to each side and try to go beyond the mounts max rotation. Even thought it was very close to the object, it felt like it needed to do a 360. Anyway, after a few tries and manually getting it close to M81 it found it, centered, started guiding and started running a plan. Guiding error were about 2 - 4 seconds when I watched the first few shots. I left and came back 30 min later and guide errors were in the 200’s and shots streaked. I paused the plan and tried to manually re align and get centered but this time it refused to do anything. It would constantly point in the wrong direction, shoot, plate solve, then continue in the wrong direction. Never had a plate solve fail unless it pointed to the ground a few times and tied to shoot. After about an hour it was late and had to pack it in. I ran everything a few days before without issues. I noticed the shoot prior the time several hours off, so I went into the mount and adjusted the time, which corrected it to one hour off without DST. Aside from that not sure what the issue is or where to start, any feedback is appreciated. Logs attached

Mount - star adventurer gti
Scope- Redcat 51
Guide - Zwo Asi 120

log.zip
94kB

    SpaceChef The calibration data should be close to the right Angle, Clear the guide calibration data and recalibrate it to try

        Tech@ZWO Hi, could you clarify a little more please. I don't get why the calibration succeeded and guided just fine for several shots then suddenly went off. But also the calibration doesn't explain the erratic behavior when the plan wasn't running and the asiair would plate solve, succeed and slew to point at the ground or wrong direction and the polar alignment was off by only off by a second.

        • w7ay replied to this.

            SpaceChef I don't get why the calibration succeeded and guided just fine for several shots then suddenly went off. But also the calibration doesn't explain the erratic behavior when the plan wasn't running and the asiair would plate solve, succeed and slew to point at the ground or wrong direction and the polar alignment was off by only off by a second.

            That kind of calibration (not perfecty 90º between the blue and red lines, so I wouldn't consider it to have "succeeded") will cause declination errors to move the RA axis, and vice versa. Typically caused by doing calibrations near to the pole.

            Where did you perform the guide calibration? When you take a high declination target like M81, you must first move the mount near to the celestial equator (+/- 30º is sort of OK. +/- 15) is even better) and calibrate the autoguiding parameters there. Only then slew to M81 and start autoguiding there.

            slew to point at the ground or wrong direction and the polar alignment was off by only off by a second.

            This is often caused by the ASIAIR losing its pier-side information after that 60º slew during polar alignment. Always home the mount right after a polar alignment session, and only then perform GOTOs (with a German mount, a GOTO with the wrong pier side will produce the effect you saw).

            Do not use auto center in ASIAIR; it is not accurate enough. After turning Auto GOTO off, do a couple of "manual plate solve, "Sync & GOTO , recapture image" (rinse and repeat those three -- be sure to recapture an image after doing the "sync and GOTO") to get a more presise result from plate solving.

            You can also manually do a Sync and then manually do a GOTO after, instead of using Sync and GOTO, which has bugs (like misidentifying horizon) after a plate solve.

            Don't waste time with polar alignment; ASIAIR is not repeatable to 15 (or more) arcseconds (try doing two polar alignments one right after another, and you wiill see). 20 arc seconds is pretty much an overkill already for CMOS type exposure times. Check the web for polar aligment error and field rotation.

            Remember, you are not using some real astrophotography software, but an ASIAIR.

            Chen

                w7ay Thank you for your insights. To ensure I'm on the right track, here's what I plan to do based on your advice:

                • Calibrate Autoguiding: Perform the autoguiding calibration near the celestial equator within +/- 15 degrees declination for stability and accuracy.
                • Polar Alignment and Homing: After polar alignment, I'll home the mount to ensure it recognizes its correct orientation.
                • Manual Control: Disable Auto GOTO and handle plate solving, syncing, and GOTO operations manually to enhance precision.
                • Repetitive Accuracy Check: Repeat the manual processes as necessary to refine alignment before moving on to my target.

                Could you confirm if these steps align with your suggestions? I appreciate your help as I navigate these settings for better astrophotography results.

                • w7ay replied to this.

                    SpaceChef Repetitive Accuracy Check: Repeat the manual processes as necessary to refine alignment before moving on to my target.

                    Yeah, but that's just to check how accurate ASIAIR polar alignment is. You really cannot repeat it to get better results since the second time you run polar alignment, it is also wrong.

                    However, as I mentioned earlier, there is not need to get polar alignment to better than a couple of dozen arc seconds. You are sweating it for no reason.

                    Check this forum, probably 3 years ago, where I posted how far off ASIAIR polar agignment error is, as a function of the error of the starting declination. If memory serves, ASIAIR has an error of 15 arc seconds when it reports 0 arc second error, even if you start 0.5 degrees in declination from the pole. And it gets worse if you start at a larger declination error from the pole.

                    Migrate to something other than ASIAIR as soon as you can -- the sooner you abandon ASIAIR, the earlier you will start getting good performance from the control software. And be able to use a myriads of devices that ASIAIR will never support.

                    Chen

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