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RE: [UncensoredTakGroup] Re: Temma 2 goto

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  • Gene Horr
    ... tracking but not the GoTo. Picking nits here. It will improve goto s but the improvement for visual work isn t worth the effort. But for long FL small
    Message 1 of 23 , May 1, 2007
      > I don't think a drift alignment will improve GoTo's. It will improve
      tracking but not the GoTo.

      Picking nits here. It will improve goto's but the improvement for visual
      work isn't worth the effort. But for long FL small chip CCD work it can be
      worthwhile.

      Gene Horr
    • Jim Lafferty
      I have found that the accuracy of my goto s is directly related to my polar alignment on the temmas (both my em200 and njp). If alignment isn t pretty good,
      Message 2 of 23 , May 1, 2007
        I have found that the accuracy of my goto's is directly related to my polar alignment on the temmas (both my em200 and njp). If alignment isn't pretty good, the object doesn't find its way onto my chip---drift alignment just makes it all the more accurate. Also the error is going to be greater the farther the slew if polar alignment is off. Jim

        Jim Lafferty

        jrlafferty@...
        shogun000@...

        -----Original Message-----
        From: "Eddy" <EddyMuriel@...>
        Date: Tue, 01 May 2007 06:34:57
        To:UncensoredTakGroup@yahoogroups.com
        Subject: [UncensoredTakGroup] Re: Temma 2 goto

        Hi,

        I don't think a drift alignment will improve GoTo's. It will improve
        tracking but not the GoTo.

        I don't use the Sky 6 but StrarryNight Pro 5 with the latest updates.
        So, I cannot commend on the Sky.

        Just for info, here is how I work. After connecting the EM-200 to
        the program and after the first slew, I need to center
        the "alignment" star with the handcontrol in order to synch. But,
        after this procedure, my GoTo's are pretty good. I am always getting
        my object on my CCD chip (a SAC10 with a 5,3x7,3mm size CCD).

        What I do after the first synch, is slewing towards a star that is
        close to my dso that I want to image. This star is always near the
        center of the above mentioned CCD. I just have to re-center the star
        a bit, synch and than slew to the dso. After a test exposure to
        check, I am usually dead on. Maybe a small correction has to be made
        for framing.

        I don't know much about the Sky 6, but maybe, as Jim mentioned, you
        should upgrade to the latest version. Also, be sure to use the
        correct UTC time for setting up the dial in the Polar alignment
        scope. Sometimes there is confusion with and without DTS.

        Cheers,
        Eddy
      • gnowellsct
        I find this discussion very puzzling, and so maybe you all can help me sort it out. First off he is using a 12.5 plossl and the field of view is about 37 arc
        Message 3 of 23 , May 1, 2007
          I find this discussion very puzzling, and so maybe you all can help me
          sort it out. First off he is using a 12.5 plossl and the field of
          view is about 37 arc minutes (I put the plossl at 50 degrees afov, fl
          of TOA 130=1000mm). So to get an object in at all is 18 arc minute
          accuracy and to be within half of that distance is 9 arc minute accuracy.

          So my first thought to this is that 9 arc minute pointing accuracy on
          a system that has no modeling is pretty good. That's excellent, in
          fact, and even fifteen to twenty arc minutes pointing error would be
          "normal" for a two star alignment.

          Now the second thought is that he is using "The Sky" and this is a
          software utility with T-point. So the answer to getting better
          accuracy is to do a 10 star model, and even better, a 25 to 30 star
          model. The more stars you add, the better the model gets.

          When you build a model that estimates telescope pointing errors
          (accounting for polar alignment and a dozen other sources of pointing
          error, people who want a good discussion should consult the Argo Navis
          user's manual where the variables are identified and explained) you
          typically DON'T want to do a "synch" (after you have a model) because
          it forces changes in the model that are not compatible with the
          previously created statistical database of errors.

          With a good pointing model the pointing error should be on the scale
          of 3 to 5 arc minutes for most users of high end amateur equipment. I
          have heard of doing better, but everything has to be tweaked just so.
          The Gemini system will do about 5 arc minutes in a typical "set it up
          on the field and do ten stars" situation.

          So here's what I'm getting at. If he is "synching" to force the model
          to change, then it's because he's not using T-point. If he's not
          using T-point, then he's trying to correct an error margin that is in
          fact well within what we would expect. So there is no issue.

          If he IS using T-point, then the solution is not to keep forcing
          things with a "synch" but to build a larger model. For visual
          observing using Argo Navis I use a ten star model. Imagers with more
          demanding applications might want a 25 to 30 star model, but they can
          sometimes "check it out" after ten stars and if that's good enough
          they can start plugging away.

          There are two ways that model building typically works in amateur systems.

          1. You keep adding stars and the model gets continually recalculated
          so that gradually your accuracy improves as you add more stars. So
          the first few alignments will have more error in them than subsequent
          alignments. (stars, not extended objects like globular clusters,
          should be used for alignments; tight circular planetaries are OK).
          2. You have to add a bunch of stars and press an explicit
          "calculation command" which then builds the model. You can add more
          stars but they don't become part of the model until you do a
          "calculate." I believe though that only Argo Navis does it this way
          and that the other systems "recalculate the model" every time you add
          a star (data point).

          These discussions can get complicated because few users take the time
          to convert their accuracy discussion into minutes of arc and so you
          get someone with an FS128 on a CGE saying he gets "dead on" accuracy
          after a 4 star alignment and next to him a guy with a c14 thinks
          that's bunk. In the case of imaging however tolerances are low
          because chips are small, but to all be on the same page we need to
          speak in terms of field of view and arc minutes, not eyepieces.

          I think the goal here should be to build a pointing model using the
          SKY and to get RMS and PSD values of around 2-3 arc minutes.

          Unless I'm REALLY not understanding the system....

          thanks
          Greg N

          ps. to read up on the underlying theory you can go to
          wildcard-innovations and find the argo navis instruction manual.
          Search in the pdf document for error terms such as HCEC or NP to find
          the place where they are all discussed as a group. These error terms
          are in general use in the Sky, Gemini, Argo Navis....and the
          professional observatories.

          GN


          --- In UncensoredTakGroup@yahoogroups.com, "Eddy" <EddyMuriel@...> wrote:
          >
          > Hi,
          >
          > I don't think a drift alignment will improve GoTo's. It will improve
          > tracking but not the GoTo.
          >

          > Cheers,
          > Eddy
          >
        • Jim Lafferty
          I never get that involved with trying to get a perfect goto. I agree, for eyeballing polar alignment via the takajashi polar scopes and doing a one star sync
          Message 4 of 23 , May 1, 2007
            I never get that involved with trying to get a perfect goto. I agree, for eyeballing polar alignment via the takajashi polar scopes and doing a one star sync the alignment is good enouigh for me because it puts the target on my st2000 chip consistantly. After that I center the target with my hand controller. I'm usually too impatient to do much more than that. The alignment is good enough so that the guiding is fine via the on board guide chip for long exposures (10-30 minutes each frame).
            Jim

            Jim Lafferty

            jrlafferty@...
            shogun000@...

