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Trouble auto-connect ASCON driver following mount intialization

John Stiner
 

I have an AP1100 GTO AE-L. I connect my laptop to the CP4 via an Icron Ranger for USB over a Cat 5e/6/7 cable (not sure if that matters).   I was out of commission for 9 months awaiting camera repairs and, in the meantime, acquired a new imaging laptop with Windows 11, so I'm fairly certain this is user error due to forgetting what little I knew before.  I'm using APCC Pro v1.9.4.3 and v.5.50.03 of the ASCOM driver.  In any event, I'm trying to get everything back up and running. I initially encountered the trouble with virtual ports and so took the actions described in the post below.  I set the virtual ports to "None" in APCC's Virtual Ports tab and in the ASCOM Driver settings, I checked the "IP Address" box which showed the "APCC REST API" box, which I also checked.

New versions of APCC Standard, Pro, and AP V2 ASCOM Driver to use as an Eltima alternative (groups.io)

After powering up the amount and opening APCC, APCC now auto-initializes and, following initialization, I can click the "Connect" button for the AP V2 Driver and it connects fine.  However, despite having "Auto-Connect" box checked for the AP V2 Driver (as well as for the Mount), for whatever reason the driver never auto-connects or attempts to do so.  Rather, I have to click on the "Connect" button.  I realize there are worse problems than having to click a button but still wonder why the driver does not auto-connect.


Re: Field Rotation

Ray Gralak
 

What do you think I am seeing when the position of my images is shifting over an extended period ? Friday night I
was taking images of M51 over a period of about 5 hours. I took the first image at about 10:30 pm when it was .just
on the west side of the meridian. The last image was at 3:30 am. I plate solved the first and last images and
measured the difference in the coordinates at the center of the two images.

The RA had shifted 7.91" and the Dec had shifted 25.5"
Mike, were you autoguiding or not? Also, were you using an APCC model or not? If you were using a model, were you using Dec Arc tracking rate correction?

-Ray


Re: Field Rotation

Howard Ritter
 

That doesn’t seem quite plausible to me. Atmospheric refraction causes a difference of about 55 arcsec in apparent elevation of an object when it’s at an elevation of 45º compared to when it’s at the zenith.

I don’t know what your latitude is, but at mine in Ohio, M51 is very close to just these positions at 2230 and 0330 currently. It looks like, at a latitude of 45º, the elevation vector is almost parallel to RA at the location of M51 during this interval. This means that the better part of that 55” would be projected onto the RA coordinate. And then, because of the fact that the lines of RA, like those of longitude, converge as they approach the pole, a line segment (say) 40" in length cutting across the lines of RA nearly perpendicularly would extend across more than 40” of RA – I believe it would be 40”/cos(Dec). The Dec of M51 is close to 45º, whose cos is ~0.7, so maybe a shift in RA of 60” or so, not the 8" or so that you saw. The effect on Dec would be first to increase it, then to decrease it, as the orientation of M51’s elevation vector relative to celestial coordinates changes, probably with little net effect, whereas you saw a shift of 25".

That said, I’m not an expert, of which there must be some in this group. It would be interesting to hear from them.

—howard

On May 29, 2022, at 9:06 AM, M Hambrick <mhambrick563@...> wrote:

Thanks for the comments Roland and Howard.

What do you think I am seeing when the position of my images is shifting over an extended period ? Friday night I was taking images of M51 over a period of about 5 hours. I took the first image at about 10:30 pm when it was .just on the west side of the meridian. The last image was at 3:30 am. I plate solved the first and last images and measured the difference in the coordinates at the center of the two images.

The RA had shifted 7.91" and the Dec had shifted 25.5"

Can this be explained by atmospheric refraction ?

Mike


Re: Field Rotation

ap@CaptivePhotons.com
 

On Sun, May 29, 2022 at 10:18 AM, christian viladrich wrote:
Years ago, when professionals used large Schmidt telescopes with large photographic glass plates, they change the polar elevation of the mount according the photographic field in order to minimize field rotation.
TSX with tPoint gives you a choice of places to point for polar alignment based on what kind of drift/rotation you want to minimize.  Below is the last polar alignment I ran with it.  The little table gave different adjustments (in arc seconds) to make for different purposes.

My answer is guiding.  :) 

Linwood



Re: Field Rotation

christian viladrich
 

Hello,

Years ago, when professionals used large Schmidt telescopes with large photographic glass plates, they change the polar elevation of the mount according the photographic field in order to minimize field rotation.

I think I have the calculation somewhere in a book. But not sure this is relevant now, even for 24x36 mm CCD sensor and 30 min integration time😉

Christian Viladrich


Le 28/05/2022 à 16:57, M Hambrick a écrit :

Am I correct in my thinking that field rotation is inevitable even on a perfectly polar aligned mount ? I seem to recall reading that somewhere on this forum.

Regardless, are there techniques besides good polar alignment that will minimize the amount of field rotation that occurs during a long series of guided exposures ? A couple possible things come to mind: 

  • Guide star selection (farther away from the axis of rotation)
  • Multiple star guiding
  • Having a mount with absolute encoders.
Mike


Re: APCC Pro model details #APCC

Ray Gralak
 

Hi Brent,

I have a few questions so that I may better understand your points.

