AP1100 Bad Stars Issues


Bill Long
 

Hello all,


I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.


Problem Statement:

Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 

Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 


Possible Red Herring or Evidence for Concern:

I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.


Polar Alignment Method:

Polemaster, 3 complete cycles per alignment, repeatable results.


Gear:

Stellarvue 80mm Refractor w/ SV80 Field Flattener

Takahashi FSQ106ED Native w/ no reducer

Takahashi TOA130 w/ 0.7x Tak Reducer 

AP1100 GTO CP4 w/ Auto-Adjusting Gearbox

ASI 183MM Pro CMOS Camera

ASI 294MC Pro CMOS Camera


Software:

APCC Pro

ASCOM v2 AP Driver

Sequence Generator Pro


All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.


The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.


The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.


Thanks for reading.




Bill Long
 

Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher than the published spec. 




From: ap-gto@... on behalf of Bill Long bill@... [ap-gto]
Sent: Saturday, February 24, 2018 10:07 AM
To: ap-gto@...
Subject: [ap-gto] AP1100 Bad Stars Issues
 
 

Hello all,


I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.


Problem Statement:

Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 

Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 


Possible Red Herring or Evidence for Concern:

I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.


Polar Alignment Method:

Polemaster, 3 complete cycles per alignment, repeatable results.


Gear:

Stellarvue 80mm Refractor w/ SV80 Field Flattener

Takahashi FSQ106ED Native w/ no reducer

Takahashi TOA130 w/ 0.7x Tak Reducer 

AP1100 GTO CP4 w/ Auto-Adjusting Gearbox

ASI 183MM Pro CMOS Camera

ASI 294MC Pro CMOS Camera


Software:

APCC Pro

ASCOM v2 AP Driver

Sequence Generator Pro


All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.


The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.


The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.


Thanks for reading.




Roland Christen
 


The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.





Ray Gralak
 

Hi Bill,

Corrected it looks like less than 1" peak-peak.

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
4986#5087004986

But PEM can't help correct for refraction and flexure issues. You might also
want to double check PHD2's polar alignment with PEMPro as there have been
some people getting more drift than they should have with the PHD2 polar
alignment tool.

However, if polar alignment checks out good and everything is tight on your
OTA assembly, to get the next level of unguided tracking performance you
probably would have to do all-sky modeling with APCC Pro.

Best regards,

-Ray Gralak
Author of APCC (Astro-Physics Command Center):
http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
cc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, February 24, 2018 10:34 AM
To: ap-gto@...
Subject: [ap-gto] Re: AP1100 Bad Stars Issues



Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher than
the
published spec.



________________________________

From: ap-gto@... <ap-gto@...> on behalf of Bill
Long
bill@... [ap-gto] <ap-gto@...>
Sent: Saturday, February 24, 2018 10:07 AM
To: ap-gto@...
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,




I have contacted A-P about some recent imaging challenges I have had, and
have
provided details to George on this problem, but I wanted to get some
thoughts from
the folks here on this forum as well, in the event someone has experienced
a similar
problem.




Problem Statement:

Out of round stars in 15 and 30 second unguided exposures, on two
different
cameras.

Out of round Stars in 60 second, 120 second, and 300 second guided
exposures on
one camera.




Possible Red Herring or Evidence for Concern:

I have run PEMPro and the readings of periodic error are wildly
inconsistent. I get up
to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is
almost 3 times
the published specification of +/- 3.5" without any error correction.




Polar Alignment Method:

Polemaster, 3 complete cycles per alignment, repeatable results.




Gear:

Stellarvue 80mm Refractor w/ SV80 Field Flattener

Takahashi FSQ106ED Native w/ no reducer

Takahashi TOA130 w/ 0.7x Tak Reducer

AP1100 GTO CP4 w/ Auto-Adjusting Gearbox

ASI 183MM Pro CMOS Camera

ASI 294MC Pro CMOS Camera




Software:

APCC Pro

ASCOM v2 AP Driver

Sequence Generator Pro




All cameras tested were properly spaced on each respective scope. I have
performed
testing with a wheel and OAG attached, as well as without any wheel or OAG
attached, and spacers in place of them to ensure accurate chip placement.
Using
CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt.
As a
test, I enabled guiding and set the RA settings very, very aggressively
and while the
problem did not completely cure itself, the roundness of the stars
improved
dramatically, and tilt was reported to be reduced to 2%.




The cameras could be involved in the problem, I am not ruling that out,
but to have
very similar results on two different cameras is suspicious, and if there
is a way to rule
out the one constant in all of this testing (the mount) I would like to do
that.




