Autoguider School is In Session

Mastering a complex piece of gear like the ST-4 autoguider requires
time -- especially when it needs to be done under a reasonably clear
sky and with temperatures that don't cause one's eyes to burn with
sweat. I held my August class last evening under a nearly full moon,
but with an otherwise pretty good sky -- only very light haze.

Remarks are at http://www.davidillig.com/ast-autoguiderschool.shtml

Davoud

--
usenet *at* davidillig dawt com

On Mon, 22 Aug 2005 17:42:11 -0400, Davoud wrote:

Mastering a complex piece of gear like the ST-4 autoguider requires
time -- especially when it needs to be done under a reasonably clear
sky and with temperatures that don't cause one's eyes to burn with
sweat. I held my August class last evening under a nearly full moon,
but with an otherwise pretty good sky -- only very light haze.

Remarks are at http://www.davidillig.com/ast-autoguiderschool.shtml

Your guiding looks pretty good- maybe a little elongation horizontally,
which I assume corresponds to your RA axis. Have you trained the PEC?
Guiders can have a hard time keeping up with PE, so I'd advise making
sure PEC is trained and enabled.

Using the ST4 standalone is useful in the field, but in an observatory
I'd plan on using it with a computer. For one thing, the guiding is a
little better (at least, it can be depending on the guiding program you
are using). But more important, you can maintain a guider correction log
which is very helpful for diagnosing problems that can (and will) crop
up. And of course, you can actually see your image. Otherwise you may be
tempted to use a device like a flip mirror, which is not a good idea.

_________________________________________________

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

Davoud:
...I held my August class last evening under a nearly full moon,
but with an otherwise pretty good sky -- only very light haze.
Remarks are at http://www.davidillig.com/ast-autoguiderschool.shtml

Chris L Peterson:
Your guiding looks pretty good- maybe a little elongation horizontally,
which I assume corresponds to your RA axis. Have you trained the PEC?
Guiders can have a hard time keeping up with PE, so I'd advise making
sure PEC is trained and enabled.

Using the ST4 standalone is useful in the field, but in an observatory
I'd plan on using it with a computer. For one thing, the guiding is a
little better (at least, it can be depending on the guiding program you
are using). But more important, you can maintain a guider correction log
which is very helpful for diagnosing problems that can (and will) crop
up. And of course, you can actually see your image. Otherwise you may be
tempted to use a device like a flip mirror, which is not a good idea.

Thanks for taking time to reply. PEC is trained and enabled, but I have
a couple of recent PEC-related updates from Meade that I haven't
installed yet. Then I'll see what is required -- add-on training or an
erase of PEC data and fresh start. One user recommended that PEC be
turned off for the Meade fork mounts when guiding with the ST-4; I
haven't thought his rationale through or tried it. My total time with
the ST-4 amounts to just a few hours (that terrible weather people have
been complaining about), and I have a substantial list of variables to
test.

MY ST-4 came with a Tau Ceti Flip-Mirror focuser, but I removed it.

Davoud

--
usenet *at* davidillig dawt com

On Tue, 23 Aug 2005 15:53:16 -0400, Davoud wrote:

One user recommended that PEC be
turned off for the Meade fork mounts when guiding with the ST-4; I
haven't thought his rationale through or tried it.

I can think of no rational reason to do that. And while I can't speak
from experience with the LX200GPS, I can say with absolute assurance
that guiding an LX200 classic with PEC turned off is virtually
impossible.

_________________________________________________

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

"Davoud" wrote in message
...

One user recommended that PEC be
turned off for the Meade fork mounts when guiding with the ST-4; I
haven't thought his rationale through or tried it.

Read he
http://www.sbig.com/sbwhtmls/st4_howto.htm

"If your mount has PEC (periodic error correction), turn it off. (Yes,
off.). The only exception to that is the Meade LX200 mounts, which often
have gears with such large errors that they cannot be effectively autoguided
without the PEC. Make sure the LX200 PEC has been very carefully programmed,
else it's worse than nothing."

