Hi Dean,

I think you are thinking of the Astro-Physics Command Center, which is still
in development.

-Ray

Hello Dean,



This is not the new Astro-Physics Command Center that Ray is still
working on. It is instead a version of the same PulseGuide you have
been using that addresses several issues primarily for southern
hemisphere observers that needed to get fixed. Anyone in the southern
hemisphere definitely needs to update to this version. There are also
a few additional items that were improved or fixed that make it
worthwhile for all of us in the north. Since the logic involved will
also apply to the new Astro-Physics Command Center, there was every
reason to go forward with the fixes even though PulseGuide is set to be
replaced with Ray's new software when it is finished.



Mag. 7 skies!



Howard Hedlund

Astro-Physics, Inc.

815-282-1513

________________________________

From: ap-gto@... [mailto:ap-gto@...] On Behalf
Of Dean S
Sent: Friday, February 15, 2008 4:40 PM
To: ap-gto@...
Subject: Re: [ap-gto] PulseGuide v1.36 is available



Hi Ray,

I thought the next version would have the object data base in it so it
could
be exactly like the handbox and I don't need a planetarium program?

Thanks,
Dean

Hi Ray,

I thought the next version would have the object data base in it so it could be exactly like the handbox and I don't need a planetarium program?

Thanks,
Dean

Hello all,

I am announcing the general availability of PulseGuide v1.36.

I want to thank Howard at AP for helping test this new version. He helped
find a few Southern hemisphere bugs and a very subtle timing bug. You can
download the new version and get a list of the new features/bug fixes here:

http://www.pulseguide.com

Direct download of the update is here:

http://www.pulseguide.com/Installs/PulseGuide136.exe

NOTE: This version will not uninstall the previous version of PulseGuide, so
you can use both versions interchangeably.

Thanks,

-Ray Gralak

Seems as though a couple different size tie wraps would work...that's what I use on my pier(and Velcro)
Chuck/divenuts

Hi,

How much effort did you put into focusing? If the ST4 is not properly
focused the guiding can be erratic.

Clear Skies,
Gert

--- In ap-gto@..., Michael Cater <nitemike1@...> wrote:

I have had no problem with the ST4 calibration mode. The problems

develops after a few minutes of guiding and then the accuracy drops
off. I will try my friend's ST4 to see if the problem is duplicated;
if his works then my ST4 is defective.

Mike

Rick K <JunkMailGoesHere@...> wrote:
If the mount works and tracks the sky without the ST4 then

it's almost

definitely the ST4. It is either incorrectly set up or the cable
connecting it to the mount is damaged or broken. Does this ST4 work
with another mount you have? Since I have never had an ST4 I would
have no idea of how to go about testing and calibrating it. There
should be lots of info on the internet though.

--- In ap-gto@..., "nitemike1" <nitemike1@> wrote:

I am new to the group. I have an AP 900 mount (V 4.12) that I bought
on Astromart. It tracks very well and the GOTO function works
flawlessly. However, I have been unable to get my ST4 to guide for
more than a few minutes at a time. I tried using the periodic error
function to correct any flaws in the RA worm but to no avail. I don't
know whether the problem is in the ST4 or the stepper motors. What
would you suggest? If it is the stepper motors is replacing them a
major expense/problem?

Thanks, Mike

---------------------------------
Be a better friend, newshound, and know-it-all with Yahoo! Mobile.

Try it now.

[Non-text portions of this message have been removed]

Michael Cater wrote:

I have had no problem with the ST4 calibration mode. The problems develops after a few minutes of guiding and then the accuracy drops off. I will try my friend's ST4 to see if the problem is duplicated; if his works then my ST4 is defective.

Mike,

It is extremely doubtful that your ST-4 is defective. The scenario that you describe isn't at all uncommon and the root cause of it is that the parameters selected are not appropriate. Just because you successfully calibrate is no guarantee that the guiding will be successful. You haven't provided nearly enough information for anyone to actually help you with this either. I would suggest that you check the group archives as Roland has explained the mount parameters needed a number of times. Then it is up to you to provide the following.

