Topics

RA Drift


Jon
 

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


MLG
 

Jon,

What kind of telescope are you using? Is it possible the drift you are seeing is really a mechanical shift in the scope, eg, SCT mirror movement?

Regards,
Chip Gentry
Austin, TX, Earth

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@...> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


topboxman
 

Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said. Which is why we have software to create pointing model of the sky to take into account of everything including refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@...> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


John Kasianowicz
 

Jon,

What kind of telescope where you using, and what is its focal length? Is the mount on a permanent pier or a tripod? Are you accounting for any residual peridoc error?

Where the two stars near the celestial equator (one just E or W of the meridian and the other near the horizon but on the same side of the meridian)?

I recently used the drift alignment method to tweak the polar alignment of a friend's AP1200GTO that supports a 5000 mm focal length Mak-Cass. It was spot for 5 minute intervals after accounting for the small periodic error).


Clear Skies,
John

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@...> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


phototwist
 

A star diameter is pretty small if properly focused with good optics.  Are you sure that PEM is enabled?  As I recall, it defaults to off even though it comes pre-programmed.

If you saw this movement on only 1 star it is possible (albeit unlikely) that the "star" is actually an asteroid.  Not likely, but easy to check.

Greg




________________________________
From: rickysguy <jmartin590@centurylink.net>
To: ap-gto@yahoogroups.com
Sent: Saturday, July 27, 2013 3:38 PM
Subject: [ap-gto] RA Drift



 
Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon




[Non-text portions of this message have been removed]


Ray Gralak <groups2@...>
 

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "rickysguy" <jmartin590@...> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial
input on the CP3?

Thanks for any answers.

Jon



Donghun
 

I have similar experience as Jon seeing drift in RA when unguided.
Can APCC correct this?

Thank you.
Donghun

--- In ap-gto@yahoogroups.com, "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial
input on the CP3?

Thanks for any answers.

Jon



Suresh Mohan
 

Which version of APCC has modeling software plz ?
Thanks
Suresh
On Jul 28, 2013, at 9:05 PM, "Dong Hun" <malonee72@hotmail.com> wrote:

I have similar experience as Jon seeing drift in RA when unguided.
Can APCC correct this?

Thank you.
Donghun

--- In ap-gto@yahoogroups.com, "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial
input on the CP3?

Thanks for any answers.

Jon



[Non-text portions of this message have been removed]


Jon
 

No mirror shift. I use a refractor.

--- In ap-gto@yahoogroups.com, "MLG" <cgentry@...> wrote:

Jon,

What kind of telescope are you using? Is it possible the drift you are seeing is really a mechanical shift in the scope, eg, SCT mirror movement?

Regards,
Chip Gentry
Austin, TX, Earth

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


Jon
 

Peter. I do my drift alignment on a star that is very near the Meridian and Celestial Equator for azimuth and another about 20 degrees above the eastern horizon on the celestial equator as most instructions dictate for drift alignment.

--- In ap-gto@yahoogroups.com, "topboxman2000" <pnagy@...> wrote:



Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said. Which is why we have software to create pointing model of the sky to take into account of everything including refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


Jon
 

Thanks for the explanation Ray. But, if the stars "apparent motion" is slower than sidereal, would that not show up as star movement in an EASTERLY direction while drift aligning as the star fall behind the mounts tracking rate? What I saw was star movement in a WESTERLY direction.

--- In ap-gto@yahoogroups.com, "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything including
refraction in the sky. I don't think you can successfully take unguided long exposure images without pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial
input on the CP3?

Thanks for any answers.

Jon



Jon
 

Hi John,

I am currently using a 106mm refractor on my Mach1 mounted on a 10" concrete pier in a domed observatory. I am running with pre-loaded PEC on.

Jon

--- In ap-gto@yahoogroups.com, jjkastro@... wrote:

Jon,

What kind of telescope where you using, and what is its focal length? Is the mount on a permanent pier or a tripod? Are you accounting for any residual peridoc error?

Where the two stars near the celestial equator (one just E or W of the meridian and the other near the horizon but on the same side of the meridian)?

I recently used the drift alignment method to tweak the polar alignment of a friend's AP1200GTO that supports a 5000 mm focal length Mak-Cass. It was spot for 5 minute intervals after accounting for the small periodic error).


