For light-curves, we recommend to store the information in an as similar format as possible to the one for :ref:`spectra` and specifically :ref:`flux-points`.
For measurements at a given time, a TIME
column should be added,
for measurements for a given time interval, TIME_MIN
and TIME_MAX
columns should be added.
As explained in :ref:`time`, times should be given as 64-bit floats, using the FITS time standard to specify a reference time point. Note that this allows some flexibility, and e.g. the commonly used "MJD values" for light curves are supported via these header keys:
MJDREFI = 0 MJDREFF = 0 TIMEUNIT= 'd'
Light curve producers are highly encouraged to always give the TIMESYS
.
For archival data this is often not given, and it's unclear if the times
are e.g. in the UTC
or TT
or some other TIMESYS
.
This is a very preliminary description, based on the discussion here: #61
If someone has time to provide a more detailed description, and to produce example files in FITS or possibly also ECSV format, this would be highly welcome.