Davoud:
One user recommended that PEC be
turned off for the Meade fork mounts when guiding with the ST-4; I
haven't thought his rationale through or tried it.

Stephen Paul:
Read he
http://www.sbig.com/sbwhtmls/st4_howto.htm

"If your mount has PEC (periodic error correction), turn it off. (Yes,
off.). The only exception to that is the Meade LX200 mounts, which often
have gears with such large errors that they cannot be effectively autoguided
without the PEC. Make sure the LX200 PEC has been very carefully programmed,
else it's worse than nothing."

Yeah, I have his treatisé among my documents. Poor guy. I've been
luckier than him. Even without PEC I can keep a star in the very small
square in a double-reticle eyepiece for quite a long time (haven't
timed it, because that's not my thing--but I can leave the observatory
and get a snack and a drink, go to the bathroom, check SAA, and go back
out and there it is.)

Davoud

--
usenet *at* davidillig dawt com

"Davoud" wrote in message
...
Davoud:
One user recommended that PEC be
turned off for the Meade fork mounts when guiding with the ST-4; I
haven't thought his rationale through or tried it.

Stephen Paul:
Read he
http://www.sbig.com/sbwhtmls/st4_howto.htm

"If your mount has PEC (periodic error correction), turn it off. (Yes,
off.). The only exception to that is the Meade LX200 mounts, which often
have gears with such large errors that they cannot be effectively
autoguided
without the PEC. Make sure the LX200 PEC has been very carefully
programmed,
else it's worse than nothing."

Yeah, I have his treatisé among my documents. Poor guy. I've been
luckier than him. Even without PEC I can keep a star in the very small
square in a double-reticle eyepiece for quite a long time (haven't
timed it, because that's not my thing--but I can leave the observatory
and get a snack and a drink, go to the bathroom, check SAA, and go back
out and there it is.)

I don't understand your response. I didn't mean to use the quote above to
slight the LX200. If you have decent tracking without PEC, then the
recommendation would seem to be turn it off and let the ST-4 guide out the
errors. That's all.

Davoud:
Yeah, I have his treatisé among my documents. Poor guy. I've been
luckier than him. Even without PEC I can keep a star in the very small
square in a double-reticle eyepiece for quite a long time (haven't
timed it, because that's not my thing--but I can leave the observatory
and get a snack and a drink, go to the bathroom, check SAA, and go back
out and there it is.)

Stephen Paul:
I don't understand your response. I didn't mean to use the quote above to
slight the LX200.

I didn't take it that way; I only meant that my experience hasn't been
as bad as his. In any case, I am by now somewhat familiar with the
strengths and limitations of the LX200 fork mount.

If you have decent tracking without PEC, then the recommendation
would seem to be turn it off and let the ST-4 guide out the errors.
That's all.

Good enough for visual use, but I don't know whether the ST-4 could
compensate. As I said earlier, I haven't yet tried guiding with the
ST-4 without PEC. My "school" nights are few and far between and I
haven't been able to run through the list of possible guiding
scenarios. For some reason I led myself to believe that the clear night
on 21 August would be the first of a string of clear nights, but I was
mistaken, and I have no idea when I'll get out again. Lack of
continuity doesn't help!

Davoud

--
usenet *at* davidillig dawt com

"Davoud" wrote in message
...

For some reason I led myself to believe that the clear night
on 21 August would be the first of a string of clear nights, but I was
mistaken, and I have no idea when I'll get out again. Lack of
continuity doesn't help!

I know exactly what you mean. That's why we're here. ;-)

I just got an ST4 as well. I've powered it on, and made sure that the relays
are kicking in, that's it. I have a G-11.

My thinking on the PEC thing is that the ST4 is oblivious to it. Possibly if
the ST4 kicks the RA drive at the same time that the PEC training kicks it,
you get too much compensation.