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Combing Ha Images

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  • Joe Morris
    I m new at adding Ha images to my LRGB data. Since I ve been exposing each Ha image for 30 min., it s hard to collect very many for combining. If one has,
    Message 1 of 9 , Feb 19, 2009
      I'm new at adding Ha images to my LRGB data. Since I've been exposing
      each Ha image for 30 min., it's hard to collect very many for
      combining. If one has, say four 30 min. images, some with quite a few
      cosmic ray hits, would average or median combine be best. I that four
      images isn't enough to even consider the sigma clip or SD mask algorithms.

      Joe Morris
    • roundycat
      Joe, I think I just proved that SD Mask will work with three images in a series of tests. See here http://www.dens-astropics.org.uk/page%2019.htm Dennis ...
      Message 2 of 9 , Feb 19, 2009
        Joe, I think I just proved that SD Mask will work with three images in
        a series of tests. See here
        http://www.dens-astropics.org.uk/page%2019.htm

        Dennis
        >

        > I'm new at adding Ha images to my LRGB data. Since I've been exposing
        > each Ha image for 30 min., it's hard to collect very many for
        > combining. If one has, say four 30 min. images, some with quite a few
        > cosmic ray hits, would average or median combine be best. I that four
        > images isn't enough to even consider the sigma clip or SD mask
        algorithms.
        >
        > Joe Morris
        >
      • Mike Dodd
        ... You might try Clip min/max (in CCDStack, if you have it). I ve also used SD with few images, and it seems to remove outliers pretty well, but might
        Message 3 of 9 , Feb 19, 2009
          Joe Morris wrote:
          > I'm new at adding Ha images to my LRGB data. Since I've been exposing
          > each Ha image for 30 min., it's hard to collect very many for
          > combining. If one has, say four 30 min. images, some with quite a few
          > cosmic ray hits, would average or median combine be best. I that four
          > images isn't enough to even consider the sigma clip or SD mask algorithms.

          You might try Clip min/max (in CCDStack, if you have it). I've also used
          SD with few images, and it seems to remove outliers pretty well, but
          might increase noise a bit.

          I recommend TRYING several methods, then look at the results and judge
          for yourself.
          --
          Mike

          Mike Dodd
          Montpelier, VA USA
          http://astronomy.mdodd.com
        • Neil Fleming
          You want to use Poisson Sigma reject in CCDStack.  Clip min/max is best used only with a deep stack.      Regards...Neil www.flemingastrophotography.com 
          Message 4 of 9 , Feb 19, 2009
            You want to use Poisson Sigma reject in CCDStack.  Clip min/max is best used only with a deep stack.
             
               Regards...Neil


            www.flemingastrophotography.com 
            Direct from Boston - brilliant diamonds in pea soup
            Also check out the astro_narrowband Yahoo group!

            --- On Thu, 2/19/09, Mike Dodd <mike@...> wrote:

            From: Mike Dodd <mike@...>
            Subject: [ccd-newastro] Re: Combining Ha Images
            To: ccd-newastro@yahoogroups.com
            Date: Thursday, February 19, 2009, 7:50 PM

            Joe Morris wrote:
            > I'm new at adding Ha images to my LRGB data. Since I've been
            exposing
            > each Ha image for 30 min., it's hard to collect very many for
            > combining. If one has, say four 30 min. images, some with quite a few
            > cosmic ray hits, would average or median combine be best. I that four
            > images isn't enough to even consider the sigma clip or SD mask
            algorithms.

            You might try Clip min/max (in CCDStack, if you have it). I've also used
            SD with few images, and it seems to remove outliers pretty well, but
            might increase noise a bit.

            I recommend TRYING several methods, then look at the results and judge
            for yourself.
            --
            Mike

            Mike Dodd
            Montpelier, VA USA
            http://astronomy.mdodd.com


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






            [Non-text portions of this message have been removed]
          • Joe Morris
            Dennis -- Very nice study. Thanks for sharing. Mike and Neil --I don t own CCD Stack yet but will take Mike s suggestion to try several methods and just pick
            Message 5 of 9 , Feb 20, 2009
              Dennis -- Very nice study. Thanks for sharing.

