Orthogonality question


Suresh Mohan
 

I know this question was discussed by Roland several years back but I seek the answer . Why does OE always show up on the east west axis
Thanks
Dr Suresh


jimmyjujames
 
Edited

If OE is short for orthogonality error.
 
An Orthogonality error (OE) is only east-west when pointing at zenith or along meridian.
OE is always in line with the counter-weight shaft.
When pointing at NCP with counter-weight shaft pointing down, OE is north-south.
 
 What is an orthogonality error (OE)?
 
 With the counter-weights down and scope pointing at NCP.
 An orthogonality error will cause the scope's viewing point to be above or below NCP.
 
 To the left or right of NCP is not an error.
 You can move Dec to remove any left or right offset.
 
 Rotating RA from east side to west side will move the scope's
 viewing point around NCP tracing out half of a circle around NCP.
 Scope will hit the pier before the other half of circle completes.
 
 Radius of this circle is your (1x) orthogonality error.
 Diameter of the circle is 2 times (2x) your orthogonality error.
 
 If you move the counter-weight shaft to west side and horizontal/level with ground, the scope's 
 viewing point will be either east or west of NCP by (1x) your orthogonality error.
 
 If you move the counter-weight shaft to east side and horizontal/level with ground,
 you will miss NCP by 1x on the other side of NCP.
 
 1x on one side of NCP, meridian flip and 1x off on other side = 2x orthogonality error when
 flipping from east to west side.
 
 If you move scope from NCP to zenith to Dec=0 to SCP, your scope's viewing point will be east or
 west of meridian by your 1x orthogonality error everywhere along that path.
 
 You will have to shim the front or rear ring to bring your viewing point back to NCP.
 
 After minimizing your orthogonality error,
 future meridian flips should result in star in FOV on both sides.
 
 If not then you may have flexure and/or worm needs re-meshing and/or
 something is loose and needs tightening.
 
As always, I may be wrong again.
Jimmy


DFisch
 

Jimmy, best explanation of OE I have ever seen or heard, great post!

On Fri, Nov 1, 2019 at 00:26 jimmyjujames <jimmy_an@...> wrote:
If OE is short for orthogonality error.
 
An Orthogonality error (OE) is only east-west when pointing at zenith.
OE is always in line with the counter-weight shaft.
When pointing at NCP with counter-weight shaft pointing down, OE is north-south.
 
 What is an orthogonality error (OE)?
 
 With the counter-weights down and scope pointing at NCP.
 An orthogonality error will cause the viewing point to be above or below NCP.
 
 To the left or right of NCP is not an error.
 You can move Dec to remove any left or right offset.
 
 Rotating RA will move the viewing point around NCP forming a circle around NCP.
 Radius of this circle is your (1x) orthogonality error.
 Diameter of the circle is 2 times (2x) your orthogonality error.
 
 If you move the counter-weight shaft to west side and horizontal/level with ground, the scope's 
 viewing point will be either east or west of NCP by (1x) your orthogonality error.
 If you move scope from NCP to zenith to Dec=0 to SCP, your scope's viewing point will be east or
 west of meridian by your 1x orthogonality error everywhere along that path.
 
 If you do a meridian flip at NCP, you will miss NCP by 1x on the other side of NCP.
 1x on one side of NCP, meridian flip and 1x off on other side = 2x orthogonality error when
 flipping from east to west side.
 
 You will have to shim the front or rear ring to bring your viewing point back to NCP.
 
 After minimizing your orthogonality error,
 future meridian flips should result in star in FOV on both sides.
 
 If not then you may have flexure and/or worm needs re-meshing and/or
 something is loose and needs tightening.
 
As always, I may be wrong again.
Jimmy


Andrew J
 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Greg Salyer
 

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Greg Salyer
 

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has another way of describing the problem and software for

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Roland Christen
 


Can OE lead to issues with Guiding?
NO! Orthogonality has nothing to do with guiding.

Roland


-----Original Message-----
From: Andrew Jones <andjones132@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:01 am
Subject: Re: [ap-gto] Orthogonality question

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Roland Christen
 

We will have a cone error correction in our upcoming keypad software.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Greg Salyer
 

Cone error correction? or detection?

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

We will have a cone error correction in our upcoming keypad software.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Roland Christen
 

Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question

Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Greg Salyer
 

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question

Cone error correction? or detection?

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

We will have a cone error correction in our upcoming keypad software.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Roland Christen
 

I believe Pole Master works regardless of cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question
Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Greg Salyer
 

I’ve been trying to understand why PoleMaster isn’t working for me. It seems like the procedure would insure that the mount is correctly aligned but the scope itself could still be off a bit due to cone error since the procedure doesn’t involve the scope. What am I missing?