* Of course the polar axis values to refine polar alignment
APCC already provides these values, so I assume you meant the conversion of the polar axis values to knob turns for the specific mount? Many other polar alignment alternatives provide faster polar alignment, so what advantage do you see in having APCC do this?

* Cone error if trying to reduce that.
Why is this important if modeling accounts for this? Do you just want a tool to measure this?

* Flexure - for troubleshooting excess flexure
I don't think there are enough samples to make a good determination of "excess flexure." There are many types of telescopes. The OTA's material, construction, diameter, and length all matter. Also affecting flexure are things like the OTA balance point, length of the OTA, the mounting plate strength, the weight of cameras, etc. There are many variables so trying to come up with a value for excess flexure for all of the variables would be difficult.

The model compensates for those items but reducing them, relying less on the model compensation seems better.
It may seem better, but these are not where you will see much gain. A more meaningful area to look into is the amount of randomness in the system. Any of the pointing terms can have a low average value but higher variance. APPM provides a way to look into this with the "5x Verify" option. APPM will run the same set of data points five times. Then, A-P staff (or I) can analyze the APPM logs for variances.

-Ray


Re: Field Rotation

M Hambrick
 

Thanks for the comments Roland and Howard.

What do you think I am seeing when the position of my images is shifting over an extended period ? Friday night I was taking images of M51 over a period of about 5 hours. I took the first image at about 10:30 pm when it was .just on the west side of the meridian. The last image was at 3:30 am. I plate solved the first and last images and measured the difference in the coordinates at the center of the two images.

The RA had shifted 7.91" and the Dec had shifted 25.5"

Can this be explained by atmospheric refraction ?

Mike


Re: APCC Pro model details #APCC

Brent Boshart
 

Some measures presented to the user would be useful:
  • Of course the polar axis values to refine polar alignment
  • Cone error if trying to reduce that.
  • Flexure - for troubleshooting excess flexure
The model compensates for those items but reducing them, relying less on the model compensation seems better.


Re: Field Rotation

Howard Ritter
 

Field rotation occurs whenever, and only when, motion occurs around two axes during tracking. Ideally, this wouldn’t happen with an equatorial mount except when the polar axis is imperfectly aligned. In practice, it can happen when atmospheric refraction moves the object higher or lower as its elevation changes and a correction in Dec is needed, but I think this is important only for long exposures at low elevations.

Field rotation due to an imperfectly aligned polar axis necessitating corrections in Dec is a consequence of spherical trigonometry and is not affected by what star in the field is chosen; only the axis of rotation depends on that, since the rotation will be centered on the guide star, or on the average position of the stars used in multiple-star guiding.

Absolute encoders don’t affect it. They only tell the control computer exactly where the telescope is pointed, factoring out things like slop and backlash in the mount between the motor shafts and the axis shafts.

—howard

On May 28, 2022, at 12:57 PM, M Hambrick <mhambrick563@...> wrote:

Am I correct in my thinking that field rotation is inevitable even on a perfectly polar aligned mount ? I seem to recall reading that somewhere on this forum.

Regardless, are there techniques besides good polar alignment that will minimize the amount of field rotation that occurs during a long series of guided exposures ? A couple possible things come to mind: 

  • Guide star selection (farther away from the axis of rotation)
  • Multiple star guiding
  • Having a mount with absolute encoders.
Mike


Re: Field Rotation

Roland Christen
 

Guiding of any kind does not affect field rotation. If you are actually experiencing field rotation, the only way to counter it is rotation of the camera in the opposite direction. This is typically done with Alt-Az mounts where field rotation is 100%.
In an equatorial mount field rotation is normally encountered only when using very short focal length, very wide field imaging equipment. It's not going to be a factor in normal astro-photography.

Rolando

-----Original Message-----
From: M Hambrick <mhambrick563@...>
To: main@ap-gto.groups.io
Sent: Sat, May 28, 2022 11:57 am
Subject: [ap-gto] Field Rotation

Am I correct in my thinking that field rotation is inevitable even on a perfectly polar aligned mount ? I seem to recall reading that somewhere on this forum.

Regardless, are there techniques besides good polar alignment that will minimize the amount of field rotation that occurs during a long series of guided exposures ? A couple possible things come to mind: 

  • Guide star selection (farther away from the axis of rotation)
  • Multiple star guiding
  • Having a mount with absolute encoders.
Mike

--
Roland Christen
Astro-Physics


Field Rotation

M Hambrick
 

Am I correct in my thinking that field rotation is inevitable even on a perfectly polar aligned mount ? I seem to recall reading that somewhere on this forum.

