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Guiding bug near the meridian

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  • hilary15xx
    A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking
    Message 1 of 17 , Aug 31 7:54 PM
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      A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking correctly. Instead of keeping the star centered, it drove the star out of the field of view, leading to the dreaded "guide star faded" message. I believe that MaxIm DL somehow decided that the target had passed the meridian, and therefore that the scope must surely have been flipped; so it started to apply corrections in the wrong direction. But since the MX is capable of tracking past the meridian, it in fact did not do a flip; so MDL should not have started reversing the corrections.

      I have been told by the MaxIm DL folks that there is no way to tell whether the scope has actually flipped. I see that ASCOM does provide a "SideOfPier" properly that would seem to answer the question. So my question is whether this API actually works, and how to get MaxIm DL to handle it correctly.

      I am posting this question on a Software Bisque forum as well.

      Here are some facts about my setup:
      - I am using MaxIm DL 5.21
      - The mount is a Paramount MX
      - MaxIm DL is configured to do autoguider control via the telescope
      - The telescope was connected via ASCOM's TheSky Controlled Telescope
      - I am using TheSkyX
      - The guider motor control was configured to reverse y upon pier flip
      - The "reverse y" setting DOES work if the scope actually does flip

      Hilary
    • rockjockjared
      SideOfPier definitely does work but it s up to the telescope manufacturer to implement it. It does work on my Gemini 1 controlled G11. SideOfPier is a get/set
      Message 2 of 17 , Sep 1, 2012
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        SideOfPier definitely does work but it's up to the telescope manufacturer to implement it. It does work on my Gemini 1 controlled G11.

        SideOfPier is a get/set parameter so you can request what side of the pier the telescope is currently on and you can use it to set the side of pier. When set SideOfPier should invoke a meridian flip provided that the position is reachable from the other side of the pier. If it is not reachable it should throw an exception.

        As far as how to get this working with Maxim...I'm not sure. This takes 2 things. 1) the ASCOM telescope driver to implement it 2) whatever software you're using must utilize it.

        I've recently been working with SideOfPier in Sequence Generator Pro for automating a meridian flip so I can tell you from the ASCOM side it does work.

        Jared

        --- In ASCOM-Talk@yahoogroups.com, "hilary15xx" <hilaryyahoo3@...> wrote:
        >
        > A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking correctly. Instead of keeping the star centered, it drove the star out of the field of view, leading to the dreaded "guide star faded" message. I believe that MaxIm DL somehow decided that the target had passed the meridian, and therefore that the scope must surely have been flipped; so it started to apply corrections in the wrong direction. But since the MX is capable of tracking past the meridian, it in fact did not do a flip; so MDL should not have started reversing the corrections.
        >
        > I have been told by the MaxIm DL folks that there is no way to tell whether the scope has actually flipped. I see that ASCOM does provide a "SideOfPier" properly that would seem to answer the question. So my question is whether this API actually works, and how to get MaxIm DL to handle it correctly.
        >
        > I am posting this question on a Software Bisque forum as well.
        >
        > Here are some facts about my setup:
        > - I am using MaxIm DL 5.21
        > - The mount is a Paramount MX
        > - MaxIm DL is configured to do autoguider control via the telescope
        > - The telescope was connected via ASCOM's TheSky Controlled Telescope
        > - I am using TheSkyX
        > - The guider motor control was configured to reverse y upon pier flip
        > - The "reverse y" setting DOES work if the scope actually does flip
        >
        > Hilary
        >
      • Bob Denny
        Hilary -- TheSky 6 and TheSky x have a scripted operation feature. This is what The ASCOM driver for TheSky uses to control the Paramount. It is the only way
        Message 3 of 17 , Sep 4, 2012
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          Hilary --

          TheSky 6 and TheSky x have a "scripted operation" feature. This is what The ASCOM driver for TheSky uses to control the Paramount. It is the only way provided for doing so. The provided functions and variables do not include side of pier info, therefore the TheSky Controlled Telescope driver does not (and cannot) provide side of pier info. Thus MaxIm has to make an educated guess. I suspect that's what they told you as well :-) I hope folks here won't be upset by this: My software ACP handles imaging through the meridian and flipping in a way that you just don't have to think about it. If your mount will track through the meridian further (in time) than your longest sub-exposure, you will lose no time around the meridian. It uses MaxIm.

            -- Bob

          A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking correctly. Instead of keeping the star centered, it drove the star out of the field of view, leading to the dreaded "guide star faded" message. I believe that MaxIm DL somehow decided that the target had passed the meridian, and therefore that the scope must surely have been flipped; so it started to apply corrections in the wrong direction. But since the MX is capable of tracking past the meridian, it in fact did not do a flip; so MDL should not have started reversing the corrections.
          