The mount is not permanently mounted. I set up and tear down each night I
image.
The axis are separated and reassembled when the mount goes outside, and
when it
comes back inside each night. In case this information is useful.




Thanks for reading.








Bill Long
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.


I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 



From: ap-gto@... on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 


The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.





Ray Gralak
 

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
4986#5087004986
Here's a link that doesn't wrap to that:

https://goo.gl/jkGLLx


-Ray Gralak
Author of APCC (Astro-Physics Command Center):
http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
cc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma


-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, February 24, 2018 10:51 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: AP1100 Bad Stars Issues



Hi Bill,

Corrected it looks like less than 1" peak-peak.

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
4986#5087004986

But PEM can't help correct for refraction and flexure issues. You might
also
want to double check PHD2's polar alignment with PEMPro as there have been
some people getting more drift than they should have with the PHD2 polar
alignment tool.

However, if polar alignment checks out good and everything is tight on
your
OTA assembly, to get the next level of unguided tracking performance you
probably would have to do all-sky modeling with APCC Pro.

Best regards,

-Ray Gralak
Author of APCC (Astro-Physics Command Center):
http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
cc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, February 24, 2018 10:34 AM
To: ap-gto@...
Subject: [ap-gto] Re: AP1100 Bad Stars Issues



Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher than
the
published spec.



________________________________

From: ap-gto@... <ap-gto@...> on behalf of Bill
Long
bill@... [ap-gto] <ap-gto@...>
Sent: Saturday, February 24, 2018 10:07 AM
To: ap-gto@...
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,




I have contacted A-P about some recent imaging challenges I have had,
and
have
provided details to George on this problem, but I wanted to get some
thoughts from
the folks here on this forum as well, in the event someone has
experienced
a similar
problem.




Problem Statement:

Out of round stars in 15 and 30 second unguided exposures, on two
different
cameras.

Out of round Stars in 60 second, 120 second, and 300 second guided
exposures on
one camera.




Possible Red Herring or Evidence for Concern:

I have run PEMPro and the readings of periodic error are wildly
inconsistent. I get up
to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is
almost 3 times
the published specification of +/- 3.5" without any error correction.




Polar Alignment Method:

Polemaster, 3 complete cycles per alignment, repeatable results.




Gear:

Stellarvue 80mm Refractor w/ SV80 Field Flattener

Takahashi FSQ106ED Native w/ no reducer

Takahashi TOA130 w/ 0.7x Tak Reducer

AP1100 GTO CP4 w/ Auto-Adjusting Gearbox

ASI 183MM Pro CMOS Camera

ASI 294MC Pro CMOS Camera




Software:

APCC Pro

ASCOM v2 AP Driver

Sequence Generator Pro




All cameras tested were properly spaced on each respective scope. I have
performed
testing with a wheel and OAG attached, as well as without any wheel or
OAG
attached, and spacers in place of them to ensure accurate chip
placement.
Using
CCDWare CCD Inspector 2, both cameras are reported to be showing 20%
tilt.
As a
test, I enabled guiding and set the RA settings very, very aggressively
and while the
problem did not completely cure itself, the roundness of the stars
improved
dramatically, and tilt was reported to be reduced to 2%.




The cameras could be involved in the problem, I am not ruling that out,
but to have
very similar results on two different cameras is suspicious, and if
there
is a way to rule
out the one constant in all of this testing (the mount) I would like to
do
that.




The mount is not permanently mounted. I set up and tear down each night
I
image.
The axis are separated and reassembled when the mount goes outside, and
when it
comes back inside each night. In case this information is useful.




Thanks for reading.










Bill Long
 

Thanks for the help Ray. I dont use PHD2 for polar alignment. I use Polemaster. I can certainly check Polar Alignment with PEMPro though. 




From: ap-gto@... on behalf of 'Ray Gralak (Groups)' groups3@... [ap-gto]
Sent: Saturday, February 24, 2018 10:50 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: AP1100 Bad Stars Issues
 
 

Hi Bill,

Corrected it looks like less than 1" peak-peak.

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
4986#5087004986

But PEM can't help correct for refraction and flexure issues. You might also
want to double check PHD2's polar alignment with PEMPro as there have been
some people getting more drift than they should have with the PHD2 polar
alignment tool.

However, if polar alignment checks out good and everything is tight on your
OTA assembly, to get the next level of unguided tracking performance you
probably would have to do all-sky modeling with APCC Pro.

