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  • A couple of pics

    We are back from the Mt. Kobau Star Party.

    Smoke filled the air across the entire province from home to Mt. Kobau, a distance of 690km. I took some pics on Thursday night but I suspect they are a loss. Clouds moved in on Friday night and no astronomy was possible. We went to bed early but I awakened at 2:00am and crawled out of the tent to have a look. It was clear but the wind was blowing too much to make use of my telescope. I set up my cameras on my double arm drive as it is rigid enough to not be affected by the wind. I used my 35mm film camera and my Nikon 4300 and took a few pics for a couple of hours. I don't have the film pics developed yet but do have a couple of pics to show from the Nikon. It (the Nikon) continues to amaze me. These two pics were taken with just the Nikon on the drive, no telescope or other magnification.

    Milky Way, greyscale, no zoom, one minute exposure.



    This is a pic of the Pleiades at three times optical zoom:




    On Saturday we attended the raffle and door prize draw. One of my grandsons, Brandon, held the winning ticket on a $1100.00 telescope. He bought $30 worth of tickets with his own allowance money. As soon as it is delivered he will be the proud owner of the best telescope in the family!




    [This message has been edited by Evan (edited 08-23-2004).]
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  • #2
    Cool pics Evan. Nice going on the scope.

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    • #3
      Evan,

      Sounds like you had fun.

      Don't mean to bring you down, just be aware that a 1 minute exposure with a PS digital camera will produce lots of noise. I suspect most of the bright spots in photo 1 are just that.

      Nice shots anyway.

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      • #4
        Nice pics although for a minute there I thought my screensaver had fouled up when I saw the first one
        I just need one more tool,just one!

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        • #5
          On the first picture; What direction was it taken from?The spaces between the stars make interesting patterns. The dark lines look like the pattern on a brook trouts back. They are very noticeable in your picture.
          What are those stars in the second picture? Is it a constellation?
          Sorry for all the questions, but even on a good night here all but the brightest stars are washed out.

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          • #6
            PaulG

            Those are stars, not noise. Two reasons: The Nikon 4300 on a time exposure first takes the exposure and then takes a dark field with the shutter closed. It then subtracts the "hot" pixels from the frame. Second reason, hot pixels are just that, a single illuminated pixel. Close examination of the image shows that the stars imaged are composed of more than one pixel. That is to be expected even though stars are a point source of light. When a point source is imaged it will produce a central spot of light surrounded by a diffraction ring known as the "airy disk". The size of this disk will vary according to brightness. Here is a closeup of a portion of the uncompressed version of the Milky Way image. It is apparent that the stars are indeed more than one pixel and also vary in size. That is not what you would see if the image contained a lot of noise.



            Rusty,

            That is the very small appearing constellation that a lot of people call the "Little Dipper". It is not the little dipper but is known as the Pleiades. As far as patterns go the distribution of stars in the sky is not random. It is affected by gravity. There are many seeming alignments that may be seen and they are called "asterisms". Keep in mind that in the pics above most of those stars cannot be seen with the naked eye.
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            • #7
              Thanks for sharing those pics Evan. Too bad about the smoke, winds and clouds tho. Congrats to Brandon, I'm sure he's going to enjoy his new scope. What kind of scope is it that he won?

              I've studdied your mount in great detail on your web site and of course am very impressed. What does it take to do the initial setup for an evenings viewing or clicking? How do you line it up to track correctly?

              Thanks

              Comment


              • #8
                The scope Brandon won is a Meade ETX 90AT. See link, it is the scope on the left.

                http://www.meade.com/catalog/etx/etx_mak.html

                Bernie,

                Polar alignment of the double arm drive is of course critical to its operation. The drive is equipped with an alignment scope that is one ocular from a roof prism binocular. The field of view has been stopped to exactly three degrees. An illuminated reticle has been added. In use I look through the ocular with both eyes open, right eye looking through the ocular. With my left eye I see Polaris and Kochab. Kochab is a star some distance from Polaris that is very close to a direct line through the celestial north pole. Polaris, although known as the "Pole Star" is not on the north celestial pole but is about 0.75 degrees away from it in the direction opposite from Kochab. With my left eye (unmagnified) I align the image of Polaris with the center of the reticle as seen by my right eye. With my right eye I align the magnified image of Polaris half way from the center of the reticle to the edge of field. Since the field of view is three degrees this places the reticle center 0.75 degrees towards Kochab. When correctly aligned the magnified image of Polaris as seen by my right eye and the unmagnified images of Polaris and Kochab as seen by my left eye make a straight line. This gives polar alignment accurate to a few arc seconds and is quick and easy to do. BTW, this is a technique I thought up myself, I have never seen it described elsewhere. It works because the modified ocular is a correct upright image since it is from a binocular.
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                • #9
                  Thank you for that explanation Evan, your method obviously works very well.

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                  • #10
                    Looks like noise to me there's white dots all over the picture

                    ------------------
                    John S.
                    Nottingham, England
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                    • #11
                      "The scope Brandon won is a Meade ETX 90AT"

                      Evan Very nice pics and wow what a nice prise.I am still saving for a new scope!!
                      I will paypal you next year for some tickets on the next one!!
                      take care
                      eddie
                      please visit my webpage:
                      http://motorworks88.webs.com/

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                      • #12
                        Just another bit of explanation of what may appear to be unlikely alignments of stars;

                        The majority of stars are double stars with the most common visible configuration being stars of similar size and brightness. Also very common are double doubles, meaning two double stars that orbit each other. Since a double double group probably formed from the same primordial disk of material they will share the same orbital plane. This means that configurations of four stars in a line are not unlikely. Even more are also likely since some star systems are triple or even quadruple orbiting another double or greater number. Of course this is taken to the extreme in the case of a spiral galaxy with billions of stars all orbiting in the approximate same plane. Even the galaxies are found in groups and those groups are found in "walls" of galaxies. These walls are the largest structures so far observed but there may be even larger structure to the universe. That remains to be seen.
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                        • #13
                          Are the red stars in your pictures really red? Red giants? Certainly not red shifted at that brightness. Or just an anomaly? I was suprised at the number visible.

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                          • #14
                            Bruce,
                            Evan's always been lucky, that night they were doing a two for one offer

                            ------------------
                            John S.
                            Nottingham, England
                            .

                            Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                            • #15
                              Sure, there are a lot of red stars out there. The colors in the Pleiades pic are a bit exaggerated due to contrast enhancement but the blue of the stars in the Pleiades themselves is accurate. However, a color CCD will also cause color artifacts at very low brightness. The red filtered pixels on a CCD are the easiest to expose. This makes some of the dim stars appear red when they really aren't. For more on the quantum efficiency of CCD detectors see here:

                              http://www.ccd.com/ccd101.html
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