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Meridian flip failed? or did it? Advice needed!


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I always use N.I.N.A and I get a meridian flipped failed message, but technically it didn't, but the image was not centered. I like to stay in the house when ive setup and only check on it now and then. All the time I have missed when the mount does the flip because I don't really know how it works, I look at my output and I can see that the images flipped but didn't exactly center them, I use a platesolver to do that. I'm imaging the california nebula at this very second and i've wasted 6 images because I didn't know when it was going to happen. It cut off a small portion of the nebula so I'm not sure what will happen when I come to stack the images, I'm hoping there's no weird artifacts, hopefully just that it's less exposed on the bits that were cut off. Is there a way I can fix this error or work out when it's about to happen so i can do it manually. It's been a problem for a long time now, sometimes theres a cable snag I'm not aware of, I just don't want to sit outside all the time.

Edited by Quetzalcoatl72
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Dont know how to fix this, i am doing the same as you which is just re-centering again after the meridian flip has passed. For some reason NINA does not follow the same tolerance of re-centering accuracy after a meridian flip as when normally re-centering. Have not bothered to look into it more because i am always by the scope when its operating so at the worst i lose 1 sub to it, but if anyone comes up with a solution later i would also like to know what it is.

As for whether you should stack the missed subs, depends on what you use to stack. APP has the MBB (multi band blending) option that can blend the missed exposures with the normal ones. If you have a short integration you will still be noticing a difference in noise around where the bad subs are blended into the good ones, so might not be worth it in the end. Also, if you have anything but perfectly matching flats you will get some gradients that are difficult to remove or just add noise to the image so in that case too its best to just scrap the bad ones.

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1 hour ago, Quetzalcoatl72 said:

I always use N.I.N.A and I get a meridian flipped failed message, but technically it didn't, but the image was not centered.

Maybe caused by the reference to the target. Seen this a couple of times in Ekos. If I tell Ekos to go to, say M45, it platesolves and starts tracking. If I start the session and leave it there, the meridian flip wil be spot on. But if I do adjustmentes to frame the target before starting capture it will be off, as you said. My solution is to create a referance sub, which can be used over several sessions. Have a small library already. Then I use the "Load image  -> Solve -> Slew" function. New coordinates are registred, and the flip will solve to these before restarting capture.

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There are at least a couple of places in NINA where you can see when the flip will happen. I have the "Telescope" pane in the imaging tab setup and the flip time is shown there plus also in the DIYMF plugin that I use in the sequencer.

This is what I have in my flip section and it works fine every time. I also have a Centre after Drift trigger as part of the sequence too though. Ignore the time that's showing as the sequence is not actually running.

1202131489_Screenshot2023-01-25223735.thumb.png.300a56bfa08f93a84126c1828629368c.png

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21 minutes ago, Rallemikken said:

Maybe caused by the reference to the target. Seen this a couple of times in Ekos. If I tell Ekos to go to, say M45, it platesolves and starts tracking. If I start the session and leave it there, the meridian flip wil be spot on. But if I do adjustmentes to frame the target before starting capture it will be off, as you said. My solution is to create a referance sub, which can be used over several sessions. Have a small library already. Then I use the "Load image  -> Solve -> Slew" function. New coordinates are registred, and the flip will solve to these before restarting capture.

I use a custom marker because the little green square is not always in the middle of the nebulas on stellarium

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12 minutes ago, Quetzalcoatl72 said:

I use a custom marker because the little green square is not always in the middle of the nebulas on stellarium

Never used NINA atall, so I can't really tell, but the coordinates to the center of your framing must be what NINA aims for after the flip. In Ekos I can solve this in two ways: Either make a flag or bookmark and manually enter the custom coordinates, and start the session from this, or make a reference frame with custom framing and platesolve according to this and run the session without more fiddling. I often do test exposures and try out framing and camera rotation when the moon is up or the clouds come and go. I don't have any rotator, but I give the final referance frame a name that tells me how the motiv is composed. Something like "M45_Horizontal_600D_200PDS.cr2" This tells me that this M45 is composed with the camera (Canon 600D) mounted 90 degrees to the tube on my SW 200PDS reflektor. I do either full horizontal or vertical; I don't like pictures with diffraction spikes all over the place. When it's time to capture, I just point Ekos to this raw Canon file and let it do it's things.

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On 25/01/2023 at 23:15, Quetzalcoatl72 said:

I use a custom marker because the little green square is not always in the middle of the nebulas on stellarium

I must confess I have found NINA meridian flips pretty painless. I use the framing tool in NINA and I have quite tight tolerances set for the accuracy and it has always worked faultlessly. It is adjustable in the plate solving options.

image.png.057e1b93b122a4b64d7f7305ea114044.png

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