Alignment of a Celestron C8-N GT with the GOTO mount.

I'm the proud new owner of a Celestron C8-N on an Equatorial mount with the NextStar GT controller.

I'm having a hard time getting it aligned.
The scope will be used from various sites, so I need to learn to align it
in a repeatable way.

Some Background:
I'm technically savey , but a complete newbe when it comes to Telescopes.

The Celestron Manual leaves a little bit to be desired.
It is a combination of manuals from three different setups, none exactly like my scope.
I've set the lattitude scale on the Equatorial mount to be = to my Latitude.
~33 degrees. near San Diego


Outline of what I've been doing:

1)I point the Mount to true north. (+/- 2 degrees hard to be more exact than that)

2)Level the tripod exactly.

3)Release the Clutches and aline the zero marks on the mount, then tighten the clutches.
When the alignment marks are aligned I would have expected that the scope might point
is some recognizable direction, it does not it points about 15 degrees east of North.

4)Start the alignment procedure.....
1)Enter Time, Date, Lat, Lon all from a GPS Receiver so they are accurate.
2)The scope slews to it's chosen star.... alas it is not even close! 20 degrees off.....
align the first star with the controller go to the second.... etc...
When I'm all done it won;t even seem to get the target object into the finder scope?

I've seen some discussion on the net about leveling the scope tube before you start, but that
looks apropriate for the AZ-EL fork mount, not the Equatorial Mount.

The drive seems to be mechancially good, I've been watching Mars and it tracks that reasonabley
well once I've gotten the unit pointed at it it tracked for several hours with only minor corrections....

Any suggestions or Guides to get started?


Paul

In article ,
says...

3)Release the Clutches and aline the zero marks on the mount, then tighten the clutches.
When the alignment marks are aligned I would have expected that the scope might point
is some recognizable direction, it does not it points about 15 degrees east of North.


I have the same telescope, and Celestron has told me that some of the
alignment marks may have "slipped" (ha ha) and that it is best to
ignore them. If your are polar aligned, then at the zero mark the scope
should be pointing North.

This was a real nightmare to diagnose, and I feel your pain. However,
once you align it properly, things will work fine.

Alex

In article ,
says...

3)Release the Clutches and aline the zero marks on the mount, then tighten the clutches.
When the alignment marks are aligned I would have expected that the scope might point
is some recognizable direction, it does not it points about 15 degrees east of North.


I have the same telescope, and Celestron has told me that some of the
alignment marks may have "slipped" (ha ha) and that it is best to
ignore them. If your are polar aligned, then at the zero mark the scope
should be pointing North.

This was a real nightmare to diagnose, and I feel your pain. However,
once you align it properly, things will work fine.

Alex

wrote in message
...
I'm the proud new owner of a Celestron C8-N on an Equatorial mount with
the NextStar GT controller.

I'm having a hard time getting it aligned.
The scope will be used from various sites, so I need to learn to align it
in a repeatable way.

Some Background:
I'm technically savey , but a complete newbe when it comes to Telescopes.

The Celestron Manual leaves a little bit to be desired.
It is a combination of manuals from three different setups, none exactly
like my scope.
I've set the lattitude scale on the Equatorial mount to be = to my
Latitude.
~33 degrees. near San Diego


Outline of what I've been doing:

1)I point the Mount to true north. (+/- 2 degrees hard to be more exact
than that)

2)Level the tripod exactly.

3)Release the Clutches and aline the zero marks on the mount, then tighten
the clutches.
When the alignment marks are aligned I would have expected that the scope
might point
is some recognizable direction, it does not it points about 15 degrees
east of North.

4)Start the alignment procedure.....
1)Enter Time, Date, Lat, Lon all from a GPS Receiver so they are accurate.
2)The scope slews to it's chosen star.... alas it is not even close! 20
degrees off.....
align the first star with the controller go to the second.... etc...
When I'm all done it won;t even seem to get the target object into the
finder scope?
It really should work here. However two obvious questions 'leap' to mind.
The difference between '20 degrees', and '15 degrees', is not a lot. In the
past, on a couple of Meade models where alignment is done a similar way, it
was fairly common to find that the alignment marks were not positioned
correctly from the factory. On these scopes, the marks were moveable, but
not obviously so, and the solution ended up being to re-align the marks...
The other thing to beware of, is that the data format from the GPS, may not
be the format expected by the unit. Caveats would be the use of decimal
degrees, versus degrees/minutes/seconds, or selection of 'daylight saving',
to 'on', when the GPS, returns UTC based time. There is also the caveat with
your time zone (depending on your GPS - some return time offset to the local
timezone, but use a 'standard', which does not allways agree with the actual
zone switches on the ground...). One hour in error, would be 15 degrees,
which again is close to your alignment error.

I've seen some discussion on the net about leveling the scope tube before
you start, but that
looks apropriate for the AZ-EL fork mount, not the Equatorial Mount.

The drive seems to be mechancially good, I've been watching Mars and it
tracks that reasonabley
well once I've gotten the unit pointed at it it tracked for several hours
with only minor corrections....

