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Re: [skymap] Re: Archeological study

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  • Mark Crossley
    Simon It doesn t make ANY difference to the star displays, I thought Chris had already responded to this. The Altitude is only used for near Earth
    Message 1 of 14 , Jan 31, 2009
      Simon

      It doesn't make ANY difference to the star displays, I thought Chris had
      already responded to this. The Altitude is only used for 'near Earth'
      calculations - satellites, local eclipse circumstances? and possibly the
      Moon?

      SMP does not show horizon depression etc due to altitude.

      Mark

      2009/1/31 Simon Allen <simon.sallen@...>

      > Yes it is in Sky Map Pro 11. Go to observer location and it is in on the
      > right of the window. However, it does not make much difference so far as
      > stars are concerned. If you know the latitude and longitude of the location
      > then you can also find the height of the observer.
      >
      > Regards,
      >
      > Simon
      >


      [Non-text portions of this message have been removed]
    • Chris Marriott
      ... From: Mark Crossley To: Sent: Saturday, January 31, 2009 11:04 PM Subject: Re: [skymap] Re:
      Message 2 of 14 , Feb 1, 2009
        ----- Original Message -----
        From: "Mark Crossley" <public@...>
        To: <skymap@yahoogroups.com>
        Sent: Saturday, January 31, 2009 11:04 PM
        Subject: Re: [skymap] Re: Archeological study


        > Simon
        >
        > It doesn't make ANY difference to the star displays, I thought Chris had
        > already responded to this. The Altitude is only used for 'near Earth'
        > calculations - satellites, local eclipse circumstances? and possibly the
        > Moon?

        It's used for a few things - the calculation of refraction, and (as you say)
        satellite positions and circumstances of local eclipses amongst others. It
        is NOT used to compute the "depression of the horizon" - astronomers ALWAYS
        measure altitude from a theoretical "sea" horizon.
      • Mark Crossley
        Chris Whilst SMP quite properly should always calculate the altitude of objects from the theoretical horizon, I can see for some people that [optionally]
        Message 3 of 14 , Feb 1, 2009
          Chris

          Whilst SMP quite properly should always calculate the altitude of objects
          from the theoretical horizon, I can see for some people that [optionally]
          displaying the horizon line in its 'depressed' position could be useful. I
          say optionally because elevation only affects the horizon if you are
          elevated relative to the surrounding land, which most of us are if only by 6
          feet!

          Maybe one for SMP 13!

          Mark

          2009/2/1 Chris Marriott <chris@...>

          >
          > ----- Original Message -----
          > From: "Mark Crossley" <public@...<public%40wilmslowastro.com>
          > >
          > To: <skymap@yahoogroups.com <skymap%40yahoogroups.com>>
          > Sent: Saturday, January 31, 2009 11:04 PM
          > Subject: Re: [skymap] Re: Archeological study
          >
          > > Simon
          > >
          > > It doesn't make ANY difference to the star displays, I thought Chris had
          > > already responded to this. The Altitude is only used for 'near Earth'
          > > calculations - satellites, local eclipse circumstances? and possibly the
          > > Moon?
          >
          > It's used for a few things - the calculation of refraction, and (as you
          > say)
          > satellite positions and circumstances of local eclipses amongst others. It
          > is NOT used to compute the "depression of the horizon" - astronomers ALWAYS
          >
          > measure altitude from a theoretical "sea" horizon.
          >
          >
          >


          [Non-text portions of this message have been removed]
        • KevinDCornwell
          Chris - I observe at 9200ft, sometimes at 14,000ft. My horizon is the pacific ocean. Is there a way for SMP to show me the visual horizon related to my
          Message 4 of 14 , Nov 1, 2009
            Chris - I observe at 9200ft, sometimes at 14,000ft. My horizon is the pacific ocean. Is there a way for SMP to show me the visual horizon related to my altitude? Or, is the difference so small that I couldn't tell the difference anyway. I'm hoping to get maybe 2 more degrees when I get to 14,000...

            Thanks,
            Kevin
            Kevin Cornwell
            observing from Mauna Kea, Hawaii.

            --- In skymap@yahoogroups.com, Mark Crossley <public@...> wrote:
            >
            > Chris
            >
            > Whilst SMP quite properly should always calculate the altitude of objects
            > from the theoretical horizon, I can see for some people that [optionally]
            > displaying the horizon line in its 'depressed' position could be useful. I
            > say optionally because elevation only affects the horizon if you are
            > elevated relative to the surrounding land, which most of us are if only by 6
            > feet!
            >
            > Maybe one for SMP 13!
            >
            > Mark
            >
            > 2009/2/1 Chris Marriott <chris@...>
            >
            > >
            > > ----- Original Message -----
            > > From: "Mark Crossley" <public@...<public%40wilmslowastro.com>
            > > >
            > > To: <skymap@yahoogroups.com <skymap%40yahoogroups.com>>
            > > Sent: Saturday, January 31, 2009 11:04 PM
            > > Subject: Re: [skymap] Re: Archeological study
            > >
            > > > Simon
            > > >
            > > > It doesn't make ANY difference to the star displays, I thought Chris had
            > > > already responded to this. The Altitude is only used for 'near Earth'
            > > > calculations - satellites, local eclipse circumstances? and possibly the
            > > > Moon?
            > >
            > > It's used for a few things - the calculation of refraction, and (as you
            > > say)
            > > satellite positions and circumstances of local eclipses amongst others. It
            > > is NOT used to compute the "depression of the horizon" - astronomers ALWAYS
            > >
            > > measure altitude from a theoretical "sea" horizon.
            > >
            > >
            > >
            >
            >
            > [Non-text portions of this message have been removed]
            >
          • chris@chrism.demon.co.uk
            ... I m afraid that s not a facility offered by the program. Sorry. Regards, Chris
            Message 5 of 14 , Nov 1, 2009
              Quoting KevinDCornwell <kevindcornwell@...>:

              > Chris - I observe at 9200ft, sometimes at 14,000ft. My horizon is
              > the pacific ocean. Is there a way for SMP to show me the visual
              > horizon related to my altitude? Or, is the difference so small that
              > I couldn't tell the difference anyway. I'm hoping to get maybe 2
              > more degrees when I get to 14,000...
              >

              I'm afraid that's not a facility offered by the program. Sorry.