1) A known good Autoguider Cable

2) Accurate Polar Alignment

3) Reasonable Parameter Settings for the ST-4.

I can assure you that both of my ST-4's worked well with my AP900 Mount.

The situation that you describe indicate that the feedback loop is out of kilter. Assuming that the Polar Alignment is good enough.


Regards

Bill


--

William R. Mattil : http://www.celestial-images.com

Thank you, for your input. I have a feeling that it's an ST4 problem.

Mike

chris1011@... wrote:
In a message dated 2/14/2008 10:36:37 AM Central Standard Time,
nitemike1@... writes:

I have had no problem with the calibration function of the ST4 as long as I
calibrate for about 10 seconds in both axis. When the guiding starts it
seems to work well for several minutes and then the numbers on the screen
progressively increase in the RA axis (as in periodic error).

1) In the old days when I was using one of these beasts, I figured out quite
quickly that I could not determine anything by looking at the numbers. I
placed a crosshair eyepiece on a seperate telescope, and while the ST4 was doing
its thing, I monitored the prosition of the star on the crosshair. So, if you
don't start out with this fundamental concept, you will probably be in the dark.
Start by watching the star motion when you calibrate. Is the star actually
moving in the 2 directions N-S and E-W? Next, press the 4 direction buttons.
Does the star actually move when you do this? If you don't do these things, then
you might as well forget trying to work with the ST4.

2) Your symptoms do not indicate periodic error. They do not indicate any
kind of mount electronics error besides maybe a slight polar misalignment (which
is not a mount problem). They indicate simply that the ST4 is probably not
sending any correction signals to the mount, and the star is simply drifting
slowly away from the center (stars will always drift for a variety of reasons not
related to the mount electronics, so this is quite normal).

Finally, your heading is misleading. It should not read "AP 900 Mount
problem", rather it should say "SBIG ST4 Problem".

Rolando

**************
The year's hottest artists on the red carpet at the
Grammy Awards. Go to AOL Music.

(http://music.aol.com/grammys?NCID=aolcmp00300000002565)








---------------------------------
Looking for last minute shopping deals? Find them fast with Yahoo! Search.

I definately know what I am doing when I use an AP mount. I
presently own an AP 6OO GOTO, a 9OO GOTO a 12OO GOTO and a 12OO QMD.
I am selling the AP 6OO Goto so I can buy a Mach1. I often carry my
AP 155 F/7 out and do a very rough polar alignment from my backyard
where you can NOT see Polaris. By synchronizing on the first few
objects I am able to find whatever I am looking for. As for webcam
imaging being incredibly simple and that once you've done Mars,
Jupiter and Saturn you are pretty much done, all I can do is laugh.
These planets change, often nightly. If you try to get images like
Alan, and I do, it is not "easy". There is an art and a science to
it. I can imagine Deep Sky imaging is great fun. I did it for a while
with an SBIG ST-6 years ago. I prefer the Sun, Moon and planets.

All the Best,

JIm Phillips

Yes, it takes time to set up and polar align so that one can do half
hour to hour long exposures without field rotation with a big chip
CCD. There is no getting around it. Multiple short exposures simply

do

not give the best results.

Webcam imaging is incredibly simple in comparison. I have done both
but prefer the big CCD and deepsky. Once you have done Mars, Jupiter
and Saturn, you are pretty much done. That is unless you are Alan
Friedman who pops up fairly regularly to post those incredible lunar
shots. VERY nice stuff indeed.

One should NEVER use SYNC with an AP mount unless you are really
familiar with how it works. RCAL instead. One of those "nearby"

goto's

might smack your scope into the pier one day otherwise. Besides, if
you are using the keypad then you have already hauled out the power
supply can 110 cord or battery, mount cords, keypad, etc. Might as
well screw in the PAS and spend a minute or two getting a close

polar

alignment. If I work at it with my PAS v3 for a bit, maybe 5 minutes
or so, I can get really close - as in good enough for imaging with

15

to 20 minute shots. For some reason my PAS v4 isn't quite as nicely
aligned. One of these days I might get around to tuning it in.