            -----Original Message-----
            From: "gnowellsct" <tim71pos@...>
            Date: Tue, 01 May 2007 13:24:27
            To:UncensoredTakGroup@yahoogroups.com
            Subject: [UncensoredTakGroup] Re: Temma 2 goto

            I find this discussion very puzzling, and so maybe you all can help me
            sort it out. First off he is using a 12.5 plossl and the field of
            view is about 37 arc minutes (I put the plossl at 50 degrees afov, fl
            of TOA 130=1000mm). So to get an object in at all is 18 arc minute
            accuracy and to be within half of that distance is 9 arc minute accuracy.

            So my first thought to this is that 9 arc minute pointing accuracy on
            a system that has no modeling is pretty good. That's excellent, in
            fact, and even fifteen to twenty arc minutes pointing error would be
            "normal" for a two star alignment.

            Now the second thought is that he is using "The Sky" and this is a
            software utility with T-point. So the answer to getting better
            accuracy is to do a 10 star model, and even better, a 25 to 30 star
            model. The more stars you add, the better the model gets.

            When you build a model that estimates telescope pointing errors
            (accounting for polar alignment and a dozen other sources of pointing
            error, people who want a good discussion should consult the Argo Navis
            user's manual where the variables are identified and explained) you
            typically DON'T want to do a "synch" (after you have a model) because
            it forces changes in the model that are not compatible with the
            previously created statistical database of errors.

            With a good pointing model the pointing error should be on the scale
            of 3 to 5 arc minutes for most users of high end amateur equipment. I
            have heard of doing better, but everything has to be tweaked just so.
            The Gemini system will do about 5 arc minutes in a typical "set it up
            on the field and do ten stars" situation.

            So here's what I'm getting at. If he is "synching" to force the model
            to change, then it's because he's not using T-point. If he's not
            using T-point, then he's trying to correct an error margin that is in
            fact well within what we would expect. So there is no issue.

            If he IS using T-point, then the solution is not to keep forcing
            things with a "synch" but to build a larger model. For visual
            observing using Argo Navis I use a ten star model. Imagers with more
            demanding applications might want a 25 to 30 star model, but they can
            sometimes "check it out" after ten stars and if that's good enough
            they can start plugging away.

            There are two ways that model building typically works in amateur systems.

            1. You keep adding stars and the model gets continually recalculated
            so that gradually your accuracy improves as you add more stars. So
            the first few alignments will have more error in them than subsequent
            alignments. (stars, not extended objects like globular clusters,
            should be used for alignments; tight circular planetaries are OK).
            2. You have to add a bunch of stars and press an explicit
            "calculation command" which then builds the model. You can add more
            stars but they don't become part of the model until you do a
            "calculate." I believe though that only Argo Navis does it this way
            and that the other systems "recalculate the model" every time you add
            a star (data point).

            These discussions can get complicated because few users take the time
            to convert their accuracy discussion into minutes of arc and so you
            get someone with an FS128 on a CGE saying he gets "dead on" accuracy
            after a 4 star alignment and next to him a guy with a c14 thinks
            that's bunk. In the case of imaging however tolerances are low
            because chips are small, but to all be on the same page we need to
            speak in terms of field of view and arc minutes, not eyepieces.

            I think the goal here should be to build a pointing model using the
            SKY and to get RMS and PSD values of around 2-3 arc minutes.

            Unless I'm REALLY not understanding the system....

            thanks
            Greg N

            ps. to read up on the underlying theory you can go to
            wildcard-innovations and find the argo navis instruction manual.
            Search in the pdf document for error terms such as HCEC or NP to find
            the place where they are all discussed as a group. These error terms
            are in general use in the Sky, Gemini, Argo Navis....and the
            professional observatories.

            GN

            --- In UncensoredTakGroup@: <mailto:UncensoredTakGroup%40yahoogroups.com> yahoogroups.com, "Eddy" <EddyMuriel@...> wrote:
            >
            > Hi,
            >
            > I don't think a drift alignment will improve GoTo's. It will improve
            > tracking but not the GoTo.
            >

            > Cheers,
            > Eddy
            >
          • Eddy
            ... visual ... can be ... Hi Gene, Probably I am wrong but I got the impression that a drift alignment will only increase the tracking accuracy. I thought that
            Message 5 of 23 , May 1, 2007
              --- In UncensoredTakGroup@yahoogroups.com, "Gene Horr" <genehorr@...>
              wrote:
              >
              > > I don't think a drift alignment will improve GoTo's. It will improve
              > tracking but not the GoTo.
              >
              > Picking nits here. It will improve goto's but the improvement for
              visual
              > work isn't worth the effort. But for long FL small chip CCD work it
              can be
              > worthwhile.
              >
              > Gene Horr
              >
              Hi Gene,

              Probably I am wrong but I got the impression that a drift alignment
              will only increase the tracking accuracy.

              I thought that good GoTo's are the result of the initial synch after
              a "reasonable" Polar alignment via the Polar scope. The software takes
              the input of the first synch into account to make up its "picture of
              the nightsky". From this point it calculates the movements towards the
              other objects. So, I did not think that a drift alignment would play a
              role in the software's calculation. Like I said, I am probably wrong,
              but that is the way I understood this.

              Cheers,
              Eddy
            • gnowellsct
              I m gathering from the statement that refining polar alignment is the means to improve pointing accuracy that the Tak hand paddle does not have error modeling?
              Message 6 of 23 , May 1, 2007
                I'm gathering from the statement that refining polar alignment is the
                means to improve pointing accuracy that the Tak hand paddle does not
                have error modeling? But still, if the scope is running off The Sky
                it should have access to error modeling.

                This is crucial. AP does NOT currently have modeling, but they will
                in the next year or so. Gemini has been offering it for close to a
                decade. The beeeeyoootiful GM2000 mount by 10micron (at NEAF) has
                error modeling built into the paddle. Most dsc boxes don't have it,
                but Argo Navis blew past them by building it in and hence is one of
                the most modern pointing systems out there. Error modeling in the
                paddle is something Tak should do to keep up. Celestron and Meade
                go-to have it. Don't know about Vixen Skysensor.

                One factor is that refractor guys have wider fovs and tend to chase
                brighter objects, so there hasn't been as much pressure on the top
                refractor+mount venues to move in this direction. But once you have
                pointing error correction you really don't have much interest in
                anything else. If you have a computer these days it should compensate
                for your polar alignment. Otherwise it's kinda like running Windows
                98. The thing can be done, and it can work, but there are better ways.

