Re: understanding how to set meridian limits for AP MAch 2 #APCC #Mach2GTO


Ray Gralak
 

Hi Morris,

What exactly is a "meridian delay?"
Meridian delay is an offset from the meridian the defines the pier side to which the mount will slew the scope.

Why is the number in your example picture negative? Shouldn't it delay the meridian flip by a positive number of
hours?
It's defined by effectively adjusting the internal clock time by the offset. So a negative value effectively is like turning back the clock 1 hour so it takes an additional hour to reach the flip point. It was done this way to be compatible with the way it was done previously (by adjusting mount time) before the command was added to the firmware.

BTW, the mount will not "flip" the scope automatically when reaching the meridian delay offset. A slew to a RA/Dec or Alt/Az coordinate will be needed to cause the mount to flip. If you are using APCC you can do that, but it's not recommended because the scope might be in the middle of an exposure if you are imaging.

(Probably a different topic.) On my mounts there are certain positions near the zenith where the long AP180 will
crash the camera into one of the pier struts, and I'd love to find a way to prevent that from happening. I also
That's a good point. There isn't a way to prevent that now. I'll ask if that is a feature I can add to APCC.

haven't figured out a procedure for making those nice horizon maps that you have in that example.
You can draw by hand, or in the daytime slew your scope to your horizon obstructions and add horizon points.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver


-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Mojo Jones
Sent: Sunday, July 19, 2020 12:18 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] understanding how to set meridian limits for AP MAch 2 #APCC #Mach2GTO

On 7/19/2020 9:29 AM, Ray Gralak wrote:


You can set the meridian delay on the Meridian tab


I've been struggling with the same understanding problems as Andrea. It might help to have some definitions
handy.

What exactly is a "meridian delay?"

Suppose I start imaging an object 30 minutes before it crosses the meridian. Is this delay the amount of time the
mount will wait before flipping? That's what "meridian delay" sounds like.

Why is the number in your example picture negative? Shouldn't it delay the meridian flip by a positive number of
hours?

What if I want to start imaging with counterweight up, and let it track into the west as it crosses the meridian?
How do I do that?

These terms have very specific meanings, and I'm struggling to attach precise definitions to them. I apologize for
that.

(Probably a different topic.) On my mounts there are certain positions near the zenith where the long AP180 will
crash the camera into one of the pier struts, and I'd love to find a way to prevent that from happening. I also
haven't figured out a procedure for making those nice horizon maps that you have in that example.

I'm sure this is all in the documentation, so I'll go hunt there. "How to build a map of forbidden zones" or "how to
map your obstructed horizon." If you have pointers they'd be welcome. :)

Best regards,
Mojo

--
Morris Jones, Monrovia, CA
BridgeMojo <http://bridgemojo.com>
Old Town Sidewalk Astronomers <http://otastro.org>
Mojo's Blog <http://mojo.whiteoaks.com>

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