          I have been told by the MaxIm DL folks that there is no way to tell whether the scope has actually flipped. I see that ASCOM does provide a "SideOfPier" properly that would seem to answer the question. So my question is whether this API actually works, and how to get MaxIm DL to handle it correctly.
          
          I am posting this question on a Software Bisque forum as well.
          
          Here are some facts about my setup:
          - I am using MaxIm DL 5.21
          - The mount is a Paramount MX
          - MaxIm DL is configured to do autoguider control via the telescope
          - The telescope was connected via ASCOM's TheSky Controlled Telescope
          - I am using TheSkyX
          - The guider motor control was configured to reverse y upon pier flip
          - The "reverse y" setting DOES work if the scope actually does flip
          
          Hilary
          
          
          
          
          
          
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        • Joe Bloggs
          I have thought for quite some time about side-of-pier and the Paramount. Now, as will become obvious, these are the musings of someone with only a smattering
          Message 4 of 17 , Sep 5, 2012
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            I have thought for quite some time about side-of-pier and the Paramount. Now, as will become obvious, these are the musings of someone with only a smattering of knowledge about ASCOM and programming as there will be a reason(s) why this wouldn't work. The following is meant to be more of a question than a statement by the way!

            Whilst the ASCOM driver cannot directly determine the side of pier is it not possible for it to infer it? My (incorrect) logic is

            1) The only area that is "ambivalent" about side of pier is the grey area around the meridian where it can point either side of the meridian
            a) if it's further east the mount must be pointing east and vice versa
            2) the meridian is determined from the local position on earth and time
            3) the grey area is determined by the "flip limits" in The Sky
            4) In the grey area past the meridian then if it simply tracks into it then the mount is still pointing east
            a) as it's a goto that causes a flip
            5) if it was in the east before and then has a goto beyond the meridian then it must flip

            I know I haven't explained this well but what I am getting at is for the driver to "know" which side it was on and then it should know what will happen in the scenario of either simply tracking through the meridian or being given a goto.

            Ultimately as the behaviour of the mount is logical and predictable given a very limited number of input variables (meridian, tracking, goto, flip limits, position prior to last goto command etc) then should the driver not be able to infer what the mount would do and so which side it will be on?

            thanks

            Paul

            --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@...> wrote:
            >
            > Hilary --
            >
            > TheSky 6 and TheSky x have a "scripted operation" feature. This is what The
            > ASCOM driver for TheSky uses to control the Paramount. It is the only way
            > provided for doing so. The provided functions and variables do not include side
            > of pier info, therefore the TheSky Controlled Telescope driver does not (and
            > cannot) provide side of pier info. Thus MaxIm has to make an educated guess. I
            > suspect that's what they told you as well :-) I hope folks here won't be upset
            > by this: My software ACP handles imaging through the meridian and flipping in a
            > way that you just don't have to think about it. If your mount will track through
            > the meridian further (in time) than your longest sub-exposure, you will lose no
            > time around the meridian. It uses MaxIm.
            >
            > -- Bob
            >
            > > A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking correctly. Instead of keeping the star centered, it drove the star out of the field of view, leading to the dreaded "guide star faded" message. I believe that MaxIm DL somehow decided that the target had passed the meridian, and therefore that the scope must surely have been flipped; so it started to apply corrections in the wrong direction. But since the MX is capable of tracking past the meridian, it in fact did not do a flip; so MDL should not have started reversing the corrections.
            > >
            > > I have been told by the MaxIm DL folks that there is no way to tell whether the scope has actually flipped. I see that ASCOM does provide a "SideOfPier" properly that would seem to answer the question. So my question is whether this API actually works, and how to get MaxIm DL to handle it correctly.
            > >
            > > I am posting this question on a Software Bisque forum as well.
            > >
            > > Here are some facts about my setup:
            > > - I am using MaxIm DL 5.21
            > > - The mount is a Paramount MX
            > > - MaxIm DL is configured to do autoguider control via the telescope
            > > - The telescope was connected via ASCOM's TheSky Controlled Telescope
            > > - I am using TheSkyX
            > > - The guider motor control was configured to reverse y upon pier flip
            > > - The "reverse y" setting DOES work if the scope actually does flip
            > >
            > > Hilary
            > >
            > >
            > >
            > >
            > >
            > >
            > > ------------------------------------
            > >
            > > For more information see http://ASCOM-Standards.org/.
            > >
            > > To unsubscribe from this group, send an email FROM THE ACCOUNT YOU USED TO SUBSCRIBE(!) to:
            > > ASCOM-Talk-unsubscribe@yahoogroups.com
            > >
            > > Yahoo! Groups Links
            > >
            > >
            > >
            > >
            >
          • Chris
            I ve added some comments inline. I assume we are talking about the TheSky Controlled Scope ASCOM driver here, where the driver goes theough TheSky to control a
            Message 5 of 17 , Sep 5, 2012
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              I've added some comments inline.

              I assume we are talking about the TheSky Controlled Scope ASCOM driver here, where the driver goes theough TheSky to control a mount.

