Date   

Re: Help with AP GTO on Parallax 125

Tim Khan
 

Mike,

Check if the setting on your hand controller is for
the proper mount. On the AP mounts you can set up the
hand controller for the 400, 600, 900, and 1200
mounts. Choose the correct one for your mount.

Remove your shims.

Alternate method for Othogonality:

Do a star drift alignment, get alignment very
accurate, center a star on the same hour as Polaris,
calibrate with that star, and slew to 90 degrees Dec
and same hour angle, check if setting circles agree
with computer. Doing this should prevent a change in
RA when slewing, just incase something is wrong with
the RA. Insure that you are pointing exactly 90
degrees in dec. If unsure of the Dec, pick a star and
manually slew using the mechanical setting circles to
90 degrees.

Rotate Mount with RA only. Look using medium to high
power through the scope. The stars in the field should
rotate perfectly around centered of the field, if not
your orthogonality is off, you can shim either ring to
bring the orthogonality in. Remember, you must be
polar aligned, and be point perfectly 90 degrees Dec.

Now slew to a star, like Regulus, recalibrate on the
star. Try slewing to other stars to see if it is
pointing properly.

I hope this helps.

Tim


--- Mike Mah <mikemah@...> wrote:
AP 155 EDFS, AP rings on 16" Parallax Dovetail on
Parallax 125 with
AP GTO.

I have had this out several times now and have been
unable to get it
to point accurately - place and time setup are
correct.

On calibrating with Polaris, I have used Pollux, but
after several
iterations, whenever the mount slews back to Pollux,
it is always off
by a couple of degrees and I have to push the East
button to
re-center Pollux. When it slews to Polaris, Polaris
will be centered.
When I slew to another object, I can find it by
pressing the East
button for the same period of time.

I haven't checked for orthogonality using the method
in the manual -
I don't know which stars straddling the meridian to
use and I can't
stay up later to use Arcturus as per manual. On spec
and assuming a
one degree error in orthogonality, I shimmed up the
front rings by
one quarter inch tonight and it didn't seem to make
any difference.

Even when I recalibrate on Pollux and then slew to
Castor there is
still variable error of about half a degree.

Any ideas?

Mike Mah

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Help with AP GTO on Parallax 125

Mike Mah
 

AP 155 EDFS, AP rings on 16" Parallax Dovetail on Parallax 125 with
AP GTO.

I have had this out several times now and have been unable to get it
to point accurately - place and time setup are correct.

On calibrating with Polaris, I have used Pollux, but after several
iterations, whenever the mount slews back to Pollux, it is always off
by a couple of degrees and I have to push the East button to
re-center Pollux. When it slews to Polaris, Polaris will be centered.
When I slew to another object, I can find it by pressing the East
button for the same period of time.

I haven't checked for orthogonality using the method in the manual -
I don't know which stars straddling the meridian to use and I can't
stay up later to use Arcturus as per manual. On spec and assuming a
one degree error in orthogonality, I shimmed up the front rings by
one quarter inch tonight and it didn't seem to make any difference.

Even when I recalibrate on Pollux and then slew to Castor there is
still variable error of about half a degree.

Any ideas?

Mike Mah


Re: GPS enabled A-P goto mounts

Louis A. Mamakos <louie@...>
 

Once SA is gone, accuracy will be improved perhaps by one order of
magnitude to about 10m as compared to about 100m with SA enabled. Of
course, if you're not moving, you can average your position and do somewhat
better than that.

Unless you are moving, GPS won't be of any help in figuring out your
orientation. (Well, you can play some games if you have multiple
antennas and do relative carrier-phase measurements to figure out
your orientation with respect to a satellite, but this is somewhat
specialized and expensive.)

But even today with SA, knowing where you are within about 100m
and what time it is within a couple of hundred nanoseconds ain't
too shabby..

louie

The government announced today that the purposeful degradation of the
GPS (Global Positioning System) signals available to civilian users
will end tonight. With selective availability (SA) disabled, accuracy
will improve by a noticeable amount. Just as significantly, the
accuracy of the time signal will improve as well.

