Date   

problem with mount resetting...

Todd Gross <toddg@...>
 

My mount is still resetting (A/P 600 GTO) Out of nowhere it just
resets and keeps running, but loses it's whereabouts. I am now using
a different battery (suspecting fluctuating voltage in the old) and
am going to swtich to a new cable tonight. If it keeps happening, is
there a cure short of sending it to a/p ?

thanks

Todd


Re: Recalibrating object position

Chuck Hancock
 

The only consumer software product that does what Chris is talking about
is The Sky, as far as I know. The software models the mount/scope
combination, in a way, and compensates for the differences with the
ideal.

Todd Gross wrote:


At 01:19 AM 5/14/00 -0000, you wrote:
Suppose I set the scope on M3 and hit the "Recal" button and then
move
on to the next object and "tweak" that position with another "Recal".
Does the keypad "remember" each correction and thus improve the
scope's pointing accuracy as each "Recal" is done? Eventually the
scope should be right on if the mount can remember each calibration.
no, it remembers only the last..

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Recommended telescope position on powerup

Mike Mah
 

On AP GTO, does the declination axis position on powerup matter?

I know the RA axis should be visually aligned to Polaris and the
mount should be fairly horizontal. Is there an optimal position for
the declination axis (e.g. vertical or horizontal) that might affect
pointing or ease of setup? On other Gotos, there are recommendations
for the position of the Dec axis on powerup.

When I powerup with the dec axis vertical and after alignment using
the Polaris routine, I find that the dec axis is oblique between
vertical and horizontal when pointing at Polaris. Is this of any
consequence?

I am trying to chase down my source of ponting error of up to one
degree.

Mike Mah


Re: Recalibrating object position

Todd Gross <toddg@...>
 

At 01:19 AM 5/14/00 -0000, you wrote:
Suppose I set the scope on M3 and hit the "Recal" button and then
move
on to the next object and "tweak" that position with another "Recal".
Does the keypad "remember" each correction and thus improve the
scope's pointing accuracy as each "Recal" is done? Eventually the
scope should be right on if the mount can remember each calibration.
no, it remembers only the last..


Recalibrating object position

Chris Spratt
 

Suppose I set the scope on M3 and hit the "Recal" button and then
move
on to the next object and "tweak" that position with another "Recal".
Does the keypad "remember" each correction and thus improve the
scope's pointing accuracy as each "Recal" is done? Eventually the
scope should be right on if the mount can remember each calibration.


Playback PEM corrections

Chris Spratt
 

If you "train" the PEM at 1x or .5x what speed should you set the
keypad at when playing back the PEM? I usually have my speed set at
12x and leave it there for the observing once set. Does this setting
compromise the PEM playback?


Re: AP600 RA Backlash

Ron Wodaski <ronw@...>
 

I've had the same thing happen. On some nights, it seems that backlash
compensation needs to be adjusted depending on what side of the meridian I'm
on.

Ron W

-----Original Message-----
From: Chris Spratt [mailto:cspratt@...]
Sent: Saturday, May 13, 2000 4:28 PM
To: ap-gto@...
Subject: [ap-gto] AP600 RA Backlash


I've noticed that when I "train" my RA backlash that the number I
chose one night isn't good the next. I thought that once calibrated
the RA backlash number would be retained for each session. Now I have
to reset it each observing session. I'm using version 2.6 of the
software (mount came end of March 2000).

On my mount the range at 12x runs from 4-6 with 5 the median most
nights.

The balance of the 8" OTA and attachments I'm using appears to be
good.


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AP600 RA Backlash

Chris Spratt
 

I've noticed that when I "train" my RA backlash that the number I
chose one night isn't good the next. I thought that once calibrated
the RA backlash number would be retained for each session. Now I have
to reset it each observing session. I'm using version 2.6 of the
software (mount came end of March 2000).

On my mount the range at 12x runs from 4-6 with 5 the median most
nights.

The balance of the 8" OTA and attachments I'm using appears to be
good.


Question - tracking rates on AP mounts

Tim Khan
 

This past weekend in the Everglades, A question was
posed to me "does your AP1200 mount have the King
tracking rate." I checked the menu to find only the
Lunar, Solar, and Sidereal tracking rates.

