[fitsbits] DATE-OBS: circulate the WCS papers!

[William Thompson]

Arnold Rots <arots at head-cfa.harvard.edu> writes:

>Within the High Energy community there is a fairly uniform usage of
>DATE-OBS; it is the start of the observation. while the end is given
>by DATE-END.  One can infer this definition by the presence of both
>keywords, or more formally by the reference in the HDUDOC keyword.

On the SOHO project, we used very similar keywords DATE_OBS and DATE_END
(i.e. with an underscore rather than a dash), with DATE_OBS giving the start
time of the observation.  The reason for the slightly different names was
because we recognized the need back in the early 90s that the SOHO project
would likely run into the Y2K problem during its lifetime.  Therefore, we
adopted the ISO format some years before it was officially adopted as part of
the FITS standard.  Thus, we had to use our own names to avoid conflicts with
the standard FITS keyword definitions.

William Thompson