[fitsbits] Associating ancillary data with primary HDU

[Rob Seaman]

Mea culpa.  I must not have made it past the Besