Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC


Eric Weiner
 

This is a continuation of a pair of other ap-gto-groups chats regarding using APCC CW up within the East Limits slews with SGPro.

Please, ANYONE with experience with APCC and SGP chime in here.  I didn't intend this to be just between Ray and I.  The question is, which meridian limits settings do you use in SGP when the "CW up in East Limits" is turned on in APCC.  And, which SGP Park Scope and/or Stop Tracking options do you have on/off when APCC horizon and meridian limits are set, turned on, and have "action to take at meridian" set to anything other than "just warn."  The goal is to take advantage of CW up slews in the eastern limits such that no meridian flip is needed for such targets; a hallmark of A-P mounts.

Like I've said in previous posts, I plan to perform a thorough set of supervised experiments with APCC and SGPro using my Mach2 as soon as I can.  I travel for work quite often, so don't have the luxury of being able to get my hands on said pieces of hardware and software as often as I'd like.  I'll post my finding.  Surely other folks have the same questions and concerns.

Instrumentation and automation of scientific and engineering equipment is a daily event for me at work.  I haven't delved into mount control commands, nor have I delved into the inner working of SGP.  Those two aspects of the hobby don't interest me.  A plug and play experience is more enjoyable.  But, I heard about the CW up in the East Limits option in APCC and went down that rabbit hole.  I have seen a number of folks ask similar questions here, over at the SGP forum, and on CN.  I've also read conflicting opinions of its safety when used with SGP or any other automation software.  So it sounds like I'll need to familiarize myself with how the APCC flip point influences SGP in more detail.

I'm numbering these points for ease of reference.  Some folks may have insight on some points and not on others.  In my layman's view, here is why I asked my original question several weeks ago in a different thread:

1a.  We all agree that if you have APCC meridian limits set correctly you are able to start with CW up with scope pointing East, and end CW up with scope pointing West without a risk of a pier collision.  Slews outside the limits will behave in a typical manner w.r.t. CW position and mount side.

2a.  In Ray's video instructions he states the "action when meridian limit reached" must be set to "just warn" for CW up slews in the East limits to work correctly.  So there is no option to have APCC perform a flip in instances where the slew did not land in the limits?  Is this why it must be setup in SGP, so SGP can handle the flip instead of APCC?

3a.   APCC Horizon limits have their own "action when limit reached," so I have set this to "stop tracking" for safety.  If I have the "stop tracking" AND "park" commands turned off (unchecked) in SGP, will APCC simply use the horizon "action when limit reached" command to stop tracking or park when the horizon is reached?  This is just a hypothetical.  I see no reason NOT to use SGP to park the scope once a sequence completes.

4a.  We all agree that in standalone mode (no external software besides APCC) that a slew command within the East Limits (with both limits set IAW Ray's instructions) that the mount will slew with CW up on the west side and scope pointing East.  Then, without any outside influence it will simply track in RA until it reaches the West Horizon Limit, then perform whichever action is set for the horizon limit.

If I'm wrong on any of these points please say so.

Assuming the above is correct, now let's add SGPro into the mix:

1b.  The equipment settings in SGP have the following options with respect to the meridian actions and scope parking / tracking (red arrows):



2b.  The first two red arrows above have to do with actions taken when the SGP sequence completes.  It seems safe to keep this checked and adds an additional safety command in addition to the APCC horizon limit action (assuming it is set to anything other than "just warn").

3b.  The next arrow is the crux of the matter here.  Here are the setting involved with that check box (red arrow):



4b.  So, simply turning these off in SGP and letting APCC handle the limits does not seem like a good option since not all targets in the night's sky will end up with slews within the east limits (and therefore a flip will be necessary).  In other words, slews that DON'T fall within the limits may require a meridian flip to be handled by SGP if imaging starts East of the meridian (other cases exist too).  I'm I off base with this statement?

5b. SGP can handle flip delays past the meridian (red arrow above), but so can APCC (see below).  Which one takes precedence? APCC or SGP?  Do they need to match? Does the "Send limits with offsets to SGPro" make the SGP "Minutes past the meridian to flip" command OBE?  This assumes the box is checked in APCC, I realize it is not in my screenshot below.



6b.  Ray said in a related thread, "All APCC does is send the meridian flip point to SGPro. This value is always displayed in APCC, and I am sure it is working correctly in the latest public APCC builds. I believe the meridian flip point value can be viewed somewhere in SGPro as well, so there should be a way to confirm the value matches what APCC has set."

I understand this, and can definitely see the flip point (or meridian limit) in APCC. I don't know if SGP provides this info. If it does, it's hidden in a log file. Does anyone know if and where to look to see if it matches APCC? What isn't so obvious in my head is how SGP interprets a CW slew when the target falls within the East limits. Any clarification on this would be most appreciated. Else, when I have a chance to play with it myself it will probably become obvious.

7b. Roland said in a previous related thread, "
I would never recommend setting up an automatic remote system with scope starting or ending up in the counterweight up position. Unattended remote operation should always be done with cwt up and flipping sides at the meridian."

No offense intended here, sincerely, but this seems like mixed messages between Ray who (correct me if I'm wrong ) says it's safe to use (conditionally), and Roland who has trepidations.  I'm hoping to hear what Roland's trepidations are.  Sure, glitches can occur with any software, and the standard cwt up and flipping sides at the meridian is a much more vetted operation with little chance of a collision if something fails.  Is that simply the concern?  

