Please help an idiot with GOTO

I feel like such an idiot for not getting this to work. Any help would
be appreciated. I'm going to describe exactly what I am doing, so
hopefully someone can see my error.

My telescope is a Celestron.

1) Polar align on polaris. Latitude scale shows 30 degrees, which is
my latitude, so I think that is ok
2) Set alignment marks on both axes
3) Start up goto
4) Set time: 21:40:00
4b) Set daylight savings
5) Set date: 08/07/03
6) Set long: 97:43:00 W
7) Set lat: 30:31:00 N

At this point I tried two methods, 'quick align' and '3 start align'

Quick align is supposed to be rough, but doesn't require alignment with
stars. I do quick align, then tell it to go to the moon. It slews in
the general direction, but is pointing slightly below the horizon. The
moon was about 30 degrees above the horizon. I used the controller to
manually move over to the moon, and then did the manual alignment thing
telling it that this is the moon. Then, I moved 20-30 degrees and told
it to go back to the moon. It went back to the orignal below-horizon
position.

Later, I try three star align. It slews to arcturus, but is about 30
degrees off in azimuth, and about 5 degrees off in elevation. I go
ahead and manually slew over. Then, it wants to slew to vega. It is
closer, but still 4-5 degrees off.

From what I have read about other's experience with GOTO, this is *way*
off. Hopefully, someone can shed some light on this for me. I have a
hunch it is somewhere in the goto setup, but I can't imagine what it
might be.

Thanks!

Alex

On Fri, 08 Aug 2003 03:57:41 GMT, Alex Kilpatrick
wrote:

I feel like such an idiot for not getting this to work. Any help would
be appreciated. I'm going to describe exactly what I am doing, so
hopefully someone can see my error.

My telescope is a Celestron.

1) Polar align on polaris. Latitude scale shows 30 degrees, which is
my latitude, so I think that is ok

So you are using a wedge? I assume so, since otherwise polar alignment makes no
sense.

I'm not very familiar with Celestrons, but it sounds like the scope thinks you
are in altaz mode, not polar. There has to be a way of telling the scope which
mode you are in. Did you use it?

Exactly what scope do you have, and how is it set up?

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Fri, 08 Aug 2003 05:34:47 GMT, Alex Kilpatrick
wrote:

I'm not sure what a wedge is. The telescope has a latitude scale that
allows you tilt the mount to a certain elevation.

Okay, forget that. It is used on fork mounted altaz scopes, but not on yours.
You have a German equatorial mount, so you are doing the right thing by tilting
it to match your latitude.


In the part of the manual that talks about tracking, it says the
following:

"When the telescope is polar aligned, this [tracking] can be
accomplished by moving the telescope in right ascension only. When
mounted in alt-az mode, the telescope must make corrections in both R.A.
and declination"

What this means is that the controller for your scope is able to deal with both
equatorial and altaz mountings. I think you need to tell it which you are using.
With your particular mount, that is equatorial, which might also be called
polar.


I think I understand that. But I have no idea how to know how my
telescope is mounted. The manual only describes one way to mount it.
The goto computer doesn't mention a way to switch modes. It seems to
imply that it is automatic.

With your mount, equatorial mounting is really the only option. But the computer
doesn't know that because the same computer is used on other scopes, with other
types of mounts. I don't see how the mode can be automatic, although it could be
set to the right default at the factory. Or not.


I don't see how you could operate the computer without being polar-
aligned. Otherwise, how it would it have a baseline to start from?

You don't necessarily need to be polar aligned. The telescope learns its own
coordinate system from the alignment. But if the computer knows your location
and time, and you are polar aligned, it should be able to slew to within a few
degrees of any target without any star alignment procedures. The scope is
probably supposed to be in a certain position when you turn it on. Also, how are
you performing the polar alignment?

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

In article ,
says...

Thanks for the help, Chris. I appreciate it.



I think I understand that. But I have no idea how to know how my
telescope is mounted. The manual only describes one way to mount it.
The goto computer doesn't mention a way to switch modes. It seems to
imply that it is automatic.

With your mount, equatorial mounting is really the only option. But the computer
doesn't know that because the same computer is used on other scopes, with other
types of mounts. I don't see how the mode can be automatic, although it could be
set to the right default at the factory. Or not.


The manual certainly doesn't cover any mode setting. About the only
thing that seems close is that you can set it to track sidereal, lunar
or solar.


I don't see how you could operate the computer without being polar-
aligned. Otherwise, how it would it have a baseline to start from?

You don't necessarily need to be polar aligned. The telescope learns its own
coordinate system from the alignment. But if the computer knows your location
and time, and you are polar aligned, it should be able to slew to within a few
degrees of any target without any star alignment procedures.

Right. That is what I thought. But without any star alignment, it has
to know its original orientation to be able to do that. That is what I
thought the polar alignment is for. This would also imply that if I am
polar aligned, then it should be within a few degrees of the first guide
star as well. My early attempts at hitting the moon were 45 degrees off
in declination.

The scope is
probably supposed to be in a certain position when you turn it on.

I assumed this was the polar alignment.

Also, how are
you performing the polar alignment?