              --- In ASCOM-Talk@yahoogroups.com, "Joe Bloggs" <yahoo@...> wrote:
              >
              > I have thought for quite some time about side-of-pier and the Paramount. Now, as will become obvious, these are the musings of someone with only a smattering of knowledge about ASCOM and programming as there will be a reason(s) why this wouldn't work. The following is meant to be more of a question than a statement by the way!
              >
              > Whilst the ASCOM driver cannot directly determine the side of pier is it not possible for it to infer it? My (incorrect) logic is
              >
              > 1) The only area that is "ambivalent" about side of pier is the grey area around the meridian where it can point either side of the meridian
              > a) if it's further east the mount must be pointing east and vice versa

              Yes, that's true.

              > 2) the meridian is determined from the local position on earth and time

              yes.

              > 3) the grey area is determined by the "flip limits" in The Sky

              I don't know about that in detail, I'm not sure if the flip limits are available to the driver.

              > 4) In the grey area past the meridian then if it simply tracks into it then the mount is still pointing east.

              What if a goto was done shortly before the scope crossed the meridian? would it be able to anticipate that it will need to flip and use the West alignment? The Celestron scopes can do this if the meridian mode is set to Prefer West.

              > a) as it's a goto that causes a flip
              > 5) if it was in the east before and then has a goto beyond the meridian then it must flip

              A Celestron scope with the meridian mode set to Prefer East would stay on the East for a goto in the grey area.

              >
              > I know I haven't explained this well but what I am getting at is for the driver to "know" which side it was on and then it should know what will happen in the scenario of either simply tracking through the meridian or being given a goto.
              >
              > Ultimately as the behaviour of the mount is logical and predictable given a very limited number of input variables (meridian, tracking, goto, flip limits, position prior to last goto command etc) then should the driver not be able to infer what the mount would do and so which side it will be on?

              There's also camera rotation to consider. Some people will rotate the camera through 180 degrees so the image alignement doesn't change when the mount flips. If the guider also rotates then the guide directions won't change but if it's a separate guider they will. The driver has no way of knowing what sort of guide setup is used.

              I'm using a Celestron scope as an example because I know more about how that behaves than I do about other mounts, especially the Paramount. This may not be relevant but it gives an idea of some of the isues - and there's every possibility that a user could use a Celestron scope through TheSky - and no way that the driver could tell.

              One thing that I've thought of is that the mount is aware of it's side of pier because the dec control buttons move in the same direction regardless of which side of the pier the mount is on. The motor movement directions will be reversed of course.

              If the commands used to send guide commands were agnostic about the pier side in the same way, so that for example a guide North command increased the declination regardless of the side of pier the scope is on that's the best that can be done. Do we know if that is the case?

              My guess is that what is happening with the OP is that Maxim is assuming that the meridian has flipped when the scope crosses the meridian and is reversing the dec guide directions at that point.

              It's also possible that TheSky could also be doing this reversal.

              The Driver is not aware of where the meridian is and is generating the same guide signals regardless of which side of the meridian the scope is on.

              All these assumptions about which side of pier the scope is on will be available in the various setups ot the various pieces of software, either in Maxim or TheSky or both.

              What's needed is some experiments, for example:
              Move the scope to a position just before the meridian.
              Issue PulseGuide commands through the driver for movement in Dec (North and South). Which way does the scope move?
              Move the scope to just after the meridian but WITHOUT doing a pier flip.
              Issue PulseGuide commands North and South and note the direction of movement of the scope. The directions should be the same as before the meridian.

              Try these two experiments with the scope on the other side of the pier. These may give movement in the opposite direction, but they should be the same for both sides of the meridian.

              If the PulseGuide direction changes as the scope passes the meridian but without doing a pier flip then the issue is with TheSky. It is assuming that the side of pier and the side of meridian is the same.

              if it doesn't then look at Maxim to see how it handles the uide direction based on the side of the pier. It may be using the side of the meridian.

              Are there logs of the guide performance? They may show if the guide directions are changed as the meridian is crossed.

              But as I said I expect there's a way of configuring the relationship between the side of pier and the meridian in both Maxim and TheSky.

              It will be difficult to implement SideOfPier in the driver because the information required to do this is not available (AFAIK). Trying to guess by using things such as the position relative to the meridian and the previous goto history will be problematic at best and could easily be unworkable. I suspect that all it will do is add a third area where this could be set incorrectly.