Thanks all,
Eric


Geof Lewis
 

Hi Eric,
You did ask for 'ANYONE' with experience with APCC and SGP to chime in. Whilst I don't use APCC I do use SGP so I 'may' be able to help with your understanding of how the AP Meridian Delay feature works, as I use that manually via the APV2 driver to control CW up imaging via SGP. I feel your frustration, but if all I do is add confusion, then please ignore and accept my apologies.
There are 2 scenarios when I use the AP Meridian Delay:
1) - to start imaging with CWs up on west side of the pier, with the scope on the east side pointing east. In this case I set the Meridian Delay in the APV2 driver to advance the Meridian 1, 2 or 3 hours to the east of the true meridian (N/S line). This tells SGP where the artificial meridian is, so that when I start the sequence, SGP plates solves the target and starts tracking in a CW up position and then just tracks through the meridian without any need for a pier flip, ending with CW's down on west side, with OTA on the east pointing west, i.e. in a normal configuration. For me this is a fairly frequent configuration, but of course I need to ensure that no pier crash will occur at the sequence start.
2) - to start imaging with CW up on the east side of the pier, OTA on west, pointing west BUT delaying the meridian flip for 1, 2 or 3 hours after the true N/S meridian. I only ever use this configuration if I need to continue imaging a target which has already past the true N/S meridian at the start of sequence, but I need to image this way to use a known guide star in my OAG when there isn't a suitable guide star available after performing a flip. This is a fairly rare occurrence, but I have configured this way on a number of occasions.

I don't know, but I suspect that APCC uses a similar Meridian Delay feature to tell SGP where you want the meridian to be, different to the true N/S meridian. I believe this is what Ray means by stating that 'All APCC needs to do is send the mount's current flip point through SGPro's API. That is literally APCC's only involvement....'

As I understand it, a significant advantage when using APPC is that you can map all the declination points at with a pier crash would occur with CWs up on both sides of the pier, which would be a great feature for me, but I also note Roland's guidance that he still would not recommend operating a rig remotely in these configurations, but only when the user is physically present.

The other meridian flip delay option that I frequently use is the one you identify in SGP, where you tell SGP to perform the flip a number of minutes after the scope has tracked to the true N/S sky meridian. I use this when I want to start SGP with the mount in a normal configuration of CW down on the east of the pier, with the scope on the west pointing east, but I want to image through the meridian without any pier flip for some period, so that the session ends with the scope on the west pointing west with CWs up, still on the east side of the pier. That is when I set the SGP 'Use Meridian Pier Flip' option to, say, 30m, 60m, 90m, 120m, etc., but of course, it is then up to me to determine that there won't be any pier crash, though Dec pier mapping in APPC may mitigate this.

As I don't use APCC all my other sequence end commands are set in SGP, e.g. park scope on completion of sequence, so I don't know how those settings would work/conflict with any similar settings in APPC.

As I stated above, if this just further confuses you, then I'm sorry, but hopefully it helps a bit.
Good luck and best regards,

Geof


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Eric Weiner <weinere@...>
Sent: 01 May 2021 10:25
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: [ap-gto] Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC
 

This is a continuation of a pair of other ap-gto-groups chats regarding using APCC CW up within the East Limits slews with SGPro.

Please, ANYONE with experience with APCC and SGP chime in here.  I didn't intend this to be just between Ray and I.  The question is, which meridian limits settings do you use in SGP when the "CW up in East Limits" is turned on in APCC.  And, which SGP Park Scope and/or Stop Tracking options do you have on/off when APCC horizon and meridian limits are set, turned on, and have "action to take at meridian" set to anything other than "just warn."  The goal is to take advantage of CW up slews in the eastern limits such that no meridian flip is needed for such targets; a hallmark of A-P mounts.

Like I've said in previous posts, I plan to perform a thorough set of supervised experiments with APCC and SGPro using my Mach2 as soon as I can.  I travel for work quite often, so don't have the luxury of being able to get my hands on said pieces of hardware and software as often as I'd like.  I'll post my finding.  Surely other folks have the same questions and concerns.

Instrumentation and automation of scientific and engineering equipment is a daily event for me at work.  I haven't delved into mount control commands, nor have I delved into the inner working of SGP.  Those two aspects of the hobby don't interest me.  A plug and play experience is more enjoyable.  But, I heard about the CW up in the East Limits option in APCC and went down that rabbit hole.  I have seen a number of folks ask similar questions here, over at the SGP forum, and on CN.  I've also read conflicting opinions of its safety when used with SGP or any other automation software.  So it sounds like I'll need to familiarize myself with how the APCC flip point influences SGP in more detail.

I'm numbering these points for ease of reference.  Some folks may have insight on some points and not on others.  In my layman's view, here is why I asked my original question several weeks ago in a different thread:

1a.  We all agree that if you have APCC meridian limits set correctly you are able to start with CW up with scope pointing East, and end CW up with scope pointing West without a risk of a pier collision.  Slews outside the limits will behave in a typical manner w.r.t. CW position and mount side.

2a.  In Ray's video instructions he states the "action when meridian limit reached" must be set to "just warn" for CW up slews in the East limits to work correctly.  So there is no option to have APCC perform a flip in instances where the slew did not land in the limits?  Is this why it must be setup in SGP, so SGP can handle the flip instead of APCC?

