This includes LST, etc.

Hisanori Furusawa Here is an example of what has been implemented for time cards and what I understand we should be generating. Before we commit to this, I'd like to re-ask a couple of clarifying questions just in case something has changed recently:

• Is UTC the only possible TIMESYS? No TAI?
• Can any of the time values contain both date and time?

TIMESYS = 'UTC'                / Time System used in the header
DATE-OBS= '2000-01-01'         / [YMD] Observation start
MJD-STR =              51544.0 / [d] MJD at exposure start
UT-STR  = '00:00:00.000'       / [HMS] UT at exposure start
HST-STR = '14:00:00.000'       / [HMS] HST at exposure start
LST-STR = '20:17:57.509'       / [HMS] LST at exposure start
MJD     =       51544.00002894 / [d] MJD at mid-exposure
UT      = '00:00:02.500'       / [HMS] UT at mid-exposure
HST     = '14:00:02.500'       / [HMS] HST at mid-exposure
LST     = '20:18:00.016'       / [HMS] LST at mid-exposure
MJD-END =       51544.00005787 / [d] MJD at exposure end
UT-END  = '00:00:05.000'       / [HMS] UT at exposure end
HST-END = '14:00:05.000'       / [HMS] HST at exposure end
LST-END = '20:18:02.523'       / [HMS] LST at exposure end

Thank you cloomis. I think the list is complete.
The MJD-STR seems to have a value format that is different from the dictionary.

MJD-STR =              51544.0 / [d] MJD at exposure start  --> F20.8

TIMESYS: in the current Subaru FITS rule, it should be 'UT'. The rule needs to be updated if TAI is really required. Also needs to check any impacts with the other systems like STARS and Gen2.

I do not think the current time keywords allow to contain the date. Under the current scheme, if you want to put a timestamp for something, either you would define such an instrument-specific keyword containing both date and time, or identify the time based on a combination of what is given by TIMESYS (it's 'UTC' now, though) and the time string in the keyword.

Unchanged since 2019-10-01 comment and revision af8dbf1. In tags 2.1.3 and later.