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Dec drift while guiding with a LX-200

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  • al brockman
    I have been very encouraged in my persuit of better tracking with the LX200 mount by use of a relay switch developed by Wesley Erickson. I tried it out for
    Message 1 of 14 , Apr 1, 2001
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      I have been very encouraged in my persuit of better tracking with the
      LX200 mount by use of a relay switch developed by Wesley Erickson. I tried
      it out for the first time two nights ago with my ST-8 and what it does is
      deceptively simple but now allows the guide chip to track in both RA and
      DEC without problems caused by DEC backlash - ala' the Death Wobbles'. It
      switches off a north or south direction so that Dec movements occur in one
      direction only to correct for the inevitable DEC drift. Over a combined 60
      minute exposure, the guide star never left the window and stayed centred.
      Normally I must switch off Dec corrections and see a slow drift over time
      that I can never quite tweak out by Drift aligning. There were occasions of
      overshoot but I think I can improve that by changing the aggressive
      setting. Is there a better way to adjust this?
      My sincere thanks to Wes.

      Regards, Alan

      ____________________________________________________________________
      Al Brockman
      Shoklo Malaria Research Unit
      PO Box 46, Mae Sot, Tak 63110
      Thailand
      http://smru.thehealthzone.com
      http://www.geocities.com/alan_astro
    • Kevin Dixon
      Good Morning Alan: Can you please describe this relay switch in a bit more detail. Is it specific to the LX-200? Do you have information on how it can be
      Message 2 of 14 , Apr 1, 2001
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        Good Morning Alan:

        Can you please describe this relay switch in a bit more detail. Is it
        specific to the LX-200? Do you have information on how it can be obtained,
        if applicable to scopes other than the LX-200?

        Clear skies,
        Kevin Dixon
        ksbtk@...

        From: "al brockman" <alanb@...>


        > I have been very encouraged in my persuit of better tracking with the
        > LX200 mount by use of a relay switch developed by Wesley Erickson. I
        tried
        > it out for the first time two nights ago with my ST-8 and what it does is
        > deceptively simple but now allows the guide chip to track in both RA and
        > DEC without problems caused by DEC backlash - ala' the Death Wobbles'. It
        > switches off a north or south direction so that Dec movements occur in one
        > direction only to correct for the inevitable DEC drift. Over a combined 60
        > minute exposure, the guide star never left the window and stayed centred.
        > Normally I must switch off Dec corrections and see a slow drift over time
        > that I can never quite tweak out by Drift aligning. There were occasions
        of
        > overshoot but I think I can improve that by changing the aggressive
        > setting. Is there a better way to adjust this?
      • Steven Jodoin
        Hello CCD-Newastro, Just a quick message promote a new website I am working on for Chris Hadfield and the crew of STS-100. You can find it at:
        Message 3 of 14 , Apr 1, 2001
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          Hello CCD-Newastro,

          Just a quick message promote a new website I am working on for Chris Hadfield and the crew of STS-100.
          You can find it at:

          http://www.sts-100.org

          Originally it started out as a few pages on our RMC Class of 82 website, but there were so many things
          that could be added the crew supported the idea of a unique domain name and additions to the site.
          Over the course of the next 4 weeks I hope to get more things available at the site including some more
          maps of Florida for people planning to attend the Launch or Landing, more photos and additional space
          and Florida related links.

          Some things of interest at STS-100.ORG include a number of training pictures for the mission not available
          elsewhere yet, a detailed mission schedule in PDF format which you can download and have on your
          local hard disk quick browsing during the mission (19-30 Apr 01), as well as some neat screen wallpapers.
          There are instructions at the site on how you can get a hold of the wallpapers for your particular screen
          resolution.  If there is sufficient demand I will make these available directly at the site in the
          future.  For now they are available through Freedrive.com and you will need an invite to obtain them
          (please follow the instructions listed on the wallpaper page).  Finally, I have just created a Yahoogroups
          email list for the mission which you can join at the homepage for the website to stay current with the
          latest from now until approx. one month after the mission.

