LSST对真实米级 imminent 影响体的模拟观测
Simulated LSST Observations of Real Metre-scale Imminent Impactors
AI总结：
本文研究了如果LSST在过去的十年中持续运行，它将能发现多少即将撞击地球的米级影响体，以及这些发现的时间提前程度，通过模拟LSST的太阳系调查模拟器Sorcha和过去十年中由轨道传感器观测到的真实火球群体，探讨哪些事件会在撞击前被观测到，并评估发现的提前时间对天文研究和行星防御的影响。
摘要：
截至2026年中期，已有11个物体在撞击地球前被发现，预警时间在2至20小时之间。利用过去十年中真实米级地球撞击体的数据，我们探讨了如果维拉·C·鲁宾天文台的遗产空间时间巡天（LSST）在过去十年中持续运行，它将能观测和发现多少即将撞击地球的物体，以及这些发现的提前时间。我们使用LSST太阳系调查模拟器Sorcha和过去十年中由轨道传感器观测到的真实火球群体，研究哪些事件会在撞击前被观测到。我们发现，LSST将观测到216个模拟物体中的30个（13.9%），大多数物体将获得2至4次观测。使用默认的链接算法，只有2个（0.9%）物体会在撞击前被发现。使用改进的链接算法，更适合快速移动物体，这一数字增加到8个（3.7%）。基于此，我们预测LSST在其10年巡天期间将发现8±2个即将撞击地球的物体，这低于之前的估计。然而，我们预测这些物体将在撞击前4天被发现，远早于当前的平均时间。这将为望远镜后续观测、有针对性的火球观测、行星防御规划和公众参与提供重要机会。此外，对于由LSST观测但由其他巡天发现的撞击体，也有显著的预发现潜力，这会立即延长观测弧，从而减少轨道和撞击位置的不确定性。在某些情况下，这些观测可能还能够将望远镜观测与撞击后观测到的火球联系起来，提供有价值的撞击前天体测量和光度数据。这对小行星研究和行星防御都有重大影响。
英文摘要：
As of mid-2026, 11 objects have been discovered prior to impacting the Earth, with warning times between 2 - 20 hours. Using real metre-sized Earth impactors from the last decade, we ask the question: ``If the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) had been operating over the last decade, how many imminent impactors would it have observed and discovered pre-impact, and how early would these discoveries have been?'' We use the LSST Solar System Survey Simulator Sorcha and a population of real fireballs observed by orbital sensors over the last decade to investigate which events would have been observed pre-impact. We find that the LSST would have observed 30 (13.9%) of the 216 simulated objects, with most objects receiving 2 - 4 observations. Using the default linking algorithm, only two (0.9%) of these objects would have been `discovered' pre-impact. Using a modified linking algorithm better suited to fast moving objects, this increases to eight (3.7%). Based on this, we predict that the LSST will discover 8 +/- 2 imminent impactors over its nominal 10 year survey, at the low end of previous estimations. However, we predict these objects to be discovered 4 days pre-impact, substantially earlier than the current average. This will bring significant opportunities for telescopic follow-up, targeted fireball observations, planetary defence planning, and public engagement. There is also significant potential for precovery for impactors observed by the LSST but discovered by other surveys, instantly lengthening observation arcs and thereby reducing the orbital and impact location uncertainties. In some cases, these observations may also enable the linkage of telescopic observations with observed fireballs post-impact, providing valuable pre-impact astrometric and photometric data. This has significant implications for both asteroid research and planetary defence.
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