Wouldn't it be neat if I could tie my GPS unit to the controller of
the A-P mount? At the very least the mount would know right where
it's positioned (latitude/longitude) and the exact date and time. It
would also know very accurately the direction of true north.

As today's press release mentions, there are many improvements to GPS
in the works ranging from more satellites to new signals being
broadcast. Unless you're a U.S. taxpayer ;-), it's free, and will
probably stay that way. Imagine a portable equatorial mount that
polar aligns itself! I expect that it will happen sooner than we
think.

Paul


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Re: Tripod for 400 GTO

Chris Spratt
 

I don't have the Davis and Sanford aluminum tripod but do use the wooden one and
this
may be more suitable in the long run if you don't get a pier.

Marc Zukoff 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: Tripod for 400 GTO

John J. Kasianowicz <surpher@...>
 

I own and use the wood tripod I bought from A-P. It's a bit heavy (I've
taken it with me to Curacao though). However, it's a stable platform for my
Traveler/AP-400 QMD. I have absolutely no regrets about purchasing it.

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.


Tripod for 400 GTO

Marc Zukoff <yooody@...>
 

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.


GPS enabled A-P goto mounts

Paul Wilson <plw@...>
 

The government announced today that the purposeful degradation of the
GPS (Global Positioning System) signals available to civilian users
will end tonight. With selective availability (SA) disabled, accuracy
will improve by a noticeable amount. Just as significantly, the
accuracy of the time signal will improve as well.

Wouldn't it be neat if I could tie my GPS unit to the controller of
the A-P mount? At the very least the mount would know right where
it's positioned (latitude/longitude) and the exact date and time. It
would also know very accurately the direction of true north.

As today's press release mentions, there are many improvements to GPS
in the works ranging from more satellites to new signals being
broadcast. Unless you're a U.S. taxpayer ;-), it's free, and will
probably stay that way. Imagine a portable equatorial mount that
polar aligns itself! I expect that it will happen sooner than we
think.

Paul


Re: Scope balancing question

Larry Denmark <kldenmark@...>
 

Wow,

Many to many "not"s in my last message <g>.

Since you stated that you can move the 9 lb. counterweight an inch or so before
noticing a difference, it implies that moving it 3 or 4 inches will make a
noticeable difference... and that's OK.

A-P makes great mounts... not sensitive beam-balances <g>.

Larry

----- Original Message -----
From: "Larry Denmark" <kldenmark@...>
To: <ap-gto@...>
Sent: Saturday, April 29, 2000 2:40 PM
Subject: Re: [ap-gto] Scope balancing question


Hi Paul,

The Traveler is light weight and there is a certain amount of inherent
stiffness
in the 600E... more so than was in my AP400 mount. But I am not certain if
you
are not experiencing a problem because I do not understand the following:

I'm not clear which axis your son had trouble turning. Did he try and rotate
the DEC axis by turning the counterweight as though it was a steering wheel
(so
as to revolve the telescope in a circle around the DEC axis, as you stated) or
did he grasp the counterweight and pull or push on the counterweight shaft (so
as to move the mount about the RA axis)? And was the traveler seated on the
mount at the time (I assume so... but do not know for sure).

If he had difficulty turning it about the DEC axis, you probably do not have a
problem. If he had trouble revolving around the RA axis, especially if the
Traveler was seated opposite the weights, the clutch plates are too tight.
They
are easy to adjust... let us know if that is the case.