          I am curious.  What are the chances of people on this list getting some pictures of STS-100 or the ISS
          during the mission (19-30 Apr 01)?

          Enjoy and hope you find some interest in this website.

          Cheers,



          Steven Jodoin
          Bendigo, Vic, Australia
          http://www.ozemap.com.au
          http://www.rmc82.org
          http://www.sts-100.org

        • Ron Wodaski
          I don t have my archive images with me, or I d be glad to help. Can you wait three months until I get back home? Ron Wodaski The New CCD Astronomy
          Message 4 of 14 , Apr 1, 2001
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            I don't have my archive images with me, or I'd be glad to help. Can you wait
            three months until I get back home? <g>

            Ron Wodaski
            The New CCD Astronomy
            http://www.newastro.com

            -----Original Message-----
            From: jeffh@... [mailto:jeffh@...]
            Sent: Saturday, March 31, 2001 3:43 PM
            To: ccd-newastro@yahoogroups.com
            Subject: [ccd-newastro] Can someone let me use their M101 B channel?


            It's snowing again here in WI, and I'm Jonesin' for some astronomy.
            A few weeks back I got 1 hour of L, and 30 minutes each of R and G of
            M101 at full resolution on my ST8E. I'd like to be able to stitch
            together the whole image, but my blue image was lost when my mount
            broke and stopped tracking (Ron W, if you're reading this you may be
            pleased to know that I traded up to an NJP).

            Anyway, I would prefer a full-resolution image from an ST8E,
            somewhere in the 30-45 minute range, but I'll take whatever. I was
            using a 5" refractor at f/8 if that gives any else any idea of scale,
            but again, that's less relevant.

            I'd just like to get some practice with my LRGB processing of
            galaxies, and besides an M51 shot that I have whipped like a dead
            horse, this is the only other I have.

            Anybody willing to help? I have broadband, so you can send me large
            files...you'll save me from the "snowy, cloudy skies blues."

            Feel free to email them to me.

            Jeff



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          • jeffh@ntsllc.com
            Ron, I did have the L-channels IR blocked, probably doubly so, since I had the SBIG/Custom Scientific IR-blocking filter and the IDAS LPS filter in place (and
            Message 5 of 14 , Apr 1, 2001
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              Ron,

              I did have the L-channels IR blocked, probably doubly so, since I had
              the SBIG/Custom Scientific IR-blocking filter and the IDAS LPS filter
              in place (and I know that blocks a good bit of IR).

              However, I didn't get the instructions from you on to use MaxIm to do
              this subtraction. Email error?

              Can you post here or try again?

