Date   

Re: RA Drift

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]


Re: RA Drift

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





Re: RA Drift

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





Re: RA Drift

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]




Re: RA Drift

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


Re: RA Drift

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



Re: RA Drift

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


Re: RA Drift

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


Latitude scale on Mach1GTO misaligned

Eric
 

Hi Everyone,

I recently purchased a 2010 Mach1GTO mount and took it out for the first time this weekend. Polar alignment and tracking were absolutely beautiful with one minor issue. The latitude scale on the mount was misaligned. I'm at 33 degrees north latitude but had to adjust the altitude up to where the scale showed around 50 degrees to get polar aligned.

It looks like the base plate with the latitude alignment marker was installed 180 degrees reversed. Here's a picture: http://i.imgur.com/BN2IlQZ.jpg

The masking tape shows where the marker should be at 0 degrees and sure enough, the measurements line up.

Is it possible for me to disassemble the mount and reverse the plate? The manual doesn't appear to show this level of disassembly and since I didn't receive the mount new, I don't know if this was done at the factory or by the previous owner.

Thanks,
Eric


1200 Mount and TheSkyX

chrishet55
 

I've been playing around with TheSkyX and using its native driver (I'll get to the ASCOM driver later...).

Before upgrading to TheSkyX, using TheSky 6, when I powered my mount up it did not start tracking till I connected the mount to TheSky6...at it would not start tracking till I slewed to the first star (i.e. unparked the mount). Now when I power the mount up it starts tracking right away (before I even connect to TheSkyX). Also, after I connect to TheSkyX, TheSkyX thinks its still parked. even though its been tracking. Finally when I park the scope it thinks its park position is the location where I was when I connected to TheSkyX, i.e. the position it was after tracking for a while.....

I know the driver they use is not an AP coded driver but I would like to figure this out...Thoughts?

-Chris


Product Registration

Gregory <fyrframe@...>
 

For the AP Staff.

I purchased my Mach 1 about Nov 2012 and just found my missing registration card. Can I still send it in to register my equipment??

Gregory
Gig Harbor, WA.


Re: RA Drift

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]


Re: RA Drift

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



Re: 900GTO slews 96hrs/1440degrees on GOTO

observe_m13
 

I am surprised too, as in that someone even tried this! Almost 100% of the time, one would remove the power. Likely why in 15 or so years this has never come up for discusssion to my recollection. Interesting result at any rate.

Here is another one to try. Do the same thing but for brevity, only "stop" the mount for a few hours. Then remove the power. This "should" induce an internal "park". Power up and resume from park. I wonder if tracking rate "stop" is still engaged and what it would do when tracking was resumed followed by a GOTO? This scenario is far more likely to occur if there is an inadvertent power loss while the mount was temporarily "stopped".

--- In ap-gto@yahoogroups.com, "Christopher Erickson" <christopher.k.erickson@...> wrote:

As part of my personal learning curve, I have my 900GTO/GTOCP3/Q/4.17 set up
next to my desk. No OTA or counterweight shaft.

Four days ago I used the hand controller to set the tracking rate to "stop"
and have had the mount idling with the power on from then to now.

Today I used the hand controller to change the tracking rate from "Stop" to
"Side" and then commanded the mount to slew to Mercury which should have
been very-close to where it was currently pointing.

To my surprise, the RA axis did four complete revolutions before pointing
towards Mercury.

I had assumed that the mount would automatically subtract 24hrs/360deg from
the current RA position whenever it exceeded 24hr/360deg.

I assume this isn't a bug so I am looking for some insight on the logic
behind this behavior so I can better-understand my mount and how to use it
most safely and effectively.

Thanks for reading!

Christopher Erickson
Consulting Engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com


Re: RA Drift

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



900GTO slews 96hrs/1440degrees on GOTO

Christopher Erickson
 

As part of my personal learning curve, I have my 900GTO/GTOCP3/Q/4.17 set up
next to my desk. No OTA or counterweight shaft.

Four days ago I used the hand controller to set the tracking rate to "stop"
and have had the mount idling with the power on from then to now.

Today I used the hand controller to change the tracking rate from "Stop" to
"Side" and then commanded the mount to slew to Mercury which should have
been very-close to where it was currently pointing.

To my surprise, the RA axis did four complete revolutions before pointing
towards Mercury.

I had assumed that the mount would automatically subtract 24hrs/360deg from
the current RA position whenever it exceeded 24hr/360deg.

I assume this isn't a bug so I am looking for some insight on the logic
behind this behavior so I can better-understand my mount and how to use it
most safely and effectively.

Thanks for reading!

Christopher Erickson
Consulting Engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com


Re: RA Drift

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]


Re: RA Drift

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


Re: RA Drift

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


Re: RA Drift

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