The question is: does the software taken into account
the position and adujust the tracking rate due to the
atmospheric refrction effects.

Is it possible to model a tracking rate as a function
of the pointed position. I do understand that this is
complex due to the nature of the atmospheric
refraction calculations.

What is the exact difference between the two tracking
rates in arcsecs/hour?

Tim




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Re: Tripod for 400 GTO

Chuck Hancock
 

I have a 400GTO mount on order right now, and have received an item for
adapting the mount to the Celestron Celestar 8 Deluxe tripod. I think
mountong ring is the same thing Steve is taking about. ADATRI is the
Part No. for this item.

All I had to do was go to the hardware store for the right length bolts
and some nuts.

Chuck Hancock

Steve Leikind wrote:


Marc,

One other suggstion is to use the 400 GTO mount with a Meade field
tripod. This is an especially good options if you happen already to
have Meade tripod. In order for this to work, you must first obtain
the special plate that Astro-Physics provides as standard equipment
with the Davis and Sanford tripod. I believe they sell this
separately for about $50. I found that this plate adapts the 400
Mount to my Meade tripod in the same way that works with the Davis
and Sanford. The holes in the plate and bolts provided with it line
up exactly with corresonding holes in my Meade tripood.

The Meade tripod is very sturdy and much more robust than the Davis
and Sanford. It weighs about 20 pounds and is designed to support 8
- 12" SCT's and their fork mounts having weights between 40-95
pounds. Note: it is possible that you could use the Celestron field
tripod in the same way though I do not have first hand experience
with this.

-Steve

--- In ap-gto@..., "Marc Zukoff" <yooody@a...> wrote:
I am anxiously awaiting my mount, but am wondering about the Davis
and Sanford aluminum tripod.Is it a good choice or is the wood
tripod
a better one, or any other suggestions. i am planning on using a 4
inch refractor for now, but hope to also obtain a 5 inch refractor
in
the next year.
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Re: pointing accuracy

Louis A. Mamakos <louie@...>
 

Hi Colt,

Yes, from one part of the sky to the opposite side I have
seen better than 2-arc-minutes accuracy. To get this kind
of accuracy you need to make sure your OTA is orthogonal
and that none of the optical elements shift in movement
(e.g. many SCT's primary mirrors will shift when you move
to another part of the sky). That is why I said I get this
accuracy with my refractor.
Ah, so this makes sense. Based on my experience with some digital
setting circles on my G-11 mount (on the waiting list for a 900GTO, sigh),
polar alignment doesn't seem significant. That's of course doing a
two star alignment.

Orthoganality does seem very important during alignment (e.g., the
SET DEC=0 step) can be difficult on the G-11 given the lack of a fixed
declination axis setting circle.

louie


Re: pointing accuracy

Ron Wodaski <ronw@...>
 

I think that pointing accuracy on any of the AP goto mounts is excellent,
and mostly depends on how well aligned you are to the celestial pole. On
nights when I have taken the time for really good polar alignment, objects
routinely show up in just about exactly the same spot on the CCD chip. On
those nights, it wouldn't matter what camera I was using; objects would be
on the chip. <g>

To get really high pointing accuracy, you must also make sure that your
scope is well aligned to the mount's RA axis, of course.

Ron Wodaski

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 8:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] pointing accuracy


Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@...
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Re: pointing accuracy

Ray Gralak <ray@...>
 

Hi Colt,

Yes, from one part of the sky to the opposite side I have
seen better than 2-arc-minutes accuracy. To get this kind
of accuracy you need to make sure your OTA is orthogonal
and that none of the optical elements shift in movement
(e.g. many SCT's primary mirrors will shift when you move
to another part of the sky). That is why I said I get this
accuracy with my refractor.

