; docformat = 'rst'
;+
; This function returns the angle between the spacecraft position and
;   a unit vector from the center of the Earth towards the center of
;   the Sun, in radians.
;
; :Examples:
;   angle = term_f(time, time_ofs=time_ofs)
;-
;+
; :Params:
;   time : in, required, type=double
;     Input time in GPS microseconds.
;   time_ofs : in, required, type=double
;     Offset from the input time in GPS microseconds.
;
; :Returns:
;   Returns the angle between the spacecraft position and
;   a unit vector from the center of the Earth towards the center of
;   the Sun, in radians
;-
function term_f, time, time_ofs=time_ofs
  scp=scpos(time+time_ofs)
  sunp=sunvec(time+time_ofs)
  return,vangle(scp,sunp)
end