              Mike and Neil --I don't own CCD Stack yet but will take Mike's
              suggestion to try several methods and just pick the best.

              Joe


              --- In ccd-newastro@yahoogroups.com, "roundycat" <den22har@...> wrote:
              >
              > Joe, I think I just proved that SD Mask will work with three images in
              > a series of tests. See here
              > http://www.dens-astropics.org.uk/page%2019.htm
              >
              > Dennis
              > >
              >
              > > I'm new at adding Ha images to my LRGB data. Since I've been exposing
              > > each Ha image for 30 min., it's hard to collect very many for
              > > combining. If one has, say four 30 min. images, some with quite a few
              > > cosmic ray hits, would average or median combine be best. I that four
              > > images isn't enough to even consider the sigma clip or SD mask
              > algorithms.
              > >
              > > Joe Morris
              > >
              >
            • Niall Saunders
              Why not try the FREE software, Deep Sky Stacker ? It has a wealth of choices when it comes to combining your images - and works very well, and VERY fast. It
              Message 6 of 9 , Feb 20, 2009
                Why not try the FREE software, "Deep Sky Stacker" ?

                It has a wealth of choices when it comes to combining your images -
                and works very well, and VERY fast. It offers an excellent
                registration system, it can even handle moving objects such as
                comets. Once registered, image sets can be stacked and re-stacked
                without having to re-register. Another huge time-saving feature, and
                the program runs comfortably on 64-bit platforms, and can use all
                available processors to speed things up even more

                It is certainly an option to the commercial programs out there.

                And it handles both FITS and DSLR images (as well as images in all of
                the most popular graphics formats).

                In fact, so long as DSS remains available, I cannot see a SINGLE need
                for any other stacking software, certainly not if all you need to
                achieve is image registration, image calibration and image stacking.

                Save your money for a decent astro-processing package - like
                PixInsight for example.

                However, as always, these comments are based on personal experience.
                I am happy to stand corrected, if people can explain to me the
                features present in CCD Stack that make it a better decision to
                choose a commercial package like CCD Stack over a free package like
                DSS. (I moved from IRIS to PixInsight for exactly that reason -
                people were able to demonstrate to me, with examples, the specific
                areas where PixInsight scored over IRIS)

                "You pays yer money, . . . . ."

                HTH

                Niall Saunders
                Clinterty Observatories
                Aberdeen, SCOTLAND

                --- In ccd-newastro@yahoogroups.com, "Joe Morris" <joemorris@...>
                wrote:
                >
                > Dennis -- Very nice study. Thanks for sharing.
                >
                > Mike and Neil --I don't own CCD Stack yet but will take Mike's
                > suggestion to try several methods and just pick the best.
                >
                > Joe
                >
                >
                > --- In ccd-newastro@yahoogroups.com, "roundycat" <den22har@> wrote:
                > >
                > > Joe, I think I just proved that SD Mask will work with three
                images in
                > > a series of tests. See here
                > > http://www.dens-astropics.org.uk/page%2019.htm
                > >
                > > Dennis
                > > >
                > >
                > > > I'm new at adding Ha images to my LRGB data. Since I've been
                exposing
                > > > each Ha image for 30 min., it's hard to collect very many for
                > > > combining. If one has, say four 30 min. images, some with
                quite a few
                > > > cosmic ray hits, would average or median combine be best. I
                that four
                > > > images isn't enough to even consider the sigma clip or SD mask
                > > algorithms.
                > > >
                > > > Joe Morris
                > > >
                > >
                >
              • Neil Fleming
                Sorry to disagree with you on this one, Niall.  Having used both, Deep Sky Stacker falls down in comparison to CCDStack in many ways:  - Sigma and clip
                Message 7 of 9 , Feb 20, 2009
                  Sorry to disagree with you on this one, Niall.  Having used both, Deep Sky Stacker falls down in comparison to CCDStack in many ways:
                   - Sigma and clip min/max data rejection for your calibration frames
                   - RMS/Time scaling of calibration frames
                   - Ability to make blooms "transparent" in order to allow accumulated shorter-exposure data to "poke" through
                   - Better registration accuracy
                   - More advanced registration (application) algorithms
                   - Far more advanced data rejection techniques, like Poisson Sigma for excellent outlier rejection in short stacks, clip min/max for smooth results in deep stacks
                   - Advanced combines like min, max, in addition to sum, mean, and median
                   - Excellent and easy-to-use implementation of DDP
                   - Similar excellent implementation of Postive Constraint deconvolution
                   - CCDStack has all of the features you mentioned below, too
                   
                  I am sure there are more, but those are the ones off the top of my head.  I dunno what I would do without it.
                   
