Function: solar-sidereal-time

solar-sidereal-time is a byte-compiled function defined in solar.el.gz.

Signature

(solar-sidereal-time T0)

Documentation

Sidereal time (in hours) in Greenwich at T0 Julian centuries.

T0 must correspond to 0 hours UT.

Source Code

;; Defined in /usr/src/emacs/lisp/calendar/solar.el.gz
(defun solar-sidereal-time (t0)
  "Sidereal time (in hours) in Greenwich at T0 Julian centuries.
T0 must correspond to 0 hours UT."
  (let* ((mean-sid-time (+ 6.6973746
                           (* 2400.051337 t0)
                           (* 0.0000258622 t0 t0)
                           (* -0.0000000017222 t0 t0 t0)))
         (et (solar-ephemeris-time (list t0 0.0)))
         (nut-i (solar-ecliptic-coordinates et nil))
         (nut (nth 3 nut-i))            ; nutation
         (i (cadr nut-i)))              ; inclination
    (mod (+ (mod (+ mean-sid-time
                    (/ (/ (* nut (solar-cosine-degrees i)) 15) 3600)) 24.0)
            24.0)
         24.0)))