• DOI:10.1088/1361-6382/aa953c
• Corpus ID: 31927794

APOLLO clock performance and normal point corrections

@article{Liang2017APOLLOCP,
  title={APOLLO clock performance and normal point corrections},
  author={Yi-tao Liang and Thomas W. Murphy and Jr. and N. R. Colmenares and James B. R. Battat},
  journal={arXiv: Instrumentation and Methods for Astrophysics},
  year={2017}
}

• Y. Liang, T. W. Murphy, +2 authors J. Battat
• Published 28 June 2017
• Physics
• arXiv: Instrumentation and Methods for Astrophysics

The Apache Point Observatory Lunar Laser-ranging Operation (APOLLO) has produced a large volume of high-quality lunar laser ranging (LLR) data since it began operating in 2006. For most of this period, APOLLO has relied on a GPS-disciplined, high-stability quartz oscillator as its frequency and time standard. The recent addition of a cesium clock as part of a timing calibration system initiated a comparison campaign between the two clocks. This has allowed correction of APOLLO range measurements--called normal points--during the overlap period, but also revealed a mechanism to correct for systematic range offsets due to clock errors in historical APOLLO data. Drift of the GPS clock on ~1000 s timescales contributed typically 2.5 mm of range error to APOLLO measurements, and we find that this may be reduced to ~1.6 mm on average. We present here a characterization of APOLLO clock errors, the method by which we correct historical data, and the resulting statistics.