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Space-to-space radio Interferometry System from Medium Earth Orbits

空间科学学报 2019年第4期39卷 544-562页

作者： MARTIN-NEIRA M KUDRIASHOV V BARAT I DUESMANN B DAGANZO E European Space Research and Technology Centre European Space Agency

This paper presents a new concept to perform space-to-space Very Long Baseline Interferometry which enables the imaging of cosmic sources at high-resolution and high-sensitivity with small *** individual apertures are embarked on separate identical satellites staggered in height into Polar or Equatorial Circular Medium Earth Orbits(PECMEO orbits).These orbits are stable and allow GNSS-based on-the-fly centimeter-level relative *** operation is possible by exchanging local oscillator components and measured signals through Inter-Satellite Links(ISL).On-board cross correlation is performed at each satellite over a delay window compatible with the accuracy of the on-the-fly relative positioning and the result sent to the *** reconstruction is completed on the ground thanks to sub-millimeter baseline retrieval from accurate GNSS orbits,ISL ranging and spacecraft attitude *** application of this concept to image the Super Massive Black Hole Sgr A*is hinted.

关键词： Space-to-space interferometry Event horizon Space radio-astronomy

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High-Resolution Broadband Millimeter-Wave Astrophysical Spectrometer with Triple Product Acousto-Optical Processor

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International Journal of astronomy and Astrophysics 2013年第4期3卷 421-430页

作者： Miguel Chavez Dagostino Alexandre S. Shcherbakov Adan Omar Arellanes Vahram Chavushyan National Institute for Astrophysics Optics & Electronics (INAOE) Puebla Mexico

An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

关键词： Astrophysical Instrumentation radio-astronomy Millimeter-Wave Spectrometer Space-and-Time Integrating Acousto-Optical Devices Optical Processing System

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