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Re: Help with RA problem

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  • alwittstein
    Jamie, I have verified that I am in Photo mode, and that camera relays are set. Please see my reply to Don for details of experimentation done tonight. Thanks,
    Message 1 of 16 , Aug 3 12:44 AM
      Jamie,

      I have verified that I am in Photo mode, and that camera relays are
      set. Please see my reply to Don for details of experimentation done
      tonight.

      Thanks,

      Arnie

      --- In ccd-newastro@yahoogroups.com, "Jamie" <rhoowl@y...> wrote:
      > hi
      >
      > those oscillations sounds like your guiding in visual mode...you
      need
      > to be in photo mode....if you are guiding through the rs232 it will
      > only be set in visual mode. you need to have camera relays set and
      > guide though the autoguider port in photomode...
      >
      > jamie
      >
      > --- In ccd-newastro@yahoogroups.com, "Arnold Wittstein"
      > <arnwittstein@e...> wrote:
      > > I'm having a problem with RA tracking with my new Gemini G-11. I
      > performed
      > > the polar align procedure that got me aligned within 2.5
      arcseconds
      > of the
      > > pole. When imaging with an SBIG ST2000 with internal autoguiding,
      > I'm
      > > getting cigar-shaped stars oriented along lines of RA.
      > > The Dec is dead on - less than one pixel error in +/-Y. The RA,
      > however,
      > > swings back and forth by as much +/- 5 pixels as I sit and watch
      > the
      > > autoguiding numbers. I know this sounds like a problem in Dec, but
      > I have
      > > the camera oriented so that RA is in the X direction, and Dec is
      Y.
      > With
      > > the scope in home position, the top of the camera faces to the
      left
      > as
      > > viewed from behind the scope/camera. I have also watched the image
      > during
      > > continuous focus mode, and can watch the stars move in +/-X as I
      > hold down
      > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/- keys.
      > >
      > > Using CCDSoft, I used a guiding exposure of four seconds.
      > Initially, the
      > > guide star starts out in the middle of the guide window. For the
      > first few
      > > exposures, the star stays fairly well centered, with errors of
      > under a
      > > pixel in both X and Y axis. Then the X axis area will creep up
      over
      > a few
      > > exposures to -1.5, -1.89, -2.5 (just an example). Then it will
      > slowly
      > > swing back, and then over shoot on the +X side. Then it will
      slowly
      > (and
      > > by slowly, again over a timespan of a few 4 second exposures)
      swing
      > back
      > > to zero and overshoot in the -X direction. This is with the
      > aggressiveness
      > > set to 5. Any higher or lower and the problem worsens. So it
      > appears to me
      > > that small proper-size corrections are being made, but that they
      > don't
      > > stop in time, and the corrections continue on longer than they
      > should. The
      > > total period of the oscillation is anywhere from 12 to 24 seconds
      > (3 - 6
      > > guiding exposures) which seems too long to be aggressiveness and
      to
      > short
      > > to be periodic error. The other settings I used in CCDSoft were
      > Minimum
      > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate of
      > the mount
      > > is set to 0.8x sidereal.
      > >
      > > I balanced the mount in both Dec and RA, and then slid the
      > counterweight
      > > down a small amount on the shaft to slightly increase weight on
      the
      > east
      > > side.
      > >
      > > I sure someone can help.
      > >
      > > Thanks,
      > >
      > > Arnie
    • Don Waid
      Arnie, I ve heard reports of the Gemini system being slow in sidereal tracking and thought this might have some bearing on your problem. It does not sound
      Message 2 of 16 , Aug 3 5:32 AM
        Arnie,

        I've heard reports of the Gemini system being "slow" in sidereal tracking and thought this might have some bearing on your problem. It does not sound like you are experiencing "slow" tracking. Your stated problem seems to be something repetitive or oscillating. The RA motor or gearbox may be at fault. I assume you have a stable power supply. (At least 13.5 to 14 volts regulated.) I do not know what the worm period is on your G-11 (My MI-250 is about 4 minutes.) but it would definitely be much longer than the oscillations you report. The motor period, or gearing, would be much shorter and this brings up my point. You might try exchanging the DEC and RA motors and see if the problem follows the motor. Since you have a very good polar alignment, you may not notice a change in DEC, but if the RA problem decreases, or is eliminated, then that would pretty much isolate the problem to the motor assembly

        Good luck,

        Don Waid
        http://www.waid-observatory.com
        .
        ----- Original Message -----
        From: alwittstein
        To: ccd-newastro@yahoogroups.com
        Sent: Wednesday, August 03, 2005 3:41 AM
        Subject: [ccd-newastro] Re: Help with RA problem


        Don,

        I tried this tonight. I disabled corrections in both X and Y axes, and
        ran the autoguider for twelve minutes. You could watch the guide star
        in the guide window swinging slowly back and forth like a pendulum
        with a period of anywhere from 12 to 24 seconds (guide exposures were
        4 seconds long). The error numbers in Y (Dec) were always less than
        two pixels, while in X (RA) they vatied as much as 10 pixels on either
        side of center. When autoguiding was turned on, you could still watch
        the guide star oscillating with the same period, but the errors in Y
        were now under a pixel, and those in X were up to 3-4 pixels only. A
        five minute guided exposure produced stars that were two to three
        times wider in RA than their height in declination.

        Arnie

        --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
        > Arnold,
        >
        > What does the mount do when you turn autoguiding off? Does the
        mount track
        > slow or fast? (ie: the star moves slowly in only one direction.)
        If it
        > does, is it slow or fast?
        >
        > Don Waid
        > http://www.waid-observatory.com
        >
        > ----- Original Message -----
        > From: "Arnold Wittstein" <arnwittstein@e...>
        > To: <ccd-newastro@yahoogroups.com>
        > Sent: Tuesday, August 02, 2005 5:09 PM
        > Subject: [ccd-newastro] Help with RA problem
        >
        >
        > > I'm having a problem with RA tracking with my new Gemini G-11. I
        performed
        > > the polar align procedure that got me aligned within 2.5
        arcseconds of the
        > > pole. When imaging with an SBIG ST2000 with internal autoguiding,
        I'm
        > > getting cigar-shaped stars oriented along lines of RA.
        > > The Dec is dead on - less than one pixel error in +/-Y. The RA,
        however,
        > > swings back and forth by as much +/- 5 pixels as I sit and watch
        the
        > > autoguiding numbers. I know this sounds like a problem in Dec, but
        I have
        > > the camera oriented so that RA is in the X direction, and Dec is
        Y. With
        > > the scope in home position, the top of the camera faces to the
        left as
        > > viewed from behind the scope/camera. I have also watched the image
        during
        > > continuous focus mode, and can watch the stars move in +/-X as I
        hold down
        > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/- keys.
        > >
        > > Using CCDSoft, I used a guiding exposure of four seconds.
        Initially, the
        > > guide star starts out in the middle of the guide window. For the
        first few
        > > exposures, the star stays fairly well centered, with errors of
        under a
        > > pixel in both X and Y axis. Then the X axis area will creep up
        over a few
        > > exposures to -1.5, -1.89, -2.5 (just an example). Then it will
        slowly
        > > swing back, and then over shoot on the +X side. Then it will
        slowly (and
        > > by slowly, again over a timespan of a few 4 second exposures)
        swing back
        > > to zero and overshoot in the -X direction. This is with the
        aggressiveness
        > > set to 5. Any higher or lower and the problem worsens. So it
        appears to me
        > > that small proper-size corrections are being made, but that they
        don't
        > > stop in time, and the corrections continue on longer than they
        should. The
        > > total period of the oscillation is anywhere from 12 to 24 seconds
        (3 - 6
        > > guiding exposures) which seems too long to be aggressiveness and
        to short
        > > to be periodic error. The other settings I used in CCDSoft were
        Minimum
        > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate of
        the mount
        > > is set to 0.8x sidereal.
        > >
        > > I balanced the mount in both Dec and RA, and then slid the
        counterweight
        > > down a small amount on the shaft to slightly increase weight on
        the east
        > > side.
        > >
        > > I sure someone can help.
        > >
        > > Thanks,
        > >
        > > Arnie
        > >
        > >
        > >
        > >
        > >
        > > Yahoo! Groups Links
        > >
        > >
        > >
        > >
        > >
        > >
        > >









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        [Non-text portions of this message have been removed]
      • Keith
        Don, Have you noticed that your mi250 is slow in RA? Mine seems to correct in one direction. Always correcting toward the bottom of the graph. Is there a way
        Message 3 of 16 , Aug 3 8:20 AM
          Don,

          Have you noticed that your mi250 is slow in RA? Mine seems to correct
          in one direction. Always correcting toward the bottom of the graph.
          Is there a way to speed it up? Also, are you getting good pointing
          accurace with yours? I love my mi250 and learning to live with the
          Gemini :-)

