Geology Reference
In-Depth Information
2 DLOD,F1,F2,UX,UY,UL,Q1,Q2
11 FORMAT(1X,F12.6,2F9.6,F11.7,2F9.3,2F9.6,F10.7,2F8.3,
1 F8.2,4F7.4,I7,A7,F6.2,2F10.6,F11.7,2A3,2F10.6,F11.7,2A3)
C Set time origin to zero.
DAY=DAY-44089.993750D0
C Find Cartesian co-ordinates of the celestial pole and their
C standard errors.
XNUT=0.39777716D0*PSI
SEXNUT=0.39777716D0*SEPSI
YNUT=EPS
SEYNUT=SEEPS
C Write out extracted co-ordinates of the celestial pole.
WRITE(2,12)I,DAY,XNUT,SEXNUT,YNUT,SEYNUT
12
FORMAT(1X,I4,F15.6,4F10.3)
10
CONTINUE
END
Tests reveal that four of the points have null values and 23 pairs of points have
identical time tags. The former were removed and the values of the latter were
averaged with weights in inverse proportion to the squares of their standard errors.
Series of 3343 points were left for analysis in the file nut.dat.
Before performing spectral analysis, the series were reduced to zero mean. The
linear trends were removed, and 18.6-year (6798.58 day), 9.3-year (6798.58
/
2day),
annual (365.25971 day), and semi-annual (365.2597
/
2 day) periodic terms were
removed by least squares fits to
x
=
i
x
t
+
j
x
+
a
x
cos (ω
1
t
)
+
b
x
sin (ω
1
t
)
+
c
x
cos (ω
2
t
)
+
d
x
sin (ω
2
t
)
+
e
x
cos (ω
3
t
)
+
f
x
sin (ω
3
t
)
+
g
x
cos (ω
4
t
)
+
h
x
sin (ω
4
t
),
(4.108)
y
=
i
y
t
+
j
y
+
a
y
cos (ω
1
t
)
+
b
y
sin (ω
1
t
)
+
c
y
cos (ω
2
t
)
+
d
y
sin (ω
2
t
)
+
e
y
cos (ω
3
t
)
+
f
y
sin (ω
3
t
)
+
g
y
cos (ω
4
t
)
+
h
y
sin (ω
4
t
),
(4.109)
where ω
1
=
2π/6798.58, ω
2
=
2ω
1
, ω
3
=
2π/365.25971 and ω
4
=
2ω
3
.Coe
cients
of the extracted terms are listed in Table 4.1.
The programme NUTRES restores the original time tags from the beginning
of the record at 44089.99375 days (Julian days minus 2,400,000) and subtracts
Tabl e 4 . 1
Coe
cients of terms extracted from the GSFC VLBI nutation series.
a
x
b
x
c
x
d
x
e
x
f
x
−
−
−
2.4496
1.9307
0.37214
0.24779
1.0785
1.7798
g
x
h
x
i
x
j
x
0.82405
0.19983
−
0.00324337
150.02
a
y
b
y
c
y
d
y
e
y
f
y
1.9026
−
2.3741
−
0.18244
0.13710
1.6863
1.2533
g
y
h
y
i
y
j
y
−
0.17113
0.71118
−
0.000665044
29.144
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