Comet rotation period
The rotation period of comet 67P/Churyumov-Gerasimenko, as measured by Rosetta.
The first measurements are from March 2014: at that time the comet completed one rotation in 12.404 hours (12 hours 24 minutes 14 seconds).
From February 2015 to May 2015 the rotation period increased noticeably, after which it decreased significantly between May 2015 and February 2016.
By the end of mission, in September 2016, the period was 12.055 hours (12 hours 3 minutes 18 seconds).
The comet rotation properties are determined by the ESA Flight Dynamics team as part of their analysis for navigation. For this they use, among other sources of information, the position of landmarks identified on NavCam images.