3a.   APCC Horizon limits have their own "action when limit reached," so I have set this to "stop tracking" for safety.  If I have the "stop tracking" AND "park" commands turned off (unchecked) in SGP, will APCC simply use the horizon "action when limit reached" command to stop tracking or park when the horizon is reached?  This is just a hypothetical.  I see no reason NOT to use SGP to park the scope once a sequence completes.

4a.  We all agree that in standalone mode (no external software besides APCC) that a slew command within the East Limits (with both limits set IAW Ray's instructions) that the mount will slew with CW up on the west side and scope pointing East.  Then, without any outside influence it will simply track in RA until it reaches the West Horizon Limit, then perform whichever action is set for the horizon limit.

If I'm wrong on any of these points please say so.

Assuming the above is correct, now let's add SGPro into the mix:

1b.  The equipment settings in SGP have the following options with respect to the meridian actions and scope parking / tracking (red arrows):



2b.  The first two red arrows above have to do with actions taken when the SGP sequence completes.  It seems safe to keep this checked and adds an additional safety command in addition to the APCC horizon limit action (assuming it is set to anything other than "just warn").

3b.  The next arrow is the crux of the matter here.  Here are the setting involved with that check box (red arrow):



4b.  So, simply turning these off in SGP and letting APCC handle the limits does not seem like a good option since not all targets in the night's sky will end up with slews within the east limits (and therefore a flip will be necessary).  In other words, slews that DON'T fall within the limits may require a meridian flip to be handled by SGP if imaging starts East of the meridian (other cases exist too).  I'm I off base with this statement?

5b. SGP can handle flip delays past the meridian (red arrow above), but so can APCC (see below).  Which one takes precedence? APCC or SGP?  Do they need to match? Does the "Send limits with offsets to SGPro" make the SGP "Minutes past the meridian to flip" command OBE?  This assumes the box is checked in APCC, I realize it is not in my screenshot below.



6b.  Ray said in a related thread, "All APCC does is send the meridian flip point to SGPro. This value is always displayed in APCC, and I am sure it is working correctly in the latest public APCC builds. I believe the meridian flip point value can be viewed somewhere in SGPro as well, so there should be a way to confirm the value matches what APCC has set."

I understand this, and can definitely see the flip point (or meridian limit) in APCC. I don't know if SGP provides this info. If it does, it's hidden in a log file. Does anyone know if and where to look to see if it matches APCC? What isn't so obvious in my head is how SGP interprets a CW slew when the target falls within the East limits. Any clarification on this would be most appreciated. Else, when I have a chance to play with it myself it will probably become obvious.

7b. Roland said in a previous related thread, "
I would never recommend setting up an automatic remote system with scope starting or ending up in the counterweight up position. Unattended remote operation should always be done with cwt up and flipping sides at the meridian."

No offense intended here, sincerely, but this seems like mixed messages between Ray who (correct me if I'm wrong ) says it's safe to use (conditionally), and Roland who has trepidations.  I'm hoping to hear what Roland's trepidations are.  Sure, glitches can occur with any software, and the standard cwt up and flipping sides at the meridian is a much more vetted operation with little chance of a collision if something fails.  Is that simply the concern?  

Thanks all,
Eric


Virus-free. www.avg.com


Eric Weiner
 

Geof,

to start imaging with CWs up on west side of the pier, with the scope on the east side pointing east. In this case I set the Meridian Delay in the APV2 driver to advance the Meridian 1, 2 or 3 hours to the east of the true meridian (N/S line). 
This was a "lightbulb" statement, and it makes perfect sense.  I incorrectly made the assumption that setting up the meridian limits in APCC would negate the need to alter the auto-populated meridian delay settings. I don't know why I thought that other than the instructions say to make sure the delay is at zero prior to starting to measure and set the meridian limits.  My error, not the APCC instructions.

After reading your post I'm not at all embarrassed to say that Ray was correct in a separate thread when he said that I didn't understand how the AP meridian delay works, but he provided no insight or instruction.  You, on the other hand, have made it very clear with your number 1 and 2 configs description. 

I see now that even prior to playing with APCC's meridian settings I was completely backwards in my thinking.  I assumed in order to take of advantage of the AP mount's ability to go CW up that one needed to push the artificial meridian west, hence delaying the flip as long as possible.  I see the error in my thinking now.  Your number 1 config makes perfect sense and completely elucidates how a APV2 driver or APCC positive delay setting can "trick" SGP.  I also understand your less often utilized number 2 config.

As I understand it, a significant advantage when using APPC is that you can map all the declination points at with a pier crash would occur with CWs up on both sides of the pier, which would be a great feature for me
Yes, it is very clear now that this is the one significant difference between using the APV2 driver versus APCC.

 but I also note Roland's guidance that he still would not recommend operating a rig remotely in these configurations, but only when the user is physically present.
Yes, his statement is disconcerting, but I suppose logically the normal CW position with a flip at or near the true meridian has much less chance for a collision if something goes wrong.