              Thanks,

              Jeff

              --- In ccd-newastro@y..., "Ron Wodaski" <ronw@n...> wrote:
              > This won't work well unless the L image was done with IR blocking.
              > Otherwise, you have IR + R + B + G in the original image, and
              performing
              > just L - R - G will leave you with B + IR.
              >
              > I've sent instructions for how to do this in Maxim separately. Be
              sure to do
              > darks and flats before you perform the math.
              >
              > Ron Wodaski
              > The New CCD Astronomy
              > http://www.newastro.com
              >
              > -----Original Message-----
              > From: jeffh@n... [mailto:jeffh@n...]
              > Sent: Saturday, March 31, 2001 7:15 PM
              > To: ccd-newastro@y...
              > Subject: [ccd-newastro] Re: Can someone let me use their M101 B
              channel?
              >
              >
              > Yeah, I already thought of that--but I wasn't sure of how to do it
              > with the software I have available. Actually, I thought someone
              like
              > you would see this and tell me how <g>. I've got MaxImDL and PS
              > 6.0...
              >
              > Anyone know how to do this subtraction?
              >
              > Jeff
              >
              > --- In ccd-newastro@y..., "Eddie Trimarchi" <eddiet@b...> wrote:
              > > You could try synthesising a B image from what you have.
              > >
              > > Theoretically L = R + G + B
              > > so B = L - R - G
              > >
              > > The trick is matching the levels first so that the B data is
              > meaningful.
              > >
              > > It can be done though.
              > >
              > > Regards,
              > >
              > > Eddie Trimarchi
              > > ~~~~~~~~~~~~~~~
              > > http://users.fan.net.au/~eddiet
              > >
              > > >-----Original Message-----
              > > >From: jeffh@n... [mailto:jeffh@n...]
              > > >Sent: Sunday, April 01, 2001 9:43 AM
              > > >To: ccd-newastro@y...
              > > >Subject: [ccd-newastro] Can someone let me use their M101 B
              > channel?
              > > >
              > > >
              > > >It's snowing again here in WI, and I'm Jonesin' for some
              > astronomy.
              > > >A few weeks back I got 1 hour of L, and 30 minutes each of R and
              G
              > of
              > > >M101 at full resolution on my ST8E. I'd like to be able to
              stitch
              > > >together the whole image, but my blue image was lost when my
              mount
              > > >broke and stopped tracking (Ron W, if you're reading this you may
              > be
              > > >pleased to know that I traded up to an NJP).
              > > >
              > > >Anyway, I would prefer a full-resolution image from an ST8E,
              > > >somewhere in the 30-45 minute range, but I'll take whatever. I
              > was
              > > >using a 5" refractor at f/8 if that gives any else any idea of
              > scale,
              > > >but again, that's less relevant.
              > > >
              > > >I'd just like to get some practice with my LRGB processing of
              > > >galaxies, and besides an M51 shot that I have whipped like a dead
              > > >horse, this is the only other I have.
              > > >
              > > >Anybody willing to help? I have broadband, so you can send me
              > large
              > > >files...you'll save me from the "snowy, cloudy skies blues."
              > > >
              > > >Feel free to email them to me.
              > > >
              > > >Jeff
              > > >
              > > >
              > > >
              > > >To unsubscribe from this group, send an email to:
              > > >ccd-newastro-unsubscribe@egroups.com
              > > >
              > > >
              > > >
              > > >Your use of Yahoo! Groups is subject to
              > http://docs.yahoo.com/info/terms/
              > > >
              > > >
              > > >
              >
              >
              >
              > To unsubscribe from this group, send an email to:
              > ccd-newastro-unsubscribe@egroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to
              http://docs.yahoo.com/info/terms/
            • Ron Wodaski
              You can do the subtraction in Maxim. If you don t normalize the images first (subtract using pixel math so all have the same background level), you can
              Message 6 of 14 , Apr 1, 2001
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                You can do the subtraction in Maxim. If you don't normalize the images first
                (subtract using pixel math so all have the same background level), you can
                compensate for color level differences using Color Balance on the color
                menu.

                Perform the subtractions in Maxim DL:

                1. Open the L, G, R images.
                2. Make the L image current.
                3. Use the Process | Pixel math menu option.
                4. Make the L image Image A.
                5. Scale factor is 100%.
                6. Make the operation Subtract.
                7. Make the G image, Image B. Scale factor 100%.
                8. Make sure add constant is set to zero.
                9. Click OK to subtract the green image from the L image.
                10. Repeat, subtracting the red image from the result of step 9.
                11. Save as "M51_synth_B.fit" or use your own naming convention.
                12. Color combine using original L, R, G, and synth_B images.

                Ron Wodaski
                The New CCD Astronomy
                http://www.newastro.com

                -----Original Message-----
                From: jeffh@... [mailto:jeffh@...]
                Sent: Saturday, March 31, 2001 7:15 PM
                To: ccd-newastro@yahoogroups.com
                Subject: [ccd-newastro] Re: Can someone let me use their M101 B channel?


                Yeah, I already thought of that--but I wasn't sure of how to do it
                with the software I have available. Actually, I thought someone like
                you would see this and tell me how <g>. I've got MaxImDL and PS
                6.0...

                Anyone know how to do this subtraction?

