Rob --

I have an AP1200GTO in a 10' TI dome. I used to spend hours drift
aligning my fork mounts, but I've never done anything more than a
quick and dirty alignment using the polar scope with the AP.

I tried shimming the tube for orthogonality, but a 0.005" piece of
brass shimstock was larger than the orthogonality error (this had to
be dumb luck -- there's no way my OTA and rings were fabricated with
that kind of precision).

My OTA is a big SCT, which has some mirror flop (probably on the
order of a couple of arc-minutes), and a horrendously long focal
length (about 4450mm with rotator and focuser on the back).

While I'm one of those people that nag Roland for a pointing model,
there's really no reason (other than that it would be cool). I've
never had a target placed outside a 26mm T5, even with all the above
caveats.

Oh, and I also find that a GLP works well as a finder. I did have
to place a dew-heater strip under mine, as the output of mine falls
off dramatically around 2°C, but the heater has eliminated that
problem. But the biggest advantage of the GLP is that in Ireland I
often observe in partly-cloudy conditions, and when the veiw starts
to go fuzzy I can turn the GLP on for a second and quickly see
(without having to getting up from my seat) whether or not I'm
getting obscured by clouds.

-- Jeff.


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

Rob,

The last time I was at your observatory, granted some time ago, I

remember

the mount being center of the dome. Regardless, it's a ten foot

dome. If

perfect pointing in an issue and you don't want to use the

computer with any

modeling, what Roland is suggesting is fast and simple. I'm not

sure what Ed

may have shown you last week, but his Polar alignment was done by

me using

PoleAlignMax , PEM was programmed by using the included PemPro

using

multiple guider cycles. Earlier issues with pointing was corrected

when I

had him check his location setup in his hand controller, TheSky,

ACP and

other programs he was using and making then identical in all

programs. His

pointing is great now.

If you are thinking ME, how can you not use the computer to have T-

Point

model active? After having just set up your Gemini G11, what is

the rush to

get another mount other than the obvious move up in mounts?

Steve



-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...] On

Behalf Of

chris1011@...
Sent: Thursday, February 22, 2007 8:24 PM
To: ap-gto@...
Subject: Re: [ap-gto] Re: Paramount ME vs. AP 1200GTO

In a message dated 2/22/2007 6:35:57 PM Central Standard Time,

W3DX@...

writes:

If A-P had the product in stock and had the pointing model in

the

hand controller, it would make this a very easy decision for me.

I

already own/use TPoint from the computer, but having a pointing
model up and running on the hand controller would be great for
visual observing when the computer is turned off.

In an observatory situation you may never need a pointing model.

You can set

up your scope to be quite orthogonal and well polar aligned, so

the only

error
would come from atmospheric refraction, and that is already

compensated in

the keypad. In my own observatory I have set up a 10" F14.6 Mak-

Cass

permanently, and I never fail to place objects in the field of a

medium

power eyepiece. I
don't ever use a pointing model and have never failed to find

something

right
off the bat. It is a simple thing to place a bright star on the

crosshair at

the beginning of the session, press Rcal and then zoom around the

area with

pretty high precision. When I go to any other area of the sky, I

first go to

a
bright star in the area, center it if it is off, and proceed to

the object I

want to observe. It takes almost no time to do that. I have a

green laser

setup
on the scope, so I don't even have to look through the finder. The

laser

beam
is as accurate as any 1x finder system, and prevents craning my

neck at odd

angles.
A pointing model is most useful for those mounts that need to be

set up each

night fresh, but for a permanent setup it is not all that

necessary (except

for those using teeny tiny chips with loooong scopes like C14s).

Rolando


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At 09:32 AM 2/27/2007, Jeff Young wrote:

While I'm one of those people that nag Roland for a pointing model,
there's really no reason (other than that it would be cool). I've
never had a target placed outside a 26mm T5, even with all the above
caveats.

You can still use TPoint with your scope with a computer ... you do not need to have a pointing model in your hand-controller.
And if you are doing visual work only, it is unlikely that you would need a pointing model. If you are doing CCD work, I am sure that you can place objects on a chip without a pointing model with a 1200 mount. TPoint would certainly make it more likely that it would be centered however. However, if you were doing CCD work, you'd have a computer anyway so you COULD use TPoint for pointing.