                     Regards...Neil


                  www.flemingastrophotography.com 
                  Direct from Boston - brilliant diamonds in pea soup
                  Also check out the astro_narrowband Yahoo group!

                  --- On Fri, 2/20/09, Niall Saunders <niall@...> wrote:

                  From: Niall Saunders <niall@...>
                  Subject: [ccd-newastro] Re: Combing Ha Images
                  To: ccd-newastro@yahoogroups.com
                  Date: Friday, February 20, 2009, 1:16 PM

                  Why not try the FREE software, "Deep Sky Stacker" ?

                  It has a wealth of choices when it comes to combining your images -
                  and works very well, and VERY fast. It offers an excellent
                  registration system, it can even handle moving objects such as
                  comets. Once registered, image sets can be stacked and re-stacked
                  without having to re-register. Another huge time-saving feature, and
                  the program runs comfortably on 64-bit platforms, and can use all
                  available processors to speed things up even more

                  It is certainly an option to the commercial programs out there.

                  And it handles both FITS and DSLR images (as well as images in all of
                  the most popular graphics formats).

                  In fact, so long as DSS remains available, I cannot see a SINGLE need
                  for any other stacking software, certainly not if all you need to
                  achieve is image registration, image calibration and image stacking.

                  Save your money for a decent astro-processing package - like
                  PixInsight for example.

                  However, as always, these comments are based on personal experience.
                  I am happy to stand corrected, if people can explain to me the
                  features present in CCD Stack that make it a better decision to
                  choose a commercial package like CCD Stack over a free package like
                  DSS. (I moved from IRIS to PixInsight for exactly that reason -
                  people were able to demonstrate to me, with examples, the specific
                  areas where PixInsight scored over IRIS)

                  "You pays yer money, . . . . ."

                  HTH

                  Niall Saunders
                  Clinterty Observatories
                  Aberdeen, SCOTLAND

                  --- In ccd-newastro@yahoogroups.com, "Joe Morris"
                  <joemorris@...>
                  wrote:
                  >
                  > Dennis -- Very nice study. Thanks for sharing.
                  >
                  > Mike and Neil --I don't own CCD Stack yet but will take Mike's
                  > suggestion to try several methods and just pick the best.
                  >
                  > Joe
                  >
                  >
                  > --- In ccd-newastro@yahoogroups.com, "roundycat"
                  <den22har@> wrote:
                  > >
                  > > Joe, I think I just proved that SD Mask will work with three
                  images in
                  > > a series of tests. See here
                  > > http://www.dens-astropics.org.uk/page%2019.htm
                  > >
                  > > Dennis
                  > > >
                  > >
                  > > > I'm new at adding Ha images to my LRGB data. Since I've
                  been
                  exposing
                  > > > each Ha image for 30 min., it's hard to collect very many
                  for
                  > > > combining. If one has, say four 30 min. images, some with
                  quite a few
                  > > > cosmic ray hits, would average or median combine be best. I
                  that four
                  > > > images isn't enough to even consider the sigma clip or SD
                  mask
                  > > algorithms.
                  > > >
                  > > > Joe Morris
                  > > >
                  > >
                  >




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






                  [Non-text portions of this message have been removed]
                • Niall Saunders
                  Hi Neil, No - please do NOT feel sorry for disagreeing with me. In fact your reply was really just the sort of response I was looking for !! You have put
                  Message 8 of 9 , Feb 20, 2009
                    Hi Neil,

                    No - please do NOT feel 'sorry' for disagreeing with me.

                    In fact your reply was really just the sort of response I was looking
                    for !!

