pointing accuracy


Colt Bednorz <colt@...>
 

What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


Ray Gralak <ray@...>
 

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@egroups.com
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Colt Bednorz <colt@...>
 

Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@egroups.com
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Ray Gralak <ray@...>
 

Hi Colt,

Yes, from one part of the sky to the opposite side I have
seen better than 2-arc-minutes accuracy. To get this kind
of accuracy you need to make sure your OTA is orthogonal
and that none of the optical elements shift in movement
(e.g. many SCT's primary mirrors will shift when you move
to another part of the sky). That is why I said I get this
accuracy with my refractor.

Take care,

-Ray

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 8:44 AM
To: ap-gto@egroups.com
Subject: Re: [ap-gto] pointing accuracy


Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@egroups.com
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Ron Wodaski <ronw@...>
 

I think that pointing accuracy on any of the AP goto mounts is excellent,
and mostly depends on how well aligned you are to the celestial pole. On
nights when I have taken the time for really good polar alignment, objects
routinely show up in just about exactly the same spot on the CCD chip. On
those nights, it wouldn't matter what camera I was using; objects would be
on the chip. <g>

To get really high pointing accuracy, you must also make sure that your
scope is well aligned to the mount's RA axis, of course.

Ron Wodaski

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 8:44 AM
To: ap-gto@egroups.com
Subject: Re: [ap-gto] pointing accuracy


Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@airmail.net]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@egroups.com
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Louis A. Mamakos <louie@...>
 

Hi Colt,

Yes, from one part of the sky to the opposite side I have
seen better than 2-arc-minutes accuracy. To get this kind
of accuracy you need to make sure your OTA is orthogonal
and that none of the optical elements shift in movement
(e.g. many SCT's primary mirrors will shift when you move
to another part of the sky). That is why I said I get this
accuracy with my refractor.
Ah, so this makes sense. Based on my experience with some digital
setting circles on my G-11 mount (on the waiting list for a 900GTO, sigh),
polar alignment doesn't seem significant. That's of course doing a
two star alignment.

Orthoganality does seem very important during alignment (e.g., the
SET DEC=0 step) can be difficult on the G-11 given the lack of a fixed
declination axis setting circle.

louie