              Chris

              >
              > thanks
              >
              > Paul
              >
              > --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@> wrote:
              > >
              > > Hilary --
              > >
              > > TheSky 6 and TheSky x have a "scripted operation" feature. This is what The
              > > ASCOM driver for TheSky uses to control the Paramount. It is the only way
              > > provided for doing so. The provided functions and variables do not include side
              > > of pier info, therefore the TheSky Controlled Telescope driver does not (and
              > > cannot) provide side of pier info. Thus MaxIm has to make an educated guess. I
              > > suspect that's what they told you as well :-) I hope folks here won't be upset
              > > by this: My software ACP handles imaging through the meridian and flipping in a
              > > way that you just don't have to think about it. If your mount will track through
              > > the meridian further (in time) than your longest sub-exposure, you will lose no
              > > time around the meridian. It uses MaxIm.
              > >
              > > -- Bob
              > >
              > > > A few nights ago I was photographing NGC 7635 with my Paramount MX. This target was set to transit at 2:45 AM. At that very moment, MaxIm DL stopped tracking correctly. Instead of keeping the star centered, it drove the star out of the field of view, leading to the dreaded "guide star faded" message. I believe that MaxIm DL somehow decided that the target had passed the meridian, and therefore that the scope must surely have been flipped; so it started to apply corrections in the wrong direction. But since the MX is capable of tracking past the meridian, it in fact did not do a flip; so MDL should not have started reversing the corrections.
              > > >
              > > > I have been told by the MaxIm DL folks that there is no way to tell whether the scope has actually flipped. I see that ASCOM does provide a "SideOfPier" properly that would seem to answer the question. So my question is whether this API actually works, and how to get MaxIm DL to handle it correctly.
              > > >
              > > > I am posting this question on a Software Bisque forum as well.
              > > >
              > > > Here are some facts about my setup:
              > > > - I am using MaxIm DL 5.21
              > > > - The mount is a Paramount MX
              > > > - MaxIm DL is configured to do autoguider control via the telescope
              > > > - The telescope was connected via ASCOM's TheSky Controlled Telescope
              > > > - I am using TheSkyX
              > > > - The guider motor control was configured to reverse y upon pier flip
              > > > - The "reverse y" setting DOES work if the scope actually does flip
              > > >
              > > > Hilary
            • Bob Denny
              Hilary -- Idea: Turn OFF Auto Pier flip in MaxIm. Now you will be able to image through the meridian and maintain guiding. Set up two Autosave sequences, one
              Message 6 of 17 , Sep 5, 2012
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                Hilary --

                Idea: Turn OFF "Auto Pier flip" in MaxIm. Now you will be able to image through the meridian and maintain guiding. Set up two Autosave sequences, one for East and one for West, including astrometric centering. Plan them so that the East one ends before the MX reaches its tracking limit. At the end of the east sequence, manually check the Pier Flip box, run the West one which will (re)slew, flipping the mount, recenter, and continue. As Chris points out in response to Joe Bloggs, if you have an image rotator things get more complex because you're going to want to continue on the same guide star, meaning you have to roll over 180 deg with the flip. If you have an AO (SBIG or SX) it gets more complex because the bumping polarities change.

                Just a thought... I haven't tried it!

                  -- Bob


              • Bob Denny
                ... It is certainly possible to infer the side of pier and that s what ACP does for mounts that don t report it. The logic is used across multiple mount types,
                Message 7 of 17 , Sep 5, 2012
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                  Joe Bloggs:
                  I have thought for quite some time about side-of-pier and the Paramount. Now, as will become obvious, these are the musings of someone with only a smattering of knowledge about ASCOM and programming as there will be a reason(s) why this wouldn't work. 
                  
                  It is certainly possible to infer the side of pier and that's what ACP does for mounts that don't report it. The logic is used across multiple mount types, and has some subtleties that I'm somewhat proud of :-) The flip limits are not available from TheSky though.

                  But Chris' concerns about TheSky's behavior when driven from the ASCOM driver are well founded. Chris implemented the pulse-guiding support in that driver, and that's what MaxIm uses when guiding via "Telescope".

                   -- Bob

                • hilary15xx
                  Bob, Thanks for all your comments. They help explain what the problems are and maybe even who to ask to fix them. I am using CCD Commander to run my sessions.
                  Message 8 of 17 , Sep 5, 2012
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                    Bob,

                    Thanks for all your comments. They help explain what the problems are and maybe even who to ask to fix them.

                    I am using CCD Commander to run my sessions. I want to leave the auto pier flip enabled so that the script doesn't need to know when the target is due to flip. (Maybe that's something I need to reconsider!) My scripts are set to run a sequence of pictures for an hour, then refocus and re-aim the scope, then start another sequence. Given how CCDC works, the scope will only flip when a new sequence of pictures is started. In the mean time, if the scope passes the meridian half way through a sequence, MaxIm DL will start guiding wrong, and I will loose a half hour of imaging time (or whatever).

                    You said that "TheSky 6 and TheSky x have a scripted operation feature", which apparently doesn't allow the ASCOM driver to determine the side of the pier. Is this something that I could expect the Bisque brothers to fix? Or are they even the right people to ask?

