-
Notifications
You must be signed in to change notification settings - Fork 0
/
naif0012.tls
152 lines (106 loc) · 5.13 KB
/
naif0012.tls
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
KPL/LSK
LEAPSECONDS KERNEL FILE
===========================================================================
Modifications:
--------------
2016, Jul. 14 NJB Modified file to account for the leapsecond that
will occur on December 31, 2016.
2015, Jan. 5 NJB Modified file to account for the leapsecond that
will occur on June 30, 2015.
2012, Jan. 5 NJB Modified file to account for the leapsecond that
will occur on June 30, 2012.
2008, Jul. 7 NJB Modified file to account for the leapsecond that
will occur on December 31, 2008.
2005, Aug. 3 NJB Modified file to account for the leapsecond that
will occur on December 31, 2005.
1998, Jul 17 WLT Modified file to account for the leapsecond that
will occur on December 31, 1998.
1997, Feb 22 WLT Modified file to account for the leapsecond that
will occur on June 30, 1997.
1995, Dec 14 KSZ Corrected date of last leapsecond from 1-1-95
to 1-1-96.
1995, Oct 25 WLT Modified file to account for the leapsecond that
will occur on Dec 31, 1995.
1994, Jun 16 WLT Modified file to account for the leapsecond on
June 30, 1994.
1993, Feb. 22 CHA Modified file to account for the leapsecond on
June 30, 1993.
1992, Mar. 6 HAN Modified file to account for the leapsecond on
June 30, 1992.
1990, Oct. 8 HAN Modified file to account for the leapsecond on
Dec. 31, 1990.
Explanation:
------------
The contents of this file are used by the routine DELTET to compute the
time difference
[1] DELTA_ET = ET - UTC
the increment to be applied to UTC to give ET.
The difference between UTC and TAI,
[2] DELTA_AT = TAI - UTC
is always an integral number of seconds. The value of DELTA_AT was 10
seconds in January 1972, and increases by one each time a leap second
is declared. Combining [1] and [2] gives
[3] DELTA_ET = ET - (TAI - DELTA_AT)
= (ET - TAI) + DELTA_AT
The difference (ET - TAI) is periodic, and is given by
[4] ET - TAI = DELTA_T_A + K sin E
where DELTA_T_A and K are constant, and E is the eccentric anomaly of the
heliocentric orbit of the Earth-Moon barycenter. Equation [4], which ignores
small-period fluctuations, is accurate to about 0.000030 seconds.
The eccentric anomaly E is given by
[5] E = M + EB sin M
where M is the mean anomaly, which in turn is given by
[6] M = M + M t
0 1
where t is the number of ephemeris seconds past J2000.
Thus, in order to compute DELTA_ET, the following items are necessary.
DELTA_TA
K
EB
M0
M1
DELTA_AT after each leap second.
The numbers, and the formulation, are taken from the following sources.
1) Moyer, T.D., Transformation from Proper Time on Earth to
Coordinate Time in Solar System Barycentric Space-Time Frame
of Reference, Parts 1 and 2, Celestial Mechanics 23 (1981),
33-56 and 57-68.
2) Moyer, T.D., Effects of Conversion to the J2000 Astronomical
Reference System on Algorithms for Computing Time Differences
and Clock Rates, JPL IOM 314.5--942, 1 October 1985.
The variable names used above are consistent with those used in the
Astronomical Almanac.
\begindata
DELTET/DELTA_T_A = 32.184
DELTET/K = 1.657D-3
DELTET/EB = 1.671D-2
DELTET/M = ( 6.239996D0 1.99096871D-7 )
DELTET/DELTA_AT = ( 10, @1972-JAN-1
11, @1972-JUL-1
12, @1973-JAN-1
13, @1974-JAN-1
14, @1975-JAN-1
15, @1976-JAN-1
16, @1977-JAN-1
17, @1978-JAN-1
18, @1979-JAN-1
19, @1980-JAN-1
20, @1981-JUL-1
21, @1982-JUL-1
22, @1983-JUL-1
23, @1985-JUL-1
24, @1988-JAN-1
25, @1990-JAN-1
26, @1991-JAN-1
27, @1992-JUL-1
28, @1993-JUL-1
29, @1994-JUL-1
30, @1996-JAN-1
31, @1997-JUL-1
32, @1999-JAN-1
33, @2006-JAN-1
34, @2009-JAN-1
35, @2012-JUL-1
36, @2015-JUL-1
37, @2017-JAN-1 )
\begintext