          Keith,

          --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
          > Arnie,
          >
          > I've heard reports of the Gemini system being "slow" in sidereal
          tracking and thought this might have some bearing on your problem.
          It does not sound like you are experiencing "slow" tracking. Your
          stated problem seems to be something repetitive or oscillating. The
          RA motor or gearbox may be at fault. I assume you have a stable
          power supply. (At least 13.5 to 14 volts regulated.) I do not know
          what the worm period is on your G-11 (My MI-250 is about 4 minutes.)
          but it would definitely be much longer than the oscillations you
          report. The motor period, or gearing, would be much shorter and this
          brings up my point. You might try exchanging the DEC and RA motors
          and see if the problem follows the motor. Since you have a very good
          polar alignment, you may not notice a change in DEC, but if the RA
          problem decreases, or is eliminated, then that would pretty much
          isolate the problem to the motor assembly
          >
          > Good luck,
          >
          > Don Waid
          > http://www.waid-observatory.com
          > .
          > ----- Original Message -----
          > From: alwittstein
          > To: ccd-newastro@yahoogroups.com
          > Sent: Wednesday, August 03, 2005 3:41 AM
          > Subject: [ccd-newastro] Re: Help with RA problem
          >
          >
          > Don,
          >
          > I tried this tonight. I disabled corrections in both X and Y
          axes, and
          > ran the autoguider for twelve minutes. You could watch the guide
          star
          > in the guide window swinging slowly back and forth like a
          pendulum
          > with a period of anywhere from 12 to 24 seconds (guide exposures
          were
          > 4 seconds long). The error numbers in Y (Dec) were always less
          than
          > two pixels, while in X (RA) they vatied as much as 10 pixels on
          either
          > side of center. When autoguiding was turned on, you could still
          watch
          > the guide star oscillating with the same period, but the errors
          in Y
          > were now under a pixel, and those in X were up to 3-4 pixels
          only. A
          > five minute guided exposure produced stars that were two to three
          > times wider in RA than their height in declination.
          >
          > Arnie
          >
          > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
          wrote:
          > > Arnold,
          > >
          > > What does the mount do when you turn autoguiding off? Does the
          > mount track
          > > slow or fast? (ie: the star moves slowly in only one
          direction.)
          > If it
          > > does, is it slow or fast?
          > >
          > > Don Waid
          > > http://www.waid-observatory.com
          > >
          > > ----- Original Message -----
          > > From: "Arnold Wittstein" <arnwittstein@e...>
          > > To: <ccd-newastro@yahoogroups.com>
          > > Sent: Tuesday, August 02, 2005 5:09 PM
          > > Subject: [ccd-newastro] Help with RA problem
          > >
          > >
          > > > I'm having a problem with RA tracking with my new Gemini G-
          11. I
          > performed
          > > > the polar align procedure that got me aligned within 2.5
          > arcseconds of the
          > > > pole. When imaging with an SBIG ST2000 with internal
          autoguiding,
          > I'm
          > > > getting cigar-shaped stars oriented along lines of RA.
          > > > The Dec is dead on - less than one pixel error in +/-Y. The
          RA,
          > however,
          > > > swings back and forth by as much +/- 5 pixels as I sit and
          watch
          > the
          > > > autoguiding numbers. I know this sounds like a problem in
          Dec, but
          > I have
          > > > the camera oriented so that RA is in the X direction, and Dec
          is
          > Y. With
          > > > the scope in home position, the top of the camera faces to
          the
          > left as
          > > > viewed from behind the scope/camera. I have also watched the
          image
          > during
          > > > continuous focus mode, and can watch the stars move in +/-X
          as I
          > hold down
          > > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/-
          keys.
          > > >
          > > > Using CCDSoft, I used a guiding exposure of four seconds.
          > Initially, the
          > > > guide star starts out in the middle of the guide window. For
          the
          > first few
          > > > exposures, the star stays fairly well centered, with errors
          of
          > under a
          > > > pixel in both X and Y axis. Then the X axis area will creep
          up
          > over a few
          > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it
          will
          > slowly
          > > > swing back, and then over shoot on the +X side. Then it will
          > slowly (and
          > > > by slowly, again over a timespan of a few 4 second exposures)
          > swing back
          > > > to zero and overshoot in the -X direction. This is with the
          > aggressiveness
          > > > set to 5. Any higher or lower and the problem worsens. So it
          > appears to me
          > > > that small proper-size corrections are being made, but that
          they
          > don't
          > > > stop in time, and the corrections continue on longer than
          they
          > should. The
          > > > total period of the oscillation is anywhere from 12 to 24
          seconds
          > (3 - 6
          > > > guiding exposures) which seems too long to be aggressiveness
          and
          > to short
          > > > to be periodic error. The other settings I used in CCDSoft
          were
          > Minimum
          > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate
          of
          > the mount
          > > > is set to 0.8x sidereal.
          > > >
          > > > I balanced the mount in both Dec and RA, and then slid the
          > counterweight
          > > > down a small amount on the shaft to slightly increase weight
          on
          > the east
          > > > side.
          > > >
          > > > I sure someone can help.
          > > >
          > > > Thanks,
          > > >
          > > > Arnie
          > > >
          > > >
          > > >
          > > >
          > > >
          > > > Yahoo! Groups Links
          > > >
          > > >
          > > >
          > > >
          > > >
          > > >
          > > >
          >
          >
          >
          >
          >
          >
          >
          >
          >
          > --------------------------------------------------------------------
          ----------
          > YAHOO! GROUPS LINKS
          >
          > a.. Visit your group "ccd-newastro" on the web.
          >
          > b.. To unsubscribe from this group, send an email to:
          > ccd-newastro-unsubscribe@yahoogroups.com
          >
          > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
          of Service.
          >
          >
          > --------------------------------------------------------------------
          ----------
          >
          >
          >
          > [Non-text portions of this message have been removed]
        • Rainer
          Hi Guys, The RA tracking speed behaviour seems to be very complex. There are G11 which are fast, ok and slow. There has been no solution so far, IMHO, as it
          Message 4 of 16 , Aug 3 8:48 AM
            Hi Guys,

            The RA tracking speed behaviour seems to be very complex. There are
            G11 which are fast, ok and slow. There has been no solution so far,
            IMHO, as it has and can have a lot of reasons.

            there was some day a good expalanation to this RA tracking taking
            into consideration the refraction of the atmosphere and that sounded
            very logical to me. My G11 for example was traking to fast in RA for
            a time and now it is more or less OK. Strange but was so.

            The worm period of the G11 is about 4min and yes there is a little
            utility gor the Gemini GoTo control which you can find here

            http://pk.darkhorizons.org/GRS.htm

            You have to connect via a serial cable your PC to the RS232 port and
            when you start it, ti reports back the settings.

            The higher the number you input as tracking rate the slower the
            Gemini will make track in RA and the lower the values you input the
            faster it tracks, eg. a value of 1800 makes your mount move 180° in
            about 15-20 minutes.