                    Another thought: can CCD Commander be made to ask the mount which side of the pier it is on? I think CCDC has some external command feature that might be able to check the ASCOM driver's SideOfPier property directly. But I think you are telling me that this wouldn't work because of that "scripted operation feature".

                    Hilary

                    --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@...> wrote:
                    >
                    > Hilary --
                    >
                    > Idea: Turn OFF "Auto Pier flip" in MaxIm. Now you will be able to image through
                    > the meridian and maintain guiding. Set up two Autosave sequences, one for East
                    > and one for West, including astrometric centering. Plan them so that the East
                    > one ends before the MX reaches its tracking limit. At the end of the east
                    > sequence, manually check the Pier Flip box, run the West one which will
                    > (re)slew, flipping the mount, recenter, and continue. As Chris points out in
                    > response to Joe Bloggs, if you have an image rotator things get more complex
                    > because you're going to want to continue on the same guide star, meaning you
                    > have to roll over 180 deg with the flip. If you have an AO (SBIG or SX) it gets
                    > more complex because the bumping polarities change.
                    >
                    > Just a thought... I haven't tried it!
                    >
                    > -- Bob
                    >
                  • hilary15xx
                    Bob, Thanks for all your comments. They help explain what the problems are and maybe even who to ask to fix them. I am using CCD Commander to run my sessions.
                    Message 9 of 17 , Sep 5, 2012
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                      Bob,

                      Thanks for all your comments. They help explain what the problems are and maybe even who to ask to fix them.

                      I am using CCD Commander to run my sessions. I want to leave the auto pier flip enabled so that the script doesn't need to know when the target is due to flip. (Maybe that's something I need to reconsider!) My scripts are set to run a sequence of pictures for an hour, then refocus and re-aim the scope, then start another sequence. Given how CCDC works, the scope will only flip when a new sequence of pictures is started. In the mean time, if the scope passes the meridian half way through a sequence, MaxIm DL will start guiding wrong, and I will loose a half hour of imaging time (or whatever).

                      You said that "TheSky 6 and TheSky x have a scripted operation feature", which apparently doesn't allow the ASCOM driver to determine the side of the pier. Is this something that I could expect the Bisque brothers to fix? Or are they even the right people to ask?

                      Another thought: can CCD Commander be made to ask the mount which side of the pier it is on? I think CCDC has some external command feature that might be able to check the ASCOM driver's SideOfPier property directly. But I think you are telling me that this wouldn't work because of that "scripted operation feature".

                      Hilary

                      --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@...> wrote:
                      >
                      > Hilary --
                      >
                      > Idea: Turn OFF "Auto Pier flip" in MaxIm. Now you will be able to image through
                      > the meridian and maintain guiding. Set up two Autosave sequences, one for East
                      > and one for West, including astrometric centering. Plan them so that the East
                      > one ends before the MX reaches its tracking limit. At the end of the east
                      > sequence, manually check the Pier Flip box, run the West one which will
                      > (re)slew, flipping the mount, recenter, and continue. As Chris points out in
                      > response to Joe Bloggs, if you have an image rotator things get more complex
                      > because you're going to want to continue on the same guide star, meaning you
                      > have to roll over 180 deg with the flip. If you have an AO (SBIG or SX) it gets
                      > more complex because the bumping polarities change.
                      >
                      > Just a thought... I haven't tried it!
                      >
                      > -- Bob
                      >
                    • astrodanco
                      Bob, does this help any? Here s the documentation for this interface (driver side):
                      Message 10 of 17 , Sep 5, 2012
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                        Bob, does this help any?

                        Here's the documentation for this interface (driver side):

                        http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1

                        For third-party applications wanting to obtain Beyond the Pole information, see this documentation:

                        http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                      • hilary15xx
                        On the face of it, the knowsBeyondThePole and beyondThePole APIs are what are needed to implement SideOfPier, right? Hilary
                        Message 11 of 17 , Sep 6, 2012
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                          On the face of it, the "knowsBeyondThePole" and "beyondThePole" APIs are what are needed to implement SideOfPier, right?