Best regards,

-Ray Gralak
Author of APCC (Astro-Physics Command Center):
http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
cc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma

> -----Original Message-----
> From: ap-gto@... [mailto:ap-gto@...]
> Sent: Saturday, February 24, 2018 10:34 AM
> To: ap-gto@...
> Subject: [ap-gto] Re: AP1100 Bad Stars Issues
>
>
>
> Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher than
the
> published spec.
>
>
>
> ________________________________
>
> From: ap-gto@... on behalf of Bill
Long
> bill@... [ap-gto]
> Sent: Saturday, February 24, 2018 10:07 AM
> To: ap-gto@...
> Subject: [ap-gto] AP1100 Bad Stars Issues
>
>
>
> Hello all,
>
>
>
>
> I have contacted A-P about some recent imaging challenges I have had, and
have
> provided details to George on this problem, but I wanted to get some
thoughts from
> the folks here on this forum as well, in the event someone has experienced
a similar
> problem.
>
>
>
>
> Problem Statement:
>
> Out of round stars in 15 and 30 second unguided exposures, on two
different
> cameras.
>
> Out of round Stars in 60 second, 120 second, and 300 second guided
exposures on
> one camera.
>
>
>
>
> Possible Red Herring or Evidence for Concern:
>
> I have run PEMPro and the readings of periodic error are wildly
inconsistent. I get up
> to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is
almost 3 times
> the published specification of +/- 3.5" without any error correction.
>
>
>
>
> Polar Alignment Method:
>
> Polemaster, 3 complete cycles per alignment, repeatable results.
>
>
>
>
> Gear:
>
> Stellarvue 80mm Refractor w/ SV80 Field Flattener
>
> Takahashi FSQ106ED Native w/ no reducer
>
> Takahashi TOA130 w/ 0.7x Tak Reducer
>
> AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
>
> ASI 183MM Pro CMOS Camera
>
> ASI 294MC Pro CMOS Camera
>
>
>
>
> Software:
>
> APCC Pro
>
> ASCOM v2 AP Driver
>
> Sequence Generator Pro
>
>
>
>
> All cameras tested were properly spaced on each respective scope. I have
performed
> testing with a wheel and OAG attached, as well as without any wheel or OAG
> attached, and spacers in place of them to ensure accurate chip placement.
Using
> CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt.
As a
> test, I enabled guiding and set the RA settings very, very aggressively
and while the
> problem did not completely cure itself, the roundness of the stars
improved
> dramatically, and tilt was reported to be reduced to 2%.
>
>
>
>
> The cameras could be involved in the problem, I am not ruling that out,
but to have
> very similar results on two different cameras is suspicious, and if there
is a way to rule
> out the one constant in all of this testing (the mount) I would like to do
that.
>
>
>
>
> The mount is not permanently mounted. I set up and tear down each night I
image.
> The axis are separated and reassembled when the mount goes outside, and
when it
> comes back inside each night. In case this information is useful.
>
>
>
>
> Thanks for reading.
>
>
>
>
>
>
>
>


Ray Gralak
 

Ok, polemaster should be good, but it doesn't hurt to double check.

Also, make sure all the knobs are tight on your mount, OTA, and camera/focuser.
Flexure can be hard to pin down.

What OTA did you say you were using?

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

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, February 24, 2018 10:54 AM
To: ap-gto@...
Subject: Re: [ap-gto] Re: AP1100 Bad Stars Issues



Thanks for the help Ray. I dont use PHD2 for polar alignment. I use
Polemaster. I can
certainly check Polar Alignment with PEMPro though.



________________________________

From: ap-gto@... <ap-gto@...> on behalf of 'Ray Gralak
(Groups)' groups3@... [ap-gto] <ap-gto@...>
Sent: Saturday, February 24, 2018 10:50 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: AP1100 Bad Stars Issues



Hi Bill,

Corrected it looks like less than 1" peak-peak.

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
4986#5087004986

But PEM can't help correct for refraction and flexure issues. You might also
want to double
check PHD2's polar alignment with PEMPro as there have been some people
getting more
drift than they should have with the PHD2 polar alignment tool.

However, if polar alignment checks out good and everything is tight on your
OTA
assembly, to get the next level of unguided tracking performance you probably
would have
to do all-sky modeling with APCC Pro.

Best regards,

-Ray Gralak
Author of APCC (Astro-Physics Command Center):
http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
cc
Author of PEMPro: http://www.ccdware.com Author of Astro-Physics V2 ASCOM
Driver:
http://www.gralak.com/apdriver Author of PulseGuide: http://www.pulseguide.com
Author
of Sigma: http://www.gralak.com/sigma

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Saturday, February 24, 2018 10:34 AM
To: ap-gto@...
Subject: [ap-gto] Re: AP1100 Bad Stars Issues



Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher
than
the
published spec.



