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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Abort current exposure when hour angle is greater than 0

  • Posts: 23
  • Thank you received: 5
Last night, I tested the meridian flip in Ekos and found a problem.

I set up a series exposures with duration 900s and the auto meridian flip was enable, then I chose a target which was near the meridian. When the hour angle was greater than 0 (this is the default value) , the scope would not flip automatically until the current exposure was finished.

In my opinion, the current exposure should be abort and dropped when hour angle is greater than 0, then perform the meridian flip immediately and restart the exposure which has been abort before. The reason is that if an exposure is very long (For example 3600s or more, my CCD can do such a long time exposure), the scope cannot track accurately when hour angle is greater than 0. In addition, the scope is in dangerous position and it might hit the tripod.

Based on my view, I urge that to stop current exposure and perform meridian flip in Ekos when auto flip is enabled and telescope hour angle is greater than 0. Then restart the exposure which has stopped before.

EDIT: There seems to have a better way to deal with this problem: comparing the time to meridian(hour angle is 0) with next exposure duration. If the exposure duration is greater than the time to meridian, wait and do not start new exposure until auto meridian flip is completed.

Does anyone come across the same problem with me ?
Main Scope: GSO RC8 (195mm f/8.2)
Focuser: MoonLite 1.5" for RC
Mount: AZ-EQ6
Guider: Moravian OAG with Moravian G1-2000M
Primary Cam: Moravian G2-3200
Filter: Johnson-Cousin BVI ; SDSS g' r' i' z' ; Strömgren b, Strömgren v, DDO-51, H-Alpha (3nm), H-Alpha(13.6nm)
Last edit: 5 years 8 months ago by starrybird.
5 years 8 months ago #26992

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  • Posts: 126
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I see two problems with your suggestion:
The client could abort a 1 hour exposure even when only a few seconds are left. Discard or keep that exposure? Then what about a few minutes left? What decides?
In your edit, what if the exposure is again one hour, and the flip will occur just before that hour has passed? Should the sequence be halted for almost an hour? That seems precious imaging time lost. It would be easier to force an early flip or a late flip.
Personally I would calculate where in the sequence a flip needs to occur, and insert a forced flip there, between exposures. With one hour exposures, the flip is then no more than half an hour early or late. I think that most setups allow for this margin before the scope hits the pier.
5 years 8 months ago #27087

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