I set the OTA so it is parallel to the polar axis and lock it down.
Then, I find polaris and adjust the screws in the mount itself to center
polaris in the scope. That is the procedure described in the manual.

Alex

On Fri, 08 Aug 2003 06:17:02 GMT, Alex Kilpatrick
wrote:

The manual certainly doesn't cover any mode setting. About the only
thing that seems close is that you can set it to track sidereal, lunar
or solar.

But the manual section you quoted before specifically mentions both polar and
altaz operation. There must be some way of telling the controller which you are
using.


The scope is
probably supposed to be in a certain position when you turn it on.

I assumed this was the polar alignment.

The purpose of polar alignment is to make sure that the polar axis of the mount
is actually parallel to the rotation axis of the Earth. This applies to any
equatorial mount, not just those with computer controls. Having the scope in the
correct startup position would be necessary so the computer has a starting
point. I don't know what this is for your scope. My Meade expects to be started
up with the OTA facing south.


Also, how are
you performing the polar alignment?

I set the OTA so it is parallel to the polar axis and lock it down.
Then, I find polaris and adjust the screws in the mount itself to center
polaris in the scope. That is the procedure described in the manual.

That is a reasonable procedure for rough polar alignment. Where is the RA when
you do this? You set the declination so the OTA is parallel to the polar axis,
but that axis could be rotated at any angle an you would still be polar aligned.
But the scope must assume that it was in some particular position at power up,
or you need to do at least a one-star alignment, and find the star by yourself.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

I did a search using Google -- I searched for "celestron" + "goto" +
"alignment".

Here are some of the results.

This link may help: http://www.darkhorizons.org/rmackay/howto.htm Notice
that he says to "set up Telescope Config" to unaligned EQ -- have you
checked your "telescope config" setting?

There may be something helpful he
http://www.nexstar11.com/downloads.shtml

Also -- you do have the scope set for NORTHERN HEMISPHERE??
--
----
JAS


"Alex Kilpatrick" wrote in message
...
I feel like such an idiot for not getting this to work. Any help would
be appreciated. I'm going to describe exactly what I am doing, so
hopefully someone can see my error.

My telescope is a Celestron.

1) Polar align on polaris. Latitude scale shows 30 degrees, which is
my latitude, so I think that is ok
2) Set alignment marks on both axes
3) Start up goto
4) Set time: 21:40:00
4b) Set daylight savings
5) Set date: 08/07/03
6) Set long: 97:43:00 W
7) Set lat: 30:31:00 N

At this point I tried two methods, 'quick align' and '3 start align'

Quick align is supposed to be rough, but doesn't require alignment with
stars. I do quick align, then tell it to go to the moon. It slews in
the general direction, but is pointing slightly below the horizon. The
moon was about 30 degrees above the horizon. I used the controller to
manually move over to the moon, and then did the manual alignment thing
telling it that this is the moon. Then, I moved 20-30 degrees and told
it to go back to the moon. It went back to the orignal below-horizon
position.

Later, I try three star align. It slews to arcturus, but is about 30
degrees off in azimuth, and about 5 degrees off in elevation. I go
ahead and manually slew over. Then, it wants to slew to vega. It is
closer, but still 4-5 degrees off.

From what I have read about other's experience with GOTO, this is *way*
off. Hopefully, someone can shed some light on this for me. I have a
hunch it is somewhere in the goto setup, but I can't imagine what it
might be.

Thanks!

Alex

Alex

If you go to Yahoo Groups they have several Celestron groups where you
can talk to other owners who have the same scope as yours

Gaz

From what I have read about other's experience with GOTO, this is *way*
off. Hopefully, someone can shed some light on this for me. I have a
hunch it is somewhere in the goto setup, but I can't imagine what it
might be.


Hi Alex:

Don't expect the alignment stars to be that close at first. Using the hand
controller, center them in an eyepiece.

What is your result when you do this?

Vis-a-vis the Moon, make sure time and time zone are correctly set.

Don't expect accurate goto on anything without precisely aligning on 2 stars.

Make sure you are moving the scope to center the CORRECT stars. Are you SURE
you centered Aldeberan, for example?

Might want to see if there's an experienced amateur in the local club who can
help you out.
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

So you are using a wedge? I assume so, since otherwise polar alignment makes
no
sense.


Hi:

I believe he's using one of the new goto CG5/GEM scopes.

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

"Gaz" wrote in message
om...
Alex

If you go to Yahoo Groups they have several Celestron groups where you
can talk to other owners who have the same scope as yours



/soap box mount

Yeah, but then I have to join yet another group to stay abreast of what's
going on.

FWIW, I belong to something like 12 yahoo groups, but I only use them as an
information resource via the search feature. I've tried using the email
feature, but then I get inundated. SAA is a much better place to hang out,
and chat about everything from the current weather, to the latest gadget.
Nothing astro related is off-topic here. I wish folks would either post to
SAA, or start another Usenet group.

But, that's just me. I've got other things to do. Reading and posting in
Usenet is simply faster and more efficient, than dealing with the bloat of a
web browser.

/soap box dismount
--
-Stephen Paul