________________________________

From: ap-gto@... <ap-gto@...> on behalf of
Bill
Long
bill@... [ap-gto] <ap-gto@...>
Sent: Saturday, February 24, 2018 10:07 AM
To: ap-gto@...
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,




I have contacted A-P about some recent imaging challenges I have had,
and
have
provided details to George on this problem, but I wanted to get some
thoughts from
the folks here on this forum as well, in the event someone has
experienced
a similar
problem.




Problem Statement:

Out of round stars in 15 and 30 second unguided exposures, on two
different
cameras.

Out of round Stars in 60 second, 120 second, and 300 second guided
exposures on
one camera.




Possible Red Herring or Evidence for Concern:

I have run PEMPro and the readings of periodic error are wildly
inconsistent. I get up
to 10" P-P of RA error. The last one I ran was close to 9" P-P. This
is
almost 3 times
the published specification of +/- 3.5" without any error correction.




Polar Alignment Method:

Polemaster, 3 complete cycles per alignment, repeatable results.




Gear:

Stellarvue 80mm Refractor w/ SV80 Field Flattener

Takahashi FSQ106ED Native w/ no reducer

Takahashi TOA130 w/ 0.7x Tak Reducer

AP1100 GTO CP4 w/ Auto-Adjusting Gearbox

ASI 183MM Pro CMOS Camera

ASI 294MC Pro CMOS Camera




Software:

APCC Pro

ASCOM v2 AP Driver

Sequence Generator Pro




All cameras tested were properly spaced on each respective scope. I
have
performed
testing with a wheel and OAG attached, as well as without any wheel or
OAG attached, and spacers in place of them to ensure accurate chip
placement.
Using
CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt.
As a
test, I enabled guiding and set the RA settings very, very
aggressively
and while the
problem did not completely cure itself, the roundness of the stars
improved
dramatically, and tilt was reported to be reduced to 2%.




The cameras could be involved in the problem, I am not ruling that
out,
but to have
very similar results on two different cameras is suspicious, and if
there
is a way to rule
out the one constant in all of this testing (the mount) I would like
to do
that.




The mount is not permanently mounted. I set up and tear down each
night I
image.
The axis are separated and reassembled when the mount goes outside,
and
when it
comes back inside each night. In case this information is useful.




Thanks for reading.










Bill Long
 

I used three.


FSQ106ED

SV80ST

TOA130


PEMPro was recorded on the FSQ.




From: ap-gto@... on behalf of 'Ray Gralak (Groups)' groups3@... [ap-gto]
Sent: Saturday, February 24, 2018 10:57 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: AP1100 Bad Stars Issues
 
 

Ok, polemaster should be good, but it doesn't hurt to double check.

Also, make sure all the knobs are tight on your mount, OTA, and camera/focuser.
Flexure can be hard to pin down.

What OTA did you say you were using?