                          Hilary

                          --- In ASCOM-Talk@yahoogroups.com, "astrodanco" <astrodanco@...> wrote:
                          >
                          > Bob, does this help any?
                          >
                          > Here's the documentation for this interface (driver side):
                          >
                          > http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1
                          >
                          > For third-party applications wanting to obtain Beyond the Pole information, see this documentation:
                          >
                          > http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                          >
                        • Tim Long
                          The SideOfPier concept is a lot more slippery than you would first think. I d suggest you read Peter s paper on it that was included in the ASCOM developer
                          Message 12 of 17 , Sep 6, 2012
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                            The 'SideOfPier' concept is a lot more slippery than you would first
                            think. I'd suggest you read Peter's paper on it that was included in the
                            ASCOM developer kit (or at
                            http://ascom.svn.sourceforge.net/viewvc/ascom/trunk/Help/Platform%20Supp
                            orting%20Documents/ASCOM%20SideOfPier%20Behaviour.pdf ). The most
                            confusing thing about it is the name, it's called SideOfPier for
                            historical reasons but really it ought to be called PointingState. The
                            pointing state does not correspond to the side of the pier that the
                            mount or scope is on, but reflects which half of the mechanical
                            declination axis you are in (i.e. 'normal' or 'reversed'). Consequently,
                            it is just as applicable to fork mounted instruments, both equatorial
                            and Alt Azimuth, as it is to GEMs. Some interesting things happen if
                            you consider limiting conditions, for example a mount at the north pole
                            can track a target around 360 degrees without a reversal, so the
                            pointing state remains constant even though it's been on both sides of
                            the pier. Any discussion of inferring SideofPier needs a thorough
                            understanding of the concept, so I'd suggest reading that paper. As an
                            aside, I'm not completely convinced that the paper is correct either -
                            Peter has limited his analysis to GEMs so I don't think he's nailed the
                            general case, which should apply equally to all mounts with two axes.

                            Regards,
                            Tim Long


                            > -----Original Message-----
                            > From: ASCOM-Talk@yahoogroups.com [mailto:ASCOM-
                            > Talk@yahoogroups.com] On Behalf Of Joe Bloggs
                            > Sent: 05 September 2012 09:23
                            > To: ASCOM-Talk@yahoogroups.com
                            > Subject: Re: [ASCOM] Guiding bug near the meridian
                            >
                            > I have thought for quite some time about side-of-pier and the
                            Paramount. Now,
                            > as will become obvious, these are the musings of someone with only a
                            > smattering of knowledge about ASCOM and programming as there will be a
                            > reason(s) why this wouldn't work. The following is meant to be more of
                            a
                            > question than a statement by the way!
                            >
                            > Whilst the ASCOM driver cannot directly determine the side of pier is
                            it not
                            > possible for it to infer it? My (incorrect) logic is
                            >
                            > 1) The only area that is "ambivalent" about side of pier is the grey
                            area around
                            > the meridian where it can point either side of the meridian
                            > a) if it's further east the mount must be pointing east and vice versa
                            > 2) the meridian is determined from the local position on earth and
                            time
                            > 3) the grey area is determined by the "flip limits" in The Sky
                            > 4) In the grey area past the meridian then if it simply tracks into it
                            then the
                            > mount is still pointing east
                            > a) as it's a goto that causes a flip
                            > 5) if it was in the east before and then has a goto beyond the
                            meridian then it
                            > must flip
                            >
                            > I know I haven't explained this well but what I am getting at is for
                            the driver to
                            > "know" which side it was on and then it should know what will happen
                            in the
                            > scenario of either simply tracking through the meridian or being given
                            a goto.
                            >
                            > Ultimately as the behaviour of the mount is logical and predictable
                            given a very
                            > limited number of input variables (meridian, tracking, goto, flip
                            limits, position
                            > prior to last goto command etc) then should the driver not be able to
                            infer what
                            > the mount would do and so which side it will be on?
                            >
                            > thanks
                            >
                            > Paul
                            >
                            > --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@...> wrote:
                            > >
                            > > Hilary --
                            > >
                            > > TheSky 6 and TheSky x have a "scripted operation" feature. This is
                            > > what The ASCOM driver for TheSky uses to control the Paramount. It
                            is
                            > > the only way provided for doing so. The provided functions and
                            > > variables do not include side of pier info, therefore the TheSky
                            > > Controlled Telescope driver does not (and
                            > > cannot) provide side of pier info. Thus MaxIm has to make an
                            educated
                            > > guess. I suspect that's what they told you as well :-) I hope folks
                            > > here won't be upset by this: My software ACP handles imaging through
                            > > the meridian and flipping in a way that you just don't have to think
                            > > about it. If your mount will track through the meridian further (in
                            > > time) than your longest sub-exposure, you will lose no time around
                            the
                            > meridian. It uses MaxIm.
                            > >
                            > > -- Bob
                            > >
                            > > > A few nights ago I was photographing NGC 7635 with my Paramount
                            MX.
                            > This target was set to transit at 2:45 AM. At that very moment, MaxIm
                            DL
                            > stopped tracking correctly. Instead of keeping the star centered, it
                            drove the
                            > star out of the field of view, leading to the dreaded "guide star
                            faded" message.
                            > I believe that MaxIm DL somehow decided that the target had passed the
                            > meridian, and therefore that the scope must surely have been flipped;
                            so it
                            > started to apply corrections in the wrong direction. But since the MX
                            is capable
                            > of tracking past the meridian, it in fact did not do a flip; so MDL
                            should not
                            > have started reversing the corrections.
                            > > >
                            > > > I have been told by the MaxIm DL folks that there is no way to
                            tell whether
                            > the scope has actually flipped. I see that ASCOM does provide a
                            "SideOfPier"
                            > properly that would seem to answer the question. So my question is
                            whether
                            > this API actually works, and how to get MaxIm DL to handle it
                            correctly.
                            > > >
                            > > > I am posting this question on a Software Bisque forum as well.
                            > > >
                            > > > Here are some facts about my setup:
                            > > > - I am using MaxIm DL 5.21
                            > > > - The mount is a Paramount MX
                            > > > - MaxIm DL is configured to do autoguider control via the
                            telescope
                            > > > - The telescope was connected via ASCOM's TheSky Controlled
                            > > > Telescope
                            > > > - I am using TheSkyX
                            > > > - The guider motor control was configured to reverse y upon pier
                            > > > flip
                            > > > - The "reverse y" setting DOES work if the scope actually does
                            flip
                            > > >
                            > > > Hilary
                            > > >
                            > > >
                            > > >
                            > > >
                            > > >
                            > > >
                            > > > ------------------------------------
                            > > >
                            > > > For more information see http://ASCOM-Standards.org/.
                            > > >
                            > > > To unsubscribe from this group, send an email FROM THE ACCOUNT YOU
                            > USED TO SUBSCRIBE(!) to:
                            > > > ASCOM-Talk-unsubscribe@yahoogroups.com
                            > > >
                            > > > Yahoo! Groups Links
                            > > >
                            > > >
                            > > >
                            > > >
                            > >
                            >
                            >
                            >
                            >
                            > ------------------------------------
                            >
                            > For more information see http://ASCOM-Standards.org/.
                            >
                            > To unsubscribe from this group, send an email FROM THE ACCOUNT YOU
                            USED
                            > TO SUBSCRIBE(!) to:
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                            >
                            >
                            >

