Normal point generation and first photon bias correction in APOLLO Lunar Laser Ranging
Normal point generation and first photon bias correction in APOLLO Lunar Laser Ranging
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发表时间：
2010
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通讯作者：
E. Michelsen
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作者：
E. Michelsen
作者：埃里克·伦纳德·迈克尔森 |摘要：阿波罗月球激光测距 (LLR) 系统多年来通过将月球轨道追踪至 1 毫米来研究重力。一般来说，LLR 提供了重力许多方面的广泛测试，包括与广义相对论 (GR) 的偏差以及重力常数 G 的时间变化率。APOLLO 的精度比以前的 LLR 测量高出约 10 倍，使得未来几年重力测试的质量提高了大约一个数量级。 APOLLO 需要复杂的数据缩减方法才能如此精确地提取距离。目前根据数据确定月球往返时间有三种选择：相关法、增强计算法和PDF拟合法。这里的结果表明 PDF 拟合方法是更可取的，可以在整个操作条件范围内实现最小的随机不确定性，并且系统误差稳定在 1 mm 以下。作为第二个主题，阿波罗系统包含一个称为“第一光子偏差”的系统误差，它会导致时间测量提前倾斜。提出并仿真了一种算法，表明该算法本质上能够在正常操作条件下实现 l 1 mm 的系统误差。然而，最终的算法需要一个根据更准确的镜头强度波动模型进行校准的校正表。这样的表格可能是未来调查的主题
Author(s): Michelsen, Eric Leonard | Abstract: The APOLLO Lunar Laser Ranging (LLR) system studies gravity by tracing out the orbit of the moon to 1 mm, over many years. LLR in general provides extensive tests of many aspects of gravity, including deviations from General Relativity (GR), and time rate-of-change of the gravitational constant, G. APOLLO's precision is approximately 10x better than previous LLR measurements, enabling about an order of magnitude improvement in tests of gravity over the coming years. APOLLO requires complex data reduction methods to extract the distance so precisely. There are currently three choices for determining the round-trip-time to the moon from the data: the correlation method, the Augmented Calculation method, and the PDF-fit method. The results here suggest the PDF- fit method as preferable, for minimum random uncertainty over the full operating range of conditions, and stable systematic error below 1 mm. As a second topic, the APOLLO system includes a systematic error called "First Photon Bias," which causes time measurements to be skewed early. An algorithm is presented and simulated, showing that it is inherently capable of achieving l 1 mm systematic error under normal operating conditions. However, the final algorithm requires a correction table calibrated from a more accurate model of shot-to-shot intensity fluctuations. Such a table could be the subject of future investigations