                For today's visual user, polar alignment no longer has to be precise
                to get very accurate pointing. Also true for photographers who want
                to take short exposure pictures.

                Gemini will actually throw in, if you ask it to, a tracking error
                correction for polar mis alignment. So the RA will move 20 seconds
                and then the Dec kicks in for 1 to fix the polar alignment tracking
                error (for example). That means that for imagers using short exposure
                times (I dunno, maybe up to 15 minutes) you don't need to refine the
                polar alignment. These systems also have polar alignment protocols
                which should get you within 1-3 arc minutes of true N (the catch is
                you have to build a new model after moving the mount). But eventually
                you'll get some field rotation on long exposures if the mount
                computerized tracking is compensating for polar misalignment.

                I would assume systems running off "The Sky" would also offer this
                option. But if you want to do an hour exposure you'll have to fix that
                polar alignment, especially at long fls.

                Argo Navis corrects for pointing error but it is a push to system on a
                GEM. It isn't connected to the motors. So it can't correct the
                tracking error (which typically is minimal).

                How sensitive is a good pointing model? Argo Navis can detect
                additional flexure and pointing issues that occur between using a c14
                on an ap900 "by itself" and the additional flexure that occurs when a
                refractor is added on top.

                Anyhow I hope the Tak paddles have upgradeable software and that Tak
                offers modeling. But most of the high end refractor groups this issue
                is delegated to "the sky."

                As a visual observer who often uses a narrow field C14, I refused to
                further consider purchasing a new AP900 when I learned it did not
                include pointing error correction in the paddle software. (since I
                don't image, I don't carry a laptop in the field) I went with an
                AP900QMD and Argo navis and get pointing accuracy in the 3-5 arc
                minute range depending on what I have piled on the mount, how many
                alignment stars I've used, and such.

                regards
                Greg N







                --- In UncensoredTakGroup@yahoogroups.com, "Jim Lafferty"
                <jrlafferty@...> wrote:
                >
                > I have found that the accuracy of my goto's is directly related to
                my polar alignment on the temmas (both my em200 and njp). If alignment
                isn't pretty good, the object doesn't find its way onto my
                chip---drift alignment just makes it all the more accurate. Also the
                error is going to be greater the farther the slew if polar alignment
                is off. Jim
                >
                > Jim Lafferty
                >
                > jrlafferty@...
                > shogun000@...
                >
                > -----Original Message-----
                > From: "Eddy" <EddyMuriel@...>
                > Date: Tue, 01 May 2007 06:34:57
                > To:UncensoredTakGroup@yahoogroups.com
                > Subject: [UncensoredTakGroup] Re: Temma 2 goto
                >
                > Hi,
                >
                > I don't think a drift alignment will improve GoTo's. It will improve
                > tracking but not the GoTo.
                >
                > I don't use the Sky 6 but StrarryNight Pro 5 with the latest updates.
                > So, I cannot commend on the Sky.
                >
                > Just for info, here is how I work. After connecting the EM-200 to
                > the program and after the first slew, I need to center
                > the "alignment" star with the handcontrol in order to synch. But,
                > after this procedure, my GoTo's are pretty good. I am always getting
                > my object on my CCD chip (a SAC10 with a 5,3x7,3mm size CCD).
                >
                > What I do after the first synch, is slewing towards a star that is
                > close to my dso that I want to image. This star is always near the
                > center of the above mentioned CCD. I just have to re-center the star
                > a bit, synch and than slew to the dso. After a test exposure to
                > check, I am usually dead on. Maybe a small correction has to be made
                > for framing.
                >
                > I don't know much about the Sky 6, but maybe, as Jim mentioned, you
                > should upgrade to the latest version. Also, be sure to use the
                > correct UTC time for setting up the dial in the Polar alignment
                > scope. Sometimes there is confusion with and without DTS.
                >
                > Cheers,
                > Eddy
                >
              • Jim Lafferty
                The tak hand controller does not have error modeling . For my use its not really necessary. Between the sky 6 and the inherent quality of the tak polar scope
                Message 7 of 23 , May 1, 2007
                  The tak hand controller does not have "error modeling". For my use its not really necessary. Between the sky 6 and the inherent quality of the tak polar scope and mount and sbig camera, I can guide and image all night to my heart's content with either my toa130 or fsq on the njp or em200. I never image at real long fl (above 1000mm) and I am sure a good drift align would improve things should I ever need to.
                  Regards!
                  Jim

                  Jim Lafferty

                  jrlafferty@...
                  shogun000@...

                  -----Original Message-----
                  From: "gnowellsct" <tim71pos@...>
                  Date: Tue, 01 May 2007 13:47:58
                  To:UncensoredTakGroup@yahoogroups.com
                  Subject: [UncensoredTakGroup] Re: Temma 2 goto

                  I'm gathering from the statement that refining polar alignment is the
                  means to improve pointing accuracy that the Tak hand paddle does not
                  have error modeling? But still, if the scope is running off The Sky
                  it should have access to error modeling.

                  This is crucial. AP does NOT currently have modeling, but they will
                  in the next year or so. Gemini has been offering it for close to a
                  decade. The beeeeyoootiful GM2000 mount by 10micron (at NEAF) has
                  error modeling built into the paddle. Most dsc boxes don't have it,
                  but Argo Navis blew past them by building it in and hence is one of
                  the most modern pointing systems out there. Error modeling in the
                  paddle is something Tak should do to keep up. Celestron and Meade
                  go-to have it. Don't know about Vixen Skysensor.

                  One factor is that refractor guys have wider fovs and tend to chase
                  brighter objects, so there hasn't been as much pressure on the top
                  refractor+mount venues to move in this direction. But once you have
                  pointing error correction you really don't have much interest in
                  anything else. If you have a computer these days it should compensate
                  for your polar alignment. Otherwise it's kinda like running Windows
                  98. The thing can be done, and it can work, but there are better ways.

                  For today's visual user, polar alignment no longer has to be precise
                  to get very accurate pointing. Also true for photographers who want
                  to take short exposure pictures.

                  Gemini will actually throw in, if you ask it to, a tracking error
                  correction for polar mis alignment. So the RA will move 20 seconds
                  and then the Dec kicks in for 1 to fix the polar alignment tracking
                  error (for example). That means that for imagers using short exposure
                  times (I dunno, maybe up to 15 minutes) you don't need to refine the
                  polar alignment. These systems also have polar alignment protocols
                  which should get you within 1-3 arc minutes of true N (the catch is
                  you have to build a new model after moving the mount). But eventually
                  you'll get some field rotation on long exposures if the mount
                  computerized tracking is compensating for polar misalignment.

                  I would assume systems running off "The Sky" would also offer this
                  option. But if you want to do an hour exposure you'll have to fix that
                  polar alignment, especially at long fls.

