SGP/APCC meridian limits vs. Homing/limits


Rodolphe G.
 

Hi Ray, Rob
Thanks for the detailed explanations, that's quite helpful, I know what I should do now!
Regards,
Rodolphe


Ray Gralak
 

Hi Rodolphe,

SGPro will take care of the flipping the mount at the appropriate time. The flip offset value in APCC is there to prevent the mount from hitting the meridian limit and performing a Parkoperation or stopping tracking to protect the mount.

So, if you are taking 10-minute images, you should add an extra 5 minutes and thus set the flip offset to 15 minutes in APCC. This moves the flip time forward 15 minutes in the mount and also in the flip time that is sent to SGPro. This will give the mount 5 minutes of buffer time before the meridian limit is reached which should be more than enough time for SGPro to move on to the next target.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]
Sent: Tuesday, September 17, 2019 1:59 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: SGP/APCC meridian limits vs. Homing/limits



Hi Rob,
Thanks for taking the time to answer.
To be frank, I'm even more confused :(

SGP seems to compute the time at which the meridian flip would theoretically occur. I let SGP manage the flip by
itself. I don't want to interfere with this - just want to ensure that the current frame is finished before the flip. I thus
changed the setting in SGP to wait for 10 more minutes,


But what should I do in APCC? Leave everything empty in APCC and the AP ASCOM driver? I noticed that setting
values there to what I believed were correct for what I wanted to achieve, ruined my session last night: the mount
has stopped in a weird position.


I wish a recommended approach / clea r directions were documented somewhere.

Thanks

Rodolphe




rob
 

well the problem is you've got 2 programs, each with potentially their own idea of when the meridian flip should happen. so Ray put in this feature that lets APCC tell SGP what the meridian delay should be. that way, APCC can be configured with some complex meridian limit surface and it can tell SGP how many minutes before that limit is reached that it should attempt a meridian flip.

if you don't want to use that feature (and in truth it's probably not necessary in a configuration like mine where i have the same limit for all declinations) you can just do something like set SGP to a 0 minute delay and set the meridian limit surface in APCC for 10 minutes past the true meridian at all declinations. i think perhaps that's not enough time though depending on what your subexposure length is.

so - how far past the meridian do you have your limits set in SGP? how far past the meridian can your mount track in the worst case before the camera hits the pier/tripod? what is your subexposure length?

rob


Rodolphe G.
 

Hi Rob,
Thanks for taking the time to answer.
To be frank, I'm even more confused :(

SGP seems to compute the time at which the meridian flip would theoretically occur. I let SGP manage the flip by itself. I don't want to interfere with this - just want to ensure that the current frame is finished before the flip. I thus changed the setting in SGP to wait for 10 more minutes,

But what should I do in APCC? Leave everything empty in APCC and the AP ASCOM driver? I noticed that setting values there to what I believed were correct for what I wanted to achieve, ruined my session last night: the mount has stopped in a weird position.

I wish a recommended approach / clear directions were documented somewhere.

Thanks

Rodolphe


rob
 

the way i have this configured is that i have a linear 'surface' defined in the meridian limit window which puts the meridian 45 minutes past the real meridian. originally i had the action set to "stop tracking" but i found that sometimes PHD2 might send a command to the mount after the limit was reached, resulting in the mount trying to start tracking again. so for a while i had it set to "park mount" but eventually i decided that if i set it to "flip mount" that perhaps SGP could recover from reaching the meridian limit. but ever since ray implemented the flip offset, this has never happened.

anyway, in the "fip offset" box i have entered 40 mins. i think what this does is tell SGP that its flip point should be 5 minutes past the real meridian (45-5), which gives 40 minutes for SGP to finish the current exposure and peform the flip. since i use 30 min exposures at maximum, this seems to work fine.

i'm not sure what would happen if i had a more complex meridian surface - say for instance if there were some areas that defined a 35 minute meridian delay. in theory that would ask SGP to flip 5 minutes before the meridian, but my understanding is that SGP won't support an early flip point on an AP mount because there are some missing methods in the ASCOM driver that they want to see. not sure what SGP does in this case; maybe it just clamps the meridian delay to 0. but then the effective offset is reduced.

rob


Rodolphe G.
 

Hi,

A bit lost here, hope somebody can shed some light on it.

I run SGP for unattended imaging sessions.

Would like to wait up to 10 minutes AFTER the theoretical meridian flip, to give a chance to the current image capture to complete.

Note I have almost no risk of having the telescope hit the pier by accident during the imaging session.


What would be the simplest way of doing this?


To me it looks like simply indicating "10" in the RA Limit box of the "Home and Limits Configuration" dialog box is enough, and of course disable settings in the "Meridian" tab altogether.


Did I get it right?


Thanks in advance,

Rodolphe