Date   

Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

observe_m13
 

--- In ap-gto@..., "Ray Gralak" <rgr@...> wrote:

Roland, why would this be necessary unless it were for long term
totally unguided imaging? I can certainly see how a T-point modelling
program would be nice to have built in, but variable tracking?
Why not? How is that bad if your autoguider has to work less?

-Ray
I'm not saying it can't be done and I'm certainly not saying it
shouldn't be done. I just don't see the reasoning behind doing it
unless it is part of long term unguided imaging. After all, if a piece
of hardware is actively guiding then does it really matter if the
guider has to correct for an ever so slight change in refraction or
some slight mechanical error? Even now, without enabling PEC, and with
an excellent polar alignment, the guider sits there quite bored.

I would much rather see a T-point style mount modeling pointing error
correction built-in. If the mount uses the calculated variable
tracking, even without the T-point style modeling, to help with more
accurate goto's then it might be worth it.

Even with all that, if this is built into the keypad then it is
essentially useless to the imager as the keypad is not a flow-through
device. It would have to be either built into the GTOCPx firmware or
it would have to be run as a software driver on an external computer.
I guess it will all come clear as it gets developed and released.


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

Ray Gralak <rgr@...>
 

Roland, why would this be necessary unless it were for long term
totally unguided imaging? I can certainly see how a T-point modelling
program would be nice to have built in, but variable tracking?
Why not? How is that bad if your autoguider has to work less?

-Ray


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

observe_m13
 

--- In ap-gto@..., chris1011@... wrote:

In a message dated 4/4/2008 4:35:32 AM Central Daylight Time,
samirkharusi@... writes:


OK, let us all admit that even a mount with perfect polar
alignment and
perfectly smooth gears, and a perfect RA drive, will still show
both RA
and Dec drift because the atmosphere refracts differently at
different
altitude pointing. I.e. perfect tracking at zenith would become
imperfect away from zenith, as Roland keeps pointing out. But, and
this
is possibly a very important BUT, the AP gto mounts can be
pulse-driven
usiing PulseGuide. Can this not be turned into a major advantage
of the
AP mounts vs all other mounts that cannot be pulse-driven? Surely
it is
not a major programming effort, ie just a software fix, to calculate
the influence of atmospheric refraction at any alt and az and provide
the correct pulses to bring the tracking ever closer to
perfection? Or
am I missing something?
Yes, the tracking rate can be modified on the fly using a program that
calculates the amount of refraction at any given point. Ray Gralack
is working on
this.

Rolando

Roland, why would this be necessary unless it were for long term
totally unguided imaging? I can certainly see how a T-point modelling
program would be nice to have built in, but variable tracking?


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

observe_m13
 

I re-read your question and still come to the conclusions of why
bother? Are you planning on unguided imaging for several hours per
exposure? I have no idea why you would need to correct the tracking
rate for the length of an average exposure, even if it were to be up
to an hour long which is highly unlikely, with the possible exception
of narrow band imaging, due to CCD well depth and blooming
limitations. Sub arc-second drive error and perfect backlash
compensation would have to be the norm. Polar alignment would have to
be quite amazing indeed - possible to do but difficult to achieve.

--- In ap-gto@..., "Samir Kharusi" <samirkharusi@...> wrote:

OK, let us all admit that even a mount with perfect polar alignment and
perfectly smooth gears, and a perfect RA drive, will still show both RA
and Dec drift because the atmosphere refracts differently at different
altitude pointing. I.e. perfect tracking at zenith would become
imperfect away from zenith, as Roland keeps pointing out. But, and this
is possibly a very important BUT, the AP gto mounts can be pulse-driven
usiing PulseGuide. Can this not be turned into a major advantage of the
AP mounts vs all other mounts that cannot be pulse-driven? Surely it is
not a major programming effort, ie just a software fix, to calculate
the influence of atmospheric refraction at any alt and az and provide
the correct pulses to bring the tracking ever closer to perfection? Or
am I missing something?


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

observe_m13
 

Why bother with this small part of the overall pointing errors. This
is basically taken care of with software such as T-point which also
zero's out other mechanical errors of the telescope system.

There have been rumours over the years of T-point or something
similar being added to the AP control firmware but until it is
officially announced and released, I wouldn't count on it. I do think
it is already present in the higher end versions of the Gemini control
system, and has been for quite some time, so it certainly isn't
something new.

Get T-point and model all these errors if you are sufficiently concerned.

Rick.

