Method of refraction angle mapping of earth'S limb
First Claim
1. A method of mapping refraction angles in a planet'"'"'s atmosphere as a function of altitude above the planet, comprising the steps of:
- providing a database of known star locations;
providing a field imager onboard a platform above the planet, said field imager having a field-of-view;
positioning said field imager to observe a region that includes a portion of the planet'"'"'s atmospheric limb as viewed from the platform;
capturing a star field image for said region using said field imager wherein said star field image includes images of stars appearing in said field-of-view;
generating, using said field imager and said database, a modeled star field image sized to match said field-of-view wherein said modeled star field image defines absolute locations of stars corresponding to stars represented by said images of stars appearing in said field-of-view; and
comparing said modeled star field image to said star field image wherein differences between said absolute locations and locations of said images of stars are indicative of a limb refraction angle field for said field-of-view.
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Abstract
Refraction angles in a planet'"'"'s atmosphere are mapped using a database of known star locations and a field imager onboard a platform above the planet. The field imager is positioned to observe a region that includes a portion of the planet'"'"'s atmospheric limb. A star field image is captured for the region. The star field image includes stars within the field imager'"'"'s field-of-view. Using the field imager and the database, a modeled star field image is generated that is matched in size to the field-of-view associated with the star field image. The modeled star field image defines absolute locations of stars corresponding to stars appearing in the field imager'"'"'s field-of-view. Differences between the absolute locations and locations of the images of stars are indicative of a limb refraction angle field.
4 Citations
23 Claims
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1. A method of mapping refraction angles in a planet'"'"'s atmosphere as a function of altitude above the planet, comprising the steps of:
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providing a database of known star locations; providing a field imager onboard a platform above the planet, said field imager having a field-of-view; positioning said field imager to observe a region that includes a portion of the planet'"'"'s atmospheric limb as viewed from the platform; capturing a star field image for said region using said field imager wherein said star field image includes images of stars appearing in said field-of-view; generating, using said field imager and said database, a modeled star field image sized to match said field-of-view wherein said modeled star field image defines absolute locations of stars corresponding to stars represented by said images of stars appearing in said field-of-view; and comparing said modeled star field image to said star field image wherein differences between said absolute locations and locations of said images of stars are indicative of a limb refraction angle field for said field-of-view. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of mapping refraction angles in a planet'"'"'s atmosphere as a function of altitude above the planet, comprising the steps of:
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providing a database of known star locations; providing a star tracker onboard a platform located above the planet, said star tracker having a field-of-view; positioning said star tracker to observe a limb region that includes a light-refracting environment and a non-light-refracting environment; capturing a star field image for said limb region using said star tracker wherein said star field image includes images of stars appearing in said field-of-view; generating, using said star tracker and said database, a modeled star field image sized to match said field-of-view wherein said modeled star field image defines absolute locations of stars corresponding to stars represented by said images of stars appearing in said field-of-view; and comparing said modeled star field image to said star field image wherein differences between said absolute locations and locations of said images of stars are indicative of a limb refraction angle field for said field-of-view. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of mapping refraction angles in a planet'"'"'s atmosphere as a function of altitude above the planet, comprising the steps of:
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providing a database of known star locations; providing a star tracker onboard a balloon, said star tracker having a field-of-view; releasing said balloon for one of an ascent through the atmosphere, a descent through the atmosphere, and stable-altitude flotation in the atmosphere; positioning said star tracker to observe a portion of the planet'"'"'s atmospheric limb; capturing a star field image for said portion of the plant'"'"'s atmospheric limb using said star tracker wherein said star field image includes images of stars appearing in said field-of-view; generating, using said star tracker and said database, a modeled star field image sized to match said field-of-view wherein said modeled star field image defines absolute locations of stars corresponding to stars represented by said images of stars appearing in said field-of-view; and comparing said modeled star field image to said star field image wherein differences between said absolute locations and locations of said images of stars are indicative of a limb refraction angle field for said field-of-view. - View Dependent Claims (20, 21, 22, 23)
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Specification