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Re: RA PEC Training

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  • johansea
    Gday Mike ... Doing the Pec will/can eliminate a lot of the problems, but not all. Even a std autoguider has its problems due to the mechanics of
    Message 1 of 20 , Sep 30, 2004
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      Gday Mike
      <..snip..>
      > At the end of the day PEC is not the answer, only an
      > autoguider will do the job me thinks.

      Doing the Pec will/can eliminate a lot of the problems, but not all.
      Even a std autoguider has its problems due to the mechanics of the
      drivetrain, inertia etc so the better you can fix PEC before
      autoguiding the better. The best option seems to be to use PEC
      training, then something like an A07, which bypasses the geartrain
      inertia altogether, but that costs a tad more.

      > I know Doc Clay has claimed some extraordinary tracking
      > capabilities for his scopes but he's about the only one reporting
      > this phenomina as far as I can see....?
      Some others have reported good basic tracking/PEC, others bad. I
      think, based on the fact Meade units are mass produced, that the law
      of averages will dictate that every now and again, one comes
      together "on spec" and a lucky sod gets it. Others get those that
      are close but not perfect, and a few get "monday specials".
      The only way to truly test is replace the worm and drive with
      precision gears and see the difference, but again the cost goes up.
      Such is life.
      Andrew Johansen Melbourne Australia
    • P. Clay Sherrod
      Not necessarily the only one with good PEC but perhaps the only one reporting it.... There are several 12 s and 14 s out there that are raking in asteroid
      Message 2 of 20 , Oct 1, 2004
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        Not necessarily the only one with good PEC but perhaps the only one reporting it....
        There are several 12's and 14's out there that are raking in asteroid discoveries and serious research (photometry and astrometry) every week, all of which are seeing very fine tracking of these scopes, with NO modifications whatsoever other than PEC training, Custom Tracking rates and SMT engaged.

        Dr. Clay
        Arkansas Sky Observatory
        10 Observatory Hill Drive, Petit Jean Mt.
        drclay@...
        MPC/cbat Obs. H41 / Petit Jean Mountain
        MPC/cbat Obs. H43 / Conway
        MPC/cbat Obs. H44 / Cascade Mountain

        ----- Original Message -----
        From: strongmanmike2002
        To: LX200GPS@yahoogroups.com
        Sent: Thursday, September 30, 2004 11:24 PM
        Subject: [LX200GPS] Re: RA PEC Training


        --- In LX200GPS@yahoogroups.com, "johansea" <johansea@o...> wrote:
        > Gday Mikey
        > Good to see ya havent fallen down a wombat hole on that nice dark
        > property of yours.
        > > I still poke ma head in occassionally though
        > > and I see people are still fiddling endlessly with their PEC
        using,
        > > amoungst other methods, your pecker :-)
        > Mk I or MK II ? ( MK II is better )
        >
        > As to others results, no idea. Only Dave Higgins and a chap from
        > Japan have posted any thorough analysis of PEC that i know of.
        > I havent seen enough sky to do any meaningful "real" runs, but
        based
        > on indoor testing ( with 2.0I ), the only way to truly "average" a
        > set of runs is to do them sequentially and export the data,
        > manipulate externally and read back in.
        > I ran a series of tests indoors where i automatically started a
        PEC
        > run at a set AZ ( so i always used the same gear locations ), then
        > sent a series of computer controlled adjustments to the scope (
        thus
        > eliminating me from the process ). The results were not very
        > consistent to say the least. As such, i would have to say that
        using
        > any method ( other than autoguiding ) will be a little hit and
        miss.
        > Andrew

        Yeh I don't know, Dave seems to have done a heap of "testing" but as
        to removing most of the periodic error with the view to
        significantly and consistantly improving tracking I doubt if it will
        prove more than just an interesting exercise really. At the end of
        the day PEC is not the answer, only an autoguider will do the job me
        thinks. I know Doc Clay has claimed some extraordinary tracking
        capabilities for his scopes but he's about the only one reporting
        this phenomina as far as I can see....?