Larry

E-mail . . . kldenmark@...
Web site . . http://home.att.net/~kldenmark/


Re: Scope balancing question

Larry Denmark <kldenmark@...>
 

Hi Paul,

The Traveler is light weight and there is a certain amount of inherent stiffness
in the 600E... more so than was in my AP400 mount. But I am not certain if you
are not experiencing a problem because I do not understand the following:

I'm not clear which axis your son had trouble turning. Did he try and rotate
the DEC axis by turning the counterweight as though it was a steering wheel (so
as to revolve the telescope in a circle around the DEC axis, as you stated) or
did he grasp the counterweight and pull or push on the counterweight shaft (so
as to move the mount about the RA axis)? And was the traveler seated on the
mount at the time (I assume so... but do not know for sure).

If he had difficulty turning it about the DEC axis, you probably do not have a
problem. If he had trouble revolving around the RA axis, especially if the
Traveler was seated opposite the weights, the clutch plates are too tight. They
are easy to adjust... let us know if that is the case.

Larry

E-mail . . . kldenmark@...
Web site . . http://home.att.net/~kldenmark/

----- Original Message -----
From: <Paul_Schroeder@...>
To: <ap-gto@...>
Sent: Saturday, April 29, 2000 1:30 PM
Subject: [ap-gto] Scope balancing question




Quick question. I have tried to be very careful in balancing my one month old
600 prior to each use, but I might be doing something wrong.

The challenge I'm having is that the instrument I'm using is fairly light (an
AP
Traveler) and the bearings on both axes of the 600 are really quite stiff
(much,
much more so than on my Great Polaris). Even with the clutches fully
disengaged, it takes a fair amount of force to rotate the mount on either
axis.
I had my ten year old son try to rotate the dec axis boy simply turning the
counterweight shaft and he had to try pretty hard to do it with only one hand.

Given that there's a lot of resistance to rotation, I'm not sure I've gotten
an
exact balance. I can move the 9 lb counterweight an inch or so up or down the
shaft with no real noticeable difference in the balance point, mainly due to
the
stiffness of the bearings.

Is this level of "stiffness" in the bearings typical? Should plus or minus
one
inch on counterweight position be considered sufficiently precise? I'm also
having problems with the clutches slipping (I don't want to over-tighten
them),
and I'm wondering if this is due to poor balancing.

Any suggestions would be appreciated!

Best regards,

Paul Schroeder


Scope balancing question

paul_schroeder@...
 

Quick question. I have tried to be very careful in balancing my one month old
600 prior to each use, but I might be doing something wrong.

The challenge I'm having is that the instrument I'm using is fairly light (an AP
Traveler) and the bearings on both axes of the 600 are really quite stiff (much,
much more so than on my Great Polaris). Even with the clutches fully
disengaged, it takes a fair amount of force to rotate the mount on either axis.
I had my ten year old son try to rotate the dec axis by simply turning the
counterweight shaft and he had to try pretty hard to do it with only one hand.

Given that there's a lot of resistance to rotation, I'm not sure I've gotten an
exact balance. I can move the 9 lb counterweight an inch or so up or down the
shaft with no real noticeable difference in the balance point, mainly due to the
stiffness of the bearings.

Is this level of "stiffness" in the bearings typical? Should plus or minus one
inch on counterweight position be considered sufficiently precise? I'm also
having problems with the clutches slipping (I don't want to over-tighten them),
and I'm wondering if this is due to poor balancing.

Any suggestions would be appreciated!

Best regards,

Paul Schroeder


Re: Slewing sound frequency

howard lazarus <lazhow@...>
 

Hi Brian;

I have had the 600 GTO for close to two years now getting mine in Oct 19998.
The sound on occasion does change and at times it depends on the balancing
of the weights or the EP you are using. The slight change in noise is there
but of absolute no importance and will not effect the accuraqncy of the
slew. SO ENJOY!
Howard Lazarus

----- Original Message -----
From: Brian Herbst <dbherbst@...>
To: <ap-gto@...>
Sent: Thursday, April 27, 2000 7:30 PM
Subject: [ap-gto] Slewing sound frequency