            regards Rainer

            --- In ccd-newastro@yahoogroups.com, "Keith" <esteskkkk@y...> wrote:
            > Don,
            >
            > Have you noticed that your mi250 is slow in RA? Mine seems to
            correct
            > in one direction. Always correcting toward the bottom of the graph.
            > Is there a way to speed it up? Also, are you getting good pointing
            > accurace with yours? I love my mi250 and learning to live with the
            > Gemini :-)
            >
            > Keith,
            >
            > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
            > > Arnie,
            > >
            > > I've heard reports of the Gemini system being "slow" in sidereal
            > tracking and thought this might have some bearing on your problem.
            > It does not sound like you are experiencing "slow" tracking. Your
            > stated problem seems to be something repetitive or oscillating.
            The
            > RA motor or gearbox may be at fault. I assume you have a stable
            > power supply. (At least 13.5 to 14 volts regulated.) I do not
            know
            > what the worm period is on your G-11 (My MI-250 is about 4
            minutes.)
            > but it would definitely be much longer than the oscillations you
            > report. The motor period, or gearing, would be much shorter and
            this
            > brings up my point. You might try exchanging the DEC and RA motors
            > and see if the problem follows the motor. Since you have a very
            good
            > polar alignment, you may not notice a change in DEC, but if the RA
            > problem decreases, or is eliminated, then that would pretty much
            > isolate the problem to the motor assembly
            > >
            > > Good luck,
            > >
            > > Don Waid
            > > http://www.waid-observatory.com
            > > .
            > > ----- Original Message -----
            > > From: alwittstein
            > > To: ccd-newastro@yahoogroups.com
            > > Sent: Wednesday, August 03, 2005 3:41 AM
            > > Subject: [ccd-newastro] Re: Help with RA problem
            > >
            > >
            > > Don,
            > >
            > > I tried this tonight. I disabled corrections in both X and Y
            > axes, and
            > > ran the autoguider for twelve minutes. You could watch the
            guide
            > star
            > > in the guide window swinging slowly back and forth like a
            > pendulum
            > > with a period of anywhere from 12 to 24 seconds (guide
            exposures
            > were
            > > 4 seconds long). The error numbers in Y (Dec) were always less
            > than
            > > two pixels, while in X (RA) they vatied as much as 10 pixels on
            > either
            > > side of center. When autoguiding was turned on, you could still
            > watch
            > > the guide star oscillating with the same period, but the errors
            > in Y
            > > were now under a pixel, and those in X were up to 3-4 pixels
            > only. A
            > > five minute guided exposure produced stars that were two to
            three
            > > times wider in RA than their height in declination.
            > >
            > > Arnie
            > >
            > > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
            > wrote:
            > > > Arnold,
            > > >
            > > > What does the mount do when you turn autoguiding off? Does
            the
            > > mount track
            > > > slow or fast? (ie: the star moves slowly in only one
            > direction.)
            > > If it
            > > > does, is it slow or fast?
            > > >
            > > > Don Waid
            > > > http://www.waid-observatory.com
            > > >
            > > > ----- Original Message -----
            > > > From: "Arnold Wittstein" <arnwittstein@e...>
            > > > To: <ccd-newastro@yahoogroups.com>
            > > > Sent: Tuesday, August 02, 2005 5:09 PM
            > > > Subject: [ccd-newastro] Help with RA problem
            > > >
            > > >
            > > > > I'm having a problem with RA tracking with my new Gemini G-
            > 11. I
            > > performed
            > > > > the polar align procedure that got me aligned within 2.5
            > > arcseconds of the
            > > > > pole. When imaging with an SBIG ST2000 with internal
            > autoguiding,
            > > I'm
            > > > > getting cigar-shaped stars oriented along lines of RA.
            > > > > The Dec is dead on - less than one pixel error in +/-Y. The
            > RA,
            > > however,
            > > > > swings back and forth by as much +/- 5 pixels as I sit and
            > watch
            > > the
            > > > > autoguiding numbers. I know this sounds like a problem in
            > Dec, but
            > > I have
            > > > > the camera oriented so that RA is in the X direction, and
            Dec
            > is
            > > Y. With
            > > > > the scope in home position, the top of the camera faces to
            > the
            > > left as
            > > > > viewed from behind the scope/camera. I have also watched
            the
            > image
            > > during
            > > > > continuous focus mode, and can watch the stars move in +/-X
            > as I
            > > hold down
            > > > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/-

            > keys.
            > > > >
            > > > > Using CCDSoft, I used a guiding exposure of four seconds.
            > > Initially, the
            > > > > guide star starts out in the middle of the guide window.
            For
            > the
            > > first few
            > > > > exposures, the star stays fairly well centered, with errors
            > of
            > > under a
            > > > > pixel in both X and Y axis. Then the X axis area will creep
            > up
            > > over a few
            > > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it
            > will
            > > slowly
            > > > > swing back, and then over shoot on the +X side. Then it
            will
            > > slowly (and
            > > > > by slowly, again over a timespan of a few 4 second
            exposures)
            > > swing back
            > > > > to zero and overshoot in the -X direction. This is with the
            > > aggressiveness
            > > > > set to 5. Any higher or lower and the problem worsens. So
            it
            > > appears to me
            > > > > that small proper-size corrections are being made, but that
            > they
            > > don't
            > > > > stop in time, and the corrections continue on longer than
            > they
            > > should. The
            > > > > total period of the oscillation is anywhere from 12 to 24
            > seconds
            > > (3 - 6
            > > > > guiding exposures) which seems too long to be
            aggressiveness
            > and
            > > to short
            > > > > to be periodic error. The other settings I used in CCDSoft
            > were
            > > Minimum
            > > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding
            rate
            > of
            > > the mount
            > > > > is set to 0.8x sidereal.
            > > > >
            > > > > I balanced the mount in both Dec and RA, and then slid the
            > > counterweight
            > > > > down a small amount on the shaft to slightly increase
            weight
            > on
            > > the east
            > > > > side.
            > > > >
            > > > > I sure someone can help.
            > > > >
            > > > > Thanks,
            > > > >
            > > > > Arnie
            > > > >
            > > > >
            > > > >
            > > > >
            > > > >
            > > > > Yahoo! Groups Links
            > > > >
            > > > >
            > > > >
            > > > >
            > > > >
            > > > >
            > > > >
            > >
            > >
            > >
            > >
            > >
            > >
            > >
            > >
            > >
            > > ------------------------------------------------------------------
            --
            > ----------
            > > YAHOO! GROUPS LINKS
            > >
            > > a.. Visit your group "ccd-newastro" on the web.
            > >
            > > b.. To unsubscribe from this group, send an email to:
            > > ccd-newastro-unsubscribe@yahoogroups.com
            > >
            > > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
            > of Service.
            > >
            > >
            > > ------------------------------------------------------------------
            --
            > ----------
            > >
            > >
            > >
            > > [Non-text portions of this message have been removed]
          • Jamie
            hi this is due to general hysteresis in your system....i have two scopes very similar...one is a ci700 and the other the new losmandy g11.... the total pe on
            Message 5 of 16 , Aug 3 11:18 AM
              hi

              this is due to general hysteresis in your system....i have two
              scopes very similar...one is a ci700 and the other the new losmandy
              g11....

              the total pe on the ci700 was like 35 arc seconds....i then lapped
              the gears....and installed a drive belt system for this scope...i
              reduced the total pe to about 15 arc seconds....when guiding...i was
              getting 3 to 4 arc seconds jumps....and still do...although it's
              better now....but i would get a normal variation of about 2 arc
              seconds...with spikes up to 4 arc seconds..one night seeing was so
              bad i had 10 arc seconds jumps....

              so seeing condition is a factor here....

              i bought a new g11 ...the total pe on this mount was about 6 or 7
              arc seconds....i still get the spikes from seeing...on a bad night
              they can still be as high as 5 arc seconds...on a good night..they
              may hold to a little over 2 arc seconds...generally...i'm able to
              get a rms of about .5 arc seconds in the x and .2 in the y....this
              is using 1 second guiding intervals...i have also set the delay
              times after exposure from .1 sec to 0.0 seconds....i have the
              guiding rate set to 0.5 in the gemini...and agressiveness set to 6
              in maxim...

              with these setting i am able to get round stars shooting at 1800mm
              with sxvh9. if seeing conditions are poor..i will get about 1 pixel
              out of round.....but i can easily fix a 1 pixel shift...if i get
              more than one pixel i trash the image....

              if you look at my site...www.grekalova...i was able to get
              completely round stars for a 1 hour exposure...

              i also think the mount will track better if the ra is not tensioned
              too tightly....

              also..do you have the new high precision worm>?

              jamie











              --- In ccd-newastro@yahoogroups.com, "alwittstein"
              <arnwittstein@e...> wrote:
              > Don,
              >
              > I tried this tonight. I disabled corrections in both X and Y axes,
              and
              > ran the autoguider for twelve minutes. You could watch the guide
              star
              > in the guide window swinging slowly back and forth like a pendulum
              > with a period of anywhere from 12 to 24 seconds (guide exposures
              were
              > 4 seconds long). The error numbers in Y (Dec) were always less
              than
              > two pixels, while in X (RA) they vatied as much as 10 pixels on
              either
              > side of center. When autoguiding was turned on, you could still
              watch
              > the guide star oscillating with the same period, but the errors in
              Y
              > were now under a pixel, and those in X were up to 3-4 pixels only.
              A
              > five minute guided exposure produced stars that were two to three
              > times wider in RA than their height in declination.
              >
              > Arnie
              >
              > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
              wrote:
              > > Arnold,
              > >
              > > What does the mount do when you turn autoguiding off? Does the
              > mount track
              > > slow or fast? (ie: the star moves slowly in only one
              direction.)
              > If it
              > > does, is it slow or fast?
              > >
              > > Don Waid
              > > http://www.waid-observatory.com
              > >
              > > ----- Original Message -----
              > > From: "Arnold Wittstein" <arnwittstein@e...>
              > > To: <ccd-newastro@yahoogroups.com>
              > > Sent: Tuesday, August 02, 2005 5:09 PM
              > > Subject: [ccd-newastro] Help with RA problem
              > >
              > >
              > > > I'm having a problem with RA tracking with my new Gemini G-11.
              I
              > performed
              > > > the polar align procedure that got me aligned within 2.5
              > arcseconds of the
              > > > pole. When imaging with an SBIG ST2000 with internal
              autoguiding,
              > I'm
              > > > getting cigar-shaped stars oriented along lines of RA.
              > > > The Dec is dead on - less than one pixel error in +/-Y. The
              RA,
              > however,
              > > > swings back and forth by as much +/- 5 pixels as I sit and
              watch
              > the
              > > > autoguiding numbers. I know this sounds like a problem in Dec,
              but
              > I have
              > > > the camera oriented so that RA is in the X direction, and Dec
              is
              > Y. With
              > > > the scope in home position, the top of the camera faces to the
              > left as
              > > > viewed from behind the scope/camera. I have also watched the
              image
              > during
              > > > continuous focus mode, and can watch the stars move in +/-X as
              I
              > hold down
              > > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/-
              keys.
              > > >
              > > > Using CCDSoft, I used a guiding exposure of four seconds.
              > Initially, the
              > > > guide star starts out in the middle of the guide window. For
              the
              > first few
              > > > exposures, the star stays fairly well centered, with errors of
              > under a
              > > > pixel in both X and Y axis. Then the X axis area will creep up
              > over a few
              > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it will
              > slowly
              > > > swing back, and then over shoot on the +X side. Then it will
              > slowly (and
              > > > by slowly, again over a timespan of a few 4 second exposures)
              > swing back
              > > > to zero and overshoot in the -X direction. This is with the
              > aggressiveness
              > > > set to 5. Any higher or lower and the problem worsens. So it
              > appears to me
              > > > that small proper-size corrections are being made, but that
              they
              > don't
              > > > stop in time, and the corrections continue on longer than they
              > should. The
              > > > total period of the oscillation is anywhere from 12 to 24
              seconds
              > (3 - 6
              > > > guiding exposures) which seems too long to be aggressiveness
              and
              > to short
              > > > to be periodic error. The other settings I used in CCDSoft
              were
              > Minimum
              > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate
              of
              > the mount
              > > > is set to 0.8x sidereal.
              > > >
              > > > I balanced the mount in both Dec and RA, and then slid the
              > counterweight
              > > > down a small amount on the shaft to slightly increase weight
              on
              > the east
              > > > side.
              > > >
              > > > I sure someone can help.
              > > >
              > > > Thanks,
              > > >
              > > > Arnie
              > > >
              > > >
              > > >
              > > >
              > > >
              > > > Yahoo! Groups Links
              > > >
              > > >
              > > >
              > > >
              > > >
              > > >
              > > >
            • Don Waid
              Keith, Yes, I have noticed some slow tracking in RA. I am not sure if what I observed was due to some slipping of the RA clutch and possibly some polar
              Message 6 of 16 , Aug 3 12:28 PM
                Keith,

