2006/06/07 by Anand Sivaramakrishnan, Rebecca Oppenheimer, Ben R. Oppenheimer · 2 citations
Physics and Astronomy · #Adaptive optics #Adaptive optics and wavefront sensing #Astrometry #Astronomy #Astronomy and Astrophysical Research #Brightness #Cardinal point #Computer science #Computer vision #Coronagraph #Exoplanet #Fiducial marker #Image (mathematics) #Image plane #Optics #Parallax #Photometry (optics) #Physics #Planet #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505192
published as Astrophys.J.647:620-629,2006 · To appear in ApJ August 2006, 27 preprint style pages 4 figures
arxiv created 2006/06/07 · openalex publication_date 2006/08/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We propose a solution to the problem of astrometric and photometric calibration of coronagraphic images with a simple optical device that, in theory, is easy to use. Our design uses the Fraunhofer approximation of Fourier optics. Placing a periodic grid of wires (we use a square grid) with known width and spacing in a pupil plane in front of the occulting coronagraphic focal plane mask produces fiducial images of the obscured star at known locations relative to the star. We also derive the intensity of these fiducial images in the coronagraphic image. These calibrator images can be used for precise relative astrometry to establish companionship of other objects in the field of view through measurement of common proper motion or common parallax, to determine orbits, and to observe disk structure around the star quantitatively. The calibrator spots also have known brightness, selectable by the coronagraph designer, permitting accurate relative photometry in the coronagraphic image. This technique, which enables precision exoplanetary science, is relevant to future coronagraphic instruments and is particularly useful for "extreme" adaptive optics and space-based coronagraphy.