Hello,

I am a new owner of a 600EGTO mount and have had a couple of
opportunities to use it. One thing that is obvious is that I am
going
to need an illuminated reticle for the callibration routine. Also,
since my left eye is next to useless, I will be anxiously awaiting
any
polar alignment scope that may be made available (next to impossible
for me to focus just one eye to infinity through the RA shaft thus
seeing Polaris is very difficult for me). Anyway, I have a question
for the veterans here: Is it normal for the mount to fluctuate in
sound frequency as it is slewing to objects? I have the slewing
speed
set at 1200 so I would have expected a uniform motor 'whine' as the
slewing is taking place. For the most part that is what I get but
occasionally it will briefly go down in frequency (as though it is
slowing down) and then recover to the steady whine that I presume
represents the proper slewing speed. It seems to be OK regarding the
pointing accuracy so maybe I am being picky with my observations?.....
Any others here observing the same thing and is this normal?

Brian Herbst


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Good polar calibration stars?

Brian Herbst <dbherbst@...>
 

Hello,

First, let me apologize to members of this group who are south of the
equator... When doing the 'N Polar Calibrate' is there a list of
good
stars to use for this exercise anywhere? The AP manual says to pick
a
star that is in the eastern or western sky that has an RA of plus or
minus 4 hours from Polaris. It then goes on to say that Arcturus for
instance would not be a good choice. Has anyone compiled a list of
good stars by season in the east and west that would meet the
requirements? I don't have the RA and DEC of various stars committed
to memory so it would be helpful (to me at least) to have a good list
of stars available so I wouldn't make the mistake of using a star
like
Arcturus which is similar in RA to Polaris. The other night I used
Betelgeuse in the west and it seemed to be OK.

Thanks,

Brian Herbst


Slewing sound frequency

Brian Herbst <dbherbst@...>
 

Hello,

I am a new owner of a 600EGTO mount and have had a couple of
opportunities to use it. One thing that is obvious is that I am
going
to need an illuminated reticle for the callibration routine. Also,
since my left eye is next to useless, I will be anxiously awaiting
any
polar alignment scope that may be made available (next to impossible
for me to focus just one eye to infinity through the RA shaft thus
seeing Polaris is very difficult for me). Anyway, I have a question
for the veterans here: Is it normal for the mount to fluctuate in
sound frequency as it is slewing to objects? I have the slewing
speed
set at 1200 so I would have expected a uniform motor 'whine' as the
slewing is taking place. For the most part that is what I get but
occasionally it will briefly go down in frequency (as though it is
slowing down) and then recover to the steady whine that I presume
represents the proper slewing speed. It seems to be OK regarding the
pointing accuracy so maybe I am being picky with my observations?.....
Any others here observing the same thing and is this normal?

Brian Herbst


Re: Abell Catalogue and things

 

Chris,

All of the 2712 Abell galaxies are included so you can request any number
from 1 to 2712. The Abell planetaries are a separate list and are not
included in the keypad.

We'll be changing the bindings on the manuals.

Regarding polar alignment, Arcturus and Aldebaran both lie on a line that
goes through the pole and Polaris. Use Capella, Rigel, Sirius, Pollux, etc
instead.
Marjorie Christen
Astro-Physics

-----Original Message-----
From: Chris Spratt [mailto:cspratt@...]
Sent: Monday, April 10, 2000 4:41 PM
To: ap-gto@...;
Subject: [ap-gto] Abell Catalogue and things

I notice that the there are 2715 Abell galaxies listed in the GOTO
Keypad listings for my 600E mount. (Not all the Abell objects are
covered). Is there a "master" list of these somewhere as I don't want
to have to scroll down the entire list and write it out to see what
is there.

Also, the keypad's (600E Goto) manual binding is a wee bit poor as
the pages are already separating after only 2 weeks. I haven't used
it that much either! (Especially not in the damp outside.) Anyone
else noticed this? The poor binding that is.

