Is my PA terrible? Am I way off?

[drivera]

Hey there,

I'm very new to this stuff, only fourth or so attempt and all this and during Summer to learn haha. 
I'm at a loss how to perfectly polar align....

Equipment: SkyGuider Pro

I use the PA Align app but when I look through the polar scope on the mount I'm sitting at a loss if I'm getting the exact right set of stars and then Polaris. My guidecam is on top of my Redcat, if I plate solve should I get the same region even if its just above? So that validates my PA?

Second - is this horrendous PA on my guiding? Any tips or help would be recommended! I am considering buying the iPolar cam too..but unsure.

Thanks 

Steve

[callisto]

Just a heads up...you cant use ipolar on iphone/android only via pc connection so when fitted your SGP is not as portable/grab go 

 

Mark

[symmetal]

As you're using a guidecam it would be much easier to use the polar alignment tool in Sharpcap Pro. You have to buy the full program to get the polar alignment option, but it's not expensive and is worth it for that tool alone even if you don't use its other features. 😀 I used to find using the polar scope awkward and time consuming and never got it to work accurately but using Sharpcap alignment only takes a minute or so with no hassle. As long as the guidescope is looking roughly towards the celestial pole when the scope is in the home position is all that is required.

A single plate solve pointing towards the NCP is not recommended for determining pointing accuracy as all RA coords are bunched very close together when near to the NCP. Sharpcap takes two platesolves with the scope turned roughly 90 degrees in RA between solves to determine where the actual NCP is and tells you to move an indicated star to a specific location on the screen to get accurate alignment.

Alan

Edited June 26, 2021 by symmetal

[Chefgage]

16 hours ago, symmetal said:

As you're using a guidecam it would be much easier to use the polar alignment tool in Sharpcap Pro. You have to buy the full program to get the polar alignment option, but it's not expensive and is worth it for that tool alone even if you don't use its other features. 😀 I used to find using the polar scope awkward and time consuming and never got it to work accurately but using Sharpcap alignment only takes a minute or so with no hassle. As long as the guidescope is looking roughly towards the celestial pole when the scope is in the home position is all that is required.

A single plate solve pointing towards the NCP is not recommended for determining pointing accuracy as all RA coords are bunched very close together when near to the NCP. Sharpcap takes two platesolves with the scope turned roughly 90 degrees in RA between solves to determine where the actual NCP is and tells you to move an indicated star to a specific location on the screen to get accurate alignment.

Alan

I would definitely agree with this. I would try and find a method that uses software to polar align effectively for you. An example I use is the asiair pro with does a similar thing as stated above. It first plate solves then moves the scope/camera 60 degrees in RA then plate solves again. This way it knows where Polaris is an also the error in direction between where the scope is pointing and where the mount is pointing. That way it then tells you how to adjust the mount so it is polar aligned. This is good as although the scope/camera is above the mount so you would think that the polar alignment would not be correct as the camera is not pointing through the mount, but the software takes care of this.

[michael8554]

A Polar Alignment error results in drift in Dec, which your graph doesn't display.

Your guide settings are struggling to correct +/- 3 arcsec swings in RA, so RMS is about 2arcsecs in that snippet of your guiding.

Michael

[drivera]

1 hour ago, michael8554 said:

A Polar Alignment error results in drift in Dec, which your graph doesn't display.

Your guide settings are struggling to correct +/- 3 arcsec swings in RA, so RMS is about 2arcsecs in that snippet of your guiding.

Michael

What would that mean for me if it's struggling to correct in RA? Is that a mount issue than a PA as such?

[drivera]

2 hours ago, Chefgage said:

I would definitely agree with this. I would try and find a method that uses software to polar align effectively for you. An example I use is the asiair pro with does a similar thing as stated above. It first plate solves then moves the scope/camera 60 degrees in RA then plate solves again. This way it knows where Polaris is an also the error in direction between where the scope is pointing and where the mount is pointing. That way it then tells you how to adjust the mount so it is polar aligned. This is good as although the scope/camera is above the mount so you would think that the polar alignment would not be correct as the camera is not pointing through the mount, but the software takes care of this.