                Jeff

                --- In ccd-newastro@y..., "Eddie Trimarchi" <eddiet@b...> wrote:
                > You could try synthesising a B image from what you have.
                >
                > Theoretically L = R + G + B
                > so B = L - R - G
                >
                > The trick is matching the levels first so that the B data is
                meaningful.
                >
                > It can be done though.
                >
                > Regards,
                >
                > Eddie Trimarchi
                > ~~~~~~~~~~~~~~~
                > http://users.fan.net.au/~eddiet
                >
                > >-----Original Message-----
                > >From: jeffh@n... [mailto:jeffh@n...]
                > >Sent: Sunday, April 01, 2001 9:43 AM
                > >To: ccd-newastro@y...
                > >Subject: [ccd-newastro] Can someone let me use their M101 B
                channel?
                > >
                > >
                > >It's snowing again here in WI, and I'm Jonesin' for some
                astronomy.
                > >A few weeks back I got 1 hour of L, and 30 minutes each of R and G
                of
                > >M101 at full resolution on my ST8E. I'd like to be able to stitch
                > >together the whole image, but my blue image was lost when my mount
                > >broke and stopped tracking (Ron W, if you're reading this you may
                be
                > >pleased to know that I traded up to an NJP).
                > >
                > >Anyway, I would prefer a full-resolution image from an ST8E,
                > >somewhere in the 30-45 minute range, but I'll take whatever. I
                was
                > >using a 5" refractor at f/8 if that gives any else any idea of
                scale,
                > >but again, that's less relevant.
                > >
                > >I'd just like to get some practice with my LRGB processing of
                > >galaxies, and besides an M51 shot that I have whipped like a dead
                > >horse, this is the only other I have.
                > >
                > >Anybody willing to help? I have broadband, so you can send me
                large
                > >files...you'll save me from the "snowy, cloudy skies blues."
                > >
                > >Feel free to email them to me.
                > >
                > >Jeff
                > >
                > >
                > >
                > >To unsubscribe from this group, send an email to:
                > >ccd-newastro-unsubscribe@egroups.com
                > >
                > >
                > >
                > >Your use of Yahoo! Groups is subject to
                http://docs.yahoo.com/info/terms/
                > >
                > >
                > >



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



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              • Ron Wodaski
                Lowering aggressiveness is a good idea. You can also shorten the maximum time for a Dec correction in most camera control packages. Ron Wodaski The New CCD
                Message 7 of 14 , Apr 1, 2001
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                  Lowering aggressiveness is a good idea. You can also shorten the maximum
                  time for a Dec correction in most camera control packages.

                  Ron Wodaski
                  The New CCD Astronomy
                  http://www.newastro.com

                  -----Original Message-----
                  From: al brockman [mailto:alanb@...]
                  Sent: Sunday, April 01, 2001 5:55 AM
                  To: ccd-newastro@yahoogroups.com
                  Subject: [ccd-newastro] Dec drift while guiding with a LX-200


                  I have been very encouraged in my persuit of better tracking with the
                  LX200 mount by use of a relay switch developed by Wesley Erickson. I tried
                  it out for the first time two nights ago with my ST-8 and what it does is
                  deceptively simple but now allows the guide chip to track in both RA and
                  DEC without problems caused by DEC backlash - ala' the Death Wobbles'. It
                  switches off a north or south direction so that Dec movements occur in one
                  direction only to correct for the inevitable DEC drift. Over a combined 60
                  minute exposure, the guide star never left the window and stayed centred.
                  Normally I must switch off Dec corrections and see a slow drift over time
                  that I can never quite tweak out by Drift aligning. There were occasions of
                  overshoot but I think I can improve that by changing the aggressive
                  setting. Is there a better way to adjust this?
                  My sincere thanks to Wes.