        Mike

        Mike



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      • strongmanmike2002
        ... reporting it.... ... asteroid discoveries and serious research (photometry and astrometry) every week, all of which are seeing very fine tracking of these
        Message 3 of 20 , Oct 1, 2004
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          --- In LX200GPS@yahoogroups.com, "P. Clay Sherrod" <drclay@t...>
          wrote:
          > Not necessarily the only one with good PEC but perhaps the only one
          reporting it....
          > There are several 12's and 14's out there that are raking in
          asteroid discoveries and serious research (photometry and astrometry)
          every week, all of which are seeing very fine tracking of these
          scopes, with NO modifications whatsoever other than PEC training,
          Custom Tracking rates and SMT engaged.]



          Hmmm?...sorry but me not convinced! :-)

          All those thinkgs can be done without great tracking accuracy, as
          Dave Higgins has shown.

          How would having SMT engaged help tracking?

          Mike Sid on IO
        • P. Clay Sherrod
          scuse me, but I have worked with David several times on attempting to perfect his tracking. I do astrometric/photometric measurements every clear night and
          Message 4 of 20 , Oct 1, 2004
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            'scuse me, but I have worked with David several times on attempting to perfect his tracking. I do astrometric/photometric measurements every clear night and good tracking/PEC is essential for accurate results.....I agree that if imaging in very short durations (i.e, less than 30 seconds for fast-movers) PE would be less of a factor, but for proper astrometry of faint asteroids or comets, durations of 180 seconds are quite typical. When imaging in a field of view of less than 4 arc minutes, PE is indeed very important.

            Dr. Clay
            --------------------
            Arkansas Sky Observatory
            Harvard MPC H41 (Petit Jean Mountain)
            Harvard MPC H43 (Conway)
            http://www.arksky.org/


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            ----- Original Message -----
            From: strongmanmike2002
            To: LX200GPS@yahoogroups.com
            Sent: Friday, October 01, 2004 6:36 AM
            Subject: [LX200GPS] Re: RA PEC Training


            --- In LX200GPS@yahoogroups.com, "P. Clay Sherrod" <drclay@t...>
            wrote:
            > Not necessarily the only one with good PEC but perhaps the only one
            reporting it....
            > There are several 12's and 14's out there that are raking in
            asteroid discoveries and serious research (photometry and astrometry)
            every week, all of which are seeing very fine tracking of these
            scopes, with NO modifications whatsoever other than PEC training,
            Custom Tracking rates and SMT engaged.]



            Hmmm?...sorry but me not convinced! :-)

            All those thinkgs can be done without great tracking accuracy, as
            Dave Higgins has shown.

            How would having SMT engaged help tracking?

            Mike Sid on IO



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          • David Shafer
            I am mounted ALT/AZ - last night I did the DEC PEC training using the Meade DSI. When I tried to do the RA PEC training I tried to align on a star to the
            Message 5 of 20 , Dec 20, 2004
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              I am mounted ALT/AZ - last night I did the DEC PEC training using
              the Meade DSI. When I tried to do the RA PEC training I tried to
              align on a star to the South, and the star was zooming out of the FOV
              so fast I could not even attempt to do PEC. The star was moving off
              the screen to the left. I have never had a problem with that much
              drift before (visual). What do I adjust to fix this problem - I
              looked at my Tracking Rate and it was at 66%. Is that the same as
              Custom Tracking Rate, or is that a different variable? What can I
              adjust to stop the drift?

              Thanks

              David Shafer
            • P. Clay Sherrod
              Which direction was the star zooming out of the field? It sounds like the telescope is not even tracking......? Did you initialize properly AND are you
              Message 6 of 20 , Dec 20, 2004
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                Which direction was the star zooming out of the field? It sounds like the telescope is not even tracking......? Did you initialize properly AND are you aligned in polar or Alt-Az mode? If the former then polar alignment is absolutely critical for good PEC....

                Dr. Clay
                --------------------
                Arkansas Sky Observatories
                Harvard MPC H41 (Petit Jean Mountain)
                Harvard MPC H43 (Conway)
                Harvard MPC H44 (Cascade Mountain)
                http://www.arksky.org/


                NOTE that all ASO outgoing mail is protected by McAfee, Zone Alarm and tcworks.net security
                and is certified Virus and Spam-free

                ----- Original Message -----
                From: David Shafer
                To: LX200GPS@yahoogroups.com
                Sent: Monday, December 20, 2004 6:51 AM
                Subject: [LX200GPS] RA PEC Training




                I am mounted ALT/AZ - last night I did the DEC PEC training using
                the Meade DSI. When I tried to do the RA PEC training I tried to
                align on a star to the South, and the star was zooming out of the FOV
                so fast I could not even attempt to do PEC. The star was moving off
                the screen to the left. I have never had a problem with that much
                drift before (visual). What do I adjust to fix this problem - I
                looked at my Tracking Rate and it was at 66%. Is that the same as
                Custom Tracking Rate, or is that a different variable? What can I
                adjust to stop the drift?

