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INDI Library v2.0.2 Released (01 Jun 2023)

Bi-monthly release with minor bug fixes and improvements

Astrometry slew to target and mount model

  • Posts: 294
  • Thank you received: 18
I use frequentely the astrometry to center an object. The solve is very quite perfect with Astap or Astrometry.net. But I don't understand why after 2 or 3 tries, the next tries do not place the object just in the center. It stay on the red aera or just outside, never in the green aera after twelve or more try. I try to increase the Accury fields to 50, but unsuccessful.

And so the mount model never rich a successful end.

Thank for your support.
iOptron GM28 - ED80 SW - MAK180 SW - ASI183MM PRO -QHY224C - RPI4 4Go + Stellarmate/Nafabox/Astroberry - Focus motor DIY
3 years 2 months ago #51252

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Which mount do you use? Do you clean the mount model before slewing to a new target? If not, please try and see if that helps. It always works for me if my SkyWatcher HEQ5 (EQMod) mount has problems centering on a target.


HTH, Wouter
Wouter van Reeven

ASI6200MM and 7 slot 2" filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and 5 slot 1.25" filter wheel with an 8" TS Ritchey-Chr├ętien on a SkyWatcher EQ6-R
3 years 2 months ago #51258

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My mount is a Celestron AVX. I try again this evening if possible. Thanks.
iOptron GM28 - ED80 SW - MAK180 SW - ASI183MM PRO -QHY224C - RPI4 4Go + Stellarmate/Nafabox/Astroberry - Focus motor DIY
3 years 2 months ago #51274

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It's a feature of the way that Celestron have implemented their slewing. When the mount does the slow final approach slew it moves to the axis position that the object was at when the slew command was sent. The slew takes several seconds so by the time the mount stops the object has moved on. This gives an error in Ra of 15 arc seconds per second that the final slew takes so usually something between 30 and 75 arc seconds.

I've been trying to get them to fix this for years, it's quite easy, just estimate how long the final slew will take and adjust the target position to allow for this.

I've been hoping they would fix this but it looks as if the only way will be to fix it in the driver - adjust the target position by the difference between the target position and where the mount stops. I've already done it for the ASCOM driver and will do it for the INDI one as well. I'm in lockdown at the moment so will get suficiently bored to do this fairly soon.

In the meantime the best thing is to relax the position tolerance, 60 or 70 arc seconds should be OK.
3 years 2 months ago #51281

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Hello Chris, this is wonderful news to me. I have a Celestron CGEM DX, and have been struggling to get the slewing to get close to a green. I have many repeats on virtually the same distance errors. For a long time I just let it solve then hit stop and sync and then move to the next target.
Not ideal, but picking my fight to get lights. My mount behaviour has been consistent over the last 5 years...
What would you need to get this fixed? What can I off for support? I have time to test, retired now.
Equipment

Sky Watcher Esprit 100ED APO
QHY5L-II Mini Guider
Pegasus PPB, DMFC
Xagyl Filter, LRGB+Ha
CGEM DX
RP4.4

William Optics RedCat 51
Star Adventurer
RP4.1
Software
KStars phd2 , Ubuntu, StarTools, Mac OS
AstroDSLR AstroGuider AstroTelescope, AstroImager, Astrometry
3 years 1 month ago #51588

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It shoud be done. The sources were updated a few days ago and it should be in the daily build by now.
The following user(s) said Thank You: Andrew Couture, Doug S
3 years 1 month ago #51593

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Looking forward to trying it out, thank you.
Equipment

Sky Watcher Esprit 100ED APO
QHY5L-II Mini Guider
Pegasus PPB, DMFC
Xagyl Filter, LRGB+Ha
CGEM DX
RP4.4

William Optics RedCat 51
Star Adventurer
RP4.1
Software
KStars phd2 , Ubuntu, StarTools, Mac OS
AstroDSLR AstroGuider AstroTelescope, AstroImager, Astrometry
3 years 1 month ago #51610

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Thank you Chris! I also have been wondering about why solves aren't achieving finer results on my CGX-L. I convinced myself after a more careful polar alignment that it was better (still not really great). I look forward to checking out your new change! Clear skies.
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
3 years 1 month ago #51612

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What I find strange, is how between (or during?) astrometry solves, the mount stops tracking.
I had the issue that if I 'Slew to Target' after a 'Capture and Solve', the mount (an iOptron ieq45) took long to reach it's target (often 4 to 5 tries). When I looked at the mount tab, i see Tracking going from ON to OFF now and then.
When I see Tracking going to OFF, I quickly manually switch it back on again. The result is that the target is almost always instantly met the next solve, and with high accuracy!
What is going on?
Latest Stellarmate on Rpi 4B, 294mm-pro, EFW-8, CEM70
3 years 1 month ago #51614

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Hello Bart, here is what my mount does on a 'Capture and Solve'. When I hit this button, tracking is on, a light is captured and then is solved. If it meets or is better than the criteria all is good.
If the error is large, tracking turns off, mount slews and then tries to centre on the object. When this slew ends, tracking is back on and a light is captured and then is solved.
For my gear, when the slew is done and the 'Stop' button gets highlighted (active) tracking is on and the process of getting another light begins.
However, if your tracking stays off, you may want to get an error.log for the mount and camera. Hope this helps
Equipment

Sky Watcher Esprit 100ED APO
QHY5L-II Mini Guider
Pegasus PPB, DMFC
Xagyl Filter, LRGB+Ha
CGEM DX
RP4.4

William Optics RedCat 51
Star Adventurer
RP4.1
Software
KStars phd2 , Ubuntu, StarTools, Mac OS
AstroDSLR AstroGuider AstroTelescope, AstroImager, Astrometry
The following user(s) said Thank You: Bart
3 years 1 month ago #51649

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  • Thank you received: 25
Ah like so!
Doesn't explain for me why the position settles better when I manually activate tracking again, although this might already be on and the lag from the network prevented me to see this or my command to take action.
Thanks for explaining and I'll test it out whenever we have clear skies again.
Latest Stellarmate on Rpi 4B, 294mm-pro, EFW-8, CEM70
3 years 1 month ago #51656

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