                Yes, I have noticed some slow tracking in RA. I am not sure if what I observed was due to some slipping of the RA clutch and possibly some polar misalignment. I refined my polar alignment and made sure my RA clutch screws were tight and the mount seemed to track some better in RA. I, like you, did not see very much DEC drift. I was informed by another very respected amateur astronomer that he had also noted this behavior in his Titan mount and in his MI-250. I have not been able to troubleshoot the problem further as I am building another observatory and currently do not have my mount set up. Hopefully I will have my new observatory operational in a few weeks and will be able to do some more troubleshooting. I have not observed the "oscillation" problem you are experiencing. I will probably try the Gemini Rate Setter program to see if I can eliminate any residual problem.

                http://pk.darkhorizons.org/GRS.htm

                I am exploring the possibility of using a different control system. There is a program developed by Mel Bartel called Scope II and an adapter by Sidereal Technology that may work with the Gemini motors and encoders. I have not done a great deal of research into this. I know of one person who built a 28 inch instrument that is using this combination. His is not a Gemini system but he thought it might work with my MI-250. The MI-250 is an excellent piece of equipment, but to be truthful, I have not been overly impressed with the Gemini control system. I also thought about the AP system, but it is rather expensive. My understanding is the cost to change to the AP system would be in the range of $3,500.00.

                Don Waid
                http://www.waid-observatory.com

                ----- Original Message -----
                From: Keith
                To: ccd-newastro@yahoogroups.com
                Sent: Wednesday, August 03, 2005 11:20 AM
                Subject: [ccd-newastro] Re: Help with RA problem


                Don,

                Have you noticed that your mi250 is slow in RA? Mine seems to correct
                in one direction. Always correcting toward the bottom of the graph.
                Is there a way to speed it up? Also, are you getting good pointing
                accurace with yours? I love my mi250 and learning to live with the
                Gemini :-)

                Keith,

                --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                > Arnie,
                >
                > I've heard reports of the Gemini system being "slow" in sidereal
                tracking and thought this might have some bearing on your problem.
                It does not sound like you are experiencing "slow" tracking. Your
                stated problem seems to be something repetitive or oscillating. The
                RA motor or gearbox may be at fault. I assume you have a stable
                power supply. (At least 13.5 to 14 volts regulated.) I do not know
                what the worm period is on your G-11 (My MI-250 is about 4 minutes.)
                but it would definitely be much longer than the oscillations you
                report. The motor period, or gearing, would be much shorter and this
                brings up my point. You might try exchanging the DEC and RA motors
                and see if the problem follows the motor. Since you have a very good
                polar alignment, you may not notice a change in DEC, but if the RA
                problem decreases, or is eliminated, then that would pretty much
                isolate the problem to the motor assembly
                >
                > Good luck,
                >
                > Don Waid
                > http://www.waid-observatory.com
                > .
                > ----- Original Message -----
                > From: alwittstein
                > To: ccd-newastro@yahoogroups.com
                > Sent: Wednesday, August 03, 2005 3:41 AM
                > Subject: [ccd-newastro] Re: Help with RA problem
                >
                >
                > Don,
                >
                > I tried this tonight. I disabled corrections in both X and Y
                axes, and
                > ran the autoguider for twelve minutes. You could watch the guide
                star
                > in the guide window swinging slowly back and forth like a
                pendulum
                > with a period of anywhere from 12 to 24 seconds (guide exposures
                were
                > 4 seconds long). The error numbers in Y (Dec) were always less
                than
                > two pixels, while in X (RA) they vatied as much as 10 pixels on
                either
                > side of center. When autoguiding was turned on, you could still
                watch
                > the guide star oscillating with the same period, but the errors
                in Y
                > were now under a pixel, and those in X were up to 3-4 pixels
                only. A
                > five minute guided exposure produced stars that were two to three
                > times wider in RA than their height in declination.
                >
                > Arnie
                >
                > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
                wrote:
                > > Arnold,
                > >
                > > What does the mount do when you turn autoguiding off? Does the
                > mount track
                > > slow or fast? (ie: the star moves slowly in only one
                direction.)
                > If it
                > > does, is it slow or fast?
                > >
                > > Don Waid
                > > http://www.waid-observatory.com
                > >
                > > ----- Original Message -----
                > > From: "Arnold Wittstein" <arnwittstein@e...>
                > > To: <ccd-newastro@yahoogroups.com>
                > > Sent: Tuesday, August 02, 2005 5:09 PM
                > > Subject: [ccd-newastro] Help with RA problem
                > >
                > >
                > > > I'm having a problem with RA tracking with my new Gemini G-
                11. I
                > performed
                > > > the polar align procedure that got me aligned within 2.5
                > arcseconds of the
                > > > pole. When imaging with an SBIG ST2000 with internal
                autoguiding,
                > I'm
                > > > getting cigar-shaped stars oriented along lines of RA.
                > > > The Dec is dead on - less than one pixel error in +/-Y. The
                RA,
                > however,
                > > > swings back and forth by as much +/- 5 pixels as I sit and
                watch
                > the
                > > > autoguiding numbers. I know this sounds like a problem in
                Dec, but
                > I have
                > > > the camera oriented so that RA is in the X direction, and Dec
                is
                > Y. With
                > > > the scope in home position, the top of the camera faces to
                the
                > left as
                > > > viewed from behind the scope/camera. I have also watched the
                image
                > during
                > > > continuous focus mode, and can watch the stars move in +/-X
                as I
                > hold down
                > > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/-
                keys.
                > > >
                > > > Using CCDSoft, I used a guiding exposure of four seconds.
                > Initially, the
                > > > guide star starts out in the middle of the guide window. For
                the
                > first few
                > > > exposures, the star stays fairly well centered, with errors
                of
                > under a
                > > > pixel in both X and Y axis. Then the X axis area will creep
                up
                > over a few
                > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it
                will
                > slowly
                > > > swing back, and then over shoot on the +X side. Then it will
                > slowly (and
                > > > by slowly, again over a timespan of a few 4 second exposures)
                > swing back
                > > > to zero and overshoot in the -X direction. This is with the
                > aggressiveness
                > > > set to 5. Any higher or lower and the problem worsens. So it
                > appears to me
                > > > that small proper-size corrections are being made, but that
                they
                > don't
                > > > stop in time, and the corrections continue on longer than
                they
                > should. The
                > > > total period of the oscillation is anywhere from 12 to 24
                seconds
                > (3 - 6
                > > > guiding exposures) which seems too long to be aggressiveness
                and
                > to short
                > > > to be periodic error. The other settings I used in CCDSoft
                were
                > Minimum
                > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate
                of
                > the mount
                > > > is set to 0.8x sidereal.
                > > >
                > > > I balanced the mount in both Dec and RA, and then slid the
                > counterweight
                > > > down a small amount on the shaft to slightly increase weight
                on
                > the east
                > > > side.
                > > >
                > > > I sure someone can help.
                > > >
                > > > Thanks,
                > > >
                > > > Arnie
                > > >
                > > >
                > > >
                > > >
                > > >
                > > > Yahoo! Groups Links
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                > > >
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > --------------------------------------------------------------------
                ----------
                > YAHOO! GROUPS LINKS
                >
                > a.. Visit your group "ccd-newastro" on the web.
                >
                > b.. To unsubscribe from this group, send an email to:
                > ccd-newastro-unsubscribe@yahoogroups.com
                >
                > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
                of Service.
                >
                >
                > --------------------------------------------------------------------
                ----------
                >
                >
                >
                > [Non-text portions of this message have been removed]