                  Regards, Alan

                  ____________________________________________________________________
                  Al Brockman
                  Shoklo Malaria Research Unit
                  PO Box 46, Mae Sot, Tak 63110
                  Thailand
                  http://smru.thehealthzone.com
                  http://www.geocities.com/alan_astro




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



                  Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                • Ron Wodaski
                  This won t work well unless the L image was done with IR blocking. Otherwise, you have IR + R + B + G in the original image, and performing just L - R - G will
                  Message 8 of 14 , Apr 1, 2001
                  • 0 Attachment
                    This won't work well unless the L image was done with IR blocking.
                    Otherwise, you have IR + R + B + G in the original image, and performing
                    just L - R - G will leave you with B + IR.

                    I've sent instructions for how to do this in Maxim separately. Be sure to do
                    darks and flats before you perform the math.

                    Ron Wodaski
                    The New CCD Astronomy
                    http://www.newastro.com

                    -----Original Message-----
                    From: jeffh@... [mailto:jeffh@...]
                    Sent: Saturday, March 31, 2001 7:15 PM
                    To: ccd-newastro@yahoogroups.com
                    Subject: [ccd-newastro] Re: Can someone let me use their M101 B channel?


                    Yeah, I already thought of that--but I wasn't sure of how to do it
                    with the software I have available. Actually, I thought someone like
                    you would see this and tell me how <g>. I've got MaxImDL and PS
                    6.0...

                    Anyone know how to do this subtraction?

                    Jeff

                    --- In ccd-newastro@y..., "Eddie Trimarchi" <eddiet@b...> wrote:
                    > You could try synthesising a B image from what you have.
                    >
                    > Theoretically L = R + G + B
                    > so B = L - R - G
                    >
                    > The trick is matching the levels first so that the B data is
                    meaningful.
                    >
                    > It can be done though.
                    >
                    > Regards,
                    >
                    > Eddie Trimarchi
                    > ~~~~~~~~~~~~~~~
                    > http://users.fan.net.au/~eddiet
                    >
                    > >-----Original Message-----
                    > >From: jeffh@n... [mailto:jeffh@n...]
                    > >Sent: Sunday, April 01, 2001 9:43 AM
                    > >To: ccd-newastro@y...
                    > >Subject: [ccd-newastro] Can someone let me use their M101 B
                    channel?
                    > >
                    > >
                    > >It's snowing again here in WI, and I'm Jonesin' for some
                    astronomy.
                    > >A few weeks back I got 1 hour of L, and 30 minutes each of R and G
                    of
                    > >M101 at full resolution on my ST8E. I'd like to be able to stitch
                    > >together the whole image, but my blue image was lost when my mount
                    > >broke and stopped tracking (Ron W, if you're reading this you may
                    be
                    > >pleased to know that I traded up to an NJP).
                    > >
                    > >Anyway, I would prefer a full-resolution image from an ST8E,
                    > >somewhere in the 30-45 minute range, but I'll take whatever. I
                    was
                    > >using a 5" refractor at f/8 if that gives any else any idea of
                    scale,
                    > >but again, that's less relevant.
                    > >
                    > >I'd just like to get some practice with my LRGB processing of
                    > >galaxies, and besides an M51 shot that I have whipped like a dead
                    > >horse, this is the only other I have.
                    > >
                    > >Anybody willing to help? I have broadband, so you can send me
                    large
                    > >files...you'll save me from the "snowy, cloudy skies blues."
                    > >
                    > >Feel free to email them to me.
                    > >
                    > >Jeff
                    > >
                    > >
                    > >
                    > >To unsubscribe from this group, send an email to:
                    > >ccd-newastro-unsubscribe@egroups.com
                    > >
                    > >
                    > >
                    > >Your use of Yahoo! Groups is subject to
                    http://docs.yahoo.com/info/terms/
                    > >
                    > >
                    > >



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



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                  • Ron Wodaski
                    You can build one. I just got permission to include the directions in the book from the originator. Briefly, you buy a standard phone wall connector, and put
                    Message 9 of 14 , Apr 1, 2001
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                      You can build one. I just got permission to include the directions in the
                      book from the originator. Briefly, you buy a standard phone wall connector,
                      and put small switches on the wires that connect to the Dec lines in the
                      guide cable.

