From: "gaffney.mark" <markgaffney@mac.com>

Date: February 19, 2008 10:35:05 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: GPUSB...

--- In Astro_IIDC@yahoogroups.com, "gaffney.mark" <markgaffney@...> wrote:

Dear Milton, Still haven`t got that messaging right?! I`ve tried slewing to the moon 

using solar system alignment then bringing it into view using adjustments to the latitude 

scale and shifts of the tripod but that method wasn`t terribly successful later for slewing 

to individual stars. That alignment on the moon does seem to correspond to my compass 

bearing quite well!? Focusing on a guide star with the CCD is going to be problematical- 

(I`ve had my nephew watch the screen whilst I perform focusing adjustments!) The scope 

has the option of adding callibration stars to the 2 star alignment so I`ll try 3 stars when 

enough of the sky is visible. I think the FCUSB is awaiting pick-up in town but the 

motorised focuser may have to wait a couple of months. Yours, Mark.

--- In Astro_IIDC@yahoogroups.com, "Milton Aupperle" <milton@> wrote:

Hi Mark;

--- In Astro_IIDC@yahoogroups.com, "gaffney.mark" markgaffney@ wrote:

Perhaps I should experiment with this first but haven`t had much of

an opportunity due to

weather. I was wondering how well my GPUSB device will compensate

for inaccurate Polar

Alignment.

It won't compensate at all. It's nothing more than a digital switch

accessed by a computer. It isn't t much different than the manual hand

controller buttons are. The only time it does any compensation is when

it tracking a guide star.

My telescope hand control isn`t yet slewing to objects correctly when

doing 2 star

alignments.

That's because it isn't polar aligned. You might get better object

finding if you use 3 stars and make sure they are well spaced apart in

both RA and Dec. It likely can determine what the

I`ve had difficulty (frustratingly) obtaining a few minutes between

showers to do

ordinary alignments! Will the GPUSB with Astro IIDC "take over" this

function providing a basic

polar alignment and Declination adjustment is made or do I have to

go back to the drawing

board with regards the initial alignments? Mark.

Are you going after Deep Sky Objects or are you going after Planetary

/ Lunar / Solar?

For planetary / lunar / solar it isn't as important, but if you want

to use really long focal lengths, then you may have difficulty keeping

the target within the small CCD field of view if it drifts a lot.

For DSO's without Accurate polar alignment Astro IIDC has to make a

large number of corrections to compensate. You also start getting star

rotation showing up in your images too, where the star rotate in your

field of view.

HTH..

Milton Aupperle