                  Argo Navis corrects for pointing error but it is a push to system on a
                  GEM. It isn't connected to the motors. So it can't correct the
                  tracking error (which typically is minimal).

                  How sensitive is a good pointing model? Argo Navis can detect
                  additional flexure and pointing issues that occur between using a c14
                  on an ap900 "by itself" and the additional flexure that occurs when a
                  refractor is added on top.

                  Anyhow I hope the Tak paddles have upgradeable software and that Tak
                  offers modeling. But most of the high end refractor groups this issue
                  is delegated to "the sky."

                  As a visual observer who often uses a narrow field C14, I refused to
                  further consider purchasing a new AP900 when I learned it did not
                  include pointing error correction in the paddle software. (since I
                  don't image, I don't carry a laptop in the field) I went with an
                  AP900QMD and Argo navis and get pointing accuracy in the 3-5 arc
                  minute range depending on what I have piled on the mount, how many
                  alignment stars I've used, and such.

                  regards
                  Greg N

                  --- In UncensoredTakGroup@: <mailto:UncensoredTakGroup%40yahoogroups.com> yahoogroups.com, "Jim Lafferty"
                  <jrlafferty@...> wrote:
                  >
                  > I have found that the accuracy of my goto's is directly related to
                  my polar alignment on the temmas (both my em200 and njp). If alignment
                  isn't pretty good, the object doesn't find its way onto my
                  chip---drift alignment just makes it all the more accurate. Also the
                  error is going to be greater the farther the slew if polar alignment
                  is off. Jim
                  >
                  > Jim Lafferty
                  >
                  > jrlafferty@...
                  > shogun000@...
                  >
                  > -----Original Message-----
                  > From: "Eddy" <EddyMuriel@...>
                  > Date: Tue, 01 May 2007 06:34:57
                  > To:UncensoredTakGroup@: <mailto:UncensoredTakGroup%40yahoogroups.com> yahoogroups.com
                  > Subject: [UncensoredTakGroup] Re: Temma 2 goto
                  >
                  > Hi,
                  >
                  > I don't think a drift alignment will improve GoTo's. It will improve
                  > tracking but not the GoTo.
                  >
                  > I don't use the Sky 6 but StrarryNight Pro 5 with the latest updates.
                  > So, I cannot commend on the Sky.
                  >
                  > Just for info, here is how I work. After connecting the EM-200 to
                  > the program and after the first slew, I need to center
                  > the "alignment" star with the handcontrol in order to synch. But,
                  > after this procedure, my GoTo's are pretty good. I am always getting
                  > my object on my CCD chip (a SAC10 with a 5,3x7,3mm size CCD).
                  >
                  > What I do after the first synch, is slewing towards a star that is
                  > close to my dso that I want to image. This star is always near the
                  > center of the above mentioned CCD. I just have to re-center the star
                  > a bit, synch and than slew to the dso. After a test exposure to
                  > check, I am usually dead on. Maybe a small correction has to be made
                  > for framing.
                  >
                  > I don't know much about the Sky 6, but maybe, as Jim mentioned, you
                  > should upgrade to the latest version. Also, be sure to use the
                  > correct UTC time for setting up the dial in the Polar alignment
                  > scope. Sometimes there is confusion with and without DTS.
                  >
                  > Cheers,
                  > Eddy
                  >
                • Morgan Spangle
                  I have an NJP with Temma 2 and it is always putting the target on the chip of a my ST2000XM camera. I set up every night in the same marked spot in my driveway
                  Message 8 of 23 , May 1, 2007
                    I have an NJP with Temma 2 and it is always putting the target on the
                    chip of a my ST2000XM camera. I set up every night in the same marked
                    spot in my driveway and polar align with the polar scope. I use the
                    Sky6 and CCDsoft to control the mount and camera. I'm using a Mewlon
                    250 at f/12, with the camera attached, no eyepiece. I use the 7 x 50
                    finder to center a alignment star, turn on the camera in 3 x 3 binning
                    focus mode, and the star is on the chip; I center and synch and from
                    there on, all of my targets are on the chip. To make sure that they
                    are all centered, I usually do a fast, 6-12 point Tpoint model, which
                    makes the mount accurate all night.

                    In my experience, the most important things for accuracy are polar
                    alignment and the Tpoint model. Sometimes I check my alignment with
                    PoleAlign Max, freeware that works great, but I've found that I don't
                    really need to refine the pole alignment much...I'm usually within 3-5
                    minutes of the pole on each axis, plenty good enough for the 30 second
                    exposures I make.

                    Make sure your polar scope is correctly aligned; if it is, you should
                    be within minutes of the pole. Make sure you align to the correct star
                    (I'm sure you do, but if you're not, that'd be a huge factor...). If
                    you can swing the expense, Tpoint really works with my NJP to get a
                    target centered on the chip with no added effort. I image double stars
                    and often hit 30-50 targets a night, so accurate slewing is essential
                    to me; Tpoint makes it happen for me.

                    Morgan


                    --- In UncensoredTakGroup@yahoogroups.com, "Eddy" <EddyMuriel@...> wrote:
                    >
                    > Hi,
                    >
                    > I don't think a drift alignment will improve GoTo's. It will improve
                    > tracking but not the GoTo.
                    >
                    > I don't use the Sky 6 but StrarryNight Pro 5 with the latest updates.
                    > So, I cannot commend on the Sky.
                    >
                    > Just for info, here is how I work. After connecting the EM-200 to
                    > the program and after the first slew, I need to center
                    > the "alignment" star with the handcontrol in order to synch. But,
                    > after this procedure, my GoTo's are pretty good. I am always getting
                    > my object on my CCD chip (a SAC10 with a 5,3x7,3mm size CCD).
                    >
                    > What I do after the first synch, is slewing towards a star that is
                    > close to my dso that I want to image. This star is always near the
                    > center of the above mentioned CCD. I just have to re-center the star
                    > a bit, synch and than slew to the dso. After a test exposure to
                    > check, I am usually dead on. Maybe a small correction has to be made
                    > for framing.
                    >
                    > I don't know much about the Sky 6, but maybe, as Jim mentioned, you
                    > should upgrade to the latest version. Also, be sure to use the
                    > correct UTC time for setting up the dial in the Polar alignment
                    > scope. Sometimes there is confusion with and without DTS.
                    >
                    > Cheers,
                    > Eddy
                    >
                  • Gene Horr
                    ... only increase the tracking accuracy. A proper alignment model requires at least 3 accurate measurement points. A single star alignment works because the
                    Message 9 of 23 , May 1, 2007
                      > Probably I am wrong but I got the impression that a drift alignment will
                      only increase the tracking accuracy.