--- In ap-gto@..., "Samir Kharusi" <samirkharusi@...> wrote:

OK, let us all admit that even a mount with perfect polar alignment and
perfectly smooth gears, and a perfect RA drive, will still show both RA
and Dec drift because the atmosphere refracts differently at different
altitude pointing. I.e. perfect tracking at zenith would become
imperfect away from zenith, as Roland keeps pointing out. But, and this
is possibly a very important BUT, the AP gto mounts can be pulse-driven
usiing PulseGuide. Can this not be turned into a major advantage of the
AP mounts vs all other mounts that cannot be pulse-driven? Surely it is
not a major programming effort, ie just a software fix, to calculate
the influence of atmospheric refraction at any alt and az and provide
the correct pulses to bring the tracking ever closer to perfection? Or
am I missing something?


Re: Leaving as GTO mount outdoors

Morgan Spangle <msfainc@...>
 

Hmmm...that's an interesting thought. What kind of hard shell did you
come up with? I have a C14 on mine so it would take a pretty good
sized barrel or drum...
Morgan

--- In ap-gto@..., "Steve..." <astropix@...> wrote:

Morgan,

For a time, I kept my AP1200 with OTA in a bag. We had some high winds
and something flying in the air hit the OTA putting a dent into it.

So I recommend a hard shell rather than a bag. I believe that even
these newer padded bags would still sustain damage from a flying object.

Steve...

www.CCDNavigator.com


Re: Leaving as GTO mount outdoors

Steve... <astropix@...>
 

Morgan,

For a time, I kept my AP1200 with OTA in a bag. We had some high winds
and something flying in the air hit the OTA putting a dent into it.

So I recommend a hard shell rather than a bag. I believe that even
these newer padded bags would still sustain damage from a flying object.

Steve...

www.CCDNavigator.com


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

Roland Christen
 

In a message dated 4/4/2008 12:06:11 PM Central Daylight Time,
mphammick@... writes:


Hence the need for a separate guide scope and camera - which would probably
be cheaper and more reliable in many ways.
Differential flexure.

Rolando


**************
Planning your summer road trip? Check out AOL Travel
Guides.

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Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

Roland Christen
 

In a message dated 4/4/2008 11:11:45 AM Central Daylight Time,
JunkMailGoesHere@... writes:


If the system as a whole is extremely well polar aligned and
moving with sub-arcsecond tracking accuracy inherently or with PEC as
seen on the meridian at 0 Dec, the rate of change due to the change in
atmospheric refraction over a five minute period most anywhere in the
sky is completely negligible unless one is imaging at extremely long
focal lengths.
Actually it's not negligeable at the arc second level. If you want no drift
in Ra or Dec over 5 minutes time span, you will need to take atmospheric
refraction into account and vary the drive rate of both axes. Between the horizon
and 45 degrees elevation, you will have an average of 1.5 arc sec drift in RA
per second of time if the drive is kept strictly at the sidereal rate.

Rolando


**************
Planning your summer road trip? Check out AOL Travel
Guides.

(http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016)


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

Roland Christen
 

In a message dated 4/4/2008 9:58:16 AM Central Daylight Time,
JunkMailGoesHere@... writes:


Roland, why would this be necessary unless it were for long term
totally unguided imaging? I can certainly see how a T-point modelling
program would be nice to have built in, but variable tracking?
T-Point does not do anything for modifying tracking. All it does is modify
pointing errors and helps polar alignment.

Modifying tracking can be of benefit for remote operations where a number of
objects are imaged for short periods of time. It is entirely possible to do 5
minute unguided imaging, and possibly even longer with sub-arc sec tracking.
You can then stack up a number of these subexposures for the final image. Giong
longer sometimes is bad because of blooming. Another use would be where
narrow band filters dim any suitable guide stars to the point where you need to do
very long guide exposures to get enough signal to guide on. Then you would
want the mount to be tracking accurately during this time period. I have used
guide exposures up to 60 seconds long at times when doing SII and Ha narrow band.

Rolando


**************
Planning your summer road trip? Check out AOL Travel
Guides.

(http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016)


Re: Atmospheric Refraction, Tracking Accuracy and PulseGuide

Roland Christen
 

In a message dated 4/4/2008 4:35:32 AM Central Daylight Time,
samirkharusi@... writes:


OK, let us all admit that even a mount with perfect polar alignment and
perfectly smooth gears, and a perfect RA drive, will still show both RA
and Dec drift because the atmosphere refracts differently at different
altitude pointing. I.e. perfect tracking at zenith would become
imperfect away from zenith, as Roland keeps pointing out. But, and this
is possibly a very important BUT, the AP gto mounts can be pulse-driven
usiing PulseGuide. Can this not be turned into a major advantage of the
AP mounts vs all other mounts that cannot be pulse-driven? Surely it is
not a major programming effort, ie just a software fix, to calculate
the influence of atmospheric refraction at any alt and az and provide
the correct pulses to bring the tracking ever closer to perfection? Or
am I missing something?
Yes, the tracking rate can be modified on the fly using a program that
calculates the amount of refraction at any given point. Ray Gralack is working on
this.