The other meridian flip delay option that I frequently use is the one you identify in SGP, where you tell SGP to perform the flip a number of minutes after the scope has tracked to the true N/S sky meridian. 
So do you uncheck "Use Auto Meridian Flip" in SGP when you're using your number 1 config, or do you just leave it enabled since SGP thinks the meridian has already been crossed?
Is there a reason you use SGP for this instead of just pushing the artificial meridian west using APV2?  I suppose it's probably just simpler to setup in SGP before a run.

A very helpful post Geof.  Thank you very much.

Eric


Geof Lewis
 

Eric,
Thanks for your reply and I'm pleased that I helped unlock the confusion. I must say that the configuration of AP's Meridian Delay with SGP was something that I struggled with initially, mainly because I kept over thinking it, when in fact it is very simple 😏.
Regarding SGPs 'Use Auto Meridian Flip' setting, my default is to have it checked, usually with 60m past meridian set, but I then play with that according to the target's declination and how far past the meridian I can track without a pier crash. I monitor the time to meridian flip display on the SGP screen to assist me with, plus I also then physically inspect where the camera/OTA is in relation to the pier, something I can only do if I'm in the observatory.
As you state, it has no significance if I'm imaging in a configuration with the scope on the east of the pier as when it tracks through the meridian it will be in a correct CWs down position, so no pier flip will be required.
Best regards,

Geof


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Eric Weiner <weinere@...>
Sent: 01 May 2021 13:23
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC
 
Geof,

to start imaging with CWs up on west side of the pier, with the scope on the east side pointing east. In this case I set the Meridian Delay in the APV2 driver to advance the Meridian 1, 2 or 3 hours to the east of the true meridian (N/S line). 
This was a "lightbulb" statement, and it makes perfect sense.  I incorrectly made the assumption that setting up the meridian limits in APCC would negate the need to alter the auto-populated meridian delay settings. I don't know why I thought that other than the instructions say to make sure the delay is at zero prior to starting to measure and set the meridian limits.  My error, not the APCC instructions.

After reading your post I'm not at all embarrassed to say that Ray was correct in a separate thread when he said that I didn't understand how the AP meridian delay works, but he provided no insight or instruction.  You, on the other hand, have made it very clear with your number 1 and 2 configs description. 

I see now that even prior to playing with APCC's meridian settings I was completely backwards in my thinking.  I assumed in order to take of advantage of the AP mount's ability to go CW up that one needed to push the artificial meridian west, hence delaying the flip as long as possible.  I see the error in my thinking now.  Your number 1 config makes perfect sense and completely elucidates how a APV2 driver or APCC positive delay setting can "trick" SGP.  I also understand your less often utilized number 2 config.

As I understand it, a significant advantage when using APPC is that you can map all the declination points at with a pier crash would occur with CWs up on both sides of the pier, which would be a great feature for me
Yes, it is very clear now that this is the one significant difference between using the APV2 driver versus APCC.

 but I also note Roland's guidance that he still would not recommend operating a rig remotely in these configurations, but only when the user is physically present.
Yes, his statement is disconcerting, but I suppose logically the normal CW position with a flip at or near the true meridian has much less chance for a collision if something goes wrong.

The other meridian flip delay option that I frequently use is the one you identify in SGP, where you tell SGP to perform the flip a number of minutes after the scope has tracked to the true N/S sky meridian. 
So do you uncheck "Use Auto Meridian Flip" in SGP when you're using your number 1 config, or do you just leave it enabled since SGP thinks the meridian has already been crossed?
Is there a reason you use SGP for this instead of just pushing the artificial meridian west using APV2?  I suppose it's probably just simpler to setup in SGP before a run.

A very helpful post Geof.  Thank you very much.

Eric


Eric Weiner
 

Actually, it isn't the same as APV2.  I just re-read the APCC instructions, and this is where I found not to touch the APCC Meridian Delay Settings when the meridian limits are active (see below).  The instructions don't go into great detail.  I've read the part regarding "dynamic meridian delay" but I'm again lost regarding how this info is processed with SGP.  


Eric Weiner
 

For completeness, here is the screenshot from the APCC instructions regarding "dynamic meridian delay:"


Geof Lewis
 

Thanks Eric,
In that case I'm don't know how APCC works differently to the APV2 driver. It looks as if it might be something to do with that Override ASCOM (driver) setting in APCC, but now I'm just guessing.....
Good luck,

Geof


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Eric Weiner <weinere@...>
Sent: 01 May 2021 13:40
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC
 
Actually, it isn't the same as APV2.  I just re-read the APCC instructions, and this is where I found not to touch the APCC Meridian Delay Settings when the meridian limits are active (see below).  The instructions don't go into great detail.  I've read the part regarding "dynamic meridian delay" but I'm again lost regarding how this info is processed with SGP.  


Virus-free. www.avg.com


Geof Lewis
 

Thanks Eric,
Both those read as I would expect them, but not having APCC I can't confirm or deny how they work with SGP. However, my bet is that they work the same way as I currently do with the APV2 driver - of course I may lose that bet.....😳
Regards,

Geof
PS As an aside, this is a very interesting topic for me as I have been thinking about upgrading the chip in my very old AP1200 CP3, so that it will work with APCC. I'd really like to have the features in APCC Pro, especially APPM, but none of it will work with the old chip in my CP3.....