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

> -----Original Message-----
> From: ap-gto@... [mailto:ap-gto@...]
> Sent: Saturday, February 24, 2018 10:54 AM
> To: ap-gto@...
> Subject: Re: [ap-gto] Re: AP1100 Bad Stars Issues
>
>
>
> Thanks for the help Ray. I dont use PHD2 for polar alignment. I use
Polemaster. I can
> certainly check Polar Alignment with PEMPro though.
>
>
>
> ________________________________
>
> From: ap-gto@... <ap-gto@...> on behalf of 'Ray Gralak
> (Groups)' groups3@... [ap-gto]
> Sent: Saturday, February 24, 2018 10:50 AM
> To: ap-gto@...
> Subject: RE: [ap-gto] Re: AP1100 Bad Stars Issues
>
>
>
> Hi Bill,
>
> Corrected it looks like less than 1" peak-peak.
>
> http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=508700
> 4986#5087004986
>
> But PEM can't help correct for refraction and flexure issues. You might also
want to double
> check PHD2's polar alignment with PEMPro as there have been some people
getting more
> drift than they should have with the PHD2 polar alignment tool.
>
> However, if polar alignment checks out good and everything is tight on your
OTA
> assembly, to get the next level of unguided tracking performance you probably
would have
> to do all-sky modeling with APCC Pro.
>
> Best regards,
>
> -Ray Gralak
> Author of APCC (Astro-Physics Command Center):
> http://www.astro-physics.com/index.htm?products/accessories/software/apcc/ap
> cc
> Author of PEMPro: http://www.ccdware.com Author of Astro-Physics V2 ASCOM
Driver:
> http://www.gralak.com/apdriver Author of PulseGuide: http://www.pulseguide.com
Author
> of Sigma: http://www.gralak.com/sigma
>
> > -----Original Message-----
> > From: ap-gto@... [mailto:ap-gto@...]
> > Sent: Saturday, February 24, 2018 10:34 AM
> > To: ap-gto@...
> > Subject: [ap-gto] Re: AP1100 Bad Stars Issues
> >
> >
> >
> > Correction, the P-P error in PEMPro was about -/+ 5" so 1.5" higher
> > than
> the
> > published spec.
> >
> >
> >
> > ________________________________
> >
> > From: ap-gto@... on behalf of
> > Bill
> Long
> > bill@... [ap-gto]
> > Sent: Saturday, February 24, 2018 10:07 AM
> > To: ap-gto@...
> > Subject: [ap-gto] AP1100 Bad Stars Issues
> >
> >
> >
> > Hello all,
> >
> >
> >
> >
> > I have contacted A-P about some recent imaging challenges I have had,
> > and
> have
> > provided details to George on this problem, but I wanted to get some
> thoughts from
> > the folks here on this forum as well, in the event someone has
> > experienced
> a similar
> > problem.
> >
> >
> >
> >
> > Problem Statement:
> >
> > Out of round stars in 15 and 30 second unguided exposures, on two
> different
> > cameras.
> >
> > Out of round Stars in 60 second, 120 second, and 300 second guided
> exposures on
> > one camera.
> >
> >
> >
> >
> > Possible Red Herring or Evidence for Concern:
> >
> > I have run PEMPro and the readings of periodic error are wildly
> inconsistent. I get up
> > to 10" P-P of RA error. The last one I ran was close to 9" P-P. This
> > is
> almost 3 times
> > the published specification of +/- 3.5" without any error correction.
> >
> >
> >
> >
> > Polar Alignment Method:
> >
> > Polemaster, 3 complete cycles per alignment, repeatable results.
> >
> >
> >
> >
> > Gear:
> >
> > Stellarvue 80mm Refractor w/ SV80 Field Flattener
> >
> > Takahashi FSQ106ED Native w/ no reducer
> >
> > Takahashi TOA130 w/ 0.7x Tak Reducer
> >
> > AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
> >
> > ASI 183MM Pro CMOS Camera
> >
> > ASI 294MC Pro CMOS Camera
> >
> >
> >
> >
> > Software:
> >
> > APCC Pro
> >
> > ASCOM v2 AP Driver
> >
> > Sequence Generator Pro
> >
> >
> >
> >
> > All cameras tested were properly spaced on each respective scope. I
> > have
> performed
> > testing with a wheel and OAG attached, as well as without any wheel or
> > OAG attached, and spacers in place of them to ensure accurate chip
placement.
> Using
> > CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt.
> As a
> > test, I enabled guiding and set the RA settings very, very
> > aggressively
> and while the
> > problem did not completely cure itself, the roundness of the stars
> improved
> > dramatically, and tilt was reported to be reduced to 2%.
> >
> >
> >
> >
> > The cameras could be involved in the problem, I am not ruling that
> > out,
> but to have
> > very similar results on two different cameras is suspicious, and if
> > there
> is a way to rule
> > out the one constant in all of this testing (the mount) I would like
> > to do
> that.
> >
> >
> >
> >
> > The mount is not permanently mounted. I set up and tear down each
> > night I
> image.
> > The axis are separated and reassembled when the mount goes outside,
> > and
> when it
> > comes back inside each night. In case this information is useful.
> >
> >
> >
> >
> > Thanks for reading.
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>


Roland Christen
 


I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.







Bill Long
 

That is all located here:


http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=5087004986#5087004986






From: ap-gto@... on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 


I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.







Roland Christen
 

Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.









Bill Long
 

I tried to attach the screenshot to this email. Not sure if Yahoo allows that.


________________________________
From: ap-gto@... <ap-gto@...> on behalf of chris1011@... [ap-gto] <ap-gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=5087004986#5087004986




________________________________
From: ap-gto@...<mailto:gto@...> <ap-gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] <ap-gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] <ap-gto@...<mailto:gto@...>>
To: ap-gto <ap-gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures.

________________________________
From: ap-gto@...<mailto:gto@...> <ap-gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] <ap-gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] <ap-gto@...<mailto:gto@...>>
To: ap-gto <ap-gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras.
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera.

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night. In case this information is useful.

Thanks for reading.


Bill Long
 

https://groups.yahoo.com/neo/groups/ap-gto/files/PEMPro_Curve.JPG





From: ap-gto@... on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando




-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... <ap-gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.









Roland Christen
 

Screen shots not allowed on Yahoo unfortunately ;^(



-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:15 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues

I tried to attach the screenshot to this email. Not sure if Yahoo allows that.