Regardless, are there techniques besides good polar alignment that will minimize the amount of field rotation that occurs during a long series of guided exposures ? A couple possible things come to mind: 

  • Guide star selection (farther away from the axis of rotation)
  • Multiple star guiding
  • Having a mount with absolute encoders.
Mike


Re: APCC Pro model details #APCC

Ray Gralak
 

Hi Eric,

I've used the polar alignment "knob" table while polar aligning, and it helped. It would have been even nicer to
have APPM tell the user which knob to turn and by how many ticks, rather than forcing the user to look up that
information in the table. That's what T-Point does.
TPoint was designed decades ago when there were not many polar alignment tools available. There are many quicker ways to do polar alignment, including using PEMPro, which is included with most A-P mounts.

Interesting that there aren't "specific good or bad values". In that case, I'm curious why the data is even shown to
the user, since the user isn't expected to do anything with the data (except the polar alignment data since those
can have an impact on field rotation)? And it seems like the data only brings up questions and confuses people.
Agreed, and it is why the pointing terms will be removed from the Pointing Model tab in the next point build. The initial reason for the terms was for checking consistency of pointing terms between runs of pointing models, but these values do not need to be presented to users.

-Ray


Re: APCC Pro model details #APCC

Eric Claeys
 

Ray,

I've used the polar alignment "knob" table while polar aligning, and it helped.  It would have been even nicer to have APPM tell the user which knob to turn and by how many ticks, rather than forcing the user to look up that information in the table.  That's what T-Point does.

Interesting that there aren't "specific good or bad values".  In that case, I'm curious why the data is even shown to the user, since the user isn't expected to do anything with the data (except the polar alignment data since those can have an impact on field rotation)?  And it seems like the data only brings up questions and confuses people.


Re: APCC Pro model details #APCC

Ray Gralak
 

Hi Eric,

It would be really nice if the documentation stated what "good" and "bad" values were based on your mount and
scope, and more importantly, what, if anything should be done to improve the numbers.
A simple example: running a T-Point model tells you your polar alignment error and says things like "Turn the
right knob 3 ticks" or "your error is good enough". However, for the other numbers it's no better than APPM in that
it also leaves you guessing regarding what, if anything should be done.
There aren't specific good or bad values. The model adjusts pointing and tracking to correct the polar alignment and other errors. What you should is more important is model repeatability, which can be improved by reducing random movements that your telescope and other equipment may introduce. There are so many different telescope and camera types out there that it would be difficult to provide more specific information than that.

BTW, adjusting polar alignment will not necessarily improve pointing or tracking. It will, however, reduce field rotation, but that mostly matters when alignment is far off. The amount each knob adjusts polar alignment can be found in APCC's help file:

https://www.apastrosoftware.com/help/apcc-pro/advanced_pointing_model.htm

-Ray


Re: Unable to update firmware of CP4

sroberts84
 

Hello Mike,
Can you share the production timeframe involved?
Or, better yet - is there a check one can make to determine if a CP4 unit has the version of silicon? 

Thanks., 


Re: Unable to update firmware of CP4

Alex
 

Ok, Mike remoted in via TeamViewer and updated the firmware.  Excellent support from AP as usual.  I should be able to update myself in the future.

Alex


Re: APCC Pro model details #APCC

Eric Claeys
 

It would be really nice if the documentation stated what "good" and "bad" values were based on your mount and scope, and more importantly,  what, if anything should be done to improve the numbers.
A simple example: running a T-Point model tells you your polar alignment error and says things like "Turn the right knob 3 ticks" or "your error is good enough".  However, for the other numbers it's no better than APPM in that it also leaves you guessing regarding what, if anything should be done. 


Re: Unable to update firmware of CP4

Konstantin v. Poschinger
 

Thanks Mike,

Konstantin 

Von meinem iPhone gesendet

Am 27.05.2022 um 18:36 schrieb Mike Hanson <mikeh@...>:

Hi Konstantin,

The symptoms have nothing to do with P02-08.  They are related to differences in silicon.

We received a different version of silicon than we specified a while back.  Unfortunately, by the time we discovered this, a few units had snuck out the door.  P02-08 is what we happened to be shipping at the time.  All versions subsequent to P02-08 accommodate multiple versions of silicon.  The silicon differences only affect field updates of firmware, which is why they test fine in the factory and in the observatory.

Regards,
Mike


Re: Unable to update firmware of CP4

Mike Hanson
 

Hi Konstantin,

The symptoms have nothing to do with P02-08.  They are related to differences in silicon.

We received a different version of silicon than we specified a while back.  Unfortunately, by the time we discovered this, a few units had snuck out the door.  P02-08 is what we happened to be shipping at the time.  All versions subsequent to P02-08 accommodate multiple versions of silicon.  The silicon differences only affect field updates of firmware, which is why they test fine in the factory and in the observatory.

Regards,
Mike


Re: Unable to update firmware of CP4

Konstantin v. Poschinger
 

Hi Mike,

can you please explain what is new in this Version. 

Konstantin 

Von meinem iPhone gesendet

Am 27.05.2022 um 14:53 schrieb Mike Hanson <mikeh@...>:

Hi Alex,

We'll contact you privately.

Anyone else with symptoms identical to Alex's, please contact us directly.  It requires a little TLC to get past P02-08 in a very small subset of control boxes.

Regards,
Mike Hanson

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