                ------------------------------------------------------------------------------
                YAHOO! GROUPS LINKS

                a.. Visit your group "ccd-newastro" on the web.

                b.. To unsubscribe from this group, send an email to:
                ccd-newastro-unsubscribe@yahoogroups.com

                c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


                ------------------------------------------------------------------------------



                [Non-text portions of this message have been removed]
              • Dean S
                Hi Al, Keith, Jamie, Don, I just posted a similar issue as this on the MI250 group although I am not sure if it is operator error at this point. I too am
                Message 7 of 16 , Aug 3 12:51 PM
                  Hi Al, Keith, Jamie, Don,

                  I just posted a similar issue as this on the MI250 group although I am not
                  sure if it is operator error at this point. I too am getting the elongated
                  stars in RA both while guiding with the STV, and unguided. And yes I have
                  it in photo mode :)

                  Last night I did a test with a reticle eyepiece and saw that the star always
                  returned to the starting point in a 4 minute cycle. Total movement was
                  about half the box, (12mm eyepiece, 9.25C scope). This does tell me that
                  the tracking is not too slow or fast, right? I watched it for 5 or 6 cycles
                  with little difference. When I added a bit more weight to the east, it
                  reduced the movement a little bit.

                  My STV shows spiking when guiding and the stars are oval. I am thinking it
                  is more seeing, balance, or correction aggressiveness settings related? My
                  LX200gps did this, but in DEC, and turns out it was caused mostly by gear
                  retrograde and balance issues. I'll try anything else if you have
                  suggestions.

                  Anyways, I am very interested in how it is resolved.

                  Thanks,
                  Dean
                  www.doghouseastronomy.com



                  ----- Original Message -----
                  From: "Don Waid" <dwaid1@...>
                  To: <ccd-newastro@yahoogroups.com>
                  Sent: Wednesday, August 03, 2005 3:28 PM
                  Subject: Re: [ccd-newastro] Re: Help with RA problem


                  > Keith,
                  >
                  > Yes, I have noticed some slow tracking in RA. I am not sure if what I
                  observed was due to some slipping of the RA clutch and possibly some polar
                  misalignment. I refined my polar alignment and made sure my RA clutch
                  screws were tight and the mount seemed to track some better in RA. I, like
                  you, did not see very much DEC drift. I was informed by another very
                  respected amateur astronomer that he had also noted this behavior in his
                  Titan mount and in his MI-250. I have not been able to troubleshoot the
                  problem further as I am building another observatory and currently do not
                  have my mount set up. Hopefully I will have my new observatory operational
                  in a few weeks and will be able to do some more troubleshooting. I have not
                  observed the "oscillation" problem you are experiencing. I will probably
                  try the Gemini Rate Setter program to see if I can eliminate any residual
                  problem.
                  >
                  > http://pk.darkhorizons.org/GRS.htm
                  >
                  > I am exploring the possibility of using a different control system. There
                  is a program developed by Mel Bartel called Scope II and an adapter by
                  Sidereal Technology that may work with the Gemini motors and encoders. I
                  have not done a great deal of research into this. I know of one person who
                  built a 28 inch instrument that is using this combination. His is not a
                  Gemini system but he thought it might work with my MI-250. The MI-250 is an
                  excellent piece of equipment, but to be truthful, I have not been overly
                  impressed with the Gemini control system. I also thought about the AP
                  system, but it is rather expensive. My understanding is the cost to change
                  to the AP system would be in the range of $3,500.00.
                  >
                  > Don Waid
                  > http://www.waid-observatory.com
                  >
                  > ----- Original Message -----
                  > From: Keith
                  > To: ccd-newastro@yahoogroups.com
                  > Sent: Wednesday, August 03, 2005 11:20 AM
                  > Subject: [ccd-newastro] Re: Help with RA problem
                  >
                  >
                  > Don,
                  >
                  > Have you noticed that your mi250 is slow in RA? Mine seems to correct
                  > in one direction. Always correcting toward the bottom of the graph.
                  > Is there a way to speed it up? Also, are you getting good pointing
                  > accurace with yours? I love my mi250 and learning to live with the
                  > Gemini :-)
                  >
                  > Keith,
                  >
                  > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                  > > Arnie,
                  > >
                  > > I've heard reports of the Gemini system being "slow" in sidereal
                  > tracking and thought this might have some bearing on your problem.
                  > It does not sound like you are experiencing "slow" tracking. Your
                  > stated problem seems to be something repetitive or oscillating. The
                  > RA motor or gearbox may be at fault. I assume you have a stable
                  > power supply. (At least 13.5 to 14 volts regulated.) I do not know
                  > what the worm period is on your G-11 (My MI-250 is about 4 minutes.)
                  > but it would definitely be much longer than the oscillations you
                  > report. The motor period, or gearing, would be much shorter and this
                  > brings up my point. You might try exchanging the DEC and RA motors
                  > and see if the problem follows the motor. Since you have a very good
                  > polar alignment, you may not notice a change in DEC, but if the RA
                  > problem decreases, or is eliminated, then that would pretty much
                  > isolate the problem to the motor assembly
                  > >
                  > > Good luck,
                  > >
                  > > Don Waid
                  > > http://www.waid-observatory.com
                  > > .
                  > > ----- Original Message -----
                  > > From: alwittstein
                  > > To: ccd-newastro@yahoogroups.com
                  > > Sent: Wednesday, August 03, 2005 3:41 AM
                  > > Subject: [ccd-newastro] Re: Help with RA problem
                  > >
                  > >
                  > > Don,
                  > >
                  > > I tried this tonight. I disabled corrections in both X and Y
                  > axes, and
                  > > ran the autoguider for twelve minutes. You could watch the guide
                  > star
                  > > in the guide window swinging slowly back and forth like a
                  > pendulum
                  > > with a period of anywhere from 12 to 24 seconds (guide exposures
                  > were
                  > > 4 seconds long). The error numbers in Y (Dec) were always less
                  > than
                  > > two pixels, while in X (RA) they vatied as much as 10 pixels on
                  > either
                  > > side of center. When autoguiding was turned on, you could still
                  > watch
                  > > the guide star oscillating with the same period, but the errors
                  > in Y
                  > > were now under a pixel, and those in X were up to 3-4 pixels
                  > only. A
                  > > five minute guided exposure produced stars that were two to three
                  > > times wider in RA than their height in declination.
                  > >
                  > > Arnie
                  > >
                  > > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
                  > wrote:
                  > > > Arnold,
                  > > >
                  > > > What does the mount do when you turn autoguiding off? Does the
                  > > mount track
                  > > > slow or fast? (ie: the star moves slowly in only one
                  > direction.)
                  > > If it
                  > > > does, is it slow or fast?
                  > > >
                  > > > Don Waid
                  > > > http://www.waid-observatory.com
                  > > >
                  > > > ----- Original Message -----
                  > > > From: "Arnold Wittstein" <arnwittstein@e...>
                  > > > To: <ccd-newastro@yahoogroups.com>
                  > > > Sent: Tuesday, August 02, 2005 5:09 PM
                  > > > Subject: [ccd-newastro] Help with RA problem
                  > > >
                  > > >
                  > > > > I'm having a problem with RA tracking with my new Gemini G-
                  > 11. I
                  > > performed
                  > > > > the polar align procedure that got me aligned within 2.5
                  > > arcseconds of the
                  > > > > pole. When imaging with an SBIG ST2000 with internal
                  > autoguiding,
                  > > I'm
                  > > > > getting cigar-shaped stars oriented along lines of RA.
                  > > > > The Dec is dead on - less than one pixel error in +/-Y. The
                  > RA,
                  > > however,
                  > > > > swings back and forth by as much +/- 5 pixels as I sit and
                  > watch
                  > > the
                  > > > > autoguiding numbers. I know this sounds like a problem in
                  > Dec, but
                  > > I have
                  > > > > the camera oriented so that RA is in the X direction, and Dec
                  > is
                  > > Y. With
                  > > > > the scope in home position, the top of the camera faces to
                  > the
                  > > left as
                  > > > > viewed from behind the scope/camera. I have also watched the
                  > image
                  > > during
                  > > > > continuous focus mode, and can watch the stars move in +/-X
                  > as I
                  > > hold down
                  > > > > the RA +/- keys, and move in +/-Y as I hold down the Dec +/-
                  > keys.
                  > > > >
                  > > > > Using CCDSoft, I used a guiding exposure of four seconds.
                  > > Initially, the
                  > > > > guide star starts out in the middle of the guide window. For
                  > the
                  > > first few
                  > > > > exposures, the star stays fairly well centered, with errors
                  > of
                  > > under a
                  > > > > pixel in both X and Y axis. Then the X axis area will creep
                  > up
                  > > over a few
                  > > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it
                  > will
                  > > slowly
                  > > > > swing back, and then over shoot on the +X side. Then it will
                  > > slowly (and
                  > > > > by slowly, again over a timespan of a few 4 second exposures)
                  > > swing back
                  > > > > to zero and overshoot in the -X direction. This is with the
                  > > aggressiveness
                  > > > > set to 5. Any higher or lower and the problem worsens. So it
                  > > appears to me
                  > > > > that small proper-size corrections are being made, but that
                  > they
                  > > don't
                  > > > > stop in time, and the corrections continue on longer than
                  > they
                  > > should. The
                  > > > > total period of the oscillation is anywhere from 12 to 24
                  > seconds
                  > > (3 - 6
                  > > > > guiding exposures) which seems too long to be aggressiveness
                  > and
                  > > to short
                  > > > > to be periodic error. The other settings I used in CCDSoft
                  > were
                  > > Minimum
                  > > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding rate
                  > of
                  > > the mount
                  > > > > is set to 0.8x sidereal.
                  > > > >
                  > > > > I balanced the mount in both Dec and RA, and then slid the
                  > > counterweight
                  > > > > down a small amount on the shaft to slightly increase weight
                  > on
                  > > the east
                  > > > > side.
                  > > > >
                  > > > > I sure someone can help.
                  > > > >
                  > > > > Thanks,
                  > > > >
                  > > > > Arnie
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > > Yahoo! Groups Links
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > > > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > >
                  > > --------------------------------------------------------------------
                  > ----------
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                  ----
                  > YAHOO! GROUPS LINKS
                  >
                  > a.. Visit your group "ccd-newastro" on the web.
                  >
                  > b.. To unsubscribe from this group, send an email to:
                  > ccd-newastro-unsubscribe@yahoogroups.com
                  >
                  > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
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                  > Yahoo! Groups Links
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                • Keith
                  Don, Let us know if you find any secrets to the mi250. Seems like a lot of folks with the 250 on this forum, so any info for fine tuning would be great. For
                  Message 8 of 16 , Aug 4 8:49 AM
                    Don,