                    You have put together a quick list, based on your formidable
                    experience, which has identified several areas that I, as someone who
                    does NOT use CCDStack, can now use to formulate a more informed
                    opinion as to whether to make the 'upgrade'.

                    It may be a while before I 'move up' - I need to now understand
                    whether any of the enhanced features are actually needed at my
                    present stage on the learning curve.

                    I am still only acquiring sub-300s exposures, one night a month if
                    the weather is nice, from an ED80 riding shotgun on a pier-mounted
                    LX90 Classic - both OTAs hooked up to DSI-II cameras, one -Pro (oddly
                    enough, mostly used for guiding on the 8"SCT, despite a nice set of
                    Astronomik filters in a 5-slot wheel) and a -IIC OSC which I find I
                    have to rely on, simply because my weather windows are so short it is
                    the only way I can get enough data to work with !!

                    I capture and store all my images (lights, darks, flats and
                    flatdarks) in RAW mode, calibrate all the RAW data in AIP4WIN, and
                    then use DSS to stack the calibrated RAW files, and also to de-bayer
                    at the same time (because the current version of AIP4WIN has no DSI
                    deBayer facility)

                    Would CCDStack allow me to 'grab' all my captured data, and
                    effectively provide me with a 'one-key-click' process to generate a
                    master calibrated image? (Accepting that I would need to determine
                    the most suitable process for a given set of data, and that I would
                    also probably pre-filter the 'duds' before hitting CCDStack -
                    something I currently do using the 'Image Series Analysis' tool in
                    AIP4WIN, then graphing the output table in MS Excel)

                    Don't get me wrong, I have no objection to well-coded commercial
                    software. I spent several years with the continuosly developing
                    PixInsight package, before finally buying into the full commercial
                    version a few months ago, and I have yet to see ANY other package
                    that even comes close to what PixInsight can do - although what you
                    guys can tease out of PhotoShop continues to amaze me as well (I have
                    CS2 and CS3, but just don't get on well with them - probably because
                    I 'grew up' with Corel and find it difficult to make the migration
                    [old dog, new tricks ??!!])

                    Maybe I need to revisit CCDStack, check out any 'demo/trial' period,
                    and then get you to hook-up to my PC and run the software through
                    it's paces on some of MY data - so that I get a feel for how it works.

                    Ahh, the wonder of the Internet !!

                    Cheers,

                    Niall Saunders
                    Clinterty Observatories
                    Aberdeen, SCOTLAND