                Thanks

                David Shafer







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              • autostaretx
                ... Remember that the DSI is like using a 6mm eyepiece... so drift effects are magnified over what you might be used to in visual work. The 66% you are
                Message 7 of 20 , Dec 20, 2004
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                  --- In LX200GPS@yahoogroups.com, "David Shafer" <davidgshafer@m...> wrote:
                  >
                  >
                  > I am mounted ALT/AZ - last night I did the DEC PEC training using
                  > the Meade DSI. When I tried to do the RA PEC training I tried to
                  > align on a star to the South, and the star was zooming out of the FOV
                  > so fast I could not even attempt to do PEC. The star was moving off
                  > the screen to the left. I have never had a problem with that much
                  > drift before (visual). What do I adjust to fix this problem - I
                  > looked at my Tracking Rate and it was at 66%. Is that the same as
                  > Custom Tracking Rate, or is that a different variable? What can I
                  > adjust to stop the drift?

                  Remember that the DSI is like using a 6mm eyepiece...
                  so drift effects are magnified over what you might be
                  used to in visual work.

                  The "66%" you are seeing is the -Guiding Rate-, not the Tracking Rate.
                  "Guiding Rate" is the speed adjustment that guiding commands will
                  add (or subract) from the default Tracking Rate.

                  Tracking Rate is a separate setting. It is also expresses as
                  a percentage adjustment, but this time against what the Autostar
                  thinks of as "sidereal". The units are tenths of percent.
                  So the Lunar Rate of "-35" means sidereal has been adjusted
                  down 3.5% slower than sidereal.

                  The first thing to do is to turn OFF all PEC.
                  Now watch the image in the DSI.
                  Determine which direction is "west" and "east" by setting
                  your Slew Speed to "2x" (or "Guide") and then push the
                  keys to see which way is "to the left".

                  If slewing west moves the image "left" , then your telescope
                  is tracking too quickly (since your image moves left all by
                  itself, too). So you'd enter a negative number to the Tracking
                  Rate adjustment. The value to set is based upon the amount
                  of drift: one unit for each arcsecond of drift per clock minute.
                  (which is equal to one arcmin per clock hour).

                  But in an Alt/Az situation, is PEC really needed?
                  Do you see the star drift back and forth in a repeating
                  pattern? (it's an 8-minute repeat, so it might be hard
                  to detect visually).
                  In a Polar setup, severe drift is a sign of inaccurate
                  wedge/mount alignment.

                  have fun
                  --dick
                • David Shafer
                  ... Rate. ... Dick - Dr. Clay - thanks for the responses. What is a good starting point for the Guide Rate? I am actually starting down the road for imaging
                  Message 8 of 20 , Dec 20, 2004
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                    --- In LX200GPS@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                    >

                    >
                    > Remember that the DSI is like using a 6mm eyepiece...
                    > so drift effects are magnified over what you might be
                    > used to in visual work.
                    >
                    > The "66%" you are seeing is the -Guiding Rate-, not the Tracking
                    Rate.
                    > "Guiding Rate" is the speed adjustment that guiding commands will
                    > add (or subract) from the default Tracking Rate.
                    >
                    > Tracking Rate is a separate setting. It is also expresses as
                    > a percentage adjustment, but this time against what the Autostar
                    > thinks of as "sidereal". The units are tenths of percent.
                    > So the Lunar Rate of "-35" means sidereal has been adjusted
                    > down 3.5% slower than sidereal.
                    >
                    > The first thing to do is to turn OFF all PEC.
                    > Now watch the image in the DSI.
                    > Determine which direction is "west" and "east" by setting
                    > your Slew Speed to "2x" (or "Guide") and then push the
                    > keys to see which way is "to the left".
                    >
                    > If slewing west moves the image "left" , then your telescope
                    > is tracking too quickly (since your image moves left all by
                    > itself, too). So you'd enter a negative number to the Tracking
                    > Rate adjustment. The value to set is based upon the amount
                    > of drift: one unit for each arcsecond of drift per clock minute.
                    > (which is equal to one arcmin per clock hour).
                    >
                    > But in an Alt/Az situation, is PEC really needed?
                    > Do you see the star drift back and forth in a repeating
                    > pattern? (it's an 8-minute repeat, so it might be hard
                    > to detect visually).
                    > In a Polar setup, severe drift is a sign of inaccurate
                    > wedge/mount alignment.
                    >
                    > have fun
                    > --dick

