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Is a meridian flip always needed if the DSO starts east of meridian?

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I did an imaging session last night at a clear sky. The session was aborted by a post meridian flip align failure, I had not the align log activated, so I cannot say what the root cause might have been.

My question to the experts: Is a meridian flip ALWAYS needed if the object starts east and ends west of meridian or can it be avoided under specific circumstances? If so, which are the prerequisites under which the flip can be avoided (geometry/equipment setup)?

Thanks for your insights!
Skywatcher HEQ-5 EQMod | ASI1600MM Pro | ASI EFW | TS61EDPH | ZWO ASI 120MM | Artesky 130mm guidescope | Raspi 4B 4GB | Waveshare Stepper Motor HAT - DIY Focuser | Stellarmate | PixInsight
1 month 2 weeks ago #85199

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Hi. You dont need a MF if you are shure your scope/camera dont collide with your mount (or other equipment) or pier and your cables are long enough. I rarly do a MF, especially with my small scopes. Only if I'm imaging near zenite or at higher DEC values it is necessary, but depends on the telescope.

You can switch that in the mount tab. Just uncheck the box at "Flip if HA>"

If you are unsure, than watch your scope after the meridian passage, if there will be problems.
1 month 2 weeks ago #85209

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Thanks Jürgen for your reply.

In fact I am not sure if my equipment can collide. I also have a fairly small scope. Currently I target the Veil nebula which at meridian passage has a DEC of about 72 degrees. And this happens at around 1AM, so one hour after midnight. I am not against the flip but had an align failure last night post flip. The reason is unknown and therefor I wanted to avoid the flip.

I might want to check early in the morning if the flip was successful.

Kurt
Skywatcher HEQ-5 EQMod | ASI1600MM Pro | ASI EFW | TS61EDPH | ZWO ASI 120MM | Artesky 130mm guidescope | Raspi 4B 4GB | Waveshare Stepper Motor HAT - DIY Focuser | Stellarmate | PixInsight
1 month 2 weeks ago #85212

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Kurt,

It all depends on how you configure everything.
If you go to an object that is close to but East of the meridian the mount can determine whether to approach it from the East or West and therefore whether a flip is required.

You really need to understand how it all works together to understand how it will work.

Paul
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1 month 2 weeks ago #85217

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The following user(s) said Thank You: Kurt Bierbaum
1 month 2 weeks ago #85227

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Thank you, Alfred, for your reply. I appreciate it.

I will investigate if I can do such a pier myself since I also did my current pier. Your equipment is much heavier than mine so a DIY one could be possible.

What is the angle of the "knick", is it 100° as mentioned in one of your links? You are located in/near Frankfurt with Latitude ~ 50°, I live close to Munich with Lat 48°, would the 100° angle be OK also for my location?

Kurt
Skywatcher HEQ-5 EQMod | ASI1600MM Pro | ASI EFW | TS61EDPH | ZWO ASI 120MM | Artesky 130mm guidescope | Raspi 4B 4GB | Waveshare Stepper Motor HAT - DIY Focuser | Stellarmate | PixInsight
1 month 2 weeks ago #85229

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I'm no expert in this but common sense makes be believe it should be about 48 degrees for Munich, too as your polar axis works like an extension to the upper part of the pier as you can see in the photograph here: jd-astronomie.de/bilder/saeulen/J72_057-061_Knicksaeule-002.png The guys offering the pier will take care of it anyway, I'd assume.
1 month 2 weeks ago #85275

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