                      A proper alignment model requires at least 3 accurate measurement points. A
                      single star alignment works because the software model "assumes" perfect
                      polar alignment for the other two dimensions. So any variation between
                      actual alignment and the polar axis, less than perfect centering of the sync
                      star, and non-orthagonal mounting of the optics will result in pointing
                      errors. In practice due to the accuracy of the Tak polar alignment 'scope
                      the first item usually is not a material problem, the second is easily fixed
                      end user practice, and the last is generally only an issue when doing a GEM
                      flip and is easily fixed by just re-syncing.

                      So with careful practice they don't have a material effect on visual use.
                      But when it comes to imaging with long FLs and smaller CCD chips they can
                      cause problems.

                      Gene Horr
                    • Eddy & Muriel
                      Ok, learned something. Eddy ... From: Gene Horr To: UncensoredTakGroup@yahoogroups.com Sent: Tuesday, 01 May, 2007 16:19 Subject: RE: [UncensoredTakGroup] Re:
                      Message 10 of 23 , May 1, 2007
                        Ok, learned something.
                        Eddy

                        ----- Original Message -----
                        From: Gene Horr
                        To: UncensoredTakGroup@yahoogroups.com
                        Sent: Tuesday, 01 May, 2007 16:19
                        Subject: RE: [UncensoredTakGroup] Re: Temma 2 goto


                        > Probably I am wrong but I got the impression that a drift alignment will
                        only increase the tracking accuracy.

                        A proper alignment model requires at least 3 accurate measurement points. A
                        single star alignment works because the software model "assumes" perfect
                        polar alignment for the other two dimensions. So any variation between
                        actual alignment and the polar axis, less than perfect centering of the sync
                        star, and non-orthagonal mounting of the optics will result in pointing
                        errors. In practice due to the accuracy of the Tak polar alignment 'scope
                        the first item usually is not a material problem, the second is easily fixed
                        end user practice, and the last is generally only an issue when doing a GEM
                        flip and is easily fixed by just re-syncing.

                        So with careful practice they don't have a material effect on visual use.
                        But when it comes to imaging with long FLs and smaller CCD chips they can
                        cause problems.

                        Gene Horr





                        [Non-text portions of this message have been removed]
                      • ancient.sull
                        As I dimly remember geometry (studied last century): Three points will define your alignment but polar alignment provides two of those points, the Celestial
                        Message 11 of 23 , May 1, 2007
                          As I dimly remember geometry (studied last century): "Three points"
                          will define your alignment but polar alignment provides two of those
                          points, the Celestial North Pole and the Celestial South Pole. So you
                          only need one more point i.e. only one star.


                          Drew S.
                          California


                          --- In UncensoredTakGroup@yahoogroups.com, "Gene Horr" <genehorr@...>
                          wrote:
                          >
                          > > Probably I am wrong but I got the impression that a drift
                          alignment will
                          > only increase the tracking accuracy.
                          >
                          > A proper alignment model requires at least 3 accurate measurement
                          points. A
                          > single star alignment works because the software model "assumes"
                          perfect
                          > polar alignment for the other two dimensions. So any variation
                          between
                          > actual alignment and the polar axis, less than perfect centering of
                          the sync
                          > star, and non-orthagonal mounting of the optics will result in
                          pointing
                          > errors. In practice due to the accuracy of the Tak polar
                          alignment 'scope
                          > the first item usually is not a material problem, the second is
                          easily fixed
                          > end user practice, and the last is generally only an issue when
                          doing a GEM
                          > flip and is easily fixed by just re-syncing.
                          >
                          > So with careful practice they don't have a material effect on
                          visual use.
                          > But when it comes to imaging with long FLs and smaller CCD chips
                          they can
                          > cause problems.
                          >
                          > Gene Horr
                          >
                        • mainenebula
                          ... John - I faced a similar dilemma when I first had my EM-200. The gotos were poor and I was very frustrated. I did a few things and it is entirely fixed
                          Message 12 of 23 , May 1, 2007
                            --- In UncensoredTakGroup@yahoogroups.com, "jptk1018" <jpk1018@...> wrote:
                            >
                            > Hello group, I have a question about the goto accuracy of my temma 2
                            > mount. Over the weekend I had planned on trying out my new 2000xm
                            > camera. After polar aligning my scope and syncing on arcturus I used
                            > the sky professional to slew to M51. With the bright moon M51 is a no
                            > go. Goto M13 I can just make it out but notice that it is about half
                            > way between the visual edge of a 12.5 mm celestron illum. plossel, and
                            > the crosshair center. Decide to go back to arcturus, not even as close
                            > as M13. Re-sync slew to vega, not very close. Go back to arcturus not
                            > what I would consider good after only going to vega and back. So to
                            > make a long story short, I slewed back and forth between vega and
                            > arcturus and not once did I get the stars in the center, or what I
                            > would think would be on the ccd chip. The mount is about 1 1/2 yrs old
                            > I bought new. Scope is Toa130. I did remove the two small straight
                            > headed screws to view the gears inside. I have to say that they look
                            > like the were made with a file, nothing precision looking about them.
                            > My main concern is not getting an object on the ccd chip. Is this
                            > excessive? Is there an adjustment that I can make. Any and all
                            > suggestion will be appreciated. Thanks John
                            >
                            John -

                            I faced a similar dilemma when I first had my EM-200. The gotos were
                            poor and I was very frustrated. I did a few things and it is entirely
                            fixed now. First upgrade to the newest fix of theSky. Next I use the
                            Tak ASCOM controller. But my true problem lay in TheSky having my
                            incorrect lat/long. I do not remember why it kept loading in the
                            incorrect values but I had to play with it for about an hour to get it
                            fixed. Now I am with Morgan - every object is on my mid sized CCD chip.

                            Dan in NY
                          • Barbara Harris
                            T point is not part of The Sky. It has to purchased separately. ... help me ... fl ... accuracy. ... on ... be ... pointing ... Navis ... because ... scale
                            Message 13 of 23 , May 1, 2007
                              T point is not part of The Sky. It has to purchased separately.

