Meridian Flip, a thought experiment

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aaron
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Meridian Flip, a thought experiment

Post by aaron »

Meridian Flip will be a big project. Let's plan.
  1. Detect a sequence is in progress.
  2. Monitor the hour angle and HA limit.
  3. When the hour angle reaches the HA Limit — or better, when HA Limit is within the next image's exposure time — trigger the flip.
  4. Pause the sequence if possible, or at least record the batch# and frame#.
  5. The flip should move to the same declination as the target, but a right ascension just past the meridian.
  6. Begin a guider calibration process.
  7. After guiding starts, maybe autofocus. Why not? we have time.
  8. When the target crosses the meridian (plus X seconds?) slew to the target
  9. Start guiding again
  10. Take an image, and plate solve to confirm we are aimed correctly. Correct if needed.
  11. Resume the sequence.
Related Properties (partial):
  • Hour angle: Mount Agent.AGENT_LIMITS.items.HA_TRACKING
  • HA Limit: target of "Mount Agent".AGENT_LIMITS.items.HA_TRACKING
  • Sequence in progress: "Imager Agent".AGENT_START_PROCESS.state == "Busy"
  • Current Batch: "Imager Agent".AGENT_IMAGER_STATS.items.BATCH
  • Current FRAME: "Imager Agent".AGENT_IMAGER_STATS.items.FRAME
  • Start Calibration: "Guider Agent".AGENT_START_PROCESS.items.CALIBRATION = true (?)
Questions:
  • Is all this necessary? Can we simply by removing some steps?
  • On the other hand, is anything missing?
  • Can Indigo pause and resume a sequence like I've described?
iMustBcrazy
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Re: Meridian Flip, a thought experiment

Post by iMustBcrazy »

It's probably easier and safe to just check that the HA limit has not been exceeded before starting the next capture. If it has, then simply re-do the "goto" to the same co-ordinates and the mount will automatically flip and re-centre the target.

Then the guiding could be recalibrated, etc.
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aaron
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Re: Meridian Flip, a thought experiment

Post by aaron »

That would be good. But I’m not sure my mount is smart enough to flip before the meridian has crossed. Or perhaps I haven’t configured it properly. EQ6R-Pro.
iMustBcrazy
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Re: Meridian Flip, a thought experiment

Post by iMustBcrazy »

aaron wrote: Sat Jan 02, 2021 7:12 pm That would be good. But I’m not sure my mount is smart enough to flip before the meridian has crossed. Or perhaps I haven’t configured it properly. EQ6R-Pro.
I have a EQ6-R Pro too. No, the mount won't flip when it crosses the meridian. It just keeps going which is good. Once the capture is done. A simple repeat of the goto command will cause the mount to flip itself because it will then try to go to a target that is in the western sky. I've tried it and it works this way - may have to stop tracking first before the goto.
JohanB
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Re: Meridian Flip, a thought experiment

Post by JohanB »

Hi all,

The mount_side_of_pier property in mount_synscan indicates whether you're on the East or West side of the pier. What i don't know for sure, is if when you change the value, it initiates a meridian flip. Never tries it, but i think so. If so, this will simplify the process a lot. May test tomorrow if the weather allows it.

Pausing the sequence has already been automated in imager agent, once a slew is initiated the running sequence is aborted, provided the related agents are set in AT and AI.

The would allow for the following simple process.

1. Monitor HA
2. When over meridian, flip the mount_side_of_pier property from East to West (assuming this will slew the mount...)
3. Take preview and Plate Solve (which Peter has made accessible for scripting! Build wil follow tomorrow)
4. Sync & Center(which will also be accessible for scripting per tomorrow. Nice :-)
5. Recalibrate guider
6. Resume (or actually restart) the sequence
7. Et voila! Done...

Regards, Johan
JohanB
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Re: Meridian Flip, a thought experiment

Post by JohanB »

Hi all,

Just set-up the mount (AZ-EQ6) and looked at the mount_side_of_pier property of mount_synscan.

Unfortunately, the property is read-only, so the flip must indeed be initiated with a new slew, once the meridian has been crossed. The property can still be used in the script before execution of the flip though, to test if a flip is really required.

Jan 3 10:46:36 ZGAstroScope indiboot[2126]: 10:46:36.339591 indigo_server: Side of pier property 'Mount SynScan'.MOUNT_SIDE_OF_PIER, state = Ok, perm = RO
Jan 3 10:46:36 ZGAstroScope indiboot[2126]: 10:46:36.339724 indigo_server: EAST = true
Jan 3 10:46:36 ZGAstroScope indiboot[2126]: 10:46:36.339796 indigo_server: WEST = false

Regards, Johan
JohanB
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Re: Meridian Flip, a thought experiment

Post by JohanB »

Hi all,

Got the script going up to the point of plate solve :-) To be able to continue we have to wait for the new build of Peter with the plate solve and sync hooks in scripting. It was tested with the latest AT v4 and AI v4, mount_synscan and CC_simulator. The log:

14:10:47.121471 indigo_server: Meridian flip: Script started, monitoring commences...
14:10:52.121767 indigo_server: Meridian flip: Slew initiated...
14:10:52.124900 indigo_server: Meridian flip: Slew in progress...
...
...
14:11:42.278999 indigo_server: Meridian flip: Slew in progress...
14:11:42.344356 indigo_server: Meridian flip: Slew in progress...
14:11:42.758643 indigo_server: Meridian flip: Slew in progress...
14:11:42.759691 indigo_server: Meridian flip: Slew complete
14:11:42.759760 indigo_server: Meridian flip: Preview intiated
14:11:42.784786 indigo_server: Meridian flip: Preview in progress...
14:11:52.901537 indigo_server: Meridian flip: Preview complete
14:11:52.901600 indigo_server: Meridian flip: Plate solve initiated

The script;
Meridian_flip.js
(3.92 KiB) Downloaded 34 times
Will continue with plate solve, sync and calibrate later today, once Peter has uploaded the new build.

Regards, Johan
iMustBcrazy
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Re: Meridian Flip, a thought experiment

Post by iMustBcrazy »

JohanB wrote: Sun Jan 03, 2021 2:19 pm Hi all,

Got the script going up to the point of plate solve
Nice!
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aaron
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Re: Meridian Flip, a thought experiment

Post by aaron »

Johan this is really impressive! Great teamwork! I can’t wait to try!
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Peter Polakovic
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Re: Meridian Flip, a thought experiment

Post by Peter Polakovic »

iMustBcrazy wrote: Sun Jan 03, 2021 2:25 pm
JohanB wrote: Sun Jan 03, 2021 2:19 pm Hi all,

Got the script going up to the point of plate solve
Nice!
Just downsized astrometry package.net for INDIGO Sky from original 250MB (with dependencies) to about 20MB. The next step is to make server side plate solver agent...
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