                      A raw copy of the instructions can be found here:

                      http://www.newastro.com/newastro/test/blockdev.htm

                      The original .doc file (Word) can be downloaded from here:

                      http://home.pacbell.net/twerick/blockdev.htm

                      Ron Wodaski
                      The New CCD Astronomy
                      http://www.newastro.com

                      -----Original Message-----
                      From: Kevin Dixon [mailto:ksbtk@...]
                      Sent: Sunday, April 01, 2001 6:41 AM
                      To: ccd-newastro@yahoogroups.com
                      Subject: Re: [ccd-newastro] Dec drift while guiding with a LX-200


                      Good Morning Alan:

                      Can you please describe this relay switch in a bit more detail. Is it
                      specific to the LX-200? Do you have information on how it can be obtained,
                      if applicable to scopes other than the LX-200?

                      Clear skies,
                      Kevin Dixon
                      ksbtk@...

                      From: "al brockman" <alanb@...>


                      > I have been very encouraged in my persuit of better tracking with the
                      > LX200 mount by use of a relay switch developed by Wesley Erickson. I
                      tried
                      > it out for the first time two nights ago with my ST-8 and what it does is
                      > deceptively simple but now allows the guide chip to track in both RA and
                      > DEC without problems caused by DEC backlash - ala' the Death Wobbles'. It
                      > switches off a north or south direction so that Dec movements occur in one
                      > direction only to correct for the inevitable DEC drift. Over a combined 60
                      > minute exposure, the guide star never left the window and stayed centred.
                      > Normally I must switch off Dec corrections and see a slow drift over time
                      > that I can never quite tweak out by Drift aligning. There were occasions
                      of
                      > overshoot but I think I can improve that by changing the aggressive
                      > setting. Is there a better way to adjust this?




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



                      Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                    • Ron Wodaski
                      You can do the subtraction in Maxim. If you don t normalize the images first (subtract using pixel math so all have the same background level), you can
                      Message 10 of 14 , Apr 1, 2001
                      • 0 Attachment
                        You can do the subtraction in Maxim. If you don't normalize the images first
                        (subtract using pixel math so all have the same background level), you can
                        compensate for color level differences using Color Balance on the color
                        menu.

                        Perform the subtractions in Maxim DL:

                        0. Perform image calibration (darks and flats) and normalize.
                        1. Open the L, G, R images.
                        2. Make the L image current.
                        3. Use the Process | Pixel math menu option.
                        4. Make the L image Image A.
                        5. Scale factor is 100%.
                        6. Make the operation Subtract.
                        7. Make the G image, Image B. Scale factor 100%.
                        8. Make sure add constant is set to zero.
                        9. Click OK to subtract the green image from the L image.
                        10. Repeat, subtracting the red image from the result of step 9.
                        11. Save as "M51_synth_B.fit" or use your own naming convention.
                        12. Color combine using original L, R, G, and synth_B images.

                        To normalize, perform pixel math setting the operation to None and the "add
                        constant" to a negative number equal to the average background value - 50.
                        This is not terribly effective if there is a gradient, however; in that
                        case, normalize to the same location in all of the image, since there isn't
                        really an average background due to the gradient. For example, use the value
                        at the upper left of each image.


                        Ron Wodaski
                        The New CCD Astronomy
                        http://www.newastro.com

                        -----Original Message-----
                        From: jeffh@... [mailto:jeffh@...]
                        Sent: Sunday, April 01, 2001 11:28 AM
                        To: ccd-newastro@yahoogroups.com
                        Subject: [ccd-newastro] Re: Can someone let me use their M101 B channel?


                        Ron,

                        I did have the L-channels IR blocked, probably doubly so, since I had
                        the SBIG/Custom Scientific IR-blocking filter and the IDAS LPS filter
                        in place (and I know that blocks a good bit of IR).