And - On choosing stars for polar alignment it is recommended in the
600E Goto Keypad manual that one doesn't use Arcturus as it is close
to Polaris in RA. As Polaris is at 2 hours and Arcturus is closer to
14-15 why is this too close? Aldebaran on the other hand is close -
under the recommended + or - 4 hours. Misprint perhaps?


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Re: Safe zone of the 600E GTO mount.

Larry Denmark <kldenmark@...>
 

For those using TheSky, by Software Bisque to control your telescope, you
can literally map out your own unique horizon lines and keep the scope
within those set boundaries... very easy to do, too.

Larry Denmark

E-mail . . . kldenmark@...
Web site . . http://home.att.net/~kldenmark/

----- Original Message -----
From: "Marj" <marj@...>
To: <ap-gto@...>
Sent: Thursday, April 27, 2000 12:10 PM
Subject: RE: [ap-gto] Safe zone of the 600E GTO mount.


Dear Mr. Bodart,
Welcome to the list. At the present time, the safe zone setting is a
simple
circle around the zenith that the user can set on the hand controller.
Perhaps more complex safe zone controls can be incorporated into
DigitalSky
Voice in the future. Charles, are you listening?
Marjorie Christen
Astro-Physics


Re: Safe zone of the 600E GTO mount.

 

Dear Mr. Bodart,
Welcome to the list. At the present time, the safe zone setting is a simple
circle around the zenith that the user can set on the hand controller.
Perhaps more complex safe zone controls can be incorporated into DigitalSky
Voice in the future. Charles, are you listening?
Marjorie Christen
Astro-Physics

-----Original Message-----
From: Philippe BODART [mailto:phbodart@...]
Sent: Monday, April 17, 2000 10:15 AM
To: AP-GTO List;
Subject: [ap-gto] Safe zone of the 600E GTO mount.

Hi everybody

I am a newbie on this list.
I am retired and I live in Provence in the South of France.
I built an observatory above my garage in the garden.
I received my new telescope one month ago.
It is a 155 EDFS refractor with a 600E GTO mount.

For the moment I am fighting with the problem of the safe zone.
I understand it is the angle between the optical axis and the vertical
under which the OTA could hit the tripod (or the pier in my case).
In other respects the overturn zone is comprised between the hour angles
of 10:40 (OTA towards West) and 22:40 or - 1:20 (OTA towards East).
As a result there is a very large safe zone for the hour angles
close to -1:20.I give more details hereafter.
Did you make the same observations?
(I apologize if the subject has already been discussed in your list).
Is there anybody at ASTROPHYSICS I could write to?
Which e-mail?

Thank you for advising me.
Regards
Philippe Bodart.

1.Overturn zone.

The overturn zone is comprised between the hour angles of 10:40
(OTA towards West) and 22:40 or - 1:20 (OTA towards East).
This zone is independant of the set up of the safe zone (see further on).
It operates if you ask for a "go to".On the other hand with the keypad
buttons you can reach any point geometrically accessible.

It is tricky as it is possible to leave the hour movement working for a
while
without any trouble after having reached the aimed object.
Unfortunately it increases the size of the safe zone when the OTA
is close to the vertical towards East (see further on).
It is a pity that this zone cannot be set up.

2.Safe zone.

It is the angle between the optical axis and the vertical under
which the OTA could hit the tripod (or the pier in my case).
The most dangerous zone is obviously related to an hour angle of -1:20
(see above).I decided to recut the collar of my pier but you will see
that it remains relatively annoying with a camera.
With HA = -1:20 I rotated the OTA until it hit the pier and I noted
the related value of the declination.The safe angle is the complement
to 90 of the altitude (that can be calculated as a function of the hour
angle,
of the declination and of the latitude of the site with the ad'hoc trigo
formula).The safe angle is not the same according to the way you are
going towards the pier (N side or S side).
My results are the following:
-with an eyepiece 16(N side) and 18 (S side).
-with the camera "horizontal" 23(N side) and 16(S side).
-with the camera "vertical" 16 (N side) and 16 (S side).
You see that with the maximum allowed set up of 20 it remains
a risk with the camera "horizontal" (in fact parallel to the RA axis,
that allows you to have the N upside on the photos).
The set up of the safe zone prevents the OTA from tilting less than the
requested value to the vertical , even if it is not dangerous.
It is the case for hour angles bigger than 0:00 for example (the system
ignores the azimuth).
If you ask for a "go to" to a position comprised in the safe zone there
is no movement and the keyboard displays the following message:
"Outside safe zone.Slewing canceled".
On the other hand with the keypad buttons you can reach any point
geometrically accessible.