                              --- In UncensoredTakGroup@yahoogroups.com, "gnowellsct"
                              <tim71pos@...> wrote:
                              >
                              > I find this discussion very puzzling, and so maybe you all can
                              help me
                              > sort it out. First off he is using a 12.5 plossl and the field of
                              > view is about 37 arc minutes (I put the plossl at 50 degrees afov,
                              fl
                              > of TOA 130=1000mm). So to get an object in at all is 18 arc minute
                              > accuracy and to be within half of that distance is 9 arc minute
                              accuracy.
                              >
                              > So my first thought to this is that 9 arc minute pointing accuracy
                              on
                              > a system that has no modeling is pretty good. That's excellent, in
                              > fact, and even fifteen to twenty arc minutes pointing error would
                              be
                              > "normal" for a two star alignment.
                              >
                              > Now the second thought is that he is using "The Sky" and this is a
                              > software utility with T-point. So the answer to getting better
                              > accuracy is to do a 10 star model, and even better, a 25 to 30 star
                              > model. The more stars you add, the better the model gets.
                              >
                              > When you build a model that estimates telescope pointing errors
                              > (accounting for polar alignment and a dozen other sources of
                              pointing
                              > error, people who want a good discussion should consult the Argo
                              Navis
                              > user's manual where the variables are identified and explained) you
                              > typically DON'T want to do a "synch" (after you have a model)
                              because
                              > it forces changes in the model that are not compatible with the
                              > previously created statistical database of errors.
                              >
                              > With a good pointing model the pointing error should be on the
                              scale
                              > of 3 to 5 arc minutes for most users of high end amateur
                              equipment. I
                              > have heard of doing better, but everything has to be tweaked just
                              so.
                              > The Gemini system will do about 5 arc minutes in a typical "set
                              it up
                              > on the field and do ten stars" situation.
                              >
                              > So here's what I'm getting at. If he is "synching" to force the
                              model
                              > to change, then it's because he's not using T-point. If he's not
                              > using T-point, then he's trying to correct an error margin that is
                              in
                              > fact well within what we would expect. So there is no issue.
                              >
                              > If he IS using T-point, then the solution is not to keep forcing
                              > things with a "synch" but to build a larger model. For visual
                              > observing using Argo Navis I use a ten star model. Imagers with
                              more
                              > demanding applications might want a 25 to 30 star model, but they
                              can
                              > sometimes "check it out" after ten stars and if that's good enough
                              > they can start plugging away.
                              >
                              > There are two ways that model building typically works in amateur
                              systems.
                              >
                              > 1. You keep adding stars and the model gets continually
                              recalculated
                              > so that gradually your accuracy improves as you add more stars.
                              So
                              > the first few alignments will have more error in them than
                              subsequent
                              > alignments. (stars, not extended objects like globular clusters,
                              > should be used for alignments; tight circular planetaries are OK).
                              > 2. You have to add a bunch of stars and press an explicit
                              > "calculation command" which then builds the model. You can add
                              more
                              > stars but they don't become part of the model until you do a
                              > "calculate." I believe though that only Argo Navis does it this
                              way
                              > and that the other systems "recalculate the model" every time you
                              add
                              > a star (data point).
                              >
                              > These discussions can get complicated because few users take the
                              time
                              > to convert their accuracy discussion into minutes of arc and so you
                              > get someone with an FS128 on a CGE saying he gets "dead on"
                              accuracy
                              > after a 4 star alignment and next to him a guy with a c14 thinks
                              > that's bunk. In the case of imaging however tolerances are low
                              > because chips are small, but to all be on the same page we need to
                              > speak in terms of field of view and arc minutes, not eyepieces.
                              >
                              > I think the goal here should be to build a pointing model using the
                              > SKY and to get RMS and PSD values of around 2-3 arc minutes.
                              >
                              > Unless I'm REALLY not understanding the system....
                              >
                              > thanks
                              > Greg N
                              >
                              > ps. to read up on the underlying theory you can go to
                              > wildcard-innovations and find the argo navis instruction manual.
                              > Search in the pdf document for error terms such as HCEC or NP to
                              find
                              > the place where they are all discussed as a group. These error
                              terms
                              > are in general use in the Sky, Gemini, Argo Navis....and the
                              > professional observatories.
                              >
                              > GN
                              >
                              >
                              > --- In UncensoredTakGroup@yahoogroups.com, "Eddy" <EddyMuriel@>
                              wrote:
                              > >
                              > > Hi,
                              > >
                              > > I don't think a drift alignment will improve GoTo's. It will
                              improve
                              > > tracking but not the GoTo.
                              > >
                              >
                              > > Cheers,
                              > > Eddy
                              > >
                              >
                            • jptk1018
                              ... Hello Group I would like to thank everybody who replied to my question. I have learned a lot, but I am still unsure what might be causing what I consider
                              Message 14 of 23 , May 1, 2007
                                --- In UncensoredTakGroup@yahoogroups.com, "Barbara Harris"
                                <barbharris1@...> wrote:
                                >
                                > T point is not part of The Sky. It has to purchased separately.
                                >
                                > --- In UncensoredTakGroup@yahoogroups.com, "gnowellsct"
                                > <tim71pos@> wrote:
                                > >
                                > > I find this discussion very puzzling, and so maybe you all can
                                > help me
                                > > sort it out. First off he is using a 12.5 plossl and the field of
                                > > view is about 37 arc minutes (I put the plossl at 50 degrees afov,
                                > fl
                                > > of TOA 130=1000mm). So to get an object in at all is 18 arc minute
                                > > accuracy and to be within half of that distance is 9 arc minute
                                > accuracy.
                                > >
                                > > So my first thought to this is that 9 arc minute pointing accuracy
                                > on
                                > > a system that has no modeling is pretty good. That's excellent, in
                                > > fact, and even fifteen to twenty arc minutes pointing error would
                                > be
                                > > "normal" for a two star alignment.
                                > >
                                > > Now the second thought is that he is using "The Sky" and this is a
                                > > software utility with T-point. So the answer to getting better
                                > > accuracy is to do a 10 star model, and even better, a 25 to 30 star
                                > > model. The more stars you add, the better the model gets.
                                > >
                                > > When you build a model that estimates telescope pointing errors
                                > > (accounting for polar alignment and a dozen other sources of
                                > pointing
                                > > error, people who want a good discussion should consult the Argo
                                > Navis
                                > > user's manual where the variables are identified and explained) you
                                > > typically DON'T want to do a "synch" (after you have a model)
                                > because
                                > > it forces changes in the model that are not compatible with the
                                > > previously created statistical database of errors.
                                > >
                                > > With a good pointing model the pointing error should be on the
                                > scale
                                > > of 3 to 5 arc minutes for most users of high end amateur
                                > equipment. I
                                > > have heard of doing better, but everything has to be tweaked just
                                > so.
                                > > The Gemini system will do about 5 arc minutes in a typical "set
                                > it up
                                > > on the field and do ten stars" situation.
                                > >
                                > > So here's what I'm getting at. If he is "synching" to force the
                                > model
                                > > to change, then it's because he's not using T-point. If he's not
                                > > using T-point, then he's trying to correct an error margin that is
                                > in
                                > > fact well within what we would expect. So there is no issue.
                                > >
                                > > If he IS using T-point, then the solution is not to keep forcing
                                > > things with a "synch" but to build a larger model. For visual
                                > > observing using Argo Navis I use a ten star model. Imagers with
                                > more
                                > > demanding applications might want a 25 to 30 star model, but they
                                > can
                                > > sometimes "check it out" after ten stars and if that's good enough
                                > > they can start plugging away.
                                > >
                                > > There are two ways that model building typically works in amateur
                                > systems.
                                > >
                                > > 1. You keep adding stars and the model gets continually
                                > recalculated
                                > > so that gradually your accuracy improves as you add more stars.
                                > So
                                > > the first few alignments will have more error in them than
                                > subsequent
                                > > alignments. (stars, not extended objects like globular clusters,
                                > > should be used for alignments; tight circular planetaries are OK).
                                > > 2. You have to add a bunch of stars and press an explicit
                                > > "calculation command" which then builds the model. You can add
                                > more
                                > > stars but they don't become part of the model until you do a
                                > > "calculate." I believe though that only Argo Navis does it this
                                > way
                                > > and that the other systems "recalculate the model" every time you
                                > add
                                > > a star (data point).
                                > >
                                > > These discussions can get complicated because few users take the
                                > time
                                > > to convert their accuracy discussion into minutes of arc and so you
                                > > get someone with an FS128 on a CGE saying he gets "dead on"
                                > accuracy
                                > > after a 4 star alignment and next to him a guy with a c14 thinks
                                > > that's bunk. In the case of imaging however tolerances are low
                                > > because chips are small, but to all be on the same page we need to
                                > > speak in terms of field of view and arc minutes, not eyepieces.
                                > >
                                > > I think the goal here should be to build a pointing model using the
                                > > SKY and to get RMS and PSD values of around 2-3 arc minutes.
                                > >
                                > > Unless I'm REALLY not understanding the system....
                                > >
                                > > thanks
                                > > Greg N
                                > >
                                > > ps. to read up on the underlying theory you can go to
                                > > wildcard-innovations and find the argo navis instruction manual.
                                > > Search in the pdf document for error terms such as HCEC or NP to
                                > find
                                > > the place where they are all discussed as a group. These error
                                > terms
                                > > are in general use in the Sky, Gemini, Argo Navis....and the
                                > > professional observatories.
                                > >
                                > > GN
                                > >
                                > >
                                > > --- In UncensoredTakGroup@yahoogroups.com, "Eddy" <EddyMuriel@>
                                > wrote:
                                > > >
                                > > > Hi,
                                > > >
                                > > > I don't think a drift alignment will improve GoTo's. It will
                                > improve
                                > > > tracking but not the GoTo.
                                > > >
                                > >
                                > > > Cheers,
                                > > > Eddy
                                > > >
                                > >
                                >