              Regards,

              Chris
            • Nigel Tasker
              With a little calculation, you could move your SMP location towards your view direction, to take account of your height of eye . This link tells you all about
              Message 6 of 14 , Nov 2, 2009
                With a little calculation, you could move your SMP location towards your view direction, to take account of your "height of eye".

                This link tells you all about it:

                http://mintaka.sdsu.edu/GF/explain/atmos_refr/dip.html

                Nigel Tasker
                ----- Original Message -----
                From: KevinDCornwell
                To: skymap@yahoogroups.com
                Sent: Monday, November 02, 2009 4:47 AM
                Subject: [skymap] Re: Archeological study


                Chris - I observe at 9200ft, sometimes at 14,000ft. My horizon is the pacific ocean. Is there a way for SMP to show me the visual horizon related to my altitude? Or, is the difference so small that I couldn't tell the difference anyway. I'm hoping to get maybe 2 more degrees when I get to 14,000...

                Thanks,
                Kevin
                Kevin Cornwell
                observing from Mauna Kea, Hawaii.

                --- In skymap@yahoogroups.com, Mark Crossley <public@...> wrote:
                >
                > Chris
                >
                > Whilst SMP quite properly should always calculate the altitude of objects
                > from the theoretical horizon, I can see for some people that [optionally]
                > displaying the horizon line in its 'depressed' position could be useful. I
                > say optionally because elevation only affects the horizon if you are
                > elevated relative to the surrounding land, which most of us are if only by 6
                > feet!
                >
                > Maybe one for SMP 13!
                >
                > Mark
                >
                > 2009/2/1 Chris Marriott <chris@...>
                >
                > >
                > > ----- Original Message -----
                > > From: "Mark Crossley" <public@...<public%40wilmslowastro.com>
                > > >
                > > To: <skymap@yahoogroups.com <skymap%40yahoogroups.com>>
                > > Sent: Saturday, January 31, 2009 11:04 PM
                > > Subject: Re: [skymap] Re: Archeological study
                > >
                > > > Simon
                > > >
                > > > It doesn't make ANY difference to the star displays, I thought Chris had
                > > > already responded to this. The Altitude is only used for 'near Earth'
                > > > calculations - satellites, local eclipse circumstances? and possibly the
                > > > Moon?
                > >
                > > It's used for a few things - the calculation of refraction, and (as you
                > > say)
                > > satellite positions and circumstances of local eclipses amongst others. It
                > > is NOT used to compute the "depression of the horizon" - astronomers ALWAYS
                > >
                > > measure altitude from a theoretical "sea" horizon.
                > >
                > >
                > >
                >
                >
                > [Non-text portions of this message have been removed]
                >




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              • Chris Marriott
                ... From: Nigel Tasker To: Sent: Monday, November 02, 2009 4:38 PM Subject: Re: [skymap] Re: Archeological
                Message 7 of 14 , Nov 2, 2009
                  ----- Original Message -----
                  From: "Nigel Tasker" <nigeltasker@...>
                  To: <skymap@yahoogroups.com>
                  Sent: Monday, November 02, 2009 4:38 PM
                  Subject: Re: [skymap] Re: Archeological study


                  > With a little calculation, you could move your SMP location towards your
                  > view direction, to take account of your "height of eye".
                  >
                  > This link tells you all about it:
                  >
                  > http://mintaka.sdsu.edu/GF/explain/atmos_refr/dip.html
                  >
                  > Nigel Tasker

                  All that the dip of the horizon does is to "lower" the horizon below the
                  horizontal, so, once you've calculated the amount, you could represent it on
                  SkyMap by a user-defined horizon line below the normal horizon.

                  Regards,

                  Chris
                • Wm. Schwittek
                  Kevin, If I ve done the math correctly, the angle of the horizon (assume the Earth is 4000 miles in radius) is: arcsin(4000/(4000+h)) where h is your height
                  Message 8 of 14 , Nov 3, 2009
                    Kevin,

                    If I've done the math correctly, the angle of the horizon (assume the
                    Earth is 4000 miles in radius) is:

                    arcsin(4000/(4000+h))

                    where h is your height above sea level in miles. So, if you were 3
                    miles up (about 15,000 ft) your horizon would be out there at 87.78
                    degrees or about 2 degrees lower than it would be at sea level (which
                    would be 90 degrees).

                    - Bill



                    Re: Archeological study
                    Posted by: "KevinDCornwell" kevindcornwell@... kevindcornwell
                    Sun Nov 1, 2009 8:47 pm (PST)


                    Chris - I observe at 9200ft, sometimes at 14,000ft. My horizon is the
                    pacific ocean. Is there a way for SMP to show me the visual horizon
                    related to my altitude? Or, is the difference so small that I couldn't
                    tell the difference anyway. I'm hoping to get maybe 2 more degrees when
                    I get to 14,000...

                    Thanks,
                    Kevin
                    Kevin Cornwell
                    observing from Mauna Kea, Hawaii.
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