                    Dick - Dr. Clay - thanks for the responses. What is a good starting
                    point for the Guide Rate? I am actually starting down the road for
                    imaging with a wide field scope (Orion 80 APO)piggybacked on the
                    LX200 on a wedge. But I am starting with PEC first and trying to
                    expand my understanding of the setup and use of the scope.

                    Good Seeing

                    David Shafer
                  • P. Clay Sherrod
                    I always start with the default setting for the Guide Rate, particularly if using a CCD/LPI, etc. to check or correct on PE. Start there and adjust
                    Message 9 of 20 , Dec 20, 2004
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                      I always start with the default setting for the Guide Rate, particularly if using a CCD/LPI, etc. to check or correct on PE. Start there and adjust accordingly.

                      Dr. Clay
                      --------------------
                      Arkansas Sky Observatories
                      Harvard MPC H41 (Petit Jean Mountain)
                      Harvard MPC H43 (Conway)
                      Harvard MPC H44 (Cascade Mountain)
                      http://www.arksky.org/


                      NOTE that all ASO outgoing mail is protected by McAfee, Zone Alarm and tcworks.net security
                      and is certified Virus and Spam-free

                      ----- Original Message -----
                      From: David Shafer
                      To: LX200GPS@yahoogroups.com
                      Sent: Monday, December 20, 2004 5:38 PM
                      Subject: [LX200GPS] Re: RA PEC Training




                      --- In LX200GPS@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                      >

                      >
                      > Remember that the DSI is like using a 6mm eyepiece...
                      > so drift effects are magnified over what you might be
                      > used to in visual work.
                      >
                      > The "66%" you are seeing is the -Guiding Rate-, not the Tracking
                      Rate.
                      > "Guiding Rate" is the speed adjustment that guiding commands will
                      > add (or subract) from the default Tracking Rate.
                      >
                      > Tracking Rate is a separate setting. It is also expresses as
                      > a percentage adjustment, but this time against what the Autostar
                      > thinks of as "sidereal". The units are tenths of percent.
                      > So the Lunar Rate of "-35" means sidereal has been adjusted
                      > down 3.5% slower than sidereal.
                      >
                      > The first thing to do is to turn OFF all PEC.
                      > Now watch the image in the DSI.
                      > Determine which direction is "west" and "east" by setting
                      > your Slew Speed to "2x" (or "Guide") and then push the
                      > keys to see which way is "to the left".
                      >
                      > If slewing west moves the image "left" , then your telescope
                      > is tracking too quickly (since your image moves left all by
                      > itself, too). So you'd enter a negative number to the Tracking
                      > Rate adjustment. The value to set is based upon the amount
                      > of drift: one unit for each arcsecond of drift per clock minute.
                      > (which is equal to one arcmin per clock hour).
                      >
                      > But in an Alt/Az situation, is PEC really needed?
                      > Do you see the star drift back and forth in a repeating
                      > pattern? (it's an 8-minute repeat, so it might be hard
                      > to detect visually).
                      > In a Polar setup, severe drift is a sign of inaccurate
                      > wedge/mount alignment.
                      >
                      > have fun
                      > --dick

                      Dick - Dr. Clay - thanks for the responses. What is a good starting
                      point for the Guide Rate? I am actually starting down the road for
                      imaging with a wide field scope (Orion 80 APO)piggybacked on the
                      LX200 on a wedge. But I am starting with PEC first and trying to
                      expand my understanding of the setup and use of the scope.

                      Good Seeing

                      David Shafer







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