Rolando


**************
Planning your summer road trip? Check out AOL Travel
Guides.

(http://travel.aol.com/travel-guide/united-states?ncid=aoltrv00030000000016)


Atmospheric Refraction, Tracking Accuracy and PulseGuide

Muhammed Samir Kharusi
 

OK, let us all admit that even a mount with perfect polar alignment and
perfectly smooth gears, and a perfect RA drive, will still show both RA
and Dec drift because the atmosphere refracts differently at different
altitude pointing. I.e. perfect tracking at zenith would become
imperfect away from zenith, as Roland keeps pointing out. But, and this
is possibly a very important BUT, the AP gto mounts can be pulse-driven
usiing PulseGuide. Can this not be turned into a major advantage of the
AP mounts vs all other mounts that cannot be pulse-driven? Surely it is
not a major programming effort, ie just a software fix, to calculate
the influence of atmospheric refraction at any alt and az and provide
the correct pulses to bring the tracking ever closer to perfection? Or
am I missing something?


Re: Leaving as GTO mount outdoors

Morgan Spangle <msfainc@...>
 

Thank you all for your informative replies - gives me the confidence
to go ahead with my plan to build a nice viewing deck surrounded by
hedges to block the neighborhood light...now on to mounting my Questar
7 OTA on my new (for me) 600EGTO...
Morgan

--- In ap-gto@..., "Richard Crisp" <rdcrisp@...> wrote:

you can easily remove the control electronics box and I recommend
that if you go through a long wet period

my ap1200gto has been in the outdoors for over four years now....

just covered up with a nice bag...


----- Original Message -----
From: Morgan Spangle
To: ap-gto@...
Sent: Thursday, April 03, 2008 9:55 AM
Subject: [ap-gto] Leaving as GTO mount outdoors


I'm considering leaving my APO 1200 GTO outdoors over the winter, so
that setup/knockdown time is lessened, and since I use it by remote
control to image anyway. I'm in the Northeast, so we do get rain,
cold, and snow; I'd have a pretty good over bungeed to the mount to
protect it, and could even keep a lightbulb going all the time to
keep moisture from accumulating under the cover. What's the group's
opinion?

Morgan Spangle





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


Re: Leaving as GTO mount outdoors

Richard Crisp
 

you can easily remove the control electronics box and I recommend that if you go through a long wet period

my ap1200gto has been in the outdoors for over four years now....

just covered up with a nice bag...

----- Original Message -----
From: Morgan Spangle
To: ap-gto@...
Sent: Thursday, April 03, 2008 9:55 AM
Subject: [ap-gto] Leaving as GTO mount outdoors


I'm considering leaving my APO 1200 GTO outdoors over the winter, so
that setup/knockdown time is lessened, and since I use it by remote
control to image anyway. I'm in the Northeast, so we do get rain,
cold, and snow; I'd have a pretty good over bungeed to the mount to
protect it, and could even keep a lightbulb going all the time to
keep moisture from accumulating under the cover. What's the group's
opinion?

Morgan Spangle


Re: Can't connect AP600E GTO through ASCOM

Bob Benamati
 

Well, I must of scared it into submission by the post... After 3 hours; multiple un- and re-installs; and a couple of restarts of the PC, it mysteriously links fine now! Go figure....

Anyway--I'm thrilled to finally be an AP owner after all these years! After struggling with the G11 for so long, I sure can't wait to give the little 600 a go (I'm still kicking myself for turning down the Mach 1 from the 1st production run, but I hope the 600 will at least compensate until my name comes up again!)