                    --- In ccd-newastro@yahoogroups.com, Neil Fleming <neilfleming@...>
                    wrote:
                    >
                    > Sorry to disagree with you on this one, Niall.  Having used both,
                    Deep Sky Stacker falls down in comparison to CCDStack in many ways:
                    >  - Sigma and clip min/max data rejection for your calibration frames
                    >  - RMS/Time scaling of calibration frames
                    >  - Ability to make blooms "transparent" in order to allow
                    accumulated shorter-exposure data to "poke" through
                    >  - Better registration accuracy
                    >  - More advanced registration (application) algorithms
                    >  - Far more advanced data rejection techniques, like Poisson Sigma
                    for excellent outlier rejection in short stacks, clip min/max for
                    smooth results in deep stacks
                    >  - Advanced combines like min, max, in addition to sum, mean, and
                    median
                    >  - Excellent and easy-to-use implementation of DDP
                    >  - Similar excellent implementation of Postive Constraint
                    deconvolution
                    >  - CCDStack has all of the features you mentioned below, too
                    >  
                    > I am sure there are more, but those are the ones off the top of my
                    head.  I dunno what I would do without it.
                    >  
                    >    Regards...Neil
                    >
                    >
                    > www.flemingastrophotography.com 
                    > Direct from Boston - brilliant diamonds in pea soup
                    > Also check out the astro_narrowband Yahoo group!
                    >
                    > --- On Fri, 2/20/09, Niall Saunders <niall@...> wrote:
                    >
                    > From: Niall Saunders <niall@...>
                    > Subject: [ccd-newastro] Re: Combing Ha Images
                    > To: ccd-newastro@yahoogroups.com
                    > Date: Friday, February 20, 2009, 1:16 PM
                    >
                    > Why not try the FREE software, "Deep Sky Stacker" ?
                    >
                    > It has a wealth of choices when it comes to combining your images -
                    > and works very well, and VERY fast. It offers an excellent
                    > registration system, it can even handle moving objects such as
                    > comets. Once registered, image sets can be stacked and re-stacked
                    > without having to re-register. Another huge time-saving feature,
                    and
                    > the program runs comfortably on 64-bit platforms, and can use all
                    > available processors to speed things up even more
                    >
                    > It is certainly an option to the commercial programs out there.
                    >
                    > And it handles both FITS and DSLR images (as well as images in all
                    of
                    > the most popular graphics formats).
                    >
                    > In fact, so long as DSS remains available, I cannot see a SINGLE
                    need
                    > for any other stacking software, certainly not if all you need to
                    > achieve is image registration, image calibration and image stacking.
                    >
                    > Save your money for a decent astro-processing package - like
                    > PixInsight for example.
                    >
                    > However, as always, these comments are based on personal
                    experience.
                    > I am happy to stand corrected, if people can explain to me the
                    > features present in CCD Stack that make it a better decision to
                    > choose a commercial package like CCD Stack over a free package like
                    > DSS. (I moved from IRIS to PixInsight for exactly that reason -
                    > people were able to demonstrate to me, with examples, the specific
                    > areas where PixInsight scored over IRIS)
                    >
                    > "You pays yer money, . . . . ."
                    >
                    > HTH
                    >
                    > Niall Saunders
                    > Clinterty Observatories
                    > Aberdeen, SCOTLAND
                    >
                    > --- In ccd-newastro@yahoogroups.com, "Joe Morris"
                    > <joemorris@>
                    > wrote:
                    > >
                    > > Dennis -- Very nice study. Thanks for sharing.
                    > >
                    > > Mike and Neil --I don't own CCD Stack yet but will take Mike's
                    > > suggestion to try several methods and just pick the best.
                    > >
                    > > Joe
                    > >
                    > >
                    > > --- In ccd-newastro@yahoogroups.com, "roundycat"
                    > <den22har@> wrote:
                    > > >
                    > > > Joe, I think I just proved that SD Mask will work with three
                    > images in
                    > > > a series of tests. See here
                    > > > http://www.dens-astropics.org.uk/page%2019.htm
                    > > >
                    > > > Dennis
                    > > > >
                    > > >
                    > > > > I'm new at adding Ha images to my LRGB data. Since I've
                    > been
                    > exposing
                    > > > > each Ha image for 30 min., it's hard to collect very many
                    > for
                    > > > > combining. If one has, say four 30 min. images, some with
                    > quite a few
                    > > > > cosmic ray hits, would average or median combine be best. I
                    > that four
                    > > > > images isn't enough to even consider the sigma clip or SD
                    > mask
                    > > > algorithms.
                    > > > >
                    > > > > Joe Morris
                    > > > >
                    > > >
                    > >
                    >
                    >
                    >
                    >
                    > ------------------------------------
                    >
                    >
                    >
                    >
                    >
                    >
                    > [Non-text portions of this message have been removed]
                    >
                  • Neil Fleming
                    Sorry for the tardy response, Niall...I ve been out at a few star parties this week!   It sounds like your approach to calibration is fine, although I would
                    Message 9 of 9 , Feb 26, 2009
                      Sorry for the tardy response, Niall...I've been out at a few star parties this week!
                       
                      It sounds like your approach to calibration is fine, although I would use CCDStack to prepare the calibration masters, unless AIP4WIN has either a sigma reject or clip min/max feature for preparing calibration masters.
                       
                      CCDStack does not have a robust "one push button" approach to processing.  But, its strength is based on the opposite...robust controls over the interim steps, like user-controllable parameters for image normalization or differing outlier rejection approaches.  That being said, Stan Moore, the author, is about to release another product called "StackerUnlimited", which is designed to be "push button", as far as I know.
                       
                      I know that PixInsight is very powerful indeed, although from what I've seen of the docs, it remains rather daunting!
                       
