This table lists some standard Flexible Image Transport System (FITS) tags, but ExifTool will extract any other tags found. See https://fits.gsfc.nasa.gov/fits_standard.html for the specification.
Tag ID Tag Name Writable Values / Notes 'AUTHOR' Author no 'BACKGRND' Background no 'COMMENT' Comment no (leading spaces are removed if PrintConv is enabled) 'DATE' CreateDate no 'DATE-END' ObservationDateEnd no 'DATE-OBS' ObservationDate no 'HISTORY' History no (leading spaces are removed if PrintConv is enabled) 'INSTRUME' Instrument no 'OBJECT' Object no 'OBSERVER' Observer no 'REFERENC' Reference no 'TELESCOP' Telescope no 'TIME-END' ObservationTimeEnd no 'TIME-OBS' ObservationTime no