                        However, I didn't get the instructions from you on to use MaxIm to do
                        this subtraction. Email error?

                        Can you post here or try again?

                        Thanks,

                        Jeff

                        --- In ccd-newastro@y..., "Ron Wodaski" <ronw@n...> wrote:
                        > This won't work well unless the L image was done with IR blocking.
                        > Otherwise, you have IR + R + B + G in the original image, and
                        performing
                        > just L - R - G will leave you with B + IR.
                        >
                        > I've sent instructions for how to do this in Maxim separately. Be
                        sure to do
                        > darks and flats before you perform the math.
                        >
                        > Ron Wodaski
                        > The New CCD Astronomy
                        > http://www.newastro.com
                        >
                        > -----Original Message-----
                        > From: jeffh@n... [mailto:jeffh@n...]
                        > Sent: Saturday, March 31, 2001 7:15 PM
                        > To: ccd-newastro@y...
                        > Subject: [ccd-newastro] Re: Can someone let me use their M101 B
                        channel?
                        >
                        >
                        > Yeah, I already thought of that--but I wasn't sure of how to do it
                        > with the software I have available. Actually, I thought someone
                        like
                        > you would see this and tell me how <g>. I've got MaxImDL and PS
                        > 6.0...
                        >
                        > Anyone know how to do this subtraction?
                        >
                        > Jeff
                        >
                        > --- In ccd-newastro@y..., "Eddie Trimarchi" <eddiet@b...> wrote:
                        > > You could try synthesising a B image from what you have.
                        > >
                        > > Theoretically L = R + G + B
                        > > so B = L - R - G
                        > >
                        > > The trick is matching the levels first so that the B data is
                        > meaningful.
                        > >
                        > > It can be done though.
                        > >
                        > > Regards,
                        > >
                        > > Eddie Trimarchi
                        > > ~~~~~~~~~~~~~~~
                        > > http://users.fan.net.au/~eddiet
                        > >
                        > > >-----Original Message-----
                        > > >From: jeffh@n... [mailto:jeffh@n...]
                        > > >Sent: Sunday, April 01, 2001 9:43 AM
                        > > >To: ccd-newastro@y...
                        > > >Subject: [ccd-newastro] Can someone let me use their M101 B
                        > channel?
                        > > >
                        > > >
                        > > >It's snowing again here in WI, and I'm Jonesin' for some
                        > astronomy.
                        > > >A few weeks back I got 1 hour of L, and 30 minutes each of R and
                        G
                        > of
                        > > >M101 at full resolution on my ST8E. I'd like to be able to
                        stitch
                        > > >together the whole image, but my blue image was lost when my
                        mount
                        > > >broke and stopped tracking (Ron W, if you're reading this you may
                        > be
                        > > >pleased to know that I traded up to an NJP).
                        > > >
                        > > >Anyway, I would prefer a full-resolution image from an ST8E,
                        > > >somewhere in the 30-45 minute range, but I'll take whatever. I
                        > was
                        > > >using a 5" refractor at f/8 if that gives any else any idea of
                        > scale,
                        > > >but again, that's less relevant.
                        > > >
                        > > >I'd just like to get some practice with my LRGB processing of
                        > > >galaxies, and besides an M51 shot that I have whipped like a dead
                        > > >horse, this is the only other I have.
                        > > >
                        > > >Anybody willing to help? I have broadband, so you can send me
                        > large
                        > > >files...you'll save me from the "snowy, cloudy skies blues."
                        > > >
                        > > >Feel free to email them to me.
                        > > >
                        > > >Jeff
                        > > >
                        > > >
                        > > >
                        > > >To unsubscribe from this group, send an email to:
                        > > >ccd-newastro-unsubscribe@egroups.com
                        > > >
                        > > >
                        > > >
                        > > >Your use of Yahoo! Groups is subject to
                        > http://docs.yahoo.com/info/terms/
                        > > >
                        > > >
                        > > >
                        >
                        >
                        >
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