                                Hello Group I would like to thank everybody who replied to my
                                question. I have learned a lot, but I am still unsure what might be
                                causing what I consider is a poor goto accuracy. That being said I was
                                using the version of the sky that Jim said had a bug in it, I have
                                upgraded to the latest version. My main reason for posting was my
                                inexperience with this mount, and the fact that for such a small
                                portion of the sky, I could not get closer then what I was. Arcturus
                                to vega is not that far ( so to speak )I polar aligned 3 different
                                times, did a half a** drift alignment and I don't think I was that far
                                off. I was just getting frustrated and unsure whether I could do a
                                goto and get an object on the ccd chip, without going out to the
                                scope. So I don't believe I will be able to try out the upgrade to the
                                sky tonight, pretty cloudy out. I will post back with the results.
                                Thanks again
                                John
                              • gnowellsct
                                OK, t-point has to be bought as an add-on. If you want 3-5 arc minute pointing accuracy that s the way to go. I don t know how fussy chips they re probably
                                Message 15 of 23 , May 1, 2007
                                  OK, t-point has to be bought as an add-on. If you want 3-5 arc minute
                                  pointing accuracy that's the way to go. I don't know how fussy chips
                                  they're probably bigger than 5 arc minutes.

                                  The point about getting longitude and latitude right is also
                                  important, as is entering the time. I had a problem with the Titan
                                  go-to until I realized I was an hour off local time. This is not true
                                  of all systems, but it is true of some.

                                  regards
                                  Greg N


                                  --- In UncensoredTakGroup@yahoogroups.com, "Barbara Harris"
                                  <barbharris1@...> wrote:
                                  >
                                  > T point is not part of The Sky. It has to purchased separately.
                                  >
                                  > --- In UncensoredTakGroup@yahoogroups.com, "gnowellsct"
                                  > <tim71pos@> wrote:
                                  > >
                                  > > I find this discussion very puzzling, and so maybe you all can
                                  > help me
                                  > > sort it out. First off he is using a 12.5 plossl and the field of
                                  > > view is about 37 arc minutes (I put the plossl at 50 degrees afov,
                                  > fl
                                  > >
                                  > > > Cheers,
                                  > > > Eddy
                                  > > >
                                  > >
                                  >
                                • Filipe Dias
                                  Could some eventual backlash be present? If you tighten the Dec. axis lock levers, and try to rotate the scope to one or ther other side, do you notice slight
                                  Message 16 of 23 , May 2, 2007
                                    Could some eventual backlash be present? If you tighten the Dec. axis lock
                                    levers, and try to rotate the scope to one or ther other side, do you notice
                                    slight movement?
                                    Try GOTOing (or manually slewing looking at coordinates) from stars with the
                                    same AR, and/or the same DEC, to see if you get closer in one direction or
                                    the other. There shouldn't be backlash in AR (due to Temma compensation),
                                    but there could be some in DEC..

                                    Don't know if pointing schemes mentioned so far account for this..

                                    Cheers,

                                    Fil.