I like looking all over the sky and when I send keypad commands to
goto someplace 120 degrees away I like it to go there and I like it

to

be in the FOV. It really doesn't take that long to do a rough polar
alignment with the PAS, but it does take a while to get everything
ready to go with power, control and cables. If I am strictly hands

on

and manually slewing the scope (push-to) then polar alignment

matters

not other than if I want to use a star atlas to combination star hop
and follow those invisible lines in the sky that cross each page.

It all depends on how you want to use your mount. I personally like

to

have it polar aligned and powered up no matter what my plans are for
the evening.



--- In ap-gto@..., "jimhp29401us" <thefamily111@> wrote:

Wow you guys who do Deep Sky imaging must need Very accurate

polar

alignment. You don't need to be that accurately alighned to use

the

GOTO. You just center then Syn on objects (Go to bright objects
initially) and soon the mount compensates and takes you to

whatever

you are looking for in that area of the sky. For webcam imaging

of

the moon, sun and planets you do not need precise polar alignment
either, just slow motion controls in both axis that allow you to

keep

the object on your laptop screen while imaging. It can roam all

over

the screen as long as it stays on and you have no problem

processing

in registax.

Jim Phillips

Hmm,

It takes me 5 minutes to cart my pier up out of the basement,

out to

the sheltered spot I usually try to observe from and set it up.

Next 5

minutes is spent bringing out the Mach1 mount and attaching it,

going

back in and getting the counterweights, and shaft is another 5
minutes, bringing out the scope another 5, going back in for the
finder, diagonal and eyepiece case or a few eyepieces to use

another 5

minutes, going back in and getting whatever I forgot to get on

one

of

the other trips another 5 minutes, all in all, about a 25 to 30
minutes before I am ready to go. If I want to have power and

roughly

polar align using the PAS so that I can goto all over the sky

it is

another 10 minutes to get the keypad, cables, power supply,

power

cord, PAS and roughly polar align so that objects pretty much

always

end up somewhere in a low power eyepiece view.

If I had a DM6 on the same pier and using the same scope it

would

take

about 10 minutes less since there are no counterweights and

there is

no need to polar align. A quick alignment on a couple of bright

stars

and away you go. Of course one could get away with a lighter

tripod

which means that there could be one less trip to make since

tripod

and

head could be managed in one trip quite easily. It is all

relative.

Is

that reduction of 10 or 15 minutes worth spending another $2500

for

a

DM6 and rigid lightweight tripod for a very marginal "grab and

go"

set-up on top of the purchase of the Mach1 and pier? I usually

reserve

the meaning of a "grab and go" as a complete unit, manageable

in one

piece with two hands most of the time but one when necessary to

open

doors. The DM6 nor the Mach1 nor any of their kinfolk need not

apply

in my mind. This is the purview of a small 60 to 80mm

lightweight

scope on a lightweight alt-az or GE on a lightweight tripod.

Plunk

it

down and if a GE plunk it down with the polar axis pointing

roughly

north. Since most of these small GE mounts use C or D cell

battery

packs, flick the switch and you should be tracking. Use the

optical

finder or unit finder or attached laser pointer to locate the

subject

and look into the eyepiece.

In all fairness, I could use a really light scope and keep it

on the

Mach1 with a really light tripod to hold everything and attempt

to

get

it all out the door without damaging myself or anything else

but I

just don't think it would be a very useful combination of

parts. The

Mach1GTO is a high quality mount and I think it should be

treated as

such. There are lots of capabilities built in and they are

worth

using.

For CCD imaging the time goes way up. At least 45 minutes to

set up.

Another 30 minutes to polar align, focus, flat frame, etc.

Another 5

to 15 minutes to get on the object, get a guide star, set up the
software to image. If I can actually, in practice, go from

nothing

to

imaging in less than an hour and a half I usually consider it a

miracle.

IF I had a permanent pier it would take less time. IF I had a
permanently aligned mount on that pier with all the doodads

attached

it would take far less time. Then again taking it another

level, IF

I

had an observatory it might only take as long as opening the
doors/roof, and powering up before I was ready to do the flats

and

go

find a subject to image. It's all relative.



