Convert Julian Date to Greenwich Apparent Sidereal Time

Find the Greenwich Apparent Sidereal Time Given any Julian Date

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Convert a specified Julian Date Vector to Greenwich Apparent Sidereal Time (GAST). The expected input matrix may contain multiple dimensions. The output matrix will be in the same size as the input matrix. Warning: Use caution when using GAST as a substitute for Greenwich Mean Sidereal Time (GMST).

To run JD2GAST, use the following code sequence:
GAST = JD2GAST(JD);

Where:
JD is the Julian Date input (days)
GAST is the resulting Greenwich Apparent Sidereal Time output (0 to 360deg)

Cite As

Darin Koblick (2026). Convert Julian Date to Greenwich Apparent Sidereal Time (https://www.mathworks.com/matlabcentral/fileexchange/28232-convert-julian-date-to-greenwich-apparent-sidereal-time), MATLAB Central File Exchange. Retrieved .

Acknowledgements

Inspired by: Julian Date to Greenwich Mean Sidereal Time

General Information

MATLAB Release Compatibility

  • Compatible with any release

Platform Compatibility

  • Windows
  • macOS
  • Linux
Version Published Release Notes Action
1.2.0.0

Updated mean obliquity of elliptic equation to be consistent with units. All units in this equation are in degrees.

1.1.0.0

Fixed bug which would re-size the input vector to [N x 1]

1.0.0.0