                      Even with excellent software like CCDStack, API4WIN, or PixInsight, I cannot imagine going without Photoshop!  Working with a "client" of mine, here is an example of what we were able to do with some combined data in Photoshop:
                      http://www.flemingastrophotography.com/astropics/interim/WO66-Rosette-Ha-RGB-!start.jpg
                      http://www.flemingastrophotography.com/astropics/interim/WO66-Rosette-Ha-RGB-!start-Ha.jpg
                      http://www.flemingastrophotography.com/astropics/interim/WO66-Rosette-Ha-RGB-final.jpg
                       
                      Regards...Neil

                      www.flemingastrophotography.com 
                      Direct from Boston - brilliant diamonds in pea soup
                      Also check out the astro_narrowband Yahoo group!

                      --- On Fri, 2/20/09, Niall Saunders <niall@...> wrote:

                      From: Niall Saunders <niall@...>
                      Subject: [ccd-newastro] CCDStack vs DeepSkyStacket (etc.) - was Re: Combing Ha Images
                      To: ccd-newastro@yahoogroups.com
                      Date: Friday, February 20, 2009, 7:05 PM

                      Hi Neil,

                      No - please do NOT feel 'sorry' for disagreeing with me.

                      In fact your reply was really just the sort of response I was looking
                      for !!

                      You have put together a quick list, based on your formidable
                      experience, which has identified several areas that I, as someone who
                      does NOT use CCDStack, can now use to formulate a more informed
                      opinion as to whether to make the 'upgrade'.

                      It may be a while before I 'move up' - I need to now understand
                      whether any of the enhanced features are actually needed at my
                      present stage on the learning curve.

                      I am still only acquiring sub-300s exposures, one night a month if
                      the weather is nice, from an ED80 riding shotgun on a pier-mounted
                      LX90 Classic - both OTAs hooked up to DSI-II cameras, one -Pro (oddly
                      enough, mostly used for guiding on the 8"SCT, despite a nice set of
                      Astronomik filters in a 5-slot wheel) and a -IIC OSC which I find I
                      have to rely on, simply because my weather windows are so short it is
                      the only way I can get enough data to work with !!

                      I capture and store all my images (lights, darks, flats and
                      flatdarks) in RAW mode, calibrate all the RAW data in AIP4WIN, and
                      then use DSS to stack the calibrated RAW files, and also to de-bayer
                      at the same time (because the current version of AIP4WIN has no DSI
                      deBayer facility)

                      Would CCDStack allow me to 'grab' all my captured data, and
                      effectively provide me with a 'one-key-click' process to generate a
                      master calibrated image? (Accepting that I would need to determine
                      the most suitable process for a given set of data, and that I would
                      also probably pre-filter the 'duds' before hitting CCDStack -
                      something I currently do using the 'Image Series Analysis' tool in
                      AIP4WIN, then graphing the output table in MS Excel)

                      Don't get me wrong, I have no objection to well-coded commercial
                      software. I spent several years with the continuosly developing
                      PixInsight package, before finally buying into the full commercial
                      version a few months ago, and I have yet to see ANY other package
                      that even comes close to what PixInsight can do - although what you
                      guys can tease out of PhotoShop continues to amaze me as well (I have
                      CS2 and CS3, but just don't get on well with them - probably because
                      I 'grew up' with Corel and find it difficult to make the migration
                      [old dog, new tricks ??!!])

                      Maybe I need to revisit CCDStack, check out any 'demo/trial' period,
                      and then get you to hook-up to my PC and run the software through
                      it's paces on some of MY data - so that I get a feel for how it works.

                      Ahh, the wonder of the Internet !!

                      Cheers,

                      Niall Saunders
                      Clinterty Observatories
                      Aberdeen, SCOTLAND