Take care,
Bob

www.pennastroimaging.com

----- Original Message -----
From: bbenamati
To: ap-gto@...
Sent: Thursday, April 03, 2008 3:42 PM
Subject: [ap-gto] Can't connect AP600E GTO through ASCOM


Hi gang,

Sorry for any cross-posts from the ASCOM group, but here's my problem:

I've recently acquired a 600E GTO CP2 (D chip series) and cannot
connect to it through any ASCOM platforms. I used to use MaxPoint,
PEMPro, etc. with my Gemini, but for some reason, I'm unable to connect
through either program using the AP GTO Mount selection. I AM able to
successfully link PulseGuide--so (I believe) my serial connection is
fine.... I'm stumped... I've updated to ASCOM 5a and installed the AP
driver v 4.1.25. Is the older mount just not able to be controlled
this way??

Thanks!

Bob


Re: Leaving as GTO mount outdoors

Christopher Go
 

I have left my AP900 98% of the year outside just covered in
Tarpoline. I only bring it in when a typhoon is coming! Never had a
problem with my mount. Although I don't have snow, I do get a lot of
rain. If AP mounts can survive in Antartica, it should survive
anywhere in the world!

Regards,
Chris

At 04:55 PM 4/3/2008, you wrote:

I'm considering leaving my APO 1200 GTO outdoors over the winter, so
that setup/knockdown time is lessened, and since I use it by remote
control to image anyway. I'm in the Northeast, so we do get rain,
cold, and snow; I'd have a pretty good over bungeed to the mount to
protect it, and could even keep a lightbulb going all the time to
keep moisture from accumulating under the cover. What's the group's
opinion?

Morgan Spangle

Christopher and Vicky Go
Christone Industries
Manufacturer and Exporter of Quality Fossil Stone and Wrought Iron Furniture
Cebu, Philippines
http://www.christone.net
Astronomy: http://astro.christone.net
Red Spot Jr: http://www.redspotjr.com


Re: Leaving as GTO mount outdoors

Klein, Adam <atk@...>
 

I've had my AP 1200 and RCOS 12.5 in a portable shelter for a few years. I haven't had an issue - other then heavy winds banging the shelter around. The system is fairly bombproof from the humidity (ask the folks in Florida).

Adam

----- Original Message -----
From: ap-gto@... <ap-gto@...>
To: ap-gto@... <ap-gto@...>
Sent: Thu Apr 03 12:55:20 2008
Subject: [ap-gto] Leaving as GTO mount outdoors

I'm considering leaving my APO 1200 GTO outdoors over the winter, so
that setup/knockdown time is lessened, and since I use it by remote
control to image anyway. I'm in the Northeast, so we do get rain,
cold, and snow; I'd have a pretty good over bungeed to the mount to
protect it, and could even keep a lightbulb going all the time to
keep moisture from accumulating under the cover. What's the group's
opinion?

Morgan Spangle


Leaving as GTO mount outdoors

Morgan Spangle <msfainc@...>
 

I'm considering leaving my APO 1200 GTO outdoors over the winter, so that setup/knockdown time is lessened, and since I use it by remote control to image anyway. I'm in the Northeast, so we do get rain, cold, and snow; I'd have a pretty good over bungeed to the mount to protect it, and could even keep a lightbulb going all the time to keep moisture from accumulating under the cover. What's the group's opinion?


Morgan Spangle


Can't connect AP600E GTO through ASCOM

Bob Benamati
 

Hi gang,

Sorry for any cross-posts from the ASCOM group, but here's my problem:

I've recently acquired a 600E GTO CP2 (D chip series) and cannot
connect to it through any ASCOM platforms. I used to use MaxPoint,
PEMPro, etc. with my Gemini, but for some reason, I'm unable to connect
through either program using the AP GTO Mount selection. I AM able to
successfully link PulseGuide--so (I believe) my serial connection is
fine.... I'm stumped... I've updated to ASCOM 5a and installed the AP
driver v 4.1.25. Is the older mount just not able to be controlled
this way??

Thanks!

Bob


Re: First Light with my new Mach1

hewholooks
 

Thanks Rick.

I have to confess, I have processed and re-processed this image until
I was happy with it. I got a new laptop at the same time and am
having a little trouble calibrating the screen. The original was WAY
too green when viewed on other monitors.

Hunter

--- In ap-gto@..., "Rick Wiggins" <rickwiggins@...> wrote:

Hi Hunter,
That is an impressive image. Great details and good color. I am
really impressed that this was done with a DSLR.
Thanks, Rick

--- In ap-gto@..., "hewholooks" <hewholooks@> wrote:

Set up the new mount yesterday afternoon and it wasn't supposed
to
be
clear - but it was. After a slight learning curve, I got these
shots
of the Leo Trio - first 5 images in this gallery (really just one
image
in 5 ways).

Thanks for looking.

http://hwilson.zenfolio.com/p781396937

Hunter