Clear Skies,
John


--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


Ray Gralak <groups2@...>
 

Which version of APCC has modeling software plz ?
APCC Pro

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of Suresh Mohan
Sent: Sunday, July 28, 2013 9:38 AM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Re: RA Drift



Which version of APCC has modeling software plz ?
Thanks
Suresh

Sent from my iPhone

On Jul 28, 2013, at 9:05 PM, "Dong Hun" <malonee72@hotmail.com <mailto:malonee72%40hotmail.com> >
wrote:

I have similar experience as Jon seeing drift in RA when unguided.
Can APCC correct this?

Thank you.
Donghun

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just
said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar
alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate
virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> [mailto:ap-
gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> ] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com>
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the
Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will
likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just
said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> <mailto:ap-
gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my
CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of
the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize"
tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking
rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am
using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a
way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second
serial
input on the CP3?

Thanks for any answers.

Jon


[Non-text portions of this message have been removed]




Ray Gralak <groups2@...>
 

I have similar experience as Jon seeing drift in RA when unguided.
Can APCC correct this?
Yes, APCC Pro can do this.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of Dong Hun
Sent: Sunday, July 28, 2013 8:35 AM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift



I have similar experience as Jon seeing drift in RA when unguided.
Can APCC correct this?

Thank you.
Donghun

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar
alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate
virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> [mailto:ap-gto@yahoogroups.com
<mailto:ap-gto%40yahoogroups.com> ] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com>
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian.
So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will
likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> <mailto:ap-
gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my
CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am
using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a
way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second
serial
input on the CP3?

Thanks for any answers.

Jon





Ray Gralak <groups2@...>
 

Thanks for the explanation Ray. But, if the stars "apparent motion" is slower than sidereal, would that not show
up as star movement in an EASTERLY direction while drift aligning as the star fall behind the mounts tracking
rate? What I saw was star movement in a WESTERLY direction.
Refraction is just one thing that affects the tracking rate. OTA flexure occurs even in refractors. Mis-Polar alignment,
however slight, can affect tracking rate over a duration of minutes.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of rickysguy
Sent: Sunday, July 28, 2013 11:07 AM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift




Thanks for the explanation Ray. But, if the stars "apparent motion" is slower than sidereal, would that not show
up as star movement in an EASTERLY direction while drift aligning as the star fall behind the mounts tracking
rate? What I saw was star movement in a WESTERLY direction.

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> , "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near the Meridian.
Correct! The *apparent* movement rate of stars is slower than sidereal because of refraction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where telescope flexure, mis-polar
alignment, and
refraction happen to balance themselves out, but this is usually rare. Modeling software can eliminate
virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> [mailto:ap-gto@yahoogroups.com
<mailto:ap-gto%40yahoogroups.com> ] On Behalf Of topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com>
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate if they are not near the Meridian.
So
if you center the star 2 or 3 hours away from the Meridian and came back in 30 minutes and the star will
likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then that might explain what I just said.
Which is why we have software to create pointing model of the sky to take into account of everything
including
refraction in the sky. I don't think you can successfully take unguided long exposure images without
pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> <mailto:ap-
gto%40yahoogroups.com> , "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my
CCD
camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am
using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a
way
to use both programs at the same time or, do I have to connect another serial/usb adapter to the second
serial
input on the CP3?

Thanks for any answers.

Jon





Jon
 

I saw movement in both stars on two different occasions and I was looking at stars not asteroids, comets, or alien vessels.

--- In ap-gto@yahoogroups.com, Greg Marshall <phototwist@...> wrote:

A star diameter is pretty small if properly focused with good optics.  Are you sure that PEM is enabled?  As I recall, it defaults to off even though it comes pre-programmed.

If you saw this movement on only 1 star it is possible (albeit unlikely) that the "star" is actually an asteroid.  Not likely, but easy to check.

Greg




________________________________
From: rickysguy <jmartin590@...>
To: ap-gto@yahoogroups.com
Sent: Saturday, July 27, 2013 3:38 PM
Subject: [ap-gto] RA Drift



 
Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon




[Non-text portions of this message have been removed]


Alan Pryor
 

Are you absolutely sure it was not alien vessels?

Just kidding. I have a Mach1 as well. For the most part it has given excellent service, but I did have a period where I experienced some shifts. I placed a call to AP and the conversation gave me a number things to check. One action was to check every bolt and cap screw for tightness. I found 2 cap screws on the dovetail plate that were not tight enough. I had installed them 2 years earlier, they worked loose. They were not real loose, just not to a tight torque. That solved my problem. However, it was the conversation with AP that got me in the right direction.

