Light curves¶
For light-curves, we recommend to store the information in an as similar format as possible to the one for Spectra and specifically SED.
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 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: https://github.com/open-gamma-ray-astro/gamma-astro-data-formats/pull/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.