GEODAS MGD77T header data
File type: Various data file
A h77t file is a header file for the Marine Geophysical Data Exchange Format (MGD77T).
It contains metadata for MGD77T marine geophysical data files used by GEODAS.
File type category:
Various data file
Date updated: October 5, 2026
Record marked as obsolete and not updated for a long time.
The h77t file extension is associated with the Marine Geophysical Data Exchange Format, an exchange format for marine geophysical data such as bathymetry, magnetics, and gravity measurements.
A h77t file stores header metadata for a related MGD77T data file. It is a supporting file rather than the main measurement-data file, so it is normally kept with the corresponding MGD77T dataset.
These files belong to GEODAS, the NOAA geophysical data software. GEODAS is obsolete.
Open the h77t file with GEODAS, the software for which it was created. The file is a header file and may not be useful when opened separately from its related MGD77T data file.
If GEODAS is unavailable, a plain-text editor may display the stored metadata, but it will not provide the format-specific functions of GEODAS.
There is no useful standalone conversion for an h77t file. It contains header metadata rather than the main marine geophysical measurements, so it should generally be preserved with its associated MGD77T data file.
To convert or export the complete dataset, use software that supports the related MGD77T data and its header information. Because GEODAS is obsolete, a compatible replacement may not preserve the h77t header as a separate file.
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