The Astrometric Gravitation Probe mission is a modern version of the 1919 Dyson-Eddington-Davidson experiment, based on a space-borne telescope with a permanent built-in eclipse, provided by a coronagraphic system. The expected improvement on experimental bounds to General Relativity and competing gravitation theories is by at least two orders of magnitude. The measurement principle is reviewed, in particular the principle of Fizeau-like combination of a set of individual inverted coronagraphs simultaneously feeding a common high resolution telescope. Also, the payload has a dual field of view property, in order to support simultaneous observations of stellar fields either very close, or far away, from the Sun, i.e. fields affected by either high or low light bending. We discuss a set of solutions introduced in the optical design to improve on technical feasibility and robustness of the optical performance against perturbations, in particular induced by manufacturing and alignment tolerances, and launch stresses.
Astrometric Science and Technology Roadmap for Astrophysics (ASTRA) is a bilateral cooperation between China and Italy with the goal of consolidating astrometric measurement concepts and technologies. In particular, the objectives include critical analysis of the Gaia methodology and performance, as well as principle demonstration experiments aimed at future innovative astrometric applications requiring high precision over large angular separations (one to 180 degrees). Such measurement technologies will be the building blocks for future instrumentation focused on the "great questions" of modern cosmology, like General Relativity validity (including Dark Matter and Dark Energy behavior), formation and evolution of structure like proto-galaxies, and planetary systems formation in bio compatibles environments. We describe three principle demonstration tests designed to address some of the potential showstoppers for high astrometric precision experiments. The three tests are focused on the key concepts of multiple fields telescopes, astrometric metrology and very fine sub-pixel precision (goal: < 1/2000 pixel) in white light.
Ground based optical observation is widely used in the field of astrometry of moving objects such as Near-Earth Objects and space debris due to its low cost and easy deployment. However, it’s difficult for traditional optical telescopes to have both large aperture and wide FOV, making it impossible to achieve both observation depth and observation efficiency. We propose the computational imaging astrometry method to solve this problem. Based on a scientific CMOS detector and a small-aperture telescope with wide FOV, through strict correction of various astronomical effects and instrumental errors, we establish a high-precision overlay enhancement method for wide-FOV astronomic images. Including displacement overlay of high frame rate images at sub-pixel scale. In the case of no mechanical tracking device, the computational imaging astrometry method enables the observation system to simultaneously track multiple types of moving objects, and exert the ability of image overlay to reduce background noise, thus improving the SNR of the target and enhancing the observation depth of the system.
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