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LX200 12" GPS alignment problem



 
 
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  #1  
Old January 3rd 05, 10:24 AM
Carl Wrightson
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Default LX200 12" GPS alignment problem

I don't suppose anyone out there has come across this issue have they? I
follow the instructions implicitly and once the alignment is complete (any
option - 1 star, 2 stars, etc) and I choose go-to for an object such as one
of the obvious planets so I know I've got the object correct (!) it points
somewhere close (same area of the sky...just about) but not in the same
field of view through the scope. The GPS location is set correctly and if I
use manual alignment with known stars it is still wrong. Sometimes (not
always), even the tracking/slew rate seems to be incorrect, and as I'm all
geared up for astrophotography that kind if spells failure from the start.

Anybody got any ideas???? Any at all???!!! :-) Through my LPI I can get a
decent image of Jupiter say, but it jumps a lot which I guess will make
stacking the images pretty near impossible, or is there something with image
processing software I can use to avoid this. I want to by the new Deep Space
Imager but with longer exposures these problems will make my purchase
worthless!


  #2  
Old January 3rd 05, 10:30 AM
md
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"Carl Wrightson" wrote in message
...
I don't suppose anyone out there has come across this issue have they? I
follow the instructions implicitly and once the alignment is complete (any
option - 1 star, 2 stars, etc) and I choose go-to for an object such as one
of the obvious planets so I know I've got the object correct (!) it points
somewhere close (same area of the sky...just about) but not in the same
field of view through the scope. The GPS location is set correctly and if I
use manual alignment with known stars it is still wrong. Sometimes (not
always), even the tracking/slew rate seems to be incorrect, and as I'm all
geared up for astrophotography that kind if spells failure from the start.

Anybody got any ideas???? Any at all???!!! :-) Through my LPI I can get a
decent image of Jupiter say, but it jumps a lot which I guess will make
stacking the images pretty near impossible, or is there something with image
processing software I can use to avoid this. I want to by the new Deep Space
Imager but with longer exposures these problems will make my purchase
worthless!


did you train the drives?
--
md
10" LX200GPS-SMT
ETX105
www.xs4all.nl/~martlian


  #3  
Old January 3rd 05, 12:08 PM
Steve Maddison
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Default

Carl Wrightson wrote:
I don't suppose anyone out there has come across this issue have
they? I follow the instructions implicitly and once the alignment
is complete (any option - 1 star, 2 stars, etc) and I choose
go-to for an object such as one of the obvious planets so I know
I've got the object correct (!) it points somewhere close (same
area of the sky...just about) but not in the same field of view
through the scope. The GPS location is set correctly and if I use
manual alignment with known stars it is still wrong. Sometimes
(not always), even the tracking/slew rate seems to be incorrect,
and as I'm all geared up for astrophotography that kind if spells
failure from the start.


The usual remedy for this and other Autostar scopes is to calibrate
and (re)train the drives. If you've recently upgraded the firmware
you'll probably want to de a reset first to be sure everything's
properly initialised. Calibration is a short, automated process, but
it pays to take your time with the largely manual training part -
high magnification and a reticle eyepiece will help a lot. The
tracking rates are something you can always play with *after*
calibrating and training.

Anybody got any ideas???? Any at all???!!! :-) Through my LPI I
can get a decent image of Jupiter say, but it jumps a lot which I
guess will make stacking the images pretty near impossible, or is
there something with image processing software I can use to avoid
this. I want to by the new Deep Space Imager but with longer
exposures these problems will make my purchase worthless!


The jumping sounds unusual to me, but it may well have to do with
backlash (or the compensation thereof) which should be fixed by the
above procedure. Another thing to check (and train the scope for) is
periodic error.

Rapid jumps will probably only cost you a frame or two when imaging
planets and stacking software can compensate for this kind of
movement during the registration (i.e. "frame alignment") process.
As you've however identified, such glitches will be a major nuisance
during longer exposures. AFAIK the LX200 tracks pretty well though,
when set up properly.

Best of luck,

Steve
  #4  
Old January 3rd 05, 02:14 PM
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Default


Carl Wrightson wrote:

Anybody got any ideas???? Any at all???!!! :-) Through my LPI I can

get a
decent image of Jupiter say, but it jumps a lot which I guess will

make
stacking the images pretty near impossible, or is there something

with image
processing software I can use to avoid this. I want to by the new

Deep Space
Imager but with longer exposures these problems will make my purchase
worthless!


Hi:

Is this only the planets? If so, check (in the Autostar) to make sure
your _time zone_ is set correctly. Also, with planets, make sure you
hit enter before goto

Peace,
Rod

  #5  
Old January 3rd 05, 02:21 PM
md
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Default


wrote in message
ups.com...

Carl Wrightson wrote:

Anybody got any ideas???? Any at all???!!! :-) Through my LPI I can

get a
decent image of Jupiter say, but it jumps a lot which I guess will

make
stacking the images pretty near impossible, or is there something

with image
processing software I can use to avoid this. I want to by the new

Deep Space
Imager but with longer exposures these problems will make my purchase
worthless!


Hi:

Is this only the planets? If so, check (in the Autostar) to make sure
your _time zone_ is set correctly.


He said the GPS worked fine, so the time/location will be ok.

Also, with planets, make sure you
hit enter before goto


that's a good tip, I made that same error 2 years ago when I used my ETX for the first time.
--
md
10" LX200GPS-SMT
ETX105
www.xs4all.nl/~martlian


  #7  
Old January 3rd 05, 06:12 PM
Chris L Peterson
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Default

On Mon, 3 Jan 2005 09:24:28 +0000 (UTC), "Carl Wrightson"
wrote:

I don't suppose anyone out there has come across this issue have they? I
follow the instructions implicitly and once the alignment is complete (any
option - 1 star, 2 stars, etc) and I choose go-to for an object such as one
of the obvious planets so I know I've got the object correct (!) it points
somewhere close (same area of the sky...just about) but not in the same
field of view through the scope. The GPS location is set correctly and if I
use manual alignment with known stars it is still wrong. Sometimes (not
always), even the tracking/slew rate seems to be incorrect, and as I'm all
geared up for astrophotography that kind if spells failure from the start.


I don't know about the GPS model, but the classic LX200 has never done a very
good job of hitting planets. You definitely can't use them for any kind of
accurate alignment. How does your scope do at hitting stars after you align it?


Anybody got any ideas???? Any at all???!!! :-) Through my LPI I can get a
decent image of Jupiter say, but it jumps a lot which I guess will make
stacking the images pretty near impossible, or is there something with image
processing software I can use to avoid this. I want to by the new Deep Space
Imager but with longer exposures these problems will make my purchase
worthless!


Well, you are at high magnification on a tiny chip, so you see every little
tracking error. The best solution is to put your scope on a wedge and use it
equatorially, so only one axis is tracking. This will also eliminate field
rotation, which makes stacking difficult (it is hard to detect a small amount of
field rotation in planetary images, unlike in images with star fields). If you
continue to operate in altaz mode, make sure you have the PEC trained on both
axes to minimize the amount of jumping around. You can have a lot of shifting
between frames and still get good stacking results.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
  #8  
Old January 15th 05, 03:50 PM
Rod Mollise
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Default


Why does the GPS model need the time zone other than to display local time? I
would think the calculations would be based on UT and position, both
available
from the GPS data.


Hi:

No, apparently not. If your time zone is incorrect, your initial alignment
stars as well as the Moon and planets will be "off".

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html
 




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