Take care,

-Ray

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 8:44 AM
To: ap-gto@...
Subject: Re: [ap-gto] pointing accuracy


Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@...
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Re: pointing accuracy

Colt Bednorz <colt@...>
 

Ray,
So, it's not only on the chip of a st7/8, but not too far off center.
I looked at what u see and that would even hit the st-4's
little chip for a standard sct.
Thanks
Colt

Ray Gralak wrote:

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@...
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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Re: pointing accuracy

Ray Gralak <ray@...>
 

Hi Colt,

With really good polar alignment (and my 5" refractor) I have
seen better than 2 arc-minutes accuracy on my 1200 GTO. And most
of that error could be from non-perfect polar alignment.

Taka care,

-Ray Gralak

-----Original Message-----
From: Colt Bednorz [mailto:colt@...]
Sent: Saturday, May 06, 2000 7:59 AM
To: ap-gto@...
Subject: [ap-gto] pointing accuracy



What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


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pointing accuracy

Colt Bednorz <colt@...>
 

What is the pointing accuracy of the A.P.1200?
Assuming everything is accurately set up, and polar
aligned, what do you normally get?
I would imagine that this feature, which I've never had, is
pretty nice for imaging those faint invisible objects.

Thanks
Colt Bednorz


Re: Help with AP GTO on Parallax 125

ericj <ericj@...>
 

Peter wrote:

Can you or anyone tell me where to find a
three-star alignment technique? I've never heard of that before. Does it
require polaris?
Hi Peter:

Please see my response to Mike's question about the "three star alignment
procedure". I think I inadvertently created it :-). If you cannot use
Polaris from your site and the two-star alignment procedure isn't working
try using a third calibration star. It helped me to get accurate alignment.
Let us know how it goes.

Clear Skies,

Eric Jamison


Re: Help with AP GTO on Parallax 125

ericj <ericj@...>
 

Mike Mah wrote:

What is the three star alignment procedure? I don't recall seeing
this in the manual.
Hi Mike:

I think I inadvertently created the "three star alignment procedure" :-). I
noticed the other night that after I had used the two star alignment
procedure (Polaris and Vega) when the scope slewed to a deep-sky object it
was not quite in the center of the field of view, even in a low power
eyepiece. On page 8 of the GTO Keypad Controller manual, items 7 through 14,
it recommends that using additional calibration stars to get a more accurate
polar alignment.

In my case after I used Regulus as my third calibration star (the "third"
star in my "three star alignment procedure") any deep-sky object that the
scope slewed to was near the center of the field of view of the 16mm Zeiss.
Normally when deep-sky observing I start off with a low power 2" eyepieces
like a 56mm Meade or 35mm Panoptic and work my up to higher power views
using the 1-1/4" eyepieces. But Sunday night it was late, I was tired, so I
just left the 16mm in. When AP comes out with the polar scope it should make
the whole polar alignment process much easier and faster.

I should mention that I have only had the mount for a short while, and only
had the chance to use it a few times, so am learning like everyone else.
Also, I did not mean to imply that the Dec setting circle on other AP GTO
mounts might be off slightly as mine was. I think I just happened to get one
that had this issue.

Clear Skies,

Eric Jamison

-----Original Message-----
From: Mike Mah <mikemah@...>
To: ap-gto@... <ap-gto@...>
Date: Friday, May 05, 2000 8:42 PM
Subject: Re: [ap-gto] Help with AP GTO on Parallax 125


Thanks for the advice, everyone.

What is the three star alignment procedure? I don't recall seeing
this in the manual.

Mike Mah


Re: Help with AP GTO on Parallax 125

Mike Mah
 

Thanks for the advice, everyone.

What is the three star alignment procedure? I don't recall seeing
this in the manual.

Mike Mah

--- In ap-gto@..., "ericj" <ericj@m...> wrote:
Hi Mike:

I just recently went through this with my 900 GTO mount so can
offer a
couple of suggestions.

This is how I tried to align the mount and scope on Polaris, as
suggested in
the AP manual that comes with the mount. After setting up the mount
and
setting the Dec setting circle to 90 degrees I would look through
the polar
alignment sight hole in the center of the polar axis to align on
Polaris.
Then I would add the counterweight shaft and counterweights, and
finally the
tube assembly. Each time I did this though I noted that OTA would
be offset
slightly to the left or west of Polaris.

