[APML] <OT> Fw: [Losmandy_users] Re: G-11 tracking issues with ST4

["joe" <jmize@svic.net>]

Here's a interesting post from the Losmandy Users group about an article to
"... intercept autoguider commands and prevent reversals in the declination
axis".  Included is a link to a PDF document to do just that.  Looks very
interesting for us ST-4 users...jeo  :)


"May You Go Among The Imperishable Stars"

Joe Mize:         http://www.svic.net/jmize
Chiefland, FL    29:24'33.4"N    82:51'37.7"W
Moon Phase:     http://tycho.usno.navy.mil/cgi-bin/phase.gif

----- Original Message ----- 
From: "Paul K" <pkane2001@hotmail.com>
To: <Losmandy_users@yahoogroups.com>
Sent: Monday, July 21, 2003 9:14 AM
Subject: [Losmandy_users] Re: G-11 tracking issues with ST4


> Jeff,
>
> --- In Losmandy_users@yahoogroups.com, "jeff_crilly" <ne14mx@s...>
> wrote:
> > during my last session I tried _calibrating_
> > at .5x for 10 seconds and _guiding_ at .5x with the
> > aggressiveness at like 6.
> > I used to calibrate at 2x and guide at .5x.
>
> I'd suspect you'll never want to callibrate at a rate higher than the
> sidereal. Doing so introduces possibility of backlash. I usually
> callibrate at 0.6x sidereal and guide at 0.5x sidereal with my Gemini-
> equipped G11.
>
> With CCDSoft, you can decrease aggressiveness, so you'd not need to
> use this trick. ST-4 does not provide an aggressiveness setting.
>
> > I also turned off guiding
> > in Y-axis and manually guided those errors out.
>
> I think you could do better by just disabling the corrections in one
> Y direction. With a slight polar misalignment, you'll only want
> corrections in the direction, opposite of the DEC drift. Any motion
> in the other direction introduces backlash and is likely to be caused
> by seeing fluctuations. By noting the DEC drift and disabling
> corrections in that direction, I eliminate all backlash problems and
> guiding performace goes up by a lot.
>
> With CCDSoft, you can disable corrections in one direction in the
> Autoguider results dialog.
>
> For ST-4, here is an article that describes the theory and
> construction of a hardware device that does the same. I just built it
> ($8 worth of parts and about 20 minutes of work) for my ST4 and it
> really works! It's an Adobe PDF file:
>
> http://ourworld.compuserve.com/homepages/twesley/blockdev.pdf
>
>
> Clear skies,
>
>         -Paul
>
>
>
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