--- In ap-gto@..., chris1011@ wrote:

In a message dated 2/11/2008 5:54:37 PM Central Standard

Time,

ivanong@ writes:

The Mach1GTO takes a while to set up and take down. Many

things

to

screw and tighten- will take you about 40 min or so.

Really? Only takes me 5 minutes to set up my Mach 1. Plunk it

into

the pier,

tighten 3 hand knobs, attach scope to the dovetail plate,

insert

eyepiece,

look. What am I missing?

Rollie




**************
The year's hottest artists on the red carpet at the Grammy
Awards. Go to AOL Music.

(http://music.aol.com/grammys?NCID=aolcmp00300000002565)

My notification from AP says beginning March continuing up to several
months after.

Jim Phillips

Dear all, is there anybody here that has an update about the

beginning of delivery of the current production run of Mach 1? I
transferred the deposit to Anacortes some months ago, last rumors I
heard was that they expected to receive some units from the end of
January but have had no more news about it..

Clear Skies
Marco


___________________________________
L'email della prossima generazione? Puoi averla con la nuova Yahoo!

Mail: http://it.docs.yahoo.com/nowyoucan.html

Yes, it takes time to set up and polar align so that one can do half
hour to hour long exposures without field rotation with a big chip
CCD. There is no getting around it. Multiple short exposures simply do
not give the best results.

Webcam imaging is incredibly simple in comparison. I have done both
but prefer the big CCD and deepsky. Once you have done Mars, Jupiter
and Saturn, you are pretty much done. That is unless you are Alan
Friedman who pops up fairly regularly to post those incredible lunar
shots. VERY nice stuff indeed.

One should NEVER use SYNC with an AP mount unless you are really
familiar with how it works. RCAL instead. One of those "nearby" goto's
might smack your scope into the pier one day otherwise. Besides, if
you are using the keypad then you have already hauled out the power
supply can 110 cord or battery, mount cords, keypad, etc. Might as
well screw in the PAS and spend a minute or two getting a close polar
alignment. If I work at it with my PAS v3 for a bit, maybe 5 minutes
or so, I can get really close - as in good enough for imaging with 15
to 20 minute shots. For some reason my PAS v4 isn't quite as nicely
aligned. One of these days I might get around to tuning it in.

I like looking all over the sky and when I send keypad commands to
goto someplace 120 degrees away I like it to go there and I like it to
be in the FOV. It really doesn't take that long to do a rough polar
alignment with the PAS, but it does take a while to get everything
ready to go with power, control and cables. If I am strictly hands on
and manually slewing the scope (push-to) then polar alignment matters
not other than if I want to use a star atlas to combination star hop
and follow those invisible lines in the sky that cross each page.

It all depends on how you want to use your mount. I personally like to
have it polar aligned and powered up no matter what my plans are for
the evening.

Dear all, is there anybody here that has an update about the beginning of delivery of the current production run of Mach 1? I transferred the deposit to Anacortes some months ago, last rumors I heard was that they expected to receive some units from the end of January but have had no more news about it..

Clear Skies
Marco


___________________________________
L'email della prossima generazione? Puoi averla con la nuova Yahoo! Mail: http://it.docs.yahoo.com/nowyoucan.html

I have had no problem with the ST4 calibration mode. The problems develops after a few minutes of guiding and then the accuracy drops off. I will try my friend's ST4 to see if the problem is duplicated; if his works then my ST4 is defective.

Mike

Rick K <JunkMailGoesHere@...> wrote:
If the mount works and tracks the sky without the ST4 then it's almost
definitely the ST4. It is either incorrectly set up or the cable
connecting it to the mount is damaged or broken. Does this ST4 work
with another mount you have? Since I have never had an ST4 I would
have no idea of how to go about testing and calibrating it. There
should be lots of info on the internet though.