                    Let us know if you find any secrets to the mi250. Seems like a lot of
                    folks with the 250 on this forum, so any info for fine tuning would
                    be great. For now I'll concentrate on getting a better polar
                    alignment if the clouds ever clear!

                    I was wondering if you have thought about putting your tutorials on
                    CD for us bandwidth challenged?

                    Keith,

                    --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                    > Keith,
                    >
                    > Yes, I have noticed some slow tracking in RA. I am not sure if
                    what I observed was due to some slipping of the RA clutch and
                    possibly some polar misalignment. I refined my polar alignment and
                    made sure my RA clutch screws were tight and the mount seemed to
                    track some better in RA. I, like you, did not see very much DEC
                    drift. I was informed by another very respected amateur astronomer
                    that he had also noted this behavior in his Titan mount and in his MI-
                    250. I have not been able to troubleshoot the problem further as I
                    am building another observatory and currently do not have my mount
                    set up. Hopefully I will have my new observatory operational in a
                    few weeks and will be able to do some more troubleshooting. I have
                    not observed the "oscillation" problem you are experiencing. I will
                    probably try the Gemini Rate Setter program to see if I can eliminate
                    any residual problem.
                    >
                    > http://pk.darkhorizons.org/GRS.htm
                    >
                    > I am exploring the possibility of using a different control
                    system. There is a program developed by Mel Bartel called Scope II
                    and an adapter by Sidereal Technology that may work with the Gemini
                    motors and encoders. I have not done a great deal of research into
                    this. I know of one person who built a 28 inch instrument that is
                    using this combination. His is not a Gemini system but he thought it
                    might work with my MI-250. The MI-250 is an excellent piece of
                    equipment, but to be truthful, I have not been overly impressed with
                    the Gemini control system. I also thought about the AP system, but
                    it is rather expensive. My understanding is the cost to change to
                    the AP system would be in the range of $3,500.00.
                    >
                    > Don Waid
                    > http://www.waid-observatory.com
                    >
                    > ----- Original Message -----
                    > From: Keith
                    > To: ccd-newastro@yahoogroups.com
                    > Sent: Wednesday, August 03, 2005 11:20 AM
                    > Subject: [ccd-newastro] Re: Help with RA problem
                    >
                    >
                    > Don,
                    >
                    > Have you noticed that your mi250 is slow in RA? Mine seems to
                    correct
                    > in one direction. Always correcting toward the bottom of the
                    graph.
                    > Is there a way to speed it up? Also, are you getting good
                    pointing
                    > accurace with yours? I love my mi250 and learning to live with
                    the
                    > Gemini :-)
                    >
                    > Keith,
                    >
                    > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
                    wrote:
                    > > Arnie,
                    > >
                    > > I've heard reports of the Gemini system being "slow" in
                    sidereal
                    > tracking and thought this might have some bearing on your
                    problem.
                    > It does not sound like you are experiencing "slow" tracking.
                    Your
                    > stated problem seems to be something repetitive or oscillating.
                    The
                    > RA motor or gearbox may be at fault. I assume you have a stable
                    > power supply. (At least 13.5 to 14 volts regulated.) I do not
                    know
                    > what the worm period is on your G-11 (My MI-250 is about 4
                    minutes.)
                    > but it would definitely be much longer than the oscillations you
                    > report. The motor period, or gearing, would be much shorter and
                    this
                    > brings up my point. You might try exchanging the DEC and RA
                    motors
                    > and see if the problem follows the motor. Since you have a very
                    good
                    > polar alignment, you may not notice a change in DEC, but if the
                    RA
                    > problem decreases, or is eliminated, then that would pretty much
                    > isolate the problem to the motor assembly
                    > >
                    > > Good luck,
                    > >
                    > > Don Waid
                    > > http://www.waid-observatory.com
                    > > .
                    > > ----- Original Message -----
                    > > From: alwittstein
                    > > To: ccd-newastro@yahoogroups.com
                    > > Sent: Wednesday, August 03, 2005 3:41 AM
                    > > Subject: [ccd-newastro] Re: Help with RA problem
                    > >
                    > >
                    > > Don,
                    > >
                    > > I tried this tonight. I disabled corrections in both X and Y
                    > axes, and
                    > > ran the autoguider for twelve minutes. You could watch the
                    guide
                    > star
                    > > in the guide window swinging slowly back and forth like a
                    > pendulum
                    > > with a period of anywhere from 12 to 24 seconds (guide
                    exposures
                    > were
                    > > 4 seconds long). The error numbers in Y (Dec) were always
                    less
                    > than
                    > > two pixels, while in X (RA) they vatied as much as 10 pixels
                    on
                    > either
                    > > side of center. When autoguiding was turned on, you could
                    still
                    > watch
                    > > the guide star oscillating with the same period, but the
                    errors
                    > in Y
                    > > were now under a pixel, and those in X were up to 3-4 pixels
                    > only. A
                    > > five minute guided exposure produced stars that were two to
                    three
                    > > times wider in RA than their height in declination.
                    > >
                    > > Arnie
                    > >
                    > > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
                    > wrote:
                    > > > Arnold,
                    > > >
                    > > > What does the mount do when you turn autoguiding off? Does
                    the
                    > > mount track
                    > > > slow or fast? (ie: the star moves slowly in only one
                    > direction.)
                    > > If it
                    > > > does, is it slow or fast?
                    > > >
                    > > > Don Waid
                    > > > http://www.waid-observatory.com
                    > > >
                    > > > ----- Original Message -----
                    > > > From: "Arnold Wittstein" <arnwittstein@e...>
                    > > > To: <ccd-newastro@yahoogroups.com>
                    > > > Sent: Tuesday, August 02, 2005 5:09 PM
                    > > > Subject: [ccd-newastro] Help with RA problem
                    > > >
                    > > >
                    > > > > I'm having a problem with RA tracking with my new Gemini
                    G-
                    > 11. I
                    > > performed
                    > > > > the polar align procedure that got me aligned within 2.5
                    > > arcseconds of the
                    > > > > pole. When imaging with an SBIG ST2000 with internal
                    > autoguiding,
                    > > I'm
                    > > > > getting cigar-shaped stars oriented along lines of RA.
                    > > > > The Dec is dead on - less than one pixel error in +/-Y.
                    The
                    > RA,
                    > > however,
                    > > > > swings back and forth by as much +/- 5 pixels as I sit
                    and
                    > watch
                    > > the
                    > > > > autoguiding numbers. I know this sounds like a problem in
                    > Dec, but
                    > > I have
                    > > > > the camera oriented so that RA is in the X direction, and
                    Dec
                    > is
                    > > Y. With
                    > > > > the scope in home position, the top of the camera faces
                    to
                    > the
                    > > left as
                    > > > > viewed from behind the scope/camera. I have also watched
                    the
                    > image
                    > > during
                    > > > > continuous focus mode, and can watch the stars move in +/-
                    X
                    > as I
                    > > hold down
                    > > > > the RA +/- keys, and move in +/-Y as I hold down the Dec
                    +/-
                    > keys.
                    > > > >
                    > > > > Using CCDSoft, I used a guiding exposure of four seconds.
                    > > Initially, the
                    > > > > guide star starts out in the middle of the guide window.
                    For
                    > the
                    > > first few
                    > > > > exposures, the star stays fairly well centered, with
                    errors
                    > of
                    > > under a
                    > > > > pixel in both X and Y axis. Then the X axis area will
                    creep
                    > up
                    > > over a few
                    > > > > exposures to -1.5, -1.89, -2.5 (just an example). Then it
                    > will
                    > > slowly
                    > > > > swing back, and then over shoot on the +X side. Then it
                    will
                    > > slowly (and
                    > > > > by slowly, again over a timespan of a few 4 second
                    exposures)
                    > > swing back
                    > > > > to zero and overshoot in the -X direction. This is with
                    the
                    > > aggressiveness
                    > > > > set to 5. Any higher or lower and the problem worsens. So
                    it
                    > > appears to me
                    > > > > that small proper-size corrections are being made, but
                    that
                    > they
                    > > don't
                    > > > > stop in time, and the corrections continue on longer than
                    > they
                    > > should. The
                    > > > > total period of the oscillation is anywhere from 12 to 24
                    > seconds
                    > > (3 - 6
                    > > > > guiding exposures) which seems too long to be
                    aggressiveness
                    > and
                    > > to short
                    > > > > to be periodic error. The other settings I used in
                    CCDSoft
                    > were
                    > > Minimum
                    > > > > Move of 0.01 second, Maximum Move of 1.0 second. Guiding
                    rate
                    > of
                    > > the mount
                    > > > > is set to 0.8x sidereal.
                    > > > >
                    > > > > I balanced the mount in both Dec and RA, and then slid
                    the
                    > > counterweight
                    > > > > down a small amount on the shaft to slightly increase
                    weight
                    > on
                    > > the east
                    > > > > side.
                    > > > >
                    > > > > I sure someone can help.
                    > > > >
                    > > > > Thanks,
                    > > > >
                    > > > > Arnie
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > > Yahoo! Groups Links
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > > ----------------------------------------------------------------
                    ----
                    > ----------
                    > > YAHOO! GROUPS LINKS
                    > >
                    > > a.. Visit your group "ccd-newastro" on the web.
                    > >
                    > > b.. To unsubscribe from this group, send an email to:
                    > > ccd-newastro-unsubscribe@yahoogroups.com
                    > >
                    > > c.. Your use of Yahoo! Groups is subject to the Yahoo!
                    Terms
                    > of Service.
                    > >
                    > >
                    > > ----------------------------------------------------------------
                    ----
                    > ----------
                    > >
                    > >
                    > >
                    > > [Non-text portions of this message have been removed]
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    >
                    > --------------------------------------------------------------------
                    ----------
                    > YAHOO! GROUPS LINKS
                    >
                    > a.. Visit your group "ccd-newastro" on the web.
                    >
                    > b.. To unsubscribe from this group, send an email to:
                    > ccd-newastro-unsubscribe@yahoogroups.com
                    >
                    > c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
                    of Service.
                    >
                    >
                    > --------------------------------------------------------------------
                    ----------
                    >
                    >
                    >
                    > [Non-text portions of this message have been removed]
                  • Dennis Persyk
                    Hi Don, You are doubtless aware that the sidereal rate is only good at the zenith, and varies at other zenith angles. When you refer to slow tracking do you
                    Message 9 of 16 , Aug 4 4:02 PM
                      Hi Don,