Once again it is a pity you cannot set up the overturn zone as the choice
made by the manufacturer spoils the safe zone.
On the other hand it is a pity that the system ignores the azimuth when
deciding if the movement is dangerous or not.
It took me a long time to realize all that and it is also a pity that
the handbook is not more explicit.


Re: problem connecting ST-7 to AP1200 GTO

Charles Sinsofsky <strfire@...>
 

Hello,
Contact A/P concerning this issue of using a ST-7 as an autoguider, and/or
controller of the telescope...call then, I have used my st-4 with no extra
equipment. please contact them at 815-282-1513 for details ok.

charles sinsofsky

----- Original Message -----
From: John Kruis <J.A.Kruis@...>
To: <ap-gto@...>
Sent: Tuesday, April 25, 2000 10:26 AM
Subject: [ap-gto] problem connecting ST-7 to AP1200 GTO


Has anyone ever experienced problems connecting the SBIG ST-7 to the AP
1200
GTO?
When I connect the St-7 TIC-cable to the mount it starts to move westward.
I checked cable connections/pinouts but I cannot get it right. My ST-7 is
about 4-5 years old.

John Kruis


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Re: problem connecting ST-7 to AP1200 GTO

Dan Knauss <dknauss@...>
 

John:

You might need an SBIG relay box. I needed one several years ago with
an ST-7 I was using with a VE Digitrack drive corrector. Without it, it
drove the mount continuously in right ascension. Give SBIG a call.

Dan Knauss

Has anyone ever experienced problems connecting the SBIG ST-7 to the AP
1200
GTO?
When I connect the St-7 TIC-cable to the mount it starts to move westward.
I checked cable connections/pinouts but I cannot get it right. My ST-7 is
about 4-5 years old.

John Kruis


Re: problem connecting ST-7 to AP1200 GTO

Ray Gralak <ray@...>
 

Hi John,

I use an ST-8E which is basically the same camera (but with a
different CCD chip) with my 1200 GTO with no problems. The
TIC cable by the way is a simple straight through 6-wire
cable you can get from Radio Shack or any other electronic
store. I would try getting another cable to see if that
is the problem. When you do start to guide with the 1200
make sure you set the button move speed down to 0.25x or
0.5x, otherwise the mount will move too fast when guiding.

-Ray Gralak

-----Original Message-----
From: John Kruis [mailto:J.A.Kruis@...]
Sent: Tuesday, April 25, 2000 7:27 AM
To: ap-gto@...
Subject: [ap-gto] problem connecting ST-7 to AP1200 GTO


Has anyone ever experienced problems connecting the SBIG ST-7
to the AP 1200
GTO?
When I connect the St-7 TIC-cable to the mount it starts to
move westward.
I checked cable connections/pinouts but I cannot get it
right. My ST-7 is
about 4-5 years old.

John Kruis


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problem connecting ST-7 to AP1200 GTO

John Kruis <J.A.Kruis@...>
 

Has anyone ever experienced problems connecting the SBIG ST-7 to the AP 1200
GTO?
When I connect the St-7 TIC-cable to the mount it starts to move westward.
I checked cable connections/pinouts but I cannot get it right. My ST-7 is
about 4-5 years old.

John Kruis