From: Alen Salamun <alien@alienworld.org>

Date: April 9, 2008 3:09:39 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Guiding Celestron mount?

Hello Milton!

I really can't belive it how Celestron would make guiding over autoguide port different as over HC commands.

Also bandwidth USB vs. Serial should be no issue at all. 115kb/s is more than enough for guiding commands and results as they are very very short.

Even if a command would be 1kb long we could issue 100 commands/s.

We clearly didn't understand us over programming help part. I wanted to say, that if you don't have Celestron mount by hand to test anything I can do it.

Well we cleared the issue, Celestron is the one to blame as it seems.

BR,

Alen

> I think you are not correct about Celestron protocol. First of all
> resolution is 0.08 arc seconds.

That's a "theoretical" number. In practice it's far less accurate.

>
> Also moving the scope is very easy in steps. You get the current
> position add/substract the amount you want to move (with 0.08 arc
> seconds resolution) and issue GOTO to calculated coordinates.

Not according to Darryl Robertson (the creator of Equinox) it isn't
simple nor reliable. Darryl and I talk a lot about stuff and most of
his GPUSB code he added to Equinox was based off of my code. Likewise
Darryl cleared up some issues I had with supporting Meade LX protocols
and shared with me some of his sample code.

And there are 2 protocols for Celestron to deal with, the older text
version and the newer Binary version, which is another complication.

> Of course mount should be polar aligned for RA/DEC goto. Alt/Az works
> without alignment.

Alt/Alz is not accurate sub pixel guiding. None of the great DSO
imagers like Richard Crisp would ever bother with Alt/Azimuth mounts.

>But isn't that so with any kind of GEM mount?

I'm not sure what you mean by this at all.

> Well I am happy to offer my assistance in supporting Celestron mounts,
> since I have quite a lot of programming experience.

I only have 20+ years of software development on the Mac.

>
> Astro IIDC is great program and why not support something as common as
> Celestron mount? Equinox, MaxDSLR... all support it.

Because we support the GPUSB and the ST4 guide ports already, which
are far lower latency than you will ever get using serial protocols.
And with GPUSB, I support a large number of mounts too for far less
effort.

Secondly, you've missed one of the advantages in not tying up that
port. You can use a program like Astro Planner or Equinox or the hand
controller to move the scope to a target and then guide off the much
more accurate and lower latency GPUSB with AstroIIDC. So you don't
have to disconnect and re-connect ports when you want to move the
scope and loose the current settings.

HTH..

Milton Aupperle