Delta UT1

R2026b

Calculate difference between principal Universal Time (UT1) and Coordinated Universal Time (UTC) according to International Astronomical Union (IAU) 2000A reference system

• 

Delta UT1 block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Aerospace Blockset / Environment / Celestial Phenomena
Aerospace Blockset / Utilities / Axes Transformations

Description

The Delta UT1 block calculates the difference between principal UT1 and UTC according to the IAU 2000A reference system and Earth orientation data. 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, Delta UT1 calculates the data using this equation, limiting the values to +/- .9s:

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

Ports

Input

UTC — UT1 for UTC

modified Julian date

UT1 for UTC, specified as a modified Julian date. Use the mjuliandate function to convert the UTC date to a modified Julian date.

Data Types: double

Output Arguments

ΔUT1 — Difference between UT1 and UTC

double

Difference between UT1 and UTC.

Data Types: double

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: 'aeroiersdata.mat' | MAT file

Default: 'aeroiersdata.mat'

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

https://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: iersurl

Type: character vector

Values: 'https://maia.usno.navy.mil/ser7/finals2000A.data' | web site address | file name

Default: 'https://maia.usno.navy.mil/ser7/finals2000A.data'

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: folder

Type: character vector

Values: 'Current Folder' | folder name

Default: 'Current Folder'

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"aerolibcelestial/Delta UT1"

"aerolibtransform2/Delta UT1"

Example: add_block("aerolibcelestial/Delta UT1","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

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

Version History

Introduced in R2017b

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).