Oh, if you want to see some aliens then visit Atlanta around Labor Day. That Saturday the Dragon-Con parade takes place, and it is a fun event. Usually there is a solar telescope display at one of the hotels too.

Good luck with your shift issue.

Alan

On Jul 28, 2013, at 2:17 PM, "rickysguy" <jmartin590@centurylink.net> wrote:

I saw movement in both stars on two different occasions and I was looking at stars not asteroids, comets, or alien vessels.

--- In ap-gto@yahoogroups.com, Greg Marshall <phototwist@...> wrote:

A star diameter is pretty small if properly focused with good optics. Are you sure that PEM is enabled? As I recall, it defaults to off even though it comes pre-programmed.

If you saw this movement on only 1 star it is possible (albeit unlikely) that the "star" is actually an asteroid. Not likely, but easy to check.

Greg




________________________________
From: rickysguy <jmartin590@...>
To: ap-gto@yahoogroups.com
Sent: Saturday, July 27, 2013 3:38 PM
Subject: [ap-gto] RA Drift




Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon




[Non-text portions of this message have been removed]



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

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John Kasianowicz
 

If you track the drift and plot it (e.g., using a CCD camera, a camera control program and PEMPro, or a FireWire camera and ASTROIIDC on a Mac), you can see if it's systematic.

--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@...> wrote:

Hi John,

I am currently using a 106mm refractor on my Mach1 mounted on a 10" concrete pier in a domed observatory. I am running with pre-loaded PEC on.

Jon

--- In ap-gto@yahoogroups.com, jjkastro@ wrote:

Jon,

What kind of telescope where you using, and what is its focal length? Is the mount on a permanent pier or a tripod? Are you accounting for any residual peridoc error?

Where the two stars near the celestial equator (one just E or W of the meridian and the other near the horizon but on the same side of the meridian)?

I recently used the drift alignment method to tweak the polar alignment of a friend's AP1200GTO that supports a 5000 mm focal length Mak-Cass. It was spot for 5 minute intervals after accounting for the small periodic error).


Clear Skies,
John


--- In ap-gto@yahoogroups.com, "rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south movement after 5 min using my CCD camera and a cross-hair overlay on the two stars I used. However, I did notice a tad (one star diameter) movement in a westerly direction. I thought that this might be due to my mount tracking a bit slow. I guess guiding would correct this, if it is due to slow tracking but, I had hoped to get 5 minutes unguided out of the mount. Is this expectation unreasonable? I see that there is an input in the AP driver to "customize" tracking like for comets but, I don't know if I should use this option or, if I did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to the mount but, since I am using the AP driver to connect through Stellarium Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both programs at the same time or, do I have to connect another serial/usb adapter to the second serial input on the CP3?

Thanks for any answers.

Jon


Roland Christen
 

As the star moves west it slowly picks up speed until it moves at the sidereal rate exactly straight overhead. The speed function is complex. There are actually places where the star moves faster than sidereal as you go further north past the zenith.

Rolando

-----Original Message-----
From: rickysguy <jmartin590@centurylink.net>
To: ap-gto <ap-gto@yahoogroups.com>
Sent: Sun, Jul 28, 2013 1:07 pm
Subject: [ap-gto] Re: RA Drift



Thanks for the explanation Ray. But, if the stars "apparent motion" is slower
than sidereal, would that not show up as star movement in an EASTERLY direction
while drift aligning as the star fall behind the mounts tracking rate? What I
saw was star movement in a WESTERLY direction.



--- In ap-gto@yahoogroups.com, "Ray Gralak" <groups2@...> wrote:

I believe stars do not move exactly at Sidereal rate if they are not near
the Meridian.

Correct! The *apparent* movement rate of stars is slower than sidereal because
of refraction.

If you were looking at the star at certain distance from the Meridian, then
that might explain what I just said.
Which is why we have software to create pointing model of the sky to take
into account of everything including
refraction in the sky. I don't think you can successfully take unguided long
exposure images without pointing
model even with perfect polar alignment.
This is mostly true. One may get lucky in certain parts of the sky where
telescope flexure, mis-polar alignment, and
refraction happen to balance themselves out, but this is usually rare.
Modeling software can eliminate virtually all of
the tracking error.

