14.6. SiderealTime.lst(): Greenwich to
local sidereal
This is the inverse of Section 14.5, “SiderealTime.gst(): Local to
Greenwich sidereal”: self is assumed to be GST, and we want
to find the equivalent LST. All we have to do is add the
longitude to the GST and renormalize to [0,24).
sidereal.py
# - - - S i d e r e a l T i m e . l s t
def lst ( self, eLong ):
"""Convert GST to LST.
[ (self is Greenwich sidereal time) and
(eLong is a longitude east of Greenwich in radians) ->
return a new SiderealTime representing the LST
at longitude eLong ]
"""
#-- 1 --
# [ deltaHours := eLong expressed in hours ]
deltaHours = radiansToHours ( eLong )
#-- 2 --
gmtHours = (self.hours + deltaHours) % 24.0
#-- 3 --
return SiderealTime ( gmtHours )
