Convert a POSIXt time to a sidereal time, using the method in Chapter 7 of reference 1. The small correction that he discusses after his equation 7.1 is not applied here.
siderealTime(t)
t  a time, in POSIXt format, e.g. as created by


A sidereal time, in hours in the range from 0 to 24.
Meeus, Jean, 1982. Astronomical formulae for Calculators. WillmannBell. Richmond VA, USA. 201 pages
Other things related to astronomy:
angle2hms()
,
eclipticalToEquatorial()
,
equatorialToLocalHorizontal()
,
julianCenturyAnomaly()
,
julianDay()
,
moonAngle()
,
sunAngle()
,
sunDeclinationRightAscension()
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