 

18 hours ago, symmetal said:

As you're using a guidecam it would be much easier to use the polar alignment tool in Sharpcap Pro. You have to buy the full program to get the polar alignment option, but it's not expensive and is worth it for that tool alone even if you don't use its other features. 😀 I used to find using the polar scope awkward and time consuming and never got it to work accurately but using Sharpcap alignment only takes a minute or so with no hassle. As long as the guidescope is looking roughly towards the celestial pole when the scope is in the home position is all that is required.

A single plate solve pointing towards the NCP is not recommended for determining pointing accuracy as all RA coords are bunched very close together when near to the NCP. Sharpcap takes two platesolves with the scope turned roughly 90 degrees in RA between solves to determine where the actual NCP is and tells you to move an indicated star to a specific location on the screen to get accurate alignment.

Alan

 

18 hours ago, callisto said:

Just a heads up...you cant use ipolar on iphone/android only via pc connection so when fitted your SGP is not as portable/grab go 

 

Mark

Thanks so much for the feedback on this.
I don't have a PC but have a Raspberry PI with Astroberry. I couldn't get the polar alignment in Ekos to work - but I might try to use a Win emulator to run Sharpcap?

I have the standard mount for the SGP and I find it so bloody hard to use the alt/alz etc knobs to move it, plus bending down at 6'4' is tough hah.

Aaah so much to learn and test ha.

[Shimonu]

8 hours ago, drivera said:

 

 

Thanks so much for the feedback on this.
I don't have a PC but have a Raspberry PI with Astroberry. I couldn't get the polar alignment in Ekos to work - but I might try to use a Win emulator to run Sharpcap?

I have the standard mount for the SGP and I find it so bloody hard to use the alt/alz etc knobs to move it, plus bending down at 6'4' is tough hah.

Aaah so much to learn and test ha.

When I tried Ekos the first time I realized that it didn't have the platesolving files installed by default. You have to download them yourself depending on what telescope and camera you're using. Or what kind of trouble were you having?

[drivera]

On 27/06/2021 at 19:01, Shimonu said:

When I tried Ekos the first time I realized that it didn't have the platesolving files installed by default. You have to download them yourself depending on what telescope and camera you're using. Or what kind of trouble were you having?

It just sits for about 20mins saying its platesolving but nothing happens? I think I downloaded the index files correctly. I might need to watch some videos again.

 

I'm still unsure from Michaels comment "Your guide settings are struggling to correct +/- 3 arcsec swings in RA, so RMS is about 2arcsecs in that snippet of your guiding."

What would this mean? Could this mean my balancing is out affecting the swings in RA, or something else?

[StevieDvd]

Not sure if we have answered your orignal question about comparing the guide camera view to the polar alignment view. They will be different as the guide camera will have a larger field of view.  When the PA apps use this camera to calculate your PA position it takes a couple of pictures and platesolves them to work out of your axis (PA) is correct. The PA routines need your location, date and time to be set correctly.

 

[michael8554]

3 hours ago, drivera said:

I'm still unsure from Michaels comment "Your guide settings are struggling to correct +/- 3 arcsec swings in RA, so RMS is about 2arcsecs in that snippet of your guiding."

What would this mean? Could this mean my balancing is out affecting the swings in RA, or something else?

I thought that was self-explanatory, but here goes:

RA starts off with a 3arcsec lurch to the east.

Correction causes a 3+ arcsec overshoot to the west.

From then on guide error stays mostly to the west, resulting in an about 2 arcsec RMS result (red line).

That's about all that can be said, based on a short duration screen shot.

Your settings are preventing effective guiding.

What are those settings ?

Zero information provided.

What exposure ?

Most guide systems have a minimum Move and Aggression settings to be at all effective, what are your settings ?

Does your guide system provide a GuideLog that can be analysed ?

Michael

[soundwave]

@drivera

This might seem really silly, but it happened to me with my SkyGuider Pro until I realized my mistake:
Polaris should be placed on the inner dial of the polar scope (in the northern hemisphere). 

I use an app that shows Polaris' location on a single dial, and at first I assumed it was the outer one. 

 

Edited June 30, 2021 by soundwave