--- In ap-gto@..., "nitemike1" <nitemike1@...> wrote:

I am new to the group. I have an AP 900 mount (V 4.12) that I bought
on Astromart. It tracks very well and the GOTO function works
flawlessly. However, I have been unable to get my ST4 to guide for
more than a few minutes at a time. I tried using the periodic error
function to correct any flaws in the RA worm but to no avail. I don't
know whether the problem is in the ST4 or the stepper motors. What
would you suggest? If it is the stepper motors is replacing them a
major expense/problem?

Thanks, Mike

---------------------------------
Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.

I have had no problem with the calibration function of the ST4 as long as I calibrate for about 10 seconds in both axis. When the guiding starts it seems to work well for several minutes and then the numbers on the screen progressively increase in the RA axis (as in periodic error). After a few minutes the values improve only to increase again in a few minutes of guiding. Eventually, the values reach the E value (>9) which means the ST4 can't find the guide star. I will probably try my friends ST4 this weekend to see if the issue is my ST4.

Mike

chris1011@... wrote:
In a message dated 2/14/2008 6:02:21 AM Central Standard Time,
nitemike1@... writes:

I am new to the group. I have an AP 900 mount (V 4.12) that I bought
on Astromart. It tracks very well and the GOTO function works
flawlessly. However, I have been unable to get my ST4 to guide for
more than a few minutes at a time. I tried using the periodic error
function to correct any flaws in the RA worm but to no avail. I don't
know whether the problem is in the ST4 or the stepper motors. What
would you suggest? If it is the stepper motors is replacing them a
major expense/problem?

1) the 900 servo mount does not have stepper motors. If it tracks very well,
then certainly the servo motors are working properly.

2) An ST4 is not an easy beast to work with. If it does not work properly,
then it will not interact with the mount. If the relays are shot or stuck in an
open or closed position, then it will not work no matter what you do with the
mount, so the first thing you need to do is find out if the 4 relays are doing
their job properly. Next thing is to make sure that the connector cable from
the ST4 to the mount is of the proper type. You will need to the trace the
pins back to the relays with an ohmmeter to make sure that the proper pins are
opening and closing when the 4 direction buttons on the ST4 are pushed. If the
ST4 is not set up properly, you can forget about using it to guide the mount.

3) you mention that you tried to use the periodic error function to correct
any flaws in the worm. What flaws are in the worm that you are trying to
correct, and how are you setting up the periodic error compensation to do this? Are
you guiding by hand and loading the PE curve this way? Are you using PEMPro?
What is your method for loading the PE curve?

Rolando

**************
The year's hottest artists on the red carpet at the
Grammy Awards. Go to AOL Music.

(http://music.aol.com/grammys?NCID=aolcmp00300000002565)








---------------------------------
Never miss a thing. Make Yahoo your homepage.

Wow you guys who do Deep Sky imaging must need Very accurate polar
alignment. You don't need to be that accurately alighned to use the
GOTO. You just center then Syn on objects (Go to bright objects
initially) and soon the mount compensates and takes you to whatever
you are looking for in that area of the sky. For webcam imaging of
the moon, sun and planets you do not need precise polar alignment
either, just slow motion controls in both axis that allow you to keep
the object on your laptop screen while imaging. It can roam all over
the screen as long as it stays on and you have no problem processing
in registax.

Jim Phillips

Hmm,

It takes me 5 minutes to cart my pier up out of the basement, out to
the sheltered spot I usually try to observe from and set it up.

Next 5

minutes is spent bringing out the Mach1 mount and attaching it,

going

back in and getting the counterweights, and shaft is another 5
minutes, bringing out the scope another 5, going back in for the
finder, diagonal and eyepiece case or a few eyepieces to use

another 5

minutes, going back in and getting whatever I forgot to get on one

of

the other trips another 5 minutes, all in all, about a 25 to 30
minutes before I am ready to go. If I want to have power and roughly
polar align using the PAS so that I can goto all over the sky it is
another 10 minutes to get the keypad, cables, power supply, power
cord, PAS and roughly polar align so that objects pretty much always
end up somewhere in a low power eyepiece view.

If I had a DM6 on the same pier and using the same scope it would

take

about 10 minutes less since there are no counterweights and there is
no need to polar align. A quick alignment on a couple of bright

stars

and away you go. Of course one could get away with a lighter tripod
which means that there could be one less trip to make since tripod

and

head could be managed in one trip quite easily. It is all relative.

