Three recent papers from the APOLLO project showed up on my VoxCharta summary of arxiv.org which may be of interest to the time-nuts community. They are to do with improving the precision and absolute calibration of the lunar laser ranging project based at the 3.5m WIYN telescope at Apache Point.
The links are: http://arxiv.org/abs/1707.00204v1 (Timing calibration of the APOLLO experiment) http://arxiv.org/abs/1706.09550v1 (An absolute calibration system for millimeter-accuracy APOLLO measurements) http://arxiv.org/abs/1706.09421v1 (APOLLO clock performance and normal point corrections) I was surprised by a few things: 1) that the size of GR effects on the Moon's position was at the 10 meter level (or ~0.01% measurable/testable level for the millimeter-level precision reached by APOLLO) and 2) the relatively coarse frequency steps the XL-DC GPSDO previously used was capable of. Does anyone know what sort of oscillator these used ? I thought most (good) OCXOs had/have a EFC at the 1e-13 level but maybe "back in the day" the availability of suitable DACs with a large dynamic range was more of an issue ? Cheers, Tim _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