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Eric Weiner <weinere@...>
Sent: 01 May 2021 13:44
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC
 
For completeness, here is the screenshot from the APCC instructions regarding "dynamic meridian delay:"


Virus-free. www.avg.com


Eric Weiner
 

Thank you Geof,

Your information was still valuable and provided insight into concepts I had wrong.  With APCC (versus APV2) it appears that once one set the meridian limits and activates them (see my APCC screenshot from my first post in this thread) that APCC somehow sets the "dynamic meridian delay," and that is somehow communicated to SGP.  That is literally the missing piece of this puzzle.  Hopefully someone who understands how this works will chime in.

Regards,
Eric


Eric Weiner
 

Geof,

I imagine you're right.  It must be that APCC analyzes the meridian limit data recorded by the user, then somehow sets the delay +/- as you indicated in your examples.  It just isn't obvious to me how that works.  I sure would like to understand that.

PS As an aside, this is a very interesting topic for me as I have been thinking about upgrading the chip in my very old AP1200 CP3, so that it will work with APCC. I'd really like to have the features in APCC Pro, especially APPM,

Being able to set, record, and recall the meridian and horizon limits for each imaging setup I have, and each imaging site I go to is a very nice feature of APCC.  APPM is very useful.  It alone may be worth the upgrade costs if you have a permanent setup, imho.  I was fortunate and APCC/APPM were included with my Mach2.

Eric


Geof Lewis
 

Thanks Eric,
I'm something of a klutz when it comes to configuring software, etc., so that really puts me off. I believe that once I've installed the new chip in the CP3, I then have to update the firmware, plus also create a new PEC curve (not that I currently use one). That's all before I even get started with APCC/APPM, though at least I believe that I'd also get PemPro with APCC Pro. I'd hate to end up trashing the mount by doing it wrong, but that's a genuine fear for me, so sometimes it's a case of if it ain't broke don't fix it....
Cheers,

Geof


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Eric Weiner <weinere@...>
Sent: 01 May 2021 14:10
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Continuation of the discussion using APCC CW up within the East Limit slews with SGPro #APCC
 
Geof,

I imagine you're right.  It must be that APCC analyzes the meridian limit data recorded by the user, then somehow sets the delay +/- as you indicated in your examples.  It just isn't obvious to me how that works.  I sure would like to understand that.

PS As an aside, this is a very interesting topic for me as I have been thinking about upgrading the chip in my very old AP1200 CP3, so that it will work with APCC. I'd really like to have the features in APCC Pro, especially APPM,

Being able to set, record, and recall the meridian and horizon limits for each imaging setup I have, and each imaging site I go to is a very nice feature of APCC.  APPM is very useful.  It alone may be worth the upgrade costs if you have a permanent setup, imho.  I was fortunate and APCC/APPM were included with my Mach2.

Eric

Virus-free. www.avg.com


 

Hi Eric

I use APCC and APPM extensively for unguided exposures on my AP1600

I use SGP exclusively for imaging (I keep saying i'll switch but it's been over a year)

I use just the defaults and enable meridian flip in SGP. it has worked without fail every night

Maybe you have requirements that are unique? I've been following this discussion but i'm at a bit of a loss regarding why it seems to be such a deep and detailed topic when for me it just works. of all the stuff i worry about on a regular basis (accumulation of dust on the telescope for some reason, where is the moon etc.) Meridian flip is the least of my concerns i'd be happy to share my screens and setup with you if you like, just drop me a line

Brian





On Sat, May 1, 2021 at 2:25 AM Eric Weiner <weinere@...> wrote:

This is a continuation of a pair of other ap-gto-groups chats regarding using APCC CW up within the East Limits slews with SGPro.

Please, ANYONE with experience with APCC and SGP chime in here.  I didn't intend this to be just between Ray and I.  The question is, which meridian limits settings do you use in SGP when the "CW up in East Limits" is turned on in APCC.  And, which SGP Park Scope and/or Stop Tracking options do you have on/off when APCC horizon and meridian limits are set, turned on, and have "action to take at meridian" set to anything other than "just warn."  The goal is to take advantage of CW up slews in the eastern limits such that no meridian flip is needed for such targets; a hallmark of A-P mounts.

Like I've said in previous posts, I plan to perform a thorough set of supervised experiments with APCC and SGPro using my Mach2 as soon as I can.  I travel for work quite often, so don't have the luxury of being able to get my hands on said pieces of hardware and software as often as I'd like.  I'll post my finding.  Surely other folks have the same questions and concerns.

Instrumentation and automation of scientific and engineering equipment is a daily event for me at work.  I haven't delved into mount control commands, nor have I delved into the inner working of SGP.  Those two aspects of the hobby don't interest me.  A plug and play experience is more enjoyable.  But, I heard about the CW up in the East Limits option in APCC and went down that rabbit hole.  I have seen a number of folks ask similar questions here, over at the SGP forum, and on CN.  I've also read conflicting opinions of its safety when used with SGP or any other automation software.  So it sounds like I'll need to familiarize myself with how the APCC flip point influences SGP in more detail.

I'm numbering these points for ease of reference.  Some folks may have insight on some points and not on others.  In my layman's view, here is why I asked my original question several weeks ago in a different thread:

1a.  We all agree that if you have APCC meridian limits set correctly you are able to start with CW up with scope pointing East, and end CW up with scope pointing West without a risk of a pier collision.  Slews outside the limits will behave in a typical manner w.r.t. CW position and mount side.