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                          • Bob Denny
                            OK, I ll save this but it s going to be a while before I can devote time to the TheSky driver. I am hell-bent to get a major release of my commercial software
                            Message 13 of 17 , Sep 6, 2012
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                              OK, I'll save this but it's going to be a while before I can devote time to the TheSky driver. I am hell-bent to get a major release of my commercial software into production before the AIC conference in 8 weeks. That means beta in a couple of weeks. It's huge and I still have 30+ items on the list. Not all will be done :-)))

                              If someone else wants to try, the sources are open, and the driver is not all that complex. It's basically a converter from ASCOM to TheSky's scripting interface. There are some practicalities. Testing will be the roughest for me because I don't own a Paramount. If someone out there with a Paramount, TheSky X, and Visual Basic skills wants to tackle it, I can give help at sticking points.

                                -- Bob

                              Bob, does this help any?
                              
                              Here's the documentation for this interface (driver side):
                              
                              http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1
                              
                              For third-party applications wanting to obtain Beyond the Pole information, see this documentation:
                              
                              http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                              
                              
                              
                              
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                            • hilary15xx
                              Bob, Thanks to you and Chris for filling in the details. I can see that this will be an interesting challenge; and no doubt even if SideOfPier does something
                              Message 14 of 17 , Sep 6, 2012
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                                Bob,

                                Thanks to you and Chris for filling in the details. I can see that this will be an interesting challenge; and no doubt even if SideOfPier does something interesting, getting MaxIm DL to do the right thing too will require some coordination. In the mean time, I'm off to rewrite my CCDCommander scripts so they are smarter about detecting the meridian flip.

                                Take care,
                                Hilary

                                --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@...> wrote:
                                >
                                > OK, I'll save this but it's going to be a while before I can devote time to the
                                > TheSky driver. I am hell-bent to get a major release of my commercial software
                                > into production before the AIC conference in 8 weeks. That means beta in a
                                > couple of weeks. It's huge and I still have 30+ items on the list. Not all will
                                > be done :-)))
                                >
                                > If someone else wants to try, the sources are open, and the driver is not all
                                > that complex. It's basically a converter from ASCOM to TheSky's scripting
                                > interface. There are some practicalities. Testing will be the roughest for me
                                > because I don't own a Paramount. If someone out there with a Paramount, TheSky
                                > X, and Visual Basic skills wants to tackle it, I can give help at sticking points.
                                >
                                > -- Bob
                                >
                                > > Bob, does this help any?
                                > >
                                > > Here's the documentation for this interface (driver side):
                                > >
                                > > http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1
                                > >
                                > > For third-party applications wanting to obtain Beyond the Pole information, see this documentation:
                                > >
                                > > http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                                > >
                                > >
                                > >
                                > >
                                > > ------------------------------------
                                > >
                                > > For more information see http://ASCOM-Standards.org/.
                                > >
                                > > To unsubscribe from this group, send an email FROM THE ACCOUNT YOU USED TO SUBSCRIBE(!) to:
                                > > ASCOM-Talk-unsubscribe@yahoogroups.com
                                > >
                                > > Yahoo! Groups Links
                                > >
                                > >
                                > >
                                > >
                                >
                              • hilary15xx
                                Oops, I forgot Tim! Thanks to you all! Hilary
                                Message 15 of 17 , Sep 6, 2012
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                                  Oops, I forgot Tim! Thanks to you all!