-Ray Gralak
Author of Astro-Physics Command Center (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@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On Behalf Of
topboxman2000
Sent: Saturday, July 27, 2013 7:03 PM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: RA Drift





Correct me if I'm wrong. I believe stars do not move exactly at Sideral rate
if they are not near the Meridian. So
if you center the star 2 or 3 hours away from the Meridian and came back in
30 minutes and the star will likely
move (very slightly) from original location in RA axis direction.

If you were looking at the star at certain distance from the Meridian, then
that might explain what I just said.
Which is why we have software to create pointing model of the sky to take
into account of everything including
refraction in the sky. I don't think you can successfully take unguided long
exposure images without pointing
model even with perfect polar alignment.

Peter

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> ,
"rickysguy" <jmartin590@> wrote:

Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south
movement after 5 min using my CCD
camera and a cross-hair overlay on the two stars I used. However, I did
notice a tad (one star diameter)
movement in a westerly direction. I thought that this might be due to my
mount tracking a bit slow. I guess
guiding would correct this, if it is due to slow tracking but, I had hoped
to get 5 minutes unguided out of the
mount. Is this expectation unreasonable? I see that there is an input in the
AP driver to "customize" tracking
like for comets but, I don't know if I should use this option or, if I did,
how much to increase the tracking rate
from sidereal.

Another question has to do with PulseGuide program. I tried to connect it
to the mount but, since I am using
the AP driver to connect through Stellarium Scope and Stellarium, Pulse
Guide will not connect. Is there a way
to use both programs at the same time or, do I have to connect another
serial/usb adapter to the second serial
input on the CP3?

Thanks for any answers.

Jon





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

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


Roland Christen
 

Drift alignment can and does eliminate Dec drift, but doing so introduces slight RA drift. There is a compromize alignment that offsets the pole slightly which reduces RA drift and results in slight Dec drift, both of which a quite a bit less than the RA drift you get with traditional drift alignment.

Right now we are working to impliment a variable rate in the mount servo. This will theoretically allow the RA rate to adjust as needed to counteract atmospheric refraction. I am in the process of testing this function. It should allow for long unguided exposures with scopes of 1000mm or less. Realistically it cannot perfectly account for refraction because this is a variable that changes with atmospheric pressure and temperature. So, to eliminate RA drift totally to a very high degree requires modeling. Especially if you have a very long focal length. And even then you will probably find that non-linear effects like mirror shift and flex will still require that you guide.

Rolando

-----Original Message-----
From: rickysguy <jmartin590@centurylink.net>
To: ap-gto <ap-gto@yahoogroups.com>
Sent: Sun, Jul 28, 2013 1:17 pm
Subject: [ap-gto] Re: RA Drift


I saw movement in both stars on two different occasions and I was looking at
stars not asteroids, comets, or alien vessels.

--- In ap-gto@yahoogroups.com, Greg Marshall <phototwist@...> wrote:

A star diameter is pretty small if properly focused with good optics. Are
you sure that PEM is enabled? As I recall, it defaults to off even though it
comes pre-programmed.

If you saw this movement on only 1 star it is possible (albeit unlikely) that
the "star" is actually an asteroid. Not likely, but easy to check.

Greg




________________________________
From: rickysguy <jmartin590@...>
To: ap-gto@yahoogroups.com
Sent: Saturday, July 27, 2013 3:38 PM
Subject: [ap-gto] RA Drift



Â
Hi all,

Getting my new Mach1 set up, I drift aligned until I got no north south
movement after 5 min using my CCD camera and a cross-hair overlay on the two
stars I used. However, I did notice a tad (one star diameter) movement in a
westerly direction. I thought that this might be due to my mount tracking a bit
slow. I guess guiding would correct this, if it is due to slow tracking but, I
had hoped to get 5 minutes unguided out of the mount. Is this expectation
unreasonable? I see that there is an input in the AP driver to "customize"
tracking like for comets but, I don't know if I should use this option or, if I
did, how much to increase the tracking rate from sidereal.

Another question has to do with PulseGuide program. I tried to connect it to
the mount but, since I am using the AP driver to connect through Stellarium
Scope and Stellarium, Pulse Guide will not connect. Is there a way to use both
programs at the same time or, do I have to connect another serial/usb adapter to
the second serial input on the CP3?

Thanks for any answers.

Jon




[Non-text portions of this message have been removed]



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

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







[Non-text portions of this message have been removed]