标题： 通过默奇森宽场阵列提高空间域感知观测的灵敏度 显示英文标题

标题： Improved Sensitivity for Space Domain Awareness Observations with the Murchison Widefield Array

摘要： 我们之前使用默奇森宽场阵列（MWA）对低地球轨道（LEO）环境的调查检测到了超过70个独特的在轨空间物体（RSOs），这是在被动雷达模式下20小时观测结果中的多个通过过程。 在本文中，我们通过展示两种方法来扩展这项工作，以提高系统的检测灵敏度。 第一种方法称为移位叠加，通过在RSO轨迹上沿天空的空间相干积分反射信号，从而提高微弱RSO信号的统计显著性。 该方法在我们之前的盲调查使用的观测数据上进行了测试，我们获得了$75\%$的检测总数增加。 第二种方法通过应用复相位校正到每个可见度，以考虑弯曲波前的影响，将MWA重新聚焦到近场RSO的位置（观测后）。 该方法在一次MWA扩展阵列对国际空间站通过的观测中成功进行了测试。 然而，由于当前相关器的硬件限制，该方法目前受到长基线上的信号去相干的限制。 我们讨论了从MWA第三阶段相关器升级中预期获得的RSO检测灵敏度提升。 最后，我们简要评论了未来将结合MWA技术的专用空间域意识（SDA）系统。 显示英文摘要

摘要： Our previously reported survey of the Low Earth Orbit (LEO) environment using the Murchison Widefield Array (MWA) detected over 70 unique Resident Space Objects (RSOs) over multiple passes, from 20 hours of observations in passive radar mode. In this paper, we extend this work by demonstrating two methods that improve the detection sensitivity of the system. The first method, called shift-stacking, increases the statistical significance of faint RSO signals through the spatially coherent integration of the reflected signal along the RSO's trajectory across the sky. This method was tested on the observations used during our previous blind survey, and we obtained a $75\%$ increase in the total number of detections. The second method re-focuses the MWA to the near-field RSO's position (post-observation), by applying a complex phase correction to each visibility to account for the curved wave-front. The method was tested successfully on an MWA extended array observation of an ISS pass. However, the method is currently limited by signal de-coherence on the long-baselines (due to the hardware constraints of the current correlator). We discuss the sensitivity improvement for RSO detections we expect from the MWA Phase 3 correlator upgrade. We conclude the paper by briefly commenting on future dedicated Space Domain Awareness (SDA) systems that will incorporate MWA technologies.