Is

that reduction of 10 or 15 minutes worth spending another $2500 for

a

DM6 and rigid lightweight tripod for a very marginal "grab and go"
set-up on top of the purchase of the Mach1 and pier? I usually

reserve

the meaning of a "grab and go" as a complete unit, manageable in one
piece with two hands most of the time but one when necessary to open
doors. The DM6 nor the Mach1 nor any of their kinfolk need not apply
in my mind. This is the purview of a small 60 to 80mm lightweight
scope on a lightweight alt-az or GE on a lightweight tripod. Plunk

it

down and if a GE plunk it down with the polar axis pointing roughly
north. Since most of these small GE mounts use C or D cell battery
packs, flick the switch and you should be tracking. Use the optical
finder or unit finder or attached laser pointer to locate the

subject

and look into the eyepiece.

In all fairness, I could use a really light scope and keep it on the
Mach1 with a really light tripod to hold everything and attempt to

get

it all out the door without damaging myself or anything else but I
just don't think it would be a very useful combination of parts. The
Mach1GTO is a high quality mount and I think it should be treated as
such. There are lots of capabilities built in and they are worth

using.

For CCD imaging the time goes way up. At least 45 minutes to set up.
Another 30 minutes to polar align, focus, flat frame, etc. Another 5
to 15 minutes to get on the object, get a guide star, set up the
software to image. If I can actually, in practice, go from nothing

to

imaging in less than an hour and a half I usually consider it a

miracle.

IF I had a permanent pier it would take less time. IF I had a
permanently aligned mount on that pier with all the doodads attached
it would take far less time. Then again taking it another level, IF

I

had an observatory it might only take as long as opening the
doors/roof, and powering up before I was ready to do the flats and

go

find a subject to image. It's all relative.



--- In ap-gto@..., chris1011@ wrote:

In a message dated 2/11/2008 5:54:37 PM Central Standard Time,
ivanong@ writes:

The Mach1GTO takes a while to set up and take down. Many things

to

screw and tighten- will take you about 40 min or so.

Really? Only takes me 5 minutes to set up my Mach 1. Plunk it into

the pier,

tighten 3 hand knobs, attach scope to the dovetail plate, insert

eyepiece,

look. What am I missing?

Rollie




**************
The year's hottest artists on the red carpet at the Grammy
Awards. Go to AOL Music.

(http://music.aol.com/grammys?NCID=aolcmp00300000002565)


[Non-text portions of this message have been removed]

Has anyone ever tried to use a laser collimator to very accurately align the reticle in the
PASILL scope? I would be interested in developing a technique for this.

Thanks for any thoughts.

If the mount works and tracks the sky without the ST4 then it's almost
definitely the ST4. It is either incorrectly set up or the cable
connecting it to the mount is damaged or broken. Does this ST4 work
with another mount you have? Since I have never had an ST4 I would
have no idea of how to go about testing and calibrating it. There
should be lots of info on the internet though.

Kent et al,

Earlier today I received the two AP adapters (LT2APM+ADATRI) which
will allow me to mate the Mach1GTO to my Losmandy G11 tripod and pier.
Typical AP engineering and quality as always.

For anyone who may be interested, the two plates (LT2APM+ADATRI) mated
together weigh approximately 5 lbs. I find this very positive since it
adds further weight to an already heavy and stable system.

Over the next day or two I will have everything all set up and I will
provide photos. The Losmandy G11 tripod and pier is a sweet match for
the Mach1GTO. Very highly recommended!

Clear skies.

Anthony.

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

Kent,

Thanks for the clarification. I am exchanging emails right now with
Christine since I would like to get the necessary adapter(s) ASAP.

Anthony.

--- In ap-gto@..., kgkirkley@ wrote:

Anthony:

Please see below,

Are you sure the second adapter (ADATRI) in your list below is
required? I just checked the AP website and I see the comment

"Adapter

to attach Losmandy HD Tripod or Losmandy MA Meade Field Tripod

Adapter

to Astro-Physics 400/600/900/Mach1 Mounts. Includes screw packet."

and

which makes no reference for a need of the second adapter.


