[R] CRAN - Package "activity" - how do you convert time (hh:mm) into radians in R 3.1.2 on Windows 7 OS 64bit

[Typhenn Brichieri-Colombi]

Hello,
I am using the "activity" package developed by Marcus Rowcliffe (released in February, 2015). This package uses time in radians to estimate activity. I have camera trap data in 24 hour times (hh:mm) - how do I convert these into radians? (e.g. My time-of-detection at 19:44, how do I convert this into radians?)
Thank you for your time and your help
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