GCOEF
SEP 1990
9909.0
GLOBAL SET
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
GCOEF 2 2 1 1.0000000D-091.00D-09
----+----0----+----0----+----0----+----0----+----0----+----0----+----0----+----0
COLUMNS FORMAT DESCRIPTION DEFAULT VALUE & UNITS
1-5 A5 GCOEF - Modifies and/or requests
the estimation of coefficients in
the geopotential model.
7 I1 Normalization indicator. 0
= 0 values unnormalized C,S [See NOTES]
= 1 values normalized C,S
= 2 values ignored C,S
15-17 I3 Degree of C and S coefficients 0
(N index). [NOTE 1]
18-20 I3 Order of C and S coefficients 0
(M index). [NOTE 1]
25-44 D20.8 A priori (or starting) value of C 0.
coefficient. [NOTE 2]
45-59 D15.3 A priori (or starting) value of S 0.
coefficient. [NOTE 2]
60-72 D13.1 Standard deviation or fractional 0.
uncertainty of C coefficient. Coefficient
will not be adjusted if this field is zero.
If the value is less than or equal to
1.0D-5, it is used as the standard deviation.
If the value is greater than 1.0D-5 (or
(SQRT(1.0D-5) for J2) it is used as the
fractional uncertainty, and the standard
deviation is computed as the fractional
uncertainty times the nominal value of the
coefficient. [NOTE 1]
73-80 D8.2 Standard deviation or fractional uncertainty 0.
of S coefficient. Coefficient will not be
adjusted if this field is zero.
If the value is less than or equal to
1.0D-5, it is used as the standard deviation
If the value is greater than 1.0D-5 it is
used as the fractional uncertainty, and the
standard deviation is computed as the
fractional uncertainty times the nominal value
of the coefficient. [NOTE 1]
NOTES:
[1] The denormalization subprogram in GEODYN underflows at degree
49 and order 48.
The geopotential coefficient denormalization equation used is:
where
for m > 0
for m = 0
and
are un-normalized coefficients.
are normalized coefficients.
[2] If the degree and/or order on the GCOEF card is greater than the
DEFAULT values [in the gravity file on unit 12], then the highest
degree and/or order that is specified on the GCOEF card must be
input on the EARTH card.
[3] If it is desired that the starting values of geopotential coefficients
be different than the a priori values for those coefficients then the
GCOEF card should be used as follows:
o GCOEF cards requesting the desired coefficient adjustments
should be included in the setup deck. The a priori values
will be indicated on these cards.
o For each coefficient pair for which the starting value is to
be different than the a priori value, an additional GCOEF
card should be in the setup deck. This GCOEF card will
indicate the starting value and come later in the deck than
the corresponding GCOEF card requesting adjustment.
[4] Nominal values of geopotential coefficients are
IF CARD OMITTED: The geopotential used will be from the gravity model
input on UNIT 12 of GEODYN-IIS unless modified by EARTH,
GCOEFC, or GCOEFS cards.
Patrick Dahiroc
1998-09-10