“Good” software includes Maxim DL. It even explains the data format and specifies the time zone.
DATE-OBS= ‘2021-07-15T23:30:15’ /YYYY-MM-DDThh:mm:ss observation start, UT
EXPTIME = 30.000000000000000 /Exposure time in seconds
EXPOSURE= 30.000000000000000 /Exposure time in seconds