                      You are doubtless aware that the sidereal rate is only good at the
                      zenith, and varies at other zenith angles. When you refer to "slow"
                      tracking do you mean the servo oscillator is actually running at too
                      low a frequency?

                      Clear skies,

                      Dennis Persyk
                      Igloo Observatory Home Page http://dpersyk.home.att.net
                      Hampshire, IL

                      --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                      > Keith,
                      > [Tremendous body of text deleted for brevity ...]
                      > Yes, I have noticed some slow tracking in RA. \> Don Waid
                      > http://www.waid-observatory.com
                      >
                      > ----- Original Message -----
                      > From: Keith
                      > To: ccd-newastro@yahoogroups.com
                      > Sent: Wednesday, August 03, 2005 11:20 AM
                      > Subject: [ccd-newastro] Re: Help with RA problem
                      >
                      >
                      > Don,
                      >
                    • Donald Waid
                      Keith, Currently I am on a business trip and will not be able to tweak my MI-250 system for a while. I ll let the group know if I have any luck with it once
                      Message 10 of 16 , Aug 6 10:53 AM
                        Keith,

                        Currently I am on a business trip and will not be able to "tweak" my
                        MI-250 system for a while. I'll let the group know if I have any
                        luck with it once I return and get my new observatory operational.

                        As to the tutorial project, I am considering a CD/DVD option but it
                        probably will not materialize for a while.

