Fisheye Lens (alt/az) to Flat (RA/Dec)?

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SUMMARY

The discussion focuses on converting alt/az coordinates from a fisheye lens image to RA/Dec coordinates. The fisheye lens captures a 180-degree view of the sky on a 640x480 pixel grid, with known zenith and north positions. The conversion process involves applying established equations to compute the RA/Dec for each pixel based on the known alt/az values. The calculations are straightforward due to the linear relationship between the azimuth and altitude from the zenith to the edge of the image.

PREREQUISITES
  • Understanding of alt/az and RA/Dec coordinate systems
  • Familiarity with fisheye lens imaging techniques
  • Basic knowledge of spherical trigonometry
  • Experience with astronomical calculations and timekeeping
NEXT STEPS
  • Research the equations for converting alt/az to RA/Dec coordinates
  • Explore software tools for processing fisheye lens images
  • Learn about the impact of time and date on celestial coordinate calculations
  • Investigate methods for visualizing RA/Dec data from pixel grids
USEFUL FOR

Astronomers, astrophotographers, and anyone involved in celestial mapping or image processing using fisheye lenses will benefit from this discussion.

solarblast
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I have a fisheye lens which sees 180 degrees of the sky. It registers the entire sky on a 640x480 grid of pixels. Let's assume I know where the zenith and north are on the plate. That allows me to find the alt/az of every pixel in the circular image. The fisheye is linear in the distance from the zenith out to the edge of the image. How do I compute the ra/dec of each pixel in the image? I know the time and date the image was taken down to 1 second of accuracy.
 
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Actually, this looks pretty straight forward. It's really nothing more than converting from horizontal to equatorial coordinates using some readily available equations on the web. Since the alt/az of each pixel is known from the linearity of both the az and alt, it amounts to making the calcs for every pixel in the circular image.
 

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