________________________________
From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=5087004986#5087004986




________________________________
From: ap-gto@...<mailto:gto@...> gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] gto@...<mailto:gto@...>>
To: ap-gto gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures.

________________________________
From: ap-gto@...<mailto:gto@...> gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] gto@...<mailto:gto@...>>
To: ap-gto gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras.
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera.

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night. In case this information is useful.

Thanks for reading.
















------------------------------------

------------------------------------

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Bill Long
 

Seems the Yahoo Group allows you to upload from the webpage.


https://groups.yahoo.com/neo/groups/ap-gto/files/PEMPro_Curve.JPG


That is the resultant curve from PEMPro. 





From: ap-gto@... <ap-gto@...> on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 12:21 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

Screen shots not allowed on Yahoo unfortunately ;^(




-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:15 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues

I tried to attach the screenshot to this email. Not sure if Yahoo allows that.


________________________________
From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:

http://ccdware.infopop.cc/eve/forums/a/tpc/f/401101098/m/8577004986?r=5087004986#5087004986




________________________________
From: ap-gto@...<mailto:gto@...> gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] gto@...<mailto:gto@...>>
To: ap-gto gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures.

________________________________
From: ap-gto@...<mailto:gto@...> gto@...<mailto:gto@...>> on behalf of chris1011@...<mailto:chris1011@...> [ap-gto] gto@...<mailto:gto@...>>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...<mailto:gto@...>
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@...<mailto:bill@...> [ap-gto] gto@...<mailto:gto@...>>
To: ap-gto gto@...<mailto:gto@...>>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras.
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera.

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P. This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night. In case this information is useful.

Thanks for reading.
















------------------------------------

------------------------------------

To UNSUBSCRIBE, or for general information on the ap-gto list
see http://groups.yahoo.com/group/ap-gto
------------------------------------

Yahoo Groups Links

<*> To visit your group on the web, go to:
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<*> Your email settings:
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Roland Christen
 

What is the PEC curve with PEM turned ON? That is what you will be using during tracking.

When you took your PE data, you said that the individual curves did not lie on top of each other, rather they moved up with each new worm cycle. That should tell you immediately that your polar alignment is not good, and you have excessive RA drift. When your polar alignment is correct (Altitude axis properly aligned), you will basically have zero RA drift and each curve will lie on top of the next, or very close to it. Then with PEM turned on, you should be able to get no tracking error for several worm cycles when you are anywhere near the meridian.

When you have RA drift, or Dec drift for that matter, you will never have round stars even when the mount is tracking to 1 arc sec levels with PEM on. RA drift is independent of periodic error and has nothing to do with mount tracking at sidereal rate. A perfect mount with zero PE will have egg shaped stars if you have drift in either axis.

Roland Christen



-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:16 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues







From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.











Bill Long
 

The PEM ON test needs to be run still, next clear night I plan to do that.


When I took my PE data, the curves seem to line up well. Here is what they looked like:


https://groups.yahoo.com/neo/groups/ap-gto/files/PEMPro%20Error.JPG


Do those look egregious to you?


As far as Polar Alignment is concerned, I used the Polemaster tool and ran it through 3 complete cycles to confirm its suggested alignment. Ray suggested I check that alignment with PEMPro the next time I am out. I will spend the 30 mins or so to get some fresh PEMPro PE data as well to see if there is any difference.





From: ap-gto@... on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 12:34 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

What is the PEC curve with PEM turned ON? That is what you will be using during tracking.

When you took your PE data, you said that the individual curves did not lie on top of each other, rather they moved up with each new worm cycle. That should tell you immediately that your polar alignment is not good, and you have excessive RA drift. When your polar alignment is correct (Altitude axis properly aligned), you will basically have zero RA drift and each curve will lie on top of the next, or very close to it. Then with PEM turned on, you should be able to get no tracking error for several worm cycles when you are anywhere near the meridian.

When you have RA drift, or Dec drift for that matter, you will never have round stars even when the mount is tracking to 1 arc sec levels with PEM on. RA drift is independent of periodic error and has nothing to do with mount tracking at sidereal rate. A perfect mount with zero PE will have egg shaped stars if you have drift in either axis.

Roland Christen




-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 2:16 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues







From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.











Roland Christen
 

The curves you posted line up because PEMPro has lined them up for you when you clicked on the X and Y alignment tabs. You had mentioned in the PEMpro postings that they did not line up and Ray pointed out that you had drift. That drift is an indication that your polar alignment is not correct, it shows RA drift. When you have RA drift, you cannot expect round stars regardless of mount PE.