2a.  In Ray's video instructions he states the "action when meridian limit reached" must be set to "just warn" for CW up slews in the East limits to work correctly.  So there is no option to have APCC perform a flip in instances where the slew did not land in the limits?  Is this why it must be setup in SGP, so SGP can handle the flip instead of APCC?

3a.   APCC Horizon limits have their own "action when limit reached," so I have set this to "stop tracking" for safety.  If I have the "stop tracking" AND "park" commands turned off (unchecked) in SGP, will APCC simply use the horizon "action when limit reached" command to stop tracking or park when the horizon is reached?  This is just a hypothetical.  I see no reason NOT to use SGP to park the scope once a sequence completes.

4a.  We all agree that in standalone mode (no external software besides APCC) that a slew command within the East Limits (with both limits set IAW Ray's instructions) that the mount will slew with CW up on the west side and scope pointing East.  Then, without any outside influence it will simply track in RA until it reaches the West Horizon Limit, then perform whichever action is set for the horizon limit.

If I'm wrong on any of these points please say so.

Assuming the above is correct, now let's add SGPro into the mix:

1b.  The equipment settings in SGP have the following options with respect to the meridian actions and scope parking / tracking (red arrows):



2b.  The first two red arrows above have to do with actions taken when the SGP sequence completes.  It seems safe to keep this checked and adds an additional safety command in addition to the APCC horizon limit action (assuming it is set to anything other than "just warn").

3b.  The next arrow is the crux of the matter here.  Here are the setting involved with that check box (red arrow):



4b.  So, simply turning these off in SGP and letting APCC handle the limits does not seem like a good option since not all targets in the night's sky will end up with slews within the east limits (and therefore a flip will be necessary).  In other words, slews that DON'T fall within the limits may require a meridian flip to be handled by SGP if imaging starts East of the meridian (other cases exist too).  I'm I off base with this statement?

5b. SGP can handle flip delays past the meridian (red arrow above), but so can APCC (see below).  Which one takes precedence? APCC or SGP?  Do they need to match? Does the "Send limits with offsets to SGPro" make the SGP "Minutes past the meridian to flip" command OBE?  This assumes the box is checked in APCC, I realize it is not in my screenshot below.



6b.  Ray said in a related thread, "All APCC does is send the meridian flip point to SGPro. This value is always displayed in APCC, and I am sure it is working correctly in the latest public APCC builds. I believe the meridian flip point value can be viewed somewhere in SGPro as well, so there should be a way to confirm the value matches what APCC has set."

I understand this, and can definitely see the flip point (or meridian limit) in APCC. I don't know if SGP provides this info. If it does, it's hidden in a log file. Does anyone know if and where to look to see if it matches APCC? What isn't so obvious in my head is how SGP interprets a CW slew when the target falls within the East limits. Any clarification on this would be most appreciated. Else, when I have a chance to play with it myself it will probably become obvious.

7b. Roland said in a previous related thread, "
I would never recommend setting up an automatic remote system with scope starting or ending up in the counterweight up position. Unattended remote operation should always be done with cwt up and flipping sides at the meridian."

No offense intended here, sincerely, but this seems like mixed messages between Ray who (correct me if I'm wrong ) says it's safe to use (conditionally), and Roland who has trepidations.  I'm hoping to hear what Roland's trepidations are.  Sure, glitches can occur with any software, and the standard cwt up and flipping sides at the meridian is a much more vetted operation with little chance of a collision if something fails.  Is that simply the concern?  

Thanks all,
Eric



--
Brian 



Brian Valente


Luca Marinelli
 

Hi Eric,

 

I responded to your thread in the SGP forum and shared my configuration in APCC and SGP, which allows CW up imaging and pre-flipping of the mount, if you desire. I have worked out an example and hopefully this will be clearer.

 

I image unattended and my goal is always to have a belt and suspenders system with redundancy so using “Just Warn” in the meridian limit tab of APCC is out of the question for me. I am never next to the mount and I regard APCC meridian limits as a safety in case anything goes wrong with the imaging run or control of the meridian flip. I use “Stop Tracking” when the meridian limit is reached so the mount cannot track past this point and I have a visual indication that something went wrong in the morning when I shut everything down.

 

SGP controls the meridian flip. SGP is controlling all imaging equipment and knows when is a good time to take a break and flip the mount. As Ray said, all APCC needs to do, is tell SGP at what time it can start flipping the mount. SGP will request a flip as soon after this time as is compatible with the imaging run. This is what is accomplished with the “Flip Offset” entry and “Send Limit with offset to SGPro” checkbox in the meridian limit tab in APCC.

 

With the camera I use on this system, at most I take 10 minute frames, so I chose 20 minutes as Flip Offset. I will always have time to complete a frame before hitting the meridian limit (where the mount would stop tracking and the imaging run abort) with this choice of Flip Offset.

 

So let’s look at an example. It’s 10am here and M31 is in the Eastern sky, just before the meridian, at a declination that is compatible with CW up imaging on my system, so I picked this target and created a sequence in SGP. I ran two scenarios: one with CW Up Slews within East Limits checked and one without checking the box.

