urn:nasa:pds:grail_gravity_derived:data_shbdr:gggrx_1200a_shb_l180
1.1
GRAIL Gravity Binary Spherical Harmonic Model: gggrx_1200a_shb_l180
1.18.0.0
Product_Observational
2023-05-24
1.1
Updated file comment regarding principal axis frame
2022-08-15
1.0
Initial PDS4 version
2012-03-01Z
2012-12-14Z
Gravity Recovery and Interior Laboratory
Mission
urn:nasa:pds:context:investigation:mission.gravity_recovery_and_interior_laboratory
data_to_investigation
Gravity Recovery and Interior Laboratory A
Host
urn:nasa:pds:context:instrument_host:spacecraft.grail-a
is_instrument_host
Gravity Recovery and Interior Laboratory B
Host
urn:nasa:pds:context:instrument_host:spacecraft.grail-b
is_instrument_host
Lunar Gravity Ranging System A for GRAIL-A
Instrument
urn:nasa:pds:context:instrument:grail-a.lgrs-a
is_instrument
Lunar Gravity Ranging System B for GRAIL-B
Instrument
urn:nasa:pds:context:instrument:grail-b.lgrs-b
is_instrument
Moon
Satellite
urn:nasa:pds:context:target:satellite.earth.moon
data_to_target
gggrx_1200a_shb_l180.dat
2016-03-01
This file contains coefficients and related data for the GSFC Lunar gravity
field GRGM1200A, a degree and order 1200 spherical harmonic model. It is
a GSFC gravity field that includes the entire GRAIL mission data (and that
does not include other data).
The covariance matrix information in this file is truncated to degree and
order 180.
Some details describing this model are:
The spherical harmonic coefficients are fully normalized (geodesy 4pi
normalized).
The uncertainties are calibrated (the formal uncertainties multiplied by
a factor of 1.635).
The reference radius = 1738.0 km
The gravitational parameter is GM = 4902.80011526323 km**3/s**2
The planetary ephemeris is de430 and defines the lunar body-fixed
coordinate system in the principal axes frame.
A Kaula type power law constraint is applied to the spherical harmonics
coefficients for degrees greater than 600 (3.6e-4/n^2).
The weighting of the KBRR data is:
0.03 microns/sec in the primary mission
0.05 microns/sec in the extended mission
The weighting of the DSN data is:
0.12mm/s in both the primary and extended mission
The nominal tidal Love number is k2 = 0.024133 +/- 0.000016
The current best reference for the GRGM1200A gravity field is
LEMOINEETAL2014, published in the Geophysical Research Letters with the
DOI number 10.1002/2014GL060027. For additional details on the GRAIL
mission, data and methods, see LEMOINEETAL2013.
This product is a set of binary tables:
a header table, a names table, a coefficients table, and a covariance
table. Definitions of the tables follow. This GRAIL moon gravity model
is in the form of a Spherical Harmonics Binary Data Record (SHBDR).
SHBDR_Header_Table
0
1
The SHBDR Header includes descriptive information about the spherical
harmonic coefficients that follow in SHBDR_Coefficients_Table. The header consists
of a single record of nine data columns requiring 56 bytes. The Header is followed by
a pad of binary integer zeroes.
9
0
56
Reference_Radius
1
1
IEEE754LSBDouble
8
km
The assumed reference radius of the spherical planet.
Constant
2
9
IEEE754LSBDouble
8
For a gravity field model
the gravitational constant GM in km cubed per second
squared for the planet. For a topography model, set to 1.
Uncertainty_in_Constant
3
17
IEEE754LSBDouble
8
For a gravity field model the uncertainty in the
gravitational constant GM in km cubed per second squared for
the planet. For a topography model, set to 0.
Degree_of_Field
4
25
SignedLSB4
4
Degree of the model field.
Order_of_Field
5
29
SignedLSB4
4
Order of the model field.
Normalization_State
6
33
SignedLSB4
4
The normalization indicator. For gravity field:
0 coefficients are unnormalized
1 coefficients are normalized
2 other.
Number_of_Names
7
37
SignedLSB4
4
Number of valid names in
the SHBDR_Names_Table. Also, the number of valid
coefficients in the SHBDR_Coefficients_Table.
Reference_Longitude
8
41
IEEE754LSBDouble
8
degree
Reference longitude for the spherical harmonic
expansion; normally 0.
Reference_Latitude
9
49
IEEE754LSBDouble
8
degree
Reference latitude for the spherical harmonic
expansion; normally 0.
SHBDR_Names_Table
512
32757
The SHBDR_Names_Table contains names for the solution parameters (including
gravity field coefficients) which will follow in SHBDR_Coefficients_Table.
The order of the names in SHBDR_Names_Table corresponds identically to the
order of the parameters in SHBDR_Coefficients_Table. Each coefficient name
is of the form Cij or Sij where i is the degree of the coefficient and j is
the order of the coefficient. Both indices are three-digit zero-filled
right-justified ASCII character strings (for example, C010005 for the 10th
degree 5th order C coefficient, or S002001 for the 2nd degree 1st order
S coefficient). The eighth byte in the table is an ASCII blank used to ensure
that the row length is equal to 8 bytes. Names of other solution parameters are
limited to 8 ASCII characters; if less than 8, they will be left-justified and
padded with ASCII blanks. The Names Table itself will be padded with ASCII blanks,
if necessary.
1
0
8
Parameter_Name
1
1
ASCII_String
8
The name of the coefficient or other solution parameter,
left-justified and padded with ASCII blanks (if needed) to 8
characters.
SHBDR_Coefficients_Table
262656
32757
The SHBDR_Coefficients_Table contains the coefficients and other
solution parameters for the spherical harmonic model. The order of the
coefficients in this table corresponds exactly to the order of the coefficient
and parameter names in SHBDR_Names_Table. The SHBDR_Coefficients_Table will be
padded with double precision zeroes.
1
0
8
Coefficient_Value
1
1
IEEE754LSBDouble
8
A coefficient Cij or Sij or other solution parameter as specified
in the SHBDR_Names_Table.
SHBDR_Covariance_Table
524800
536526903
The SHBDR_Covariance_Table
contains the covariances for the spherical harmonic model
coefficients and other solution parameters. The order of
the covariances in this table is defined as columnwise
vector storage of the upper triangular matrix formed by
the product of the SHBDR Names Table with its transpose.
For example, if the Names Table has four entries A, B,
C, and D, then the covariances are given by the column
vectors in the upper triangular matrix of:
| A | [ A B C D ] = | AA AB AC AD |
| B | | BA BB BC BD |
| C | | CA CB CC CD |
| D | | DA DB DC DD |
That is, the covariance table will list (in this order)
AA, AB, BB, AC, BC, CC, AD, BD, CD, and DD.
The SHBDR_Covariance_Table will be padded with double
precision zeroes
1
0
8
Covariance_Value
1
1
IEEE754LSBDouble
8
The covariance value for the coefficients and other
solution parameters specified by the product of SHBDR_Names_Table
with its transpose, after omitting redundant terms.
gggrx_1200a_shb_l180.lbl
0
PDS3
Original PDS3 label
Carriage-Return Line-Feed