I will spend the 30 mins or so to get some fresh PEMPro PE data as well to see if there is any difference.
Why bother, you already have less than 1 arc sec performance. What do you expect to achieve with yet another PEMPro run? Your tracking with PEM on is essentially perfect. If you do a simple analysis of the PEM on data that you posted, you will probably find that the periodic error is on the order of 1/2 arc second. You will not exceed that and can only get the same or worse.

Ray, can you do a quick analysis of that PEM-on run and post the resultant PE curve?

Roland Christen


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 3:17 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



The PEM ON test needs to be run still, next clear night I plan to do that.

When I took my PE data, the curves seem to line up well. Here is what they looked like:


Do those look egregious to you?

As far as Polar Alignment is concerned, I used the Polemaster tool and ran it through 3 complete cycles to confirm its suggested alignment. Ray suggested I check that alignment with PEMPro the next time I am out. I will spend the 30 mins or so to get some fresh PEMPro PE data as well to see if there is any difference.




From: ap-gto@... <ap-gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:34 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
What is the PEC curve with PEM turned ON? That is what you will be using during tracking.

When you took your PE data, you said that the individual curves did not lie on top of each other, rather they moved up with each new worm cycle. That should tell you immediately that your polar alignment is not good, and you have excessive RA drift. When your polar alignment is correct (Altitude axis properly aligned), you will basically have zero RA drift and each curve will lie on top of the next, or very close to it. Then with PEM turned on, you should be able to get no tracking error for several worm cycles when you are anywhere near the meridian.

When you have RA drift, or Dec drift for that matter, you will never have round stars even when the mount is tracking to 1 arc sec levels with PEM on. RA drift is independent of periodic error and has nothing to do with mount tracking at sidereal rate. A perfect mount with zero PE will have egg shaped stars if you have drift in either axis.

Roland Christen



-----Original Message-----
From: Bill Long bill@... [ap-gto] <ap-gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:16 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues







From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.













Bill Long
 

Well, where PEMPro wanted me to point, and stay in the green per the PEMPro Wizard was blocked by a tree, so I had to slew a bit further west to get clear skies. Perhaps that has something to do with the drift?




From: ap-gto@... on behalf of chris1011@... [ap-gto]
Sent: Saturday, February 24, 2018 2:35 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The curves you posted line up because PEMPro has lined them up for you when you clicked on the X and Y alignment tabs. You had mentioned in the PEMpro postings that they did not line up and Ray pointed out that you had drift. That drift is an indication that your polar alignment is not correct, it shows RA drift. When you have RA drift, you cannot expect round stars regardless of mount PE.


I will spend the 30 mins or so to get some fresh PEMPro PE data as well to see if there is any difference.
Why bother, you already have less than 1 arc sec performance. What do you expect to achieve with yet another PEMPro run? Your tracking with PEM on is essentially perfect. If you do a simple analysis of the PEM on data that you posted, you will probably find that the periodic error is on the order of 1/2 arc second. You will not exceed that and can only get the same or worse.

Ray, can you do a quick analysis of that PEM-on run and post the resultant PE curve?

Roland Christen


-----Original Message-----
From: Bill Long bill@... [ap-gto]
To: ap-gto
Sent: Sat, Feb 24, 2018 3:17 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



The PEM ON test needs to be run still, next clear night I plan to do that.

When I took my PE data, the curves seem to line up well. Here is what they looked like:


Do those look egregious to you?

As far as Polar Alignment is concerned, I used the Polemaster tool and ran it through 3 complete cycles to confirm its suggested alignment. Ray suggested I check that alignment with PEMPro the next time I am out. I will spend the 30 mins or so to get some fresh PEMPro PE data as well to see if there is any difference.




From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:34 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
What is the PEC curve with PEM turned ON? That is what you will be using during tracking.

When you took your PE data, you said that the individual curves did not lie on top of each other, rather they moved up with each new worm cycle. That should tell you immediately that your polar alignment is not good, and you have excessive RA drift. When your polar alignment is correct (Altitude axis properly aligned), you will basically have zero RA drift and each curve will lie on top of the next, or very close to it. Then with PEM turned on, you should be able to get no tracking error for several worm cycles when you are anywhere near the meridian.

When you have RA drift, or Dec drift for that matter, you will never have round stars even when the mount is tracking to 1 arc sec levels with PEM on. RA drift is independent of periodic error and has nothing to do with mount tracking at sidereal rate. A perfect mount with zero PE will have egg shaped stars if you have drift in either axis.

Roland Christen



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:16 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues







From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 12:07 PM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 
Maybe I'm missing something, but I see only the raw data, not the PEC curve. Can you point it out?

