Incorrect FITS headers - by: PDB

Hello,

Found 2 issues with the FITS headers in current Libindi/Ekos

1. Missing FILTER keyword in header
When Filter is selected to be part of the capture filename, then the FILTER keyword not written in the FITS header. When filtername is selected to be part of the filename, the FILTER keyword appears in the header. Think it should always be there.

2. Incorrect DATE-OBS format
The time in DATE-OBS keyword is formatted with a Z at the end

strftime(iso8601, sizeof(iso8601), "%Y-%m-%dT%H:%M:%S", tp);

// Add millisecond and Z for Zulu/UTC time.
snprintf(ts, 32, "%s.%03dZ", iso8601, static_cast<int>(startExposureTime.tv_usec / 1000.0));

return (ts); strftime(iso8601, sizeof(iso8601), "%Y-%m-%dT%H:%M:%S", tp);

// Add millisecond and Z for Zulu/UTC time.
snprintf(ts, 32, "%s.%03dZ", iso8601, static_cast<int>(startExposureTime.tv_usec / 1000.0));

return (ts);

This is not correct according to the FITS standard:

KEYWORD: DATE-OBS
REFERENCE: FITS Standard
STATUS: reserved
HDU: any
VALUE: string
COMMENT: date of the observation
DEFINITION: The date of the observation, in the format specified in the
FITS Standard. The old date format was 'yy/mm/dd' and may be used only
for dates from 1900 through 1999. The new Y2K compliant date format is
'yyyy-mm-dd' or 'yyyy-mm-ddTHH:MM:SS[.sss]'.

When doing data reduction on a series of images, data reduction in AstroImageJ does not read these dates. (If I update all headers and remove the Z, data reductionb will work)

Think this should be brought into accordance with standard FITS.

Thanks,

Paul