                        Don Waid
                        http://www.waid-observatory.com


                        --- In ccd-newastro@yahoogroups.com, "Keith" <esteskkkk@y...> wrote:
                        > Don,
                        >
                        > Let us know if you find any secrets to the mi250. Seems like a lot
                        of
                        > folks with the 250 on this forum, so any info for fine tuning would
                        > be great. For now I'll concentrate on getting a better polar
                        > alignment if the clouds ever clear!
                        >
                        > I was wondering if you have thought about putting your tutorials on
                        > CD for us bandwidth challenged?
                        >
                        > Keith,
                        >
                        > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                        > > Keith,
                        > >
                        > > Yes, I have noticed some slow tracking in RA. I am not sure if
                        > what I observed was due to some slipping of the RA clutch and
                        > possibly some polar misalignment. I refined my polar alignment and
                        > made sure my RA clutch screws were tight and the mount seemed to
                        > track some better in RA. I, like you, did not see very much DEC
                        > drift. I was informed by another very respected amateur astronomer
                        > that he had also noted this behavior in his Titan mount and in his
                        MI-
                        > 250. I have not been able to troubleshoot the problem further as I
                        > am building another observatory and currently do not have my mount
                        > set up. Hopefully I will have my new observatory operational in a
                        > few weeks and will be able to do some more troubleshooting. I have
                        > not observed the "oscillation" problem you are experiencing. I
                        will
                        > probably try the Gemini Rate Setter program to see if I can
                        eliminate
                        > any residual problem.
                        > >
                        > > http://pk.darkhorizons.org/GRS.htm
                        > >
                        > > I am exploring the possibility of using a different control
                        > system. There is a program developed by Mel Bartel called Scope II
                        > and an adapter by Sidereal Technology that may work with the Gemini
                        > motors and encoders. I have not done a great deal of research into
                        > this. I know of one person who built a 28 inch instrument that is
                        > using this combination. His is not a Gemini system but he thought
                        it
                        > might work with my MI-250. The MI-250 is an excellent piece of
                        > equipment, but to be truthful, I have not been overly impressed
                        with
                        > the Gemini control system. I also thought about the AP system, but
                        > it is rather expensive. My understanding is the cost to change to
                        > the AP system would be in the range of $3,500.00.
                        > >
                        > > Don Waid
                        > > http://www.waid-observatory.com
                        > >
                        > > ----- Original Message -----
                        > > From: Keith
                        > > To: ccd-newastro@yahoogroups.com
                        > > Sent: Wednesday, August 03, 2005 11:20 AM
                        > > Subject: [ccd-newastro] Re: Help with RA problem
                        > >
                        > >
                        > > Don,
                        > >
                        > > Have you noticed that your mi250 is slow in RA? Mine seems to
                        > correct
                        > > in one direction. Always correcting toward the bottom of the
                        > graph.
                        > > Is there a way to speed it up? Also, are you getting good
                        > pointing
                        > > accurace with yours? I love my mi250 and learning to live with
                        > the
                        > > Gemini :-)
                        > >
                        > > Keith,
                        > >
                        > > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...>
                        > wrote:
                        > > > Arnie,
                        > > >
                        > > > I've heard reports of the Gemini system being "slow" in
                        > sidereal
                        > > tracking and thought this might have some bearing on your
                        > problem.
                        > > It does not sound like you are experiencing "slow" tracking.
                        > Your
                        > > stated problem seems to be something repetitive or
                        oscillating.
                        > The
                        > > RA motor or gearbox may be at fault. I assume you have a
                        stable
                        > > power supply. (At least 13.5 to 14 volts regulated.) I do not
                        > know
                        > > what the worm period is on your G-11 (My MI-250 is about 4
                        > minutes.)
                        > > but it would definitely be much longer than the oscillations
                        you
                        > > report. The motor period, or gearing, would be much shorter
                        and
                        > this
                        > > brings up my point. You might try exchanging the DEC and RA
                        > motors
                        > > and see if the problem follows the motor. Since you have a
                        very
                        > good
                        > > polar alignment, you may not notice a change in DEC, but if the
                        > RA
                        > > problem decreases, or is eliminated, then that would pretty
                        much
                        > > isolate the problem to the motor assembly
                        > > >
                        > > > Good luck,
                        > > >
                        > > > Don Waid
                        > > > http://www.waid-observatory.com
                        > > > .
                        > > > ----- Original Message -----
                        > > > From: alwittstein
                        > > > To: ccd-newastro@yahoogroups.com
                        > > > Sent: Wednesday, August 03, 2005 3:41 AM
                        > > > Subject: [ccd-newastro] Re: Help with RA problem
                        > > >
                        > > >
                        > > > Don,
                        > > >
                        > > > I tried this tonight. I disabled corrections in both X and
                        Y
                        > > axes, and
                        > > > ran the autoguider for twelve minutes. You could watch the
                        > guide
                        > > star
                        > > > in the guide window swinging slowly back and forth like a
                        > > pendulum
                        > > > with a period of anywhere from 12 to 24 seconds (guide
                        > exposures
                        > > were
                        > > > 4 seconds long). The error numbers in Y (Dec) were always
                        > less
                        > > than
                        > > > two pixels, while in X (RA) they vatied as much as 10
                        pixels
                        > on
                        > > either
                        > > > side of center. When autoguiding was turned on, you could
                        > still
                        > > watch
                        > > > the guide star oscillating with the same period, but the
                        > errors
                        > > in Y
                        > > > were now under a pixel, and those in X were up to 3-4
                        pixels
                        > > only. A
                        > > > five minute guided exposure produced stars that were two to
                        > three
                        > > > times wider in RA than their height in declination.
                        > > >
                        > > > Arnie
                        > > >
                        > > > --- In ccd-newastro@yahoogroups.com, "Don Waid"
                        <dwaid1@b...>
                        > > wrote:
                        > > > > Arnold,
                        > > > >
                        > > > > What does the mount do when you turn autoguiding off?
                        Does
                        > the
                        > > > mount track
                        > > > > slow or fast? (ie: the star moves slowly in only one
                        > > direction.)
                        > > > If it
                        > > > > does, is it slow or fast?
                        > > > >
                        > > > > Don Waid
                        > > > > http://www.waid-observatory.com
                        > > > >
                        > > > > ----- Original Message -----
                        > > > > From: "Arnold Wittstein" <arnwittstein@e...>
                        > > > > To: <ccd-newastro@yahoogroups.com>
                        > > > > Sent: Tuesday, August 02, 2005 5:09 PM
                        > > > > Subject: [ccd-newastro] Help with RA problem
                        > > > >
                        > > > >
                        > > > > > I'm having a problem with RA tracking with my new
                        Gemini
                        > G-
                        > > 11. I
                        > > > performed
                        > > > > > the polar align procedure that got me aligned within
                        2.5
                        > > > arcseconds of the
                        > > > > > pole. When imaging with an SBIG ST2000 with internal
                        > > autoguiding,
                        > > > I'm
                        > > > > > getting cigar-shaped stars oriented along lines of RA.
                        > > > > > The Dec is dead on - less than one pixel error in +/-Y.
                        > The
                        > > RA,
                        > > > however,
                        > > > > > swings back and forth by as much +/- 5 pixels as I sit
                        > and
                        > > watch
                        > > > the
                        > > > > > autoguiding numbers. I know this sounds like a problem
                        in
                        > > Dec, but
                        > > > I have
                        > > > > > the camera oriented so that RA is in the X direction,
                        and
                        > Dec
                        > > is
                        > > > Y. With
                        > > > > > the scope in home position, the top of the camera faces
                        > to
                        > > the
                        > > > left as
                        > > > > > viewed from behind the scope/camera. I have also
                        watched
                        > the
                        > > image
                        > > > during
                        > > > > > continuous focus mode, and can watch the stars move in
                        +/-
                        > X
                        > > as I
                        > > > hold down
                        > > > > > the RA +/- keys, and move in +/-Y as I hold down the
                        Dec
                        > +/-
                        > > keys.
                        > > > > >
                        > > > > > Using CCDSoft, I used a guiding exposure of four
                        seconds.
                        > > > Initially, the
                        > > > > > guide star starts out in the middle of the guide
                        window.
                        > For
                        > > the
                        > > > first few
                        > > > > > exposures, the star stays fairly well centered, with
                        > errors
                        > > of
                        > > > under a
                        > > > > > pixel in both X and Y axis. Then the X axis area will
                        > creep
                        > > up
                        > > > over a few
                        > > > > > exposures to -1.5, -1.89, -2.5 (just an example). Then
                        it
                        > > will
                        > > > slowly
                        > > > > > swing back, and then over shoot on the +X side. Then it
                        > will
                        > > > slowly (and
                        > > > > > by slowly, again over a timespan of a few 4 second
                        > exposures)
                        > > > swing back
                        > > > > > to zero and overshoot in the -X direction. This is with
                        > the
                        > > > aggressiveness
                        > > > > > set to 5. Any higher or lower and the problem worsens.
                        So
                        > it
                        > > > appears to me
                        > > > > > that small proper-size corrections are being made, but
                        > that
                        > > they
                        > > > don't
                        > > > > > stop in time, and the corrections continue on longer
                        than
                        > > they
                        > > > should. The
                        > > > > > total period of the oscillation is anywhere from 12 to
                        24
                        > > seconds
                        > > > (3 - 6
                        > > > > > guiding exposures) which seems too long to be
                        > aggressiveness
                        > > and
                        > > > to short
                        > > > > > to be periodic error. The other settings I used in
                        > CCDSoft
                        > > were
                        > > > Minimum
                        > > > > > Move of 0.01 second, Maximum Move of 1.0 second.
                        Guiding
                        > rate
                        > > of
                        > > > the mount
                        > > > > > is set to 0.8x sidereal.
                        > > > > >
                        > > > > > I balanced the mount in both Dec and RA, and then slid
                        > the
                        > > > counterweight
                        > > > > > down a small amount on the shaft to slightly increase
                        > weight
                        > > on
                        > > > the east
                        > > > > > side.
                        > > > > >
                        > > > > > I sure someone can help.
                        > > > > >
                        > > > > > Thanks,
                        > > > > >
                        > > > > > Arnie
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > > Yahoo! Groups Links
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > > --------------------------------------------------------------
                        --
                        > ----
                        > > ----------
                        > > > YAHOO! GROUPS LINKS
                        > > >
                        > > > a.. Visit your group "ccd-newastro" on the web.
                        > > >
                        > > > b.. To unsubscribe from this group, send an email to:
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                      • Donald Waid
                        Dennis, Yes, I am aware that sidereal tracking is not accurate at lower elevations. I ve tried King Adaptive rate, which should help with this, but I really
                        Message 11 of 16 , Aug 6 11:06 AM
                          Dennis,

                          Yes, I am aware that sidereal tracking is not accurate at lower
                          elevations. I've tried King Adaptive rate, which should help with
                          this, but I really need to do a lot more troubleshooting to determine
                          if the problem is actually in the drivers or not. I suspected I had
                          a RA clutch slipping problem and the last time I did any work with
                          the scope I made sure clutch screws were tight and it seemed to help
                          but did not completely eliminate the problem. I was also using the
                          AO-7 and there could be a problem with it. I plan on testing the
                          mount without the AO-7 and see if that helps.

                          Don Waid
                          http://www.waid-observatory.com


                          --- In ccd-newastro@yahoogroups.com, "Dennis Persyk" <dpersyk@a...>
                          wrote:
                          > Hi Don,
                          >
                          > You are doubtless aware that the sidereal rate is only good at the
                          > zenith, and varies at other zenith angles. When you refer
                          to "slow"
                          > tracking do you mean the servo oscillator is actually running at
                          too
                          > low a frequency?
                          >
                          > Clear skies,
                          >
                          > Dennis Persyk
                          > Igloo Observatory Home Page http://dpersyk.home.att.net
                          > Hampshire, IL
                          >
                          > --- In ccd-newastro@yahoogroups.com, "Don Waid" <dwaid1@b...> wrote:
                          > > Keith,
                          > > [Tremendous body of text deleted for brevity ...]
                          > > Yes, I have noticed some slow tracking in RA. \> Don Waid
                          > > http://www.waid-observatory.com
                          > >
                          > > ----- Original Message -----
                          > > From: Keith
                          > > To: ccd-newastro@yahoogroups.com
                          > > Sent: Wednesday, August 03, 2005 11:20 AM
                          > > Subject: [ccd-newastro] Re: Help with RA problem
                          > >
                          > >
                          > > Don,
                          > >
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