                                    On 5/2/07, jptk1018 <jpk1018@...> wrote:
                                    >
                                    > --- In UncensoredTakGroup@yahoogroups.com<UncensoredTakGroup%40yahoogroups.com>,
                                    > "Barbara Harris"
                                    >
                                    > <barbharris1@...> wrote:
                                    > >
                                    > > T point is not part of The Sky. It has to purchased separately.
                                    > >
                                    > > --- In UncensoredTakGroup@yahoogroups.com<UncensoredTakGroup%40yahoogroups.com>,
                                    > "gnowellsct"
                                    > > <tim71pos@> wrote:
                                    > > >
                                    > > > I find this discussion very puzzling, and so maybe you all can
                                    > > help me
                                    > > > sort it out. First off he is using a 12.5 plossl and the field of
                                    > > > view is about 37 arc minutes (I put the plossl at 50 degrees afov,
                                    > > fl
                                    > > > of TOA 130=1000mm). So to get an object in at all is 18 arc minute
                                    > > > accuracy and to be within half of that distance is 9 arc minute
                                    > > accuracy.
                                    > > >
                                    > > > So my first thought to this is that 9 arc minute pointing accuracy
                                    > > on
                                    > > > a system that has no modeling is pretty good. That's excellent, in
                                    > > > fact, and even fifteen to twenty arc minutes pointing error would
                                    > > be
                                    > > > "normal" for a two star alignment.
                                    > > >
                                    > > > Now the second thought is that he is using "The Sky" and this is a
                                    > > > software utility with T-point. So the answer to getting better
                                    > > > accuracy is to do a 10 star model, and even better, a 25 to 30 star
                                    > > > model. The more stars you add, the better the model gets.
                                    > > >
                                    > > > When you build a model that estimates telescope pointing errors
                                    > > > (accounting for polar alignment and a dozen other sources of
                                    > > pointing
                                    > > > error, people who want a good discussion should consult the Argo
                                    > > Navis
                                    > > > user's manual where the variables are identified and explained) you
                                    > > > typically DON'T want to do a "synch" (after you have a model)
                                    > > because
                                    > > > it forces changes in the model that are not compatible with the
                                    > > > previously created statistical database of errors.
                                    > > >
                                    > > > With a good pointing model the pointing error should be on the
                                    > > scale
                                    > > > of 3 to 5 arc minutes for most users of high end amateur
                                    > > equipment. I
                                    > > > have heard of doing better, but everything has to be tweaked just
                                    > > so.
                                    > > > The Gemini system will do about 5 arc minutes in a typical "set
                                    > > it up
                                    > > > on the field and do ten stars" situation.
                                    > > >
                                    > > > So here's what I'm getting at. If he is "synching" to force the
                                    > > model
                                    > > > to change, then it's because he's not using T-point. If he's not
                                    > > > using T-point, then he's trying to correct an error margin that is
                                    > > in
                                    > > > fact well within what we would expect. So there is no issue.
                                    > > >
                                    > > > If he IS using T-point, then the solution is not to keep forcing
                                    > > > things with a "synch" but to build a larger model. For visual
                                    > > > observing using Argo Navis I use a ten star model. Imagers with
                                    > > more
                                    > > > demanding applications might want a 25 to 30 star model, but they
                                    > > can
                                    > > > sometimes "check it out" after ten stars and if that's good enough
                                    > > > they can start plugging away.
                                    > > >
                                    > > > There are two ways that model building typically works in amateur
                                    > > systems.
                                    > > >
                                    > > > 1. You keep adding stars and the model gets continually
                                    > > recalculated
                                    > > > so that gradually your accuracy improves as you add more stars.
                                    > > So
                                    > > > the first few alignments will have more error in them than
                                    > > subsequent
                                    > > > alignments. (stars, not extended objects like globular clusters,
                                    > > > should be used for alignments; tight circular planetaries are OK).
                                    > > > 2. You have to add a bunch of stars and press an explicit
                                    > > > "calculation command" which then builds the model. You can add
                                    > > more
                                    > > > stars but they don't become part of the model until you do a
                                    > > > "calculate." I believe though that only Argo Navis does it this
                                    > > way
                                    > > > and that the other systems "recalculate the model" every time you
                                    > > add
                                    > > > a star (data point).
                                    > > >
                                    > > > These discussions can get complicated because few users take the
                                    > > time
                                    > > > to convert their accuracy discussion into minutes of arc and so you
                                    > > > get someone with an FS128 on a CGE saying he gets "dead on"
                                    > > accuracy
                                    > > > after a 4 star alignment and next to him a guy with a c14 thinks
                                    > > > that's bunk. In the case of imaging however tolerances are low
                                    > > > because chips are small, but to all be on the same page we need to
                                    > > > speak in terms of field of view and arc minutes, not eyepieces.
                                    > > >
                                    > > > I think the goal here should be to build a pointing model using the
                                    > > > SKY and to get RMS and PSD values of around 2-3 arc minutes.
                                    > > >
                                    > > > Unless I'm REALLY not understanding the system....
                                    > > >
                                    > > > thanks
                                    > > > Greg N
                                    > > >
                                    > > > ps. to read up on the underlying theory you can go to
                                    > > > wildcard-innovations and find the argo navis instruction manual.
                                    > > > Search in the pdf document for error terms such as HCEC or NP to
                                    > > find
                                    > > > the place where they are all discussed as a group. These error
                                    > > terms
                                    > > > are in general use in the Sky, Gemini, Argo Navis....and the
                                    > > > professional observatories.
                                    > > >
                                    > > > GN
                                    > > >
                                    > > >
                                    > > > --- In UncensoredTakGroup@yahoogroups.com<UncensoredTakGroup%40yahoogroups.com>,
                                    > "Eddy" <EddyMuriel@>
                                    > > wrote:
                                    > > > >
                                    > > > > Hi,
                                    > > > >
                                    > > > > I don't think a drift alignment will improve GoTo's. It will
                                    > > improve
                                    > > > > tracking but not the GoTo.
                                    > > > >
                                    > > >
                                    > > > > Cheers,
                                    > > > > Eddy
                                    > > > >
                                    > > >
                                    > >
                                    >
                                    > Hello Group I would like to thank everybody who replied to my
                                    > question. I have learned a lot, but I am still unsure what might be
                                    > causing what I consider is a poor goto accuracy. That being said I was
                                    > using the version of the sky that Jim said had a bug in it, I have
                                    > upgraded to the latest version. My main reason for posting was my
                                    > inexperience with this mount, and the fact that for such a small
                                    > portion of the sky, I could not get closer then what I was. Arcturus
                                    > to vega is not that far ( so to speak )I polar aligned 3 different
                                    > times, did a half a** drift alignment and I don't think I was that far
                                    > off. I was just getting frustrated and unsure whether I could do a
                                    > goto and get an object on the ccd chip, without going out to the
                                    > scope. So I don't believe I will be able to try out the upgrade to the
                                    > sky tonight, pretty cloudy out. I will post back with the results.
                                    > Thanks again
                                    > John
                                    >
                                    >
                                    >


                                    --
                                    Fil.


                                    [Non-text portions of this message have been removed]
                                  • ancient.sull
                                    ... axis lock ... you notice ... Or is _any_ screw loose in the mount? I don t have an EM200 (I have another Tak Mount) so I can t be specific but there are
                                    Message 17 of 23 , May 2, 2007
                                      --- In UncensoredTakGroup@yahoogroups.com, "Filipe Dias"
                                      <filipe.marques.dias@...> wrote:
                                      >
                                      > Could some eventual backlash be present? If you tighten the Dec.
                                      axis lock
                                      > levers, and try to rotate the scope to one or ther other side, do
                                      you notice
                                      > slight movement?

                                      Or is _any_ screw loose in the mount? I don't have an EM200 (I have
                                      another Tak Mount) so I can't be specific but there are lots and lots
                                      of screws and they all need to be snug. Take the OTA and saddle off,
                                      start at the top and tighten every screw you can find working your
                                      way down the mount.

                                      My mount (EM400) has a black top that has 4 small screws set in deep
                                      recesses. Those were a little loose as I got the mount, allowing play.

                                      Don't tighten to the point you damage the threads, but do make
                                      everything snug with a hex wrench.

                                      Drew Sullivan
                                      California
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