 

Conventional imaging with only West Limits checked (safety limit):

 

Take a look at the screenshot. Meridian flip is controlled by SGP and APCC is setup to pass the meridian limit with flip offset to SGP. If you compare the timer until meridian flip in APCC (2h 38m 11s) with the timer in SGP (2h 19m 36s) – circled in blue in the screenshot – you’ll see that the difference between the two is exactly the Flip Offset: SGP will request a meridian flip as soon as possible after the timer runs out and it will have 20 minutes before the mount bumps into the actual meridian safety limit set in APCC.

 

This is my usual mode of imaging. I image multiple targets during the night to make efficient use of dark hours and this mode is safe, works, and is efficient. I launched the sequence in SGP and you can see in the 3D View that the mount is CW down, West pointing East, in a conventional position. APCC has passed the time to flip to SGP and in Meridian Flip Options you see 80 minutes past meridian to flip. That number is set dynamically by SGP based on the information about the meridian with flip offset passed along by APCC. You don’t change this number manually. Try changing the Flip Offset and you will see that this number and the timer at the bottom of the SGP window update automatically.

 

CW up imaging using East Limits checked (opportunity limit):

 

The same target M31 is within the East meridian limits and so I can also choose to start imaging with CW up and pre-flip the mount. All I need to do is check the East Limits checkbox in the meridian limit tab in APCC and everything else stays the same. The advantage of this setup is: 1) APCC still acts as the ultimate safety limit – if everything else fails and the mount reaches the meridian limit, the mount will stop tracking. 2) If you have multiple targets in your SGP run and some start the imaging run within East limits, some don’t, the ones that allow a start with CW up will use that configuration, the ones that don’t will start in a standard CW down position. I have used this mode of operation unattended without any adverse consequences.

 

When I start the imaging run, you can see that the Scope timer in SGP says N/A because no flip will be requested during this run. In the 3D View you can see that the scope is starting the imaging run CW up, because it is possible. Easy peasy.

 

That’s about it. It’s really not that complicated if you use two guiding principles: 1) the imaging application requests meridian flips because it knows when it can do it without interrupting other operations, 2) APCC is responsible for the safety of the gear.

 

Cheers,

 

Luca

 


Eric Weiner
 

Howdy Brian,

Thanks for your comments. Meridian flip hasn't been the primary discussion.  As I've reported, I have been using that config with the default settings in SGP since I got my Mach2 back in January.  The main discussion and questions I've been asking relate to using APCC with the meridian limits active and CW up in East and West limits active. 

I agree this has created quite the rabbit hole.  It is simply because earlier questions I asked (here and the SGP forum), as well as others' discussions on CN have significantly muddied the waters.  Nobody is willing or able to define A) if it's safe (APCC says it isn't and Ray just last night said that warning is wrong), B) what are the setting to use in SGP (I think that discussion was put to rest for me today by Geof), and C) How does APCC dynamic meridian delay work?  The last is, I think, the only real remaining question.  Some folks here almost seem offended that I question how it works, or seem annoyed that I post here.  Isn't that what this user forum is for???? 

When you say you use the SGP defaults and enable meridian flip, do you have the APCC meridian limits set and active, or do you only use the "standard" CW and pier side positioning?  If so, how did you know to ignore the very stern warning APCC throws when you check the East Limits box?

This isn't about special or unique requirements.  This is about understanding my equipment, fully.  This is about learning about 2 months ago that AP mounts can, uniquely, start with the CW up on the west side with the scope pointing east (and, therefore avoiding flips altogether).  This is less about "need" and more about my inquisitiveness and wanting to fully understand my options.  I have mostly unobstructed views from east to west looking south on my property, and being able to start CW up with scope pointing east and finishing CW down and scope pointing was intriguing.

This discussion is also compounded with my limited time to experiment with the APCC "CW up" features, and the multiple warnings I've gotten from Ray to Roland to the warning APCC throws when you check the East Limits box (again, Ray said last night that warning is old and will be removed at next build).

Again, i have NOT been asking about pier flips.   It has been about avoiding them.

Regards,
Eric


Eric Weiner
 

Luca,

Your goals are also very much my own.  This is precisely the info I was hoping for from someone experienced using APCC in this manner.  You are a Rockstar for taking the time to produce these examples. Thank you. It's good to know that "just warn" isn't the only option that works with East Limits enabled.  I wonder why Ray says it must be set to "just warn" in his video.  How did you know you can ignore the warning APCC throws when you check the "East Limits" box?

Try changing the Flip Offset and you will see that this number and the timer at the bottom of the SGP window update automatically.

I see.  Thank you for that advice.

I would still like to know how the dynamic meridian delay functions, but that's the engineer in me.  I think we can lay this thread to rest.

Kind regards,
Eric


Luca Marinelli
 

On Sat, May 1, 2021 at 11:18 AM, Eric Weiner wrote:
  How did you know you can ignore the warning APCC throws when you check the "East Limits" box?

I didn't. I stood next to the mount and gave it a shot to see if it worked. I guess that's the physicist in me :)

If that's a completely irresponsible thing to do, I am sure Ray will set me straight but, so far, it hasn't caused any issues.

Luca


Ray Gralak
 

Eric,

 

> How does APCC dynamic meridian delay work? 

