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| #! /usr/local/bin/python3.6
"""
グリニジ視恒星時 GAST(= Greenwich Apparent Sidereal Time)等の計算
: IAU2006 による計算
* IAU SOFA(International Astronomical Union, Standards of Fundamental Astronomy)
の提供する C ソースコード "gst06.c" 等で実装されているアルゴリズムを使用する。
* 参考サイト
- [SOFA Library Issue 2016-05-03 for ANSI C: Complete List]
(http://www.iausofa.org/2016_0503_C/CompleteList.html)
- [USNO Circular 179]
(http://aa.usno.navy.mil/publications/docs/Circular_179.php)
- [IERS Conventions Center]
(http://62.161.69.131/iers/conv2003/conv2003_c5.html)
Date Author Version
2016.06.21 mk-mode.com 1.00 新規作成
Copyright(C) 2016 mk-mode.com All Rights Reserved.
---
引数: 日時(TT（地球時）)
書式：YYYYMMDD or YYYYMMDDHHMMSS
無指定なら現在(システム日時)を地球時とみなす。
"""
from datetime import datetime
import re
import sys
import traceback
# Original library
from lib import cip_cio as lcc
from lib import const as lcst
from lib import greenwich as lgw
from lib import nutation as lnt
from lib import precision as lpr
from lib import rotation_fw as lfw
from lib import time as ltm
class GreenwichTime:
def __init__(self):
self.__get_arg()
def exec(self):
try:
# === Time calculation
self.jd = ltm.calc_jd(self.tt)
self.jc = ltm.calc_jc(self.jd)
self.dt = ltm.calc_dt(self.tt)
self.ut1 = ltm.tt2ut1(self.tt, self.dt)
self.jd_ut1 = ltm.calc_jd(self.ut1)
# === Fukushima-Williams angles for frame bias and precession.
# Ref: iauPfw06(date1, date2, &gamb, &phib, &psib, &epsa)
prec = lpr.Precision(self.jc)
self.gam_b, self.phi_b, self.psi_b = prec.calc_pfw_06()
self.eps_a = prec.calc_obl_06()
# === Nutation components.
# Ref: iauNut06a(date1, date2, &dp, &de)
nut = lnt.Nutation(self.jc)
self.d_psi, self.d_eps = nut.calc_nut_06_a()
# === Equinox based nutation x precession x bias matrix.
# Ref: iauFw2m(gamb, phib, psib + dp, epsa + de, rnpb)
r_fw = lfw.RotationFw()
self.r_mtx = r_fw.fw2m(
self.gam_b, self.phi_b,
self.psi_b + self.d_psi,
self.eps_a + self.d_eps
)
# === Extract CIP coordinates.
# Ref: iauBpn2xy(rnpb, &x, &y)
cc = lcc.CipCio(self.jc)
self.x, self.y = cc.bpn2xy(self.r_mtx)
# === The CIO locator, s.
# Ref: iauS06(tta, ttb, x, y)
self.s = cc.s_06(self.x, self.y)
# Greenwich time
gw = lgw.Greenwich(self.jd_ut1)
# === Greenwich apparent sidereal time.
# Ref: iauEra00(uta, utb), iauEors(rnpb, s)
self.era = gw.era_00()
self.eo = gw.eors(self.r_mtx, self.s)
self.gast = gw.gast(self.era, self.eo)
self.gast_deg = self.gast / lcst.PI_180
# === Greenwich mean sidereal time, IAU 2006.
# Ref: iauGmst06(uta, utb, tta, ttb)
self.gmst = gw.gmst(self.era, self.jc)
self.gmst_deg = self.gmst / lcst.PI_180
# === Equation of Equinoxes
self.ee = gw.ee(self.gast, self.gmst)
self.ee_deg = self.ee / lcst.PI_180
# === Display
self.__display()
except Exception as e:
raise
def __get_arg(self):
""" コマンドライン引数の取得
* コマンドライン引数で指定した日時を self.tt に設定
* コマンドライン引数が存在しなければ、現在時刻を self.tt に設定
"""
try:
if len(sys.argv) < 2:
self.tt = datetime.now()
return
if re.search(r"^(\d{8}|\d{14}|\d{20})$", sys.argv[1]):
dt = sys.argv[1].ljust(20, "0")
else:
sys.exit(0)
try:
self.tt = datetime.strptime(dt, "%Y%m%d%H%M%S%f")
except ValueError as e:
print("Invalid date!")
sys.exit(0)
except Exception as e:
raise
def __display(self):
""" Display """
try:
print((
" TT = {}\n"
" UT1 = {}\n"
" JD(TT) = {}\n"
"JD(UT1) = {}\n"
" JC = {}\n"
" DT = {}\n"
" GAMMA_ = {}\n"
" PHI_ = {}\n"
" PSI_ = {}\n"
" EPS_A = {}\n"
" D_PSI = {}\n"
" D_EPS = {}\n"
" r_mtx = \n{}\n"
" x = {}\n"
" y = {}\n"
" s = {}\n"
" ERA = {} rad\n"
" EO = {} rad\n"
" GAST = {} rad\n"
" = {} °\n"
" = {}\n"
" GMST = {} rad\n"
" = {} °\n"
" = {}\n"
" EE = {} rad\n"
" = {} °\n"
" = {}"
).format(
self.tt.strftime("%Y-%m-%d %H:%M:%S.%f"),
self.ut1.strftime("%Y-%m-%d %H:%M:%S.%f"),
self.jd,
self.jd_ut1,
self.jc,
self.dt,
self.gam_b,
self.phi_b,
self.psi_b,
self.eps_a,
self.d_psi,
self.d_eps,
self.r_mtx,
self.x,
self.y,
self.s,
self.era,
self.eo,
self.gast,
self.gast_deg,
ltm.deg2hms(self.gast_deg),
self.gmst,
self.gmst_deg,
ltm.deg2hms(self.gmst_deg),
self.ee,
self.ee_deg,
ltm.deg2hms(self.ee_deg)
))
except Exception as e:
raise
if __name__ == '__main__':
try:
GreenwichTime().exec()
except Exception as e:
traceback.print_exc()
sys.exit(1)
|