                      --- In ccd-newastro@yahoogroups.com, Neil Fleming <neilfleming@...>
                      wrote:
                      >
                      > Sorry to disagree with you on this one, Niall.  Having used both,
                      Deep Sky Stacker falls down in comparison to CCDStack in many ways:
                      >  - Sigma and clip min/max data rejection for your calibration frames
                      >  - RMS/Time scaling of calibration frames
                      >  - Ability to make blooms "transparent" in order to allow
                      accumulated shorter-exposure data to "poke" through
                      >  - Better registration accuracy
                      >  - More advanced registration (application) algorithms
                      >  - Far more advanced data rejection techniques, like Poisson Sigma
                      for excellent outlier rejection in short stacks, clip min/max for
                      smooth results in deep stacks
                      >  - Advanced combines like min, max, in addition to sum, mean, and
                      median
                      >  - Excellent and easy-to-use implementation of DDP
                      >  - Similar excellent implementation of Postive Constraint
                      deconvolution
                      >  - CCDStack has all of the features you mentioned below, too
                      >  
                      > I am sure there are more, but those are the ones off the top of my
                      head.  I dunno what I would do without it.
                      >  
                      >    Regards...Neil
                      >
                      >
                      > www.flemingastrophotography.com 
                      > Direct from Boston - brilliant diamonds in pea soup
                      > Also check out the astro_narrowband Yahoo group!
                      >
                      > --- On Fri, 2/20/09, Niall Saunders <niall@...> wrote:
                      >
                      > From: Niall Saunders <niall@...>
                      > Subject: [ccd-newastro] Re: Combing Ha Images
                      > To: ccd-newastro@yahoogroups.com
                      > Date: Friday, February 20, 2009, 1:16 PM
                      >
                      > Why not try the FREE software, "Deep Sky Stacker" ?
                      >
                      > It has a wealth of choices when it comes to combining your images -
                      > and works very well, and VERY fast. It offers an excellent
                      > registration system, it can even handle moving objects such as
                      > comets. Once registered, image sets can be stacked and re-stacked
                      > without having to re-register. Another huge time-saving feature,
                      and
                      > the program runs comfortably on 64-bit platforms, and can use all
                      > available processors to speed things up even more
                      >
                      > It is certainly an option to the commercial programs out there.
                      >
                      > And it handles both FITS and DSLR images (as well as images in all
                      of
                      > the most popular graphics formats).
                      >
                      > In fact, so long as DSS remains available, I cannot see a SINGLE
                      need
                      > for any other stacking software, certainly not if all you need to
                      > achieve is image registration, image calibration and image stacking.
                      >
                      > Save your money for a decent astro-processing package - like
                      > PixInsight for example.
                      >
                      > However, as always, these comments are based on personal
                      experience.
                      > I am happy to stand corrected, if people can explain to me the
                      > features present in CCD Stack that make it a better decision to
                      > choose a commercial package like CCD Stack over a free package like
                      > DSS. (I moved from IRIS to PixInsight for exactly that reason -
                      > people were able to demonstrate to me, with examples, the specific
                      > areas where PixInsight scored over IRIS)
                      >
                      > "You pays yer money, . . . . ."
                      >
                      > HTH
                      >
                      > Niall Saunders
                      > Clinterty Observatories
                      > Aberdeen, SCOTLAND
                      >
                      > --- In ccd-newastro@yahoogroups.com, "Joe Morris"
                      > <joemorris@>
                      > wrote:
                      > >
                      > > Dennis -- Very nice study. Thanks for sharing.
                      > >
                      > > Mike and Neil --I don't own CCD Stack yet but will take
                      Mike's
                      > > suggestion to try several methods and just pick the best.
                      > >
                      > > Joe
                      > >
                      > >
                      > > --- In ccd-newastro@yahoogroups.com, "roundycat"
                      > <den22har@> wrote:
                      > > >
                      > > > Joe, I think I just proved that SD Mask will work with three
                      > images in
                      > > > a series of tests. See here
                      > > > http://www.dens-astropics.org.uk/page%2019.htm
                      > > >
                      > > > Dennis
                      > > > >
                      > > >
                      > > > > I'm new at adding Ha images to my LRGB data. Since
                      I've
                      > been
                      > exposing
                      > > > > each Ha image for 30 min., it's hard to collect very
                      many
                      > for
                      > > > > combining. If one has, say four 30 min. images, some with
                      > quite a few
                      > > > > cosmic ray hits, would average or median combine be best.
                      I
                      > that four
                      > > > > images isn't enough to even consider the sigma clip or
                      SD
                      > mask
                      > > > algorithms.
                      > > > >
                      > > > > Joe Morris


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