Greg

On Nov 1, 2019, at 1:09 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I believe Pole Master works regardless of cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question
Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Roland Christen
 

Cone error is an error that is in your telescope. It is NOT an error that is in the mount. Pole master is not attached to your telescope where the cone error exists. Pole master has no cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 12:24 pm
Subject: Re: [ap-gto] Orthogonality question

I’ve been trying to understand why PoleMaster isn’t working for me. It seems like the procedure would insure that the mount is correctly aligned but the scope itself could still be off a bit due to cone error since the procedure doesn’t involve the scope. What am I missing?

Greg

On Nov 1, 2019, at 1:09 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I believe Pole Master works regardless of cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question
Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Geert
 

Greg, Polemaster is to align the polar axis of the mount correctly.  Nothing less, nothing more.  To correct for cone error and/or align the scope to the sky, other routines are necessary but the  correct pointing of the polar axis is a prerequisite and will help with those other routines.

Geert

Op vr 1 nov. 2019 om 18:24 schreef Greg Salyer <astronutcase@...>:

I’ve been trying to understand why PoleMaster isn’t working for me. It seems like the procedure would insure that the mount is correctly aligned but the scope itself could still be off a bit due to cone error since the procedure doesn’t involve the scope. What am I missing?

Greg

On Nov 1, 2019, at 1:09 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011=aol.com@groups.io> wrote:


I believe Pole Master works regardless of cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question
Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Greg Salyer
 

Perhaps I’m using the terms incorrectly. I think the mount, the scope and the connection between the mount and scope all need to be correctly aligned for PoleMaster to be useful. It sounds like your using the term orthogonality error to refer to the mount component and cone error to refer to the scope component. Is that right? All I’m saying is that if one of them is off then PoleMaster won’t provide the polar alignment desired (nor would any other polar alignment method). Since PoleMaster doesn’t seem to work for me then I suspect one of these is off in my system. Since I always use guiding, a small error here isn’t a big deal. I just wondered why PoleMaster wasn’t successful. If this doesn’t explain what’s happening then I have no idea what is wrong. 

Greg

On Nov 1, 2019, at 1:40 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


Cone error is an error that is in your telescope. It is NOT an error that is in the mount. Pole master is not attached to your telescope where the cone error exists. Pole master has no cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 12:24 pm
Subject: Re: [ap-gto] Orthogonality question

I’ve been trying to understand why PoleMaster isn’t working for me. It seems like the procedure would insure that the mount is correctly aligned but the scope itself could still be off a bit due to cone error since the procedure doesn’t involve the scope. What am I missing?

Greg

On Nov 1, 2019, at 1:09 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011@...> wrote:


I believe Pole Master works regardless of cone error.

Roland



-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question
Cone error correction? or detection?
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
We will have a cone error correction in our upcoming keypad software.
 
Roland
 
 
 
-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question
Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.
 
Greg
 
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question
 
Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.
 
Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.
 
Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.

Andrew J


Roland Christen
 


I think the mount, the scope and the connection between the mount and scope all need to be correctly aligned for PoleMaster to be useful.
Pole master does not use your scope. It is independent of what scope you place on the Dec cradle plate. Pole master doesn't even need to be aiming exactly along the RA axis to work correctly. It does its job regardless of orthogonality.

Roland


-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 1:05 pm
Subject: Re: [ap-gto] Orthogonality question

Perhaps I’m using the terms incorrectly. I think the mount, the scope and the connection between the mount and scope all need to be correctly aligned for PoleMaster to be useful. It sounds like your using the term orthogonality error to refer to the mount component and cone error to refer to the scope component. Is that right? All I’m saying is that if one of them is off then PoleMaster won’t provide the polar alignment desired (nor would any other polar alignment method). Since PoleMaster doesn’t seem to work for me then I suspect one of these is off in my system. Since I always use guiding, a small error here isn’t a big deal. I just wondered why PoleMaster wasn’t successful. If this doesn’t explain what’s happening then I have no idea what is wrong. 

Greg




Greg Salyer
 

Geert, that makes sense.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Geert
Sent: Friday, November 1, 2019 1:48 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Greg, Polemaster is to align the polar axis of the mount correctly.  Nothing less, nothing more.  To correct for cone error and/or align the scope to the sky, other routines are necessary but the  correct pointing of the polar axis is a prerequisite and will help with those other routines.

 

Geert

 

Op vr 1 nov. 2019 om 18:24 schreef Greg Salyer <astronutcase@...>:

I’ve been trying to understand why PoleMaster isn’t working for me. It seems like the procedure would insure that the mount is correctly aligned but the scope itself could still be off a bit due to cone error since the procedure doesn’t involve the scope. What am I missing?