                                  Hilary

                                  --- In ASCOM-Talk@yahoogroups.com, "hilary15xx" <hilaryyahoo3@...> wrote:
                                  >
                                  > Bob,
                                  >
                                  > Thanks to you and Chris for filling in the details. I can see that this will be an interesting challenge; and no doubt even if SideOfPier does something interesting, getting MaxIm DL to do the right thing too will require some coordination. In the mean time, I'm off to rewrite my CCDCommander scripts so they are smarter about detecting the meridian flip.
                                  >
                                  > Take care,
                                  > Hilary
                                  >
                                  > --- In ASCOM-Talk@yahoogroups.com, Bob Denny <rdenny@> wrote:
                                  > >
                                  > > OK, I'll save this but it's going to be a while before I can devote time to the
                                  > > TheSky driver. I am hell-bent to get a major release of my commercial software
                                  > > into production before the AIC conference in 8 weeks. That means beta in a
                                  > > couple of weeks. It's huge and I still have 30+ items on the list. Not all will
                                  > > be done :-)))
                                  > >
                                  > > If someone else wants to try, the sources are open, and the driver is not all
                                  > > that complex. It's basically a converter from ASCOM to TheSky's scripting
                                  > > interface. There are some practicalities. Testing will be the roughest for me
                                  > > because I don't own a Paramount. If someone out there with a Paramount, TheSky
                                  > > X, and Visual Basic skills wants to tackle it, I can give help at sticking points.
                                  > >
                                  > > -- Bob
                                  > >
                                  > > > Bob, does this help any?
                                  > > >
                                  > > > Here's the documentation for this interface (driver side):
                                  > > >
                                  > > > http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1
                                  > > >
                                  > > > For third-party applications wanting to obtain Beyond the Pole information, see this documentation:
                                  > > >
                                  > > > http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                                  > > >
                                  > > >
                                  > > >
                                  > > >
                                  > > > ------------------------------------
                                  > > >
                                  > > > For more information see http://ASCOM-Standards.org/.
                                  > > >
                                  > > > To unsubscribe from this group, send an email FROM THE ACCOUNT YOU USED TO SUBSCRIBE(!) to:
                                  > > > ASCOM-Talk-unsubscribe@yahoogroups.com
                                  > > >
                                  > > > Yahoo! Groups Links
                                  > > >
                                  > > >
                                  > > >
                                  > > >
                                  > >
                                  >
                                • scope_sapiens
                                  The current driver uses the RASCOMTele interface, not the X2 one. There s nothing I can see in that which will allow the pointing state to be determined.
                                  Message 16 of 17 , Sep 7, 2012
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                                    The current driver uses the RASCOMTele interface, not the X2 one. There's nothing I can see in that which will allow the pointing state to be determined.

                                    Changing to the X2 interface would be a big thing and I'm not sure this is appropriate because my understanding is that the X2 interface is for sending commands from TheSky to a telescope driver and in this case we have a driver that's sending commands to TheSky.

                                    Chris

                                    --- In ASCOM-Talk@yahoogroups.com, "hilary15xx" <hilaryyahoo3@...> wrote:
                                    >
                                    > On the face of it, the "knowsBeyondThePole" and "beyondThePole" APIs are what are needed to implement SideOfPier, right?
                                    >
                                    > Hilary
                                    >
                                    > --- In ASCOM-Talk@yahoogroups.com, "astrodanco" <astrodanco@> wrote:
                                    > >
                                    > > Bob, does this help any?
                                    > >
                                    > > Here's the documentation for this interface (driver side):
                                    > >
                                    > > http://www.bisque.com/x2standard/class_asymmetrical_equatorial_interface.html#ad422c0fa8649c453f8b943d152f678e1
                                    > >
                                    > > For third-party applications wanting to obtain Beyond the Pole information, see this documentation:
                                    > >
                                    > > http://www.bisque.com/scripttheskyx/classsky6_r_a_s_c_o_m_tele.html#a5b49d7170516e44b43023317edaa473d
                                    > >
                                    >
                                  • Bob Denny
                                    Yes, for clarification of this confusing issue: http://ascom-standards.org/FAQs/TheSky.htm
                                    Message 17 of 17 , Sep 10, 2012
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                                      Yes, for clarification of this confusing issue:

                                      http://ascom-standards.org/FAQs/TheSky.htm

                                      The current driver uses the RASCOMTele interface, not the X2 one.  There's nothing I can see in that which will allow the pointing state to be determined.
                                      
                                      Changing to the X2 interface would be a big thing and I'm not sure this is appropriate because my understanding is that the X2 interface is for sending commands from TheSky to a telescope driver and in this case we have a driver that's sending commands to TheSky.

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