#### Re: Unguided imaging and atmospheric refraction

Ray Gralak

Hi Allen,

What is the non refracted pole?
Using refraction correction while polar aligning?
Yes. Both PEMPro and APPM (in APCC Pro) will calculate polar alignment to the refracted pole.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Allen Ruckle
Sent: Wednesday, October 14, 2020 8:04 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Unguided imaging and atmospheric refraction

Ray,
What is the non refracted pole?

Using refraction correction while polar aligning?

aruckle
On Sep 20, 2020, at 12:43 PM, Ray Gralak <groups3@...> wrote:

Clearly this is a complicated issue with no “perfect” answer.
There will always be a variable tracking rate depending on sky position, so the best solution is polar aligning to the
non-refracted pole.

This works for both unguided and guided setups, as it minimizes field rotation over a long period during which
images are collected.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center): https://www.astro-physics.com/apcc-pro
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of davidcfinch9 via groups.io
Sent: Sunday, September 20, 2020 12:04 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Unguided imaging and atmospheric refraction

Clearly this is a complicated issue with no “perfect” answer. The difference in refraction rates with varying
atmospheric conditions adds another level of complexity to this discussion. Without fear of “polishing cannonballs,”
I
don’t think you can go far wrong by polar aligning using your best method and then by spending the time to develop
accurate modeling for your system. You will still be subject to the whims of our atmosphere. The proof will always
be