These were just announced last week and I believe both are needed.
Perhaps someone from AP could comment.

Also, the first adapter you describe (LT2APM) seems to be for the
Losmandy HD tripod. Is this the same tripod as the well-known

Losmandy

G11? Going by shear memory, the HD may be the code for the Losmandy
HGM mount which may have the same (?) tripod pier anyway.

The Losmandy HD Tripod is the standard G-11 tripod which uses a

6inch

interface.
Check the Losmandy site and they have a lighter weight tripod as

well.

The Losmandy 'Titan' uses a bigger tripod with a 7inch interface.


Kent Kirkley




**************Biggest Grammy Award surprises of all time on AOL

Music.

(http://music.aol.com/grammys/pictures/never-won-a-grammy?NCID=aolcmp003000000025

48)


[Non-text portions of this message have been removed]

In a message dated 2/14/2008 10:36:37 AM Central Standard Time,
nitemike1@... writes:

I have had no problem with the calibration function of the ST4 as long as I
calibrate for about 10 seconds in both axis. When the guiding starts it
seems to work well for several minutes and then the numbers on the screen
progressively increase in the RA axis (as in periodic error).

1) In the old days when I was using one of these beasts, I figured out quite
quickly that I could not determine anything by looking at the numbers. I
placed a crosshair eyepiece on a seperate telescope, and while the ST4 was doing
its thing, I monitored the prosition of the star on the crosshair. So, if you
don't start out with this fundamental concept, you will probably be in the dark.
Start by watching the star motion when you calibrate. Is the star actually
moving in the 2 directions N-S and E-W? Next, press the 4 direction buttons.
Does the star actually move when you do this? If you don't do these things, then
you might as well forget trying to work with the ST4.

2) Your symptoms do not indicate periodic error. They do not indicate any
kind of mount electronics error besides maybe a slight polar misalignment (which
is not a mount problem). They indicate simply that the ST4 is probably not
sending any correction signals to the mount, and the star is simply drifting
slowly away from the center (stars will always drift for a variety of reasons not
related to the mount electronics, so this is quite normal).

Finally, your heading is misleading. It should not read "AP 900 Mount
problem", rather it should say "SBIG ST4 Problem".

Rolando


**************
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In a message dated 2/14/2008 6:02:21 AM Central Standard Time,
nitemike1@... writes:

I am new to the group. I have an AP 900 mount (V 4.12) that I bought
on Astromart. It tracks very well and the GOTO function works
flawlessly. However, I have been unable to get my ST4 to guide for
more than a few minutes at a time. I tried using the periodic error
function to correct any flaws in the RA worm but to no avail. I don't
know whether the problem is in the ST4 or the stepper motors. What
would you suggest? If it is the stepper motors is replacing them a
major expense/problem?

1) the 900 servo mount does not have stepper motors. If it tracks very well,
then certainly the servo motors are working properly.

2) An ST4 is not an easy beast to work with. If it does not work properly,
then it will not interact with the mount. If the relays are shot or stuck in an
open or closed position, then it will not work no matter what you do with the
mount, so the first thing you need to do is find out if the 4 relays are doing
their job properly. Next thing is to make sure that the connector cable from
the ST4 to the mount is of the proper type. You will need to the trace the
pins back to the relays with an ohmmeter to make sure that the proper pins are
opening and closing when the 4 direction buttons on the ST4 are pushed. If the
ST4 is not set up properly, you can forget about using it to guide the mount.

3) you mention that you tried to use the periodic error function to correct
any flaws in the worm. What flaws are in the worm that you are trying to
correct, and how are you setting up the periodic error compensation to do this? Are
you guiding by hand and loading the PE curve this way? Are you using PEMPro?
What is your method for loading the PE curve?

Rolando


**************
The year's hottest artists on the red carpet at the
Grammy Awards. Go to AOL Music.

(http://music.aol.com/grammys?NCID=aolcmp00300000002565)