So the point is, if you are using a hand-controller, it is likely that you are doing visual work, and a pointing model in that case simply gives you bragging rights and really will contribute little to your viewing enjoyment.

Enjoy your mount, worry less.


Dave

I do visual work and find a pointing model to be very useful for
improving accuracy with a less than perfectly aligned AP900. It has
nothing to do with bragging rights and everything to do with locating
an object at the edge of detection. I understand the mount is
mechanically capable of incredible pointing accuracy when the RA axis
is nearly perfectly polar aligned and the telescope OTA is
orthogonal. But when you have 2 hours and must set up from scratch
there is not much time for achieving this alignment perfection. In
this case having a model to continually improve accuracy while you
observe makes sense.

I use the PDA version of The Sky with TPoint and it improves the
pointing enough to ensure the object is very near the center of the
field with a casual setup of my AP900. Having this capability in the
hand control would be more useful because there is one less device
and fewer things to go wrong. TPoint also provides the ability to
tweak various model parameters for even greater accuracy but I just
use the default parameters and find it works fine. Hopefully the AP
implementation will make it simple and easy to use.

Bryan

--- In ap-gto@..., "David B. Toth" <ve3gyq@...> wrote:

You can still use TPoint with your scope with a computer ... you do
not need to have a pointing model in your hand-controller.
And if you are doing visual work only, it is unlikely that you

would

need a pointing model. If you are doing CCD work, I am sure that

you

can place objects on a chip without a pointing model with a 1200
mount. TPoint would certainly make it more likely that it would be
centered however. However, if you were doing CCD work, you'd have a
computer anyway so you COULD use TPoint for pointing.

So the point is, if you are using a hand-controller, it is likely
that you are doing visual work, and a pointing model in that case
simply gives you bragging rights and really will contribute little

to

your viewing enjoyment.

Enjoy your mount, worry less.


Dave

At 08:52 AM 2/28/2007, Bryan Henry wrote:

I do visual work and find a pointing model to be very useful for
improving accuracy with a less than perfectly aligned AP900. It has
nothing to do with bragging rights and everything to do with locating
an object at the edge of detection. I understand the mount is
mechanically capable of incredible pointing accuracy when the RA axis
is nearly perfectly polar aligned and the telescope OTA is
orthogonal. But when you have 2 hours and must set up from scratch
there is not much time for achieving this alignment perfection. In
this case having a model to continually improve accuracy while you
observe makes sense.

Bryan: I certainly wasn't trying to belittle anyone's effort to improve their pointing.
I have an older AP800 mount but usually use my Paramount ME when I go portable
(although it is usually in my observatory) ... I use TPoint to polar align and THEN I do
a small pointing model later (I also have TheSKY PE with TPoint).

It had been my experience though that the polar alignment scope got me pretty close for visual
observing so that pointing was not too bad. But, it of course depends on the FL of the OTA and
whether you are sure of what you saw - i.e. if you are trying to see things at the limits of detection,
I understand one feels more honest if they were more sure that the object WAS actual in a place
to be seen, rather than using averted imagination. I usually don't try to find real faint things visually
with the 7" f/7, but maybe the time has come to push the envelope a bit!

I use the PDA version of The Sky with TPoint and it improves the
pointing enough to ensure the object is very near the center of the
field with a casual setup of my AP900. Having this capability in the
hand control would be more useful because there is one less device
and fewer things to go wrong. TPoint also provides the ability to
tweak various model parameters for even greater accuracy but I just
use the default parameters and find it works fine. Hopefully the AP
implementation will make it simple and easy to use.

Well, Rolando et al have been pretty innovative in the past, so nothing would surprise me. Since you
have TPoint, you'd have the best of both worlds.

Enjoy,
Dave

At 11:05 AM 2/28/2007, David B. Toth wrote:

It had been my experience though that the polar alignment scope got
me pretty close for visual
observing so that pointing was not too bad.

Just to be clear:
I meant with the AP800 ... the ME doesn't have a polar alignment scope.

Dave