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Re: Help with RA problem

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  • alwittstein
    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
    Message 1 of 16 , Aug 3, 2005
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      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
      > >
      > >
      > >
      > >
      > >
      > >
      > >
    • 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 2 of 16 , Aug 3, 2005
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        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 3 of 16 , Aug 3, 2005
        • 0 Attachment
          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 4 of 16 , Aug 3, 2005
          • 0 Attachment
            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 5 of 16 , Aug 3, 2005
            • 0 Attachment
              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 6 of 16 , Aug 3, 2005
              • 0 Attachment
                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 7 of 16 , Aug 3, 2005
                • 0 Attachment
                  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 8 of 16 , Aug 3, 2005
                  • 0 Attachment
                    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
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > > > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >
                    > > --------------------------------------------------------------------
                    > ----------
                    > > 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]
                    >
                    >
                    >
                    >
                    >
                    > Yahoo! Groups Links
                    >
                    >
                    >
                    >
                    >
                    >
                  • 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 9 of 16 , Aug 4, 2005
                    • 0 Attachment
                      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 10 of 16 , Aug 4, 2005
                      • 0 Attachment
                        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 11 of 16 , Aug 6, 2005
                        • 0 Attachment
                          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
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > >
                          > > > > >
                          > > >
                          > > >
                          > > >
                          > > >
                          > > >
                          > > >
                          > > >
                          > > >
                          > > >
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                          > > >
                          > > > [Non-text portions of this message have been removed]
                          > >
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                          > > [Non-text portions of this message have been removed]
                        • 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 12 of 16 , Aug 6, 2005
                          • 0 Attachment
                            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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