Meridian Flip #EXOS2 #ASCOM


Timothy Myers
 

I have read a lot about Meridian Flip with various scope control formats. 0I have read that some mounts do and some don't, does the PMC-8 support meridian flip?
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Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Jim McKee
 

APT and NINA will automate meridian flip.  Just works as part of serial ascom control.  You can give it a try inside and make sure it works for you.  Slew to a target near meridian (east) and give it a try.
--
Scope:        Orion EON 115mm APO
Mounts
:      ES EXOS2-GT w/ PMC-8
Cameras:   ZWO ASI 071MC Pro, Canon 6D Mk 2, Canon 7D2,  EOS 60D Asto Modified
Lens:
          Canon EF 100-400mm f/4.5-5.6L IS II
Misc:          TELRAD, ZWO ASI120MM Guide Camera, Astromania 60mm Guidescope, Senso Sesto Focus Motor
Software:   EXPLORESTARS IOS & WIN, Stellarium. NINA,  APT, DSS, PixInsight, Photoshop CC
Computer:  Dell Latitude E5450, Windows 10


Wes Mcdonald
 

What Jim states is correct and illustrates why it would not be necessary absolutely for the PMC8 to do anything at the meridian.  The short answer to the question is no, the PMC8 driver does not do anything at meridian.  That is left to the application in charge of scope motion and activity.

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Timothy Myers
 

Reason I was asking was that NINA asks questions bout Meridian Flip and your mount. I am way off from attempting things like this but thought there needed to be some compatibility at the mount level for it to work. I will keep reading and learning NINA. there is a lot to do there. Wow!!!
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE, SkyWatcher 100ED Pro
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600MC, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7
Laptop:           Lenovo


Jerry Hubbell - Explore Scientific VP Engineering
 

Hi Tim,

The way this normally works is that the ASCOM Client mount control program such as NINA will ask whether to stop the mount tracking at the Meridian, or at some time before the Meridian, or it will ask whether to perform a Meridian flip aka pier flip at when it gets to the Meridian. It really is as simple as that. 

If you do not enable the Meridian flip, or a Meridian stop, the PMC-Eight will happily track past the Meridian. Advanced astrophotographers can take advantage of this behavior to continue imaging if they are taking an important sequence of images that they do not want to interrupt. The best images are taken when the object is at the highest altitude in the southern sky  which is at the Meridian, so once you understand that you want to try and do this as much as you can, without the telescope hitting the tripod, of course.  With our pier mounted G11 in our observatory, we can typically track past the Meridian for about an hour or so.

To find out more about the need for a Meridian flip for GEM mounts, see this page 

http://astronomy.mdodd.com/gem_movement.html

--
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!


Parag Modi
 

I was doing an imaging session last night and experienced an automatic meridian flip.  I was using APT, ASCOM with my iEXOS-100 and a Nikon D7200.  I did not have APT configured for automatic meridian flip, however I was using APT dithering on every two frames for up to 10 pixel random moves.  I am using POTH Hub with PMC-8 ASCOM driver.  Here's the sequence of events:  As my target got to meridian, on the next subsequent dither the mount automatically flipped.  Fortunately I was nearby.  After the flip, I could not locate my target in my FOV so I stopped he imaging session, waited about 20 minutes and re-centered my target using APT/Platesolve before resuming my imaging session.

Any idea what could have forced a meridian flip?  In the ASCOM setup, under coordinate management dialog I see settings for GEM Flip delay which I had set to default to 0.  Could that be the explanation?

All in all my session went well, but I would have preferred to continue imaging since there is very little chance of me running into the tripod due to my small setup.

Thank you,


--
Parag Modi

Mounts: ES iEXOS-100
Scopes: APS-C Sigma 18-300 mm
Cameras:  Nikon D7200 (Unmodified)
Misc: Bahtinov Mask, K&F Concept Clear night filter
Software: ExploreStars, Stellarium


Wes Mcdonald
 

Parag

When the dither happened the new commanded position was likely beyond meridian.  This resulted in a meridian flip.  Any goto that has a location across the meridian will generate a flip.  The mount will not do a flip if it is just tracking along.

Wes.


--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


Parag Modi
 

Wes,

Thank you.  A couple of questions:
1) Is there a way to delay this behavior?
2) What could have caused my target not within my FOV after the flip?

If after the flip my target would have remained centered, I could have probably continued my imaging session.

--
Parag Modi

Mounts: ES iEXOS-100
Scopes: APS-C Sigma 18-300 mm
Cameras:  Nikon D7200 (Unmodified)
Misc: Bahtinov Mask, K&F Concept Clear night filter
Software: ExploreStars, Stellarium


Wes Mcdonald
 

Parag

There is no way to prevent the flip if your Astro program insists on dithering near the meridian. Nina will pause imaging at a time before flip. I guess planning is the only thing you can do 

As for centering on a target after a flip there are several things that come to mind but they all basically get down to mount alignment imperfections.  The mount it self can make the perfect move.  But if there are any errors with alignment and all the things that affect alignment it won’t hit the flipped target.  The thing to do after a meridian flip is to platesolve again and continue imaging.   Nina will do this for you. I guess with apt you will just have to be there. 

Wes


--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


Steve Siedentop
 

Parag -

Check out PointCraft for plate solving in APT.    There are a number of YouTube videos that go into great detail on how to use and customize it.  You’ll definitely want to plate solve if a meridian flip is in your imaging sequence, intentionally or not.  

Current discussion aside, platesolving in general is a wise addition to your imaging routine.  Once you use it, you’ll wonder how you ever got along without it.

-Steve

On Mon, Feb 8, 2021 at 8:29 AM Wes Mcdonald <wesmcd6@...> wrote:
Parag

There is no way to prevent the flip if your Astro program insists on dithering near the meridian. Nina will pause imaging at a time before flip. I guess planning is the only thing you can do 

As for centering on a target after a flip there are several things that come to mind but they all basically get down to mount alignment imperfections.  The mount it self can make the perfect move.  But if there are any errors with alignment and all the things that affect alignment it won’t hit the flipped target.  The thing to do after a meridian flip is to platesolve again and continue imaging.   Nina will do this for you. I guess with apt you will just have to be there. 

Wes


--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


--
Mounts: ES PMC-8 G11 with Ruland Couplers and One Piece Worm Blocks, Skywatcher NEQ-6
Scopes: ES ED127CF FCD100, Orion 6” Mak, Stellarvue SV80EDT, Coronado Solarmax 40
Cameras:  CentralDS CDS-600, CentralDS Astro 60D, Orion Starshoot SSAG
Msc: Moonlite Focusers, Astrozap Dew Straps, Pegasus Ultimate PowerBox
Software: PixInsight, Cartes du Ciel, BackyardEOS, SkySafari