Meridian Flip - Forums

Topic starter

Mar 16, 2024

Using a WO FLT 91, ASIAIR, ASI 2600, ASI 120 guiding, EQ6-R Pro. Getting some great images and learning how to process them. Much thanks to Scott Horton.

Setting up tonight. Most of my sessions face S or SE. Everything is focused, autoguiding set. Planning on 10 min exposures.

Activating Autorun, the first message is scope will flip in 960seconds. I understand this is the meridian flip (I programmed into my runs). Makes sense, however it delays the beginning of shooting sessions and image capture.

Is this a common occurrence (I guess so when shooting nearly overhead), any ways to mitigate the delay in shooting, etc. It's frustrating, having to wait for images to start capturing, but I think I understand the reason the rig does this.

Any insights would be appreciated.

Thank you

Respectful Engaging

Dennis Spender

Topic starter

Mar 16, 2024

Oh, I neglected to add;

After the meridian flip, the ASIAIR refocuses (takes about 4 minutes) and re calibrates the autoguiding (takes about 5 minutes).

Ultimately I assume all these machinations lead to crisper detail in my images, just takes a while. Don't know if there are any shortcuts or work arounds to consider.

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Drew Hackney

Mar 16, 2024 · Edited: Mar 16, 2024

I use an ASIAIR to run my imaging sessions too, though I'm currently shooting OSC and I don't have an autofocuser yet. When whatever I'm imaging is within an exposure time or two of a meridian flip at the start of my night, I'll do one of a few things:

1. I'll get good focus and take my flats while I'm waiting. I have to reframe my target and recalibrate my autoguiding after this, but the flip would do that anyway.
2. I'll turn the flip off in the ASIAIR software, take a one or two exposures, then tell my ASIAIR to go to the target. If my target has crossed the meridian, the ASIAIR will do a meridian flip. But I also have a compact setup so I'm not too worried about my imaging train running into my tripod and I figure flipping a minute or two late won't hurt anything.
3. If there are other people at my dark site with me I'll annoy them by talking about equipment while I wait.

You can maybe program the ASIAIR to flip a couple minutes early, but I haven't had to play with those settings too much.

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Tim Ray

Mar 16, 2024

I'm sleeping long before the flip occurs. I assume it takes a few minutes to plate solve, do the flip, plate solve to target, restart guiding. PHD2 allows for a meridian flip without recalibration, do an autofocus run, then after all that - resume the sequence. Magic.

I am just having some fun with this post…, I'm not an ASIAIR user, not much help. but the meridian flips take several minutes if more than a single plate solve to target after the flip is required. Time to reload the coffee cup. Regardless of which software you use, SGP, NINA, ASIAIR's, Sharpcap etc, it beats the old days before digital setting circles with a nail at each end of the tube for a DIY zero power finder…

CS Tim

Dave Rust

Mar 16, 2024

Your experience is normal. Flip, focus, and recalibration typically take place immediately after the flip.

It's good to go through all of the steps…though you can disable "calibration after flip" if you are confident that your guidescope or OAF won't shift with the change in gravity (I have disabled that step on my rig). Refocusing is a good idea for reflectors because it will compensate for a slight change in mirror alignment since the mirror's locks have to be off ("mirror flop"). But refocus is probably not needed on your refractor.

And it's normal for ASI to pause exposures if the flip is coming sooner than the next complete exposure. So it may say, "Flip in 134 seconds." Good that it paused, 'cause I'm doing 180 sec subs!

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Dennis Spender

Topic starter

Mar 16, 2024

All makes sense. There is a price (time) to pay for good images and there are innumerable images available to capture.