Rolando



-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 2:04 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



That is all located here:






From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 11:59 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.
You posted two raw PEMPro runs, but no analysis of the actual PE value. Your estimate of 9 to 10 arc sec P-P is not backed by actual analysis. Please post the actual PE as analyzed by PEMPro so that people who read these posts do not get the false impression that we ship mounts that are out of spec. The value that defines the mount's PE is created when you press the tab "Create a PEC Curve". You will see in the upper right the value of the mount's periodic error in +- arc seconds.

Roland Christen
Astro-Physics Inc.


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:52 pm
Subject: Re: [ap-gto] AP1100 Bad Stars Issues



I sent another mail correcting my original statement. I had some more coffee, then read it again. Ray had a look at the curve via the PEMPro forums and I think we are good to go on that front.

I will test this again, with PEMPro enabled and guiding running. I suspect that my results will be better. Thanks for the info about expectations for non-guided exposures. 


From: ap-gto@... gto@...> on behalf of chris1011@... [ap-gto] gto@...>
Sent: Saturday, February 24, 2018 10:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] AP1100 Bad Stars Issues
 
 

The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.
First of all, 9" P-P is only 28% larger than +- 3.5". The error of 9" P-P is equal to +- 4.5 ".

I believe you misunderstand what periodic error is and how it is measured and specified.
A screen capture of the PEMPro run would be helpful, along with the PEMPro analysis of Periodic error. Remember, when you are doing a PEMPro run on the sky, the raw data also contains errors caused by atmospheric seeing. These can easily add 3 arc sec or more to your raw data. PEMPro analysis removes these non-periodic errors caused by seeing, drift, etc and provides the true mount tracking performance.

I saw your images that you sent and they looked normal to me and George. The 15 sec images had perfectly round stars, consistent with typical winter seeing.

I would never expect unguided images to be round for a number of reasons, none of which are mount related. In other words, even if the mount tracked perfectly, I would not expect round star images in an unguided exposure of any normal length.

A better indication of performance is the RMS value of your guiding, using one of the popular guiding programs (MaximDL or PHD). You can use these programs to determine the base level of atmospheric seeing errors and the resultant guided performance in arc sec RMS. During guiding, when the RMS values of RA and Dec are close to equal, you will have round stars on your images.

Rolando


-----Original Message-----
From: Bill Long bill@... [ap-gto] gto@...>
To: ap-gto gto@...>
Sent: Sat, Feb 24, 2018 12:07 pm
Subject: [ap-gto] AP1100 Bad Stars Issues



Hello all,

I have contacted A-P about some recent imaging challenges I have had, and have provided details to George on this problem, but I wanted to get some thoughts from the folks here on this forum as well, in the event someone has experienced a similar problem.

Problem Statement:
Out of round stars in 15 and 30 second unguided exposures, on two different cameras. 
Out of round Stars in 60 second, 120 second, and 300 second guided exposures on one camera. 

Possible Red Herring or Evidence for Concern:
I have run PEMPro and the readings of periodic error are wildly inconsistent. I get up to 10" P-P of RA error. The last one I ran was close to 9" P-P.  This is almost 3 times the published specification of +/- 3.5" without any error correction.

Polar Alignment Method:
Polemaster, 3 complete cycles per alignment, repeatable results.

Gear:
Stellarvue 80mm Refractor w/ SV80 Field Flattener
Takahashi FSQ106ED Native w/ no reducer
Takahashi TOA130 w/ 0.7x Tak Reducer 
AP1100 GTO CP4 w/ Auto-Adjusting Gearbox
ASI 183MM Pro CMOS Camera
ASI 294MC Pro CMOS Camera

Software:
APCC Pro
ASCOM v2 AP Driver
Sequence Generator Pro

All cameras tested were properly spaced on each respective scope. I have performed testing with a wheel and OAG attached, as well as without any wheel or OAG attached, and spacers in place of them to ensure accurate chip placement. Using CCDWare CCD Inspector 2, both cameras are reported to be showing 20% tilt. As a test, I enabled guiding and set the RA settings very, very aggressively and while the problem did not completely cure itself, the roundness of the stars improved dramatically, and tilt was reported to be reduced to 2%.

The cameras could be involved in the problem, I am not ruling that out, but to have very similar results on two different cameras is suspicious, and if there is a way to rule out the one constant in all of this testing (the mount) I would like to do that.

The mount is not permanently mounted. I set up and tear down each night I image. The axis are separated and reassembled when the mount goes outside, and when it comes back inside each night.  In case this information is useful.

Thanks for reading.