 

Greg



On Nov 1, 2019, at 1:09 PM, uncarollo2 <chris1011@...> via Groups.Io <chris1011=aol.com@groups.io> wrote:



I believe Pole Master works regardless of cone error.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:59 am
Subject: Re: [ap-gto] Orthogonality question

Sounds great. I've never been able to get PoleMaster to work. The best I can do is about 8' off (so I use PEMPro). Do you think it could be because of Cone Error?

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:29 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Cone error correction. There is an easy way to detect it. In this new keypad routine, you simply go to a star on one side of the meridian, center it and press Recal. Then send the mount to a star the other side of the meridian with the same or similar Dec, center it and press Recal. The cone error is extracted and set in the servo. From then on any time you flip sides the cone error will be compensated. The only place where this cannot work is around the poles because it is a physical impossibility.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 11:15 am
Subject: Re: [ap-gto] Orthogonality question

Cone error correction? or detection?

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 12:02 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

We will have a cone error correction in our upcoming keypad software.

 

Roland

 

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 10:14 am
Subject: Re: [ap-gto] Orthogonality question

Another name for orthogonality error is cone error. Site https://www.sharpcap.co.uk/conesharp has a good description of the problem and software to measure it. Apparently some mounts do allow an adjustment to correct for it. If you search for cone error I'm sure you will find more.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Andrew Jones
Sent: Friday, November 1, 2019 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

Suresh, I also have a couple of questions about Orthogonality error (OE). I hope you don’t mind me jumping in on this thread.

Can OE lead to issues with Guiding? I have continued to struggle to dial in my guiding and keep the total RMS error below 1.00. It is usually closer to 1.20 arc minutes. I have tried using the PHD2 settings recommended in a previous post by Rolando, and although they did help, I still struggle with guiding my Mach1 with a TEC140 attached (with or without an APPM pointing model). According my PemPro my polar alignment is +/- 2 arc mins. So, I suspect the issue is caused by OE. I am not that familiar with OE or how to correct for it.

 

Is OE something that can be detected by PemPro? It seems like that would be the right tool for the job. My rig is used solely for imaging, so I am looking for an imaging solution to help identify and recommend the OE adjustments that need to be made to correct for it.  I have seen instructions where it ask to point the OTA towards zenith on one side of the pier, then set a 1-hour meridian delay and slew to the same spot on the other side of the pier. The problem I have is that with the TEC140 and my imaging gear, I am almost hitting the pier when the scope is pointed at Zenith. So, setting a 1-hour meridian delay (which I assume means a weights up position) is not really a good option. Finally, is the best option to adjust for OE to put strips of cut up soda cans in the saddle to push the back end of the scope one way or the other? I am surprised someone has not produced a saddle that has OE adjustments built in. The Soda can method does not seem like an easily repeatable process.

 

Anyway, as I have never had to adjust for OE, I am looking for advice on the best way to go about detecting it and then fixing it on the Mach1. Any advice would be greatly appreciated.


Andrew J


Greg Salyer
 

Roland, thanks for trying to help but I think you and I are talking around each other. However, Geert's comment makes perfect sense to me and I believe explains what I'm experiencing with PoleMaster.

 

Greg

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of uncarollo2 <chris1011@...> via Groups.Io
Sent: Friday, November 1, 2019 2:13 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Orthogonality question

 

 

I think the mount, the scope and the connection between the mount and scope all need to be correctly aligned for PoleMaster to be useful.

Pole master does not use your scope. It is independent of what scope you place on the Dec cradle plate. Pole master doesn't even need to be aiming exactly along the RA axis to work correctly. It does its job regardless of orthogonality.

 

Roland

 

 

-----Original Message-----
From: Greg Salyer <astronutcase@...>
To: main <main@ap-gto.groups.io>
Sent: Fri, Nov 1, 2019 1:05 pm
Subject: Re: [ap-gto] Orthogonality question

Perhaps I’m using the terms incorrectly. I think the mount, the scope and the connection between the mount and scope all need to be correctly aligned for PoleMaster to be useful. It sounds like your using the term orthogonality error to refer to the mount component and cone error to refer to the scope component. Is that right? All I’m saying is that if one of them is off then PoleMaster won’t provide the polar alignment desired (nor would any other polar alignment method). Since PoleMaster doesn’t seem to work for me then I suspect one of these is off in my system. Since I always use guiding, a small error here isn’t a big deal. I just wondered why PoleMaster wasn’t successful. If this doesn’t explain what’s happening then I have no idea what is wrong. 

 

Greg

 

 

 


Andrew J
 

@Greg. Thanks for the tip about Cone Sharp. I was reading through the instructions and it sounded great, until I read the last bullet point about requiring "A decent view of the southern sky (due south), able to see stars with a declination of ~0”. Unfortunately, I do not have a clear view of the southern sky. I live in a sub-division and there is a house directly behind my observatory. The best I could probably do would be a declination of around 30 degrees above the horizon. I might still give it a try, but not sure if it will work.

 

Andrew J