 

It is “dynamic” because the meridian delay can automatically change when declination changes. I'm going to copy a paragraph out of the APCC help, which you can find at this link:

 

https://www.siriusimaging.com/Help/APCC/index.html?meridian_tab.htm

 

Instead of just a single meridian limit for all declinations, you can configure an arbitrary number of different limits at different declinations. This is useful because at each declination there can be a different hour angle at which the telescope will touch the pier.  In declination regions where the telescope can theoretically go the full 6 hours past in the west, the meridian limits can establish horizon tracking limits for the practical distance past the meridian where you can reasonably continue to work.  Likewise, in the east, they can set the practical horizon ahead of the meridian where you can reasonably start an image.

 

To configure the dynamic meridian delay values you use APCC’s Meridian Limit Explorer (perhaps in the daytime) to map the counterweight-up limits of your specific scope on your mount. The limits (meridian delays) will be different depending on the scope and the latitude of the site. Once you do it once, you will see that it is pretty easy to use. Here are three different links explaining the operation in more detail:

 

https://www.siriusimaging.com/Help/APCC/meridian_limits_explorer.htm

 

https://www.siriusimaging.com/Help/APCC/using_the_meridian_tracking_li.htm

 

https://www.siriusimaging.com/Help/APCC/add_meridian_limit_tracking_po.htm

 

After defining the limits, when using APCC with SGPro, APCC will be able to automatically use the pre-defined limit for the mount’s current declination and pier side.

 

I hope this information helps to explain what “dynamic meridian delay” means.

 

-Ray

 


Manusfisch
 

Luca, thank you for that logical and brilliant explanation of the interplay

TJF Mobile

On May 1, 2021, at 10:46, Luca Marinelli <photo@...> wrote:



Hi Eric,

 

I responded to your thread in the SGP forum and shared my configuration in APCC and SGP, which allows CW up imaging and pre-flipping of the mount, if you desire. I have worked out an example and hopefully this will be clearer.

 

I image unattended and my goal is always to have a belt and suspenders system with redundancy so using “Just Warn” in the meridian limit tab of APCC is out of the question for me. I am never next to the mount and I regard APCC meridian limits as a safety in case anything goes wrong with the imaging run or control of the meridian flip. I use “Stop Tracking” when the meridian limit is reached so the mount cannot track past this point and I have a visual indication that something went wrong in the morning when I shut everything down.

 

SGP controls the meridian flip. SGP is controlling all imaging equipment and knows when is a good time to take a break and flip the mount. As Ray said, all APCC needs to do, is tell SGP at what time it can start flipping the mount. SGP will request a flip as soon after this time as is compatible with the imaging run. This is what is accomplished with the “Flip Offset” entry and “Send Limit with offset to SGPro” checkbox in the meridian limit tab in APCC.

 

With the camera I use on this system, at most I take 10 minute frames, so I chose 20 minutes as Flip Offset. I will always have time to complete a frame before hitting the meridian limit (where the mount would stop tracking and the imaging run abort) with this choice of Flip Offset.

 

So let’s look at an example. It’s 10am here and M31 is in the Eastern sky, just before the meridian, at a declination that is compatible with CW up imaging on my system, so I picked this target and created a sequence in SGP. I ran two scenarios: one with CW Up Slews within East Limits checked and one without checking the box.

 

Conventional imaging with only West Limits checked (safety limit):

 

Take a look at the screenshot. Meridian flip is controlled by SGP and APCC is setup to pass the meridian limit with flip offset to SGP. If you compare the timer until meridian flip in APCC (2h 38m 11s) with the timer in SGP (2h 19m 36s) – circled in blue in the screenshot – you’ll see that the difference between the two is exactly the Flip Offset: SGP will request a meridian flip as soon as possible after the timer runs out and it will have 20 minutes before the mount bumps into the actual meridian safety limit set in APCC.

 

This is my usual mode of imaging. I image multiple targets during the night to make efficient use of dark hours and this mode is safe, works, and is efficient. I launched the sequence in SGP and you can see in the 3D View that the mount is CW down, West pointing East, in a conventional position. APCC has passed the time to flip to SGP and in Meridian Flip Options you see 80 minutes past meridian to flip. That number is set dynamically by SGP based on the information about the meridian with flip offset passed along by APCC. You don’t change this number manually. Try changing the Flip Offset and you will see that this number and the timer at the bottom of the SGP window update automatically.

 

CW up imaging using East Limits checked (opportunity limit):

 

The same target M31 is within the East meridian limits and so I can also choose to start imaging with CW up and pre-flip the mount. All I need to do is check the East Limits checkbox in the meridian limit tab in APCC and everything else stays the same. The advantage of this setup is: 1) APCC still acts as the ultimate safety limit – if everything else fails and the mount reaches the meridian limit, the mount will stop tracking. 2) If you have multiple targets in your SGP run and some start the imaging run within East limits, some don’t, the ones that allow a start with CW up will use that configuration, the ones that don’t will start in a standard CW down position. I have used this mode of operation unattended without any adverse consequences.

 

When I start the imaging run, you can see that the Scope timer in SGP says N/A because no flip will be requested during this run. In the 3D View you can see that the scope is starting the imaging run CW up, because it is possible. Easy peasy.

 

That’s about it. It’s really not that complicated if you use two guiding principles: 1) the imaging application requests meridian flips because it knows when it can do it without interrupting other operations, 2) APCC is responsible for the safety of the gear.

 

Cheers,

 

Luca