At first I thought that I had somehow shifted the mount a little
when adding
the counterweights and tube assembly, so would just "pick up" (more
like
nudge) the mount and scope until Polaris was aligned through the
scope. But
I found that even after using the two star alignment method I would
not end
up anywhere near the deep-sky object that I was trying to find
using the GTO
feature.

So finally I looked through the polar alignment sight hole and to
my
surprise Polaris was no where to be seen, even though it was still
centered
in scope. At this point I figured the problem had to be that the
rings were
not orthogonal with the mount. So off came the OTA and after
checking the
rings realized they were fine. I then removed the ribbed mounting
plate and
examined it to see if there could be a problem with it. It was fine
too
however.

My next thought was that since I had used the used the scope and
rings on my
home made Dob mount for the past four years that somehow I warped
the rings
slightly (I rotate the rings on their sides and attach side
bearings to
them; a photo of how they look is on my web page at
http://www.metro2000.net/~ericj, and click on Telescopes). I
couldn't be
sure if this was a problem or not, and figured the only way to be
sure was
to find another pair of AP mounting rings that would not be warped.
Since I
have only had my 5.1" AP for less then a year I figured the
likelihood that
these rings would be warped as the rings for the 7.1" were was
unlikely.

So off came the 7.1" and rings, and on went the 5.1" and rings.
Same
problem. Finally, I decided to look down the polar alignment sight
hole from
the front to see if it looked aligned correctly. It didn't. With
the setting
circle to 90 degrees the Dec axis seemed off to one side. I aligned
it by
eye so that it appeared to be aligned correctly, and noted that the
Dec
setting circle read 87 degrees. Back on went the 5.1" with rings,
and this
time with the mount aligned on Polaris the scope was aligned on
Polaris as
well.

Did the two star alignment method, but although the scope slewed
closer to
the deep-sky object it still was off. So I finally tried using
three star to
align the mount: Polaris, Vega, and Regulus. This time, the scope
slewed to
M101 correctly, and with the high contrast of the 5.1" the galaxy
was sharp,
well defined and surprisingly bright. Tried a few more objects and
the
results were the same.

At this point, even though it was a during the work week, and it
was almost
midnight, I couldn't resist the temptation of not using the 7.1".
So off
came the 5.1" and on went the 7.1". This time I was even more
careful when
aligning the mount, so I got to the point that I just left a 16mm
Zeiss
eyepiece in the MaxBright when slewing from object to object and
they were
often very close to the center of the FOV, which in the 16mm is
around half
a degree or so. I finally got to bed around 2 AM, but it was worth
it, even
though I dead tired the next day a work.

So I have a couple of suggestions for you. First, check to make
sure that
the rings and OTA is orthogonal with the mount.

Second, check to see if, when looking down the front of the polar
alignment
sight hole on your mount, if the Dec axis is centered or not. If
not, you
cold have the same problem that I do. I have sent an e-mail to Marj
and
mentioned it so she is aware of the situation. Whether yours has
the same
problem or not I am not sure, but you can check.

Third, when you are doing you alignment do not use the N-S-E-W
buttons to
recenter the star if it is off to one side. Use the altitude and
azimuth
adjusters on your mount for this.

Fourth, try using three star rather then two.

Hope this helps. For what it is worth, I have found the 900 to be a
very
fine and stable mount. I got into astronomy in the early 1970's,
and got
quite use to star hopping to find deep-sky objects. When computer
controlled
telescopes first came out I did not think I would ever want one.
However,
since I have now had a chance to use the GTO feature I realize that
there
are many deep-sky objects, like some of the fainter NGC or IC
objects, that
will be much easier to find and observe now. So I look forward to
many years
of finding and observing with my AP scopes and mounts.

Clear Skies,

Eric Jamison


Re: Help with AP GTO on Parallax 125

steppzimmr@...
 

In a message dated 5/5/00 1:33:50 AM Mid-Atlantic Daylight Time,
ericj@... writes:

Fourth, try using three star rather then two.
Hi, I am very interested in this issue because I have the same problem with
my AP 600EGTO and cannot use polaris from my site. I've tried AP's two-star
alignment without success. Can you or anyone tell me where to find a
three-star alignment technique? I've never heard of that before. Does it
require polaris?

Peter