Any suggestions or Guides to get started?
Try being completely 'lateral'. Setup the scope as you have been, then when
it goes to the first star, instead of using the hand controller, slacken the
clutches, and manually point the tube close to the target. Then retighten,
and just use the hand controller to 'tweak' the position. If you then find
that it gets close to the second star without problems, it really suggests
the alignment marks are out of position by the amount that you have to move
the tube when you slacken it (you could even note down the dial readings,
and work out the amount you should 'offset' the position).

Best Wishes

wrote in message
...
I'm the proud new owner of a Celestron C8-N on an Equatorial mount with
the NextStar GT controller.

I'm having a hard time getting it aligned.
The scope will be used from various sites, so I need to learn to align it
in a repeatable way.

Some Background:
I'm technically savey , but a complete newbe when it comes to Telescopes.

The Celestron Manual leaves a little bit to be desired.
It is a combination of manuals from three different setups, none exactly
like my scope.
I've set the lattitude scale on the Equatorial mount to be = to my
Latitude.
~33 degrees. near San Diego


Outline of what I've been doing:

1)I point the Mount to true north. (+/- 2 degrees hard to be more exact
than that)

2)Level the tripod exactly.

3)Release the Clutches and aline the zero marks on the mount, then tighten
the clutches.
When the alignment marks are aligned I would have expected that the scope
might point
is some recognizable direction, it does not it points about 15 degrees
east of North.

4)Start the alignment procedure.....
1)Enter Time, Date, Lat, Lon all from a GPS Receiver so they are accurate.
2)The scope slews to it's chosen star.... alas it is not even close! 20
degrees off.....
align the first star with the controller go to the second.... etc...
When I'm all done it won;t even seem to get the target object into the
finder scope?
It really should work here. However two obvious questions 'leap' to mind.
The difference between '20 degrees', and '15 degrees', is not a lot. In the
past, on a couple of Meade models where alignment is done a similar way, it
was fairly common to find that the alignment marks were not positioned
correctly from the factory. On these scopes, the marks were moveable, but
not obviously so, and the solution ended up being to re-align the marks...
The other thing to beware of, is that the data format from the GPS, may not
be the format expected by the unit. Caveats would be the use of decimal
degrees, versus degrees/minutes/seconds, or selection of 'daylight saving',
to 'on', when the GPS, returns UTC based time. There is also the caveat with
your time zone (depending on your GPS - some return time offset to the local
timezone, but use a 'standard', which does not allways agree with the actual
zone switches on the ground...). One hour in error, would be 15 degrees,
which again is close to your alignment error.

I've seen some discussion on the net about leveling the scope tube before
you start, but that
looks apropriate for the AZ-EL fork mount, not the Equatorial Mount.

The drive seems to be mechancially good, I've been watching Mars and it
tracks that reasonabley
well once I've gotten the unit pointed at it it tracked for several hours
with only minor corrections....

Any suggestions or Guides to get started?
Try being completely 'lateral'. Setup the scope as you have been, then when
it goes to the first star, instead of using the hand controller, slacken the
clutches, and manually point the tube close to the target. Then retighten,
and just use the hand controller to 'tweak' the position. If you then find
that it gets close to the second star without problems, it really suggests
the alignment marks are out of position by the amount that you have to move
the tube when you slacken it (you could even note down the dial readings,
and work out the amount you should 'offset' the position).

Best Wishes

In article ,
says...
Alex, Thanks for your quick response....
How do you like your scope?


So far, it has been great. Once you get the alignment working, it finds
things well, and tracks well also.

There are two axis to align....
So it should be pointed north at what declination?
Point at polaris?
Tube Level?
Some other combination?


I think that the manual for the mount (CG-5) describes the process for
setting zero declination. If you follow that procedure, you will see
that the alignment marks don't line up. At that point, you could just
make some new alignment marks, or for more accuracy just follow that
procedure each night before you get started.

On my telescope, the RA marks are aligned. If you look at how the
declination marks are aligned, you may notice that the top sticker is
centered on the seam on the plastic housing surrounding the OTA clamp.
Unfortunately, that plastic housing is not exactly perpendicular to the
polar axis. My guess is that someone at the factory was just aligning
the sticker to that seam, and not to where it is supposed to be.

Good luck!

Alex

In article ,
says...
Alex, Thanks for your quick response....
How do you like your scope?


So far, it has been great. Once you get the alignment working, it finds
things well, and tracks well also.

There are two axis to align....
So it should be pointed north at what declination?
Point at polaris?
Tube Level?
Some other combination?


I think that the manual for the mount (CG-5) describes the process for
setting zero declination. If you follow that procedure, you will see
that the alignment marks don't line up. At that point, you could just
make some new alignment marks, or for more accuracy just follow that
procedure each night before you get started.

On my telescope, the RA marks are aligned. If you look at how the
declination marks are aligned, you may notice that the top sticker is
centered on the seam on the plastic housing surrounding the OTA clamp.
Unfortunately, that plastic housing is not exactly perpendicular to the
polar axis. My guess is that someone at the factory was just aligning
the sticker to that seam, and not to where it is supposed to be.

Good luck!

Alex