Re: Meridian flip - software or firmware issue? #iEXOS-100 #ASCOM #FIRMWARE #pmc-eight

Walter Vinci

Sorry, I should have explained better my use case. Sometimes I found myself ready to start imaging a subject that is about to pass the meridian (say in 30mins), but didn’t quite. Then I would be happy to start imaging pre-flipped, if you wish, so that I do not have to interrupt the imaging session in between. 

In this case goto doesn’t work since ASCOM will tell the mount to orient the counterweight down, as it should. No biggie, as you said a manual slew will work. I was just thinking whether a manual flip commanded by APT is a functionality I misunderstood, if it is a bug in APT or there is a problem with the ASCOm driver.

Thanks anyway for the feedback!

On May 18, 2021, at 1:49 PM, Jerry Hubbell - Explore Scientific VP Engineering <jrh@...> wrote:

On Tue, May 18, 2021 at 03:25 PM, Jerry Hubbell - Explore Scientific VP Engineering wrote:
If you want to do a Meridian flip "early" you can only do that manually
I forgot to state also that there is a better alternative to doing a Meridian Flip "on-time" The PMC-EIght and driver is fully capable of tracking up to an hour past the Meridian (depending on mount/scope configuration) and if you are in the middle of an imaging run, it is best to not schedule the Meridian flip until at least 5 minutes past the Meridian. I think that this should be possible if you are using an automation program like NINA or APT (I don't know). I use MaxIm dl and it allows me to delay the meridian flip.  This is a better approach than trying to do the flip "early" and will not run into the issue when trying to do a plate solve immediately after the flip causing a pier-side miscalculation.
Jerry Hubbell
Vice President of Engineering

Explore Scientific, LLC.
jrh at
1010 S. 48th Street
Springdale, AR 72762

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
: 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!


Walter Vinci

Starfield 0.8 Field Flattener/Reducer.
ZWO ASI290mm-mini & Orion 50mm Guide Scope
Canon EOS Rebel SL1
SharpCap, APT, PHD2, SiriL, Stellarium

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