Earth Orientation Parameters

Calculate Earth orientation parameters (EOP)

• 

Libraries:
Aerospace Blockset / Environment / Celestial Phenomena

Description

The Earth Orientation Parameters block calculates these parameters:

• Difference between the UTC and Universal Time (UT1)

• Movement of the rotation axis with respect to the crust of the Earth

• Adjustment to the location of the Celestial Intermediate Pole (CIP)

By default, this block uses a prepopulated list of International Earth Rotation and Reference Systems Service (IERS) data. This list contains measured and calculated (predicted) data supplied by the IERS. The IERS measures and calculates this data for a set of predetermined dates. For dates after those listed in the prepopulated list, Earth Orientation Parameters calculates the ΔUT1 using this equation, limiting the values to +/- 0.9 s:

UT1-UTC=0.5309-0.00123(MJD-57808)-(UT2-UT1) 

Use this block when your application uses Earth Centered Inertial to Earth Centered Earth Fixed transformations, such as for high altitude applications.

Ports

Input

UTC_MJD — UT1 for UTC

scalar

UT1 for UTC, specified as a scalar modified Julian date. Use the Julian Date Conversion block to convert the UTC date to a modified Julian date.

Data Types: double

Output

ΔUT1 — Difference between UT1 and UTC

scalar

Difference between UT1 and UTC, specified as a scalar, in seconds.

Data Types: double

[xp,yp] — Polar displacement of Earth

vector

Polar displacement of the Earth, [xp,yp], specified as a vector, in radians, from the motion of the Earth crust, along the x- and y-axes.

Data Types: double

[dX,dY] — Adjustment to location of Celestial Intermediate Pole (CIP)

vector

Adjustment to the location of the Celestial Intermediate Pole (CIP), specified as a vector, in radians. This location ([dX,dY]) is along the x- and y-axes.

Data Types: double

ΔUT1_err — Return errors for the measured and predicted values in the IERS data

vector

Return errors for the measured and predicted values in the IERS data for the difference between UT1 and UTC, specified as a vector, in seconds.

Dependencies

This port is enabled when the Output parameter error is selected.

[xp,yp]_err — Return errors for the measured and predicted values in the IERS data

vector

Return errors for the measured and predicted values in the IERS data for the polar displacement of Earth, specified as a vector, in radians.

Dependencies

This port is enabled when the Output parameter error is selected.

[dX,dY]_err — Return errors for the measured and predicted values in the IERS data

vector

Return errors for the measured and predicted values in the IERS data for the adjustment to location of Celestial Intermediate Pole (CIP), specified as a vector, in radians.

Dependencies

This port is enabled when the Output parameter error is selected.

Parameters

IERS data file — Earth orientation data

aeroiersdata.mat (default) | MAT-file

Custom list of Earth orientation data, specified in a MAT-file.

Programmatic Use

Block Parameter: FileName

Type: character vector

Values: scalar

Default: 'aeroiersdata.mat'

Output parameter error — Enable output ports to return errors

off (default) | on

Select this parameter to enable output ports to return errors for the measured and predicted values in the IERS data file:

• Difference between UT1 and UTC

• Polar displacement of Earth

• Adjustment to location of Celestial Intermediate Pole (CIP)

Dependencies

Selecting this check box enables these ports:

• ΔUT1_err

• [xp,yp]_err

• [dX,dY]_err

Programmatic Use

Block Parameter: OutputError

Type: character vector

Values: scalar

Default: 'off'

Action for out-of-range input — Out-of-range block behavior

None (default) | Warning | Error

Out-of-range block behavior, specified as:

Action	Description
None	No action.
Warning	Warning in the Diagnostic Viewer, model simulation continues.
Error (default)	Error in the Diagnostic Viewer, model simulation stops.

Programmatic Use

Block Parameter: action

Type: character vector

Values: 'None' | 'Warning' | 'Error'

Default: 'Warning'

IERS data URL — Web site or Earth orientation data file

http://maia.usno.navy.mil/ser7/finals2000A.data (default) | web site address | file name

Web site or Earth orientation data file containing the Earth orientation data according to the IAU 2000A, specified as a web site address or file name.

Note

If you receive an error message while accessing the default site, use one of these alternate sites:

• https://datacenter.iers.org/data/latestVersion/10_FINALS.DATA_IAU2000_V2013_0110.txt

• ftp://cddis.gsfc.nasa.gov/pub/products/iers/finals2000A.data

Programmatic Use

Block Parameter: FileName

Type: character vector

Values: scalar

Default: 'aeroiersdata.mat'

Destination folder — Folder for IERS data file

current Folder (default)

Folder for IERS data file, specified as a character array or string. Before running this function, create foldername with write permission.

To create the IERS data file in the destination folder, click the Create button.

Programmatic Use

Block Parameter: FileName

Type: character vector

Values: scalar

Default: 'aeroiersdata.mat'

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2018b

R2020b: Updated aeroiersdata.mat file

The contents of the aeroiersdata.mat file have been updated. Correspondingly, the output of this block will have different results when using the default value ('aeroiersdata.mat') as the value of the IERS data file parameter. The results reflect more accurate external data from the International Earth Rotation and Reference Systems Service (IERS).