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15255Re: First calibrated image

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  • Frank Barrett
    May 1, 2003
      Randy, Paul, Don, and Ron,

      Thanks, I feel very encouraged by your warm responses.
      The lightbox seems to be working out quite well. When I first got
      the white acrylic sheets I thought there was no way those 4 little
      LEDs could shed enough light, but it really works. Thanks again to
      Don for sharing his plans.
      Polar alignment indeed was very good this night, but I have to give
      some credit to the new worm of the G11 as well. I haven't done the
      math on this setup but I think it's in the neighborhood of 3-4
      arcsecs per pixel. I haven't measured PE on this mount but I'm
      guessing it must be in that neighborhood, no?
      Indeed the flats look good. With the f/3.3 FR on the C8 I get a very
      noticeable hot spot, which up till now I've been trying to remove
      (unsuccessfully) in Photoshop. With the flats it's completely
      removed. I love it!
      Let me end with one question. Since this is a brand new camera I
      haven't had the opportunity to get it dirty <g> and I see no dust
      motes or donuts on the flats. I have some images from a couple weeks
      ago taken with the exact same setup which have not been flat
      fielded. Any harm in applying these flats to those images?

      Frank
      http://celestialwonders.com

      --- In ccd-newastro@yahoogroups.com, "Wodaski Yahoo account"
      <yahoo@w...> wrote:
      > First, that's a really nice M101. Details are sharp, stars are
      really
      > round - a neat effort. The flat fielding must be good, too, because
      I see no
      > evidence of any flaws.
      >
      > Ron Wodaski
      > author of The New CCD Astronomy
      > http://www.newastro.com
      >
      >
      > -----Original Message-----
      > From: Frank Barrett [mailto:frankb02@b...]
      > Sent: Wednesday, April 30, 2003 4:08 PM
      > To: ccd-newastro@yahoogroups.com
      > Subject: [ccd-newastro] First calibrated image
      >
      >
      > Here's my first attempt at a fully calibrated image with my new
      > light box. In keeping with the recent theme it is, of course, of
      > M101 ;)
      > I'm just a bit concerned over the noise in this image. I would have
      > thought that an hour long exposure would not have resulted in so
      > much noise in the faint arms. Am I overstretching this with curves?
      >
      > http://celestialwonders.com/m101b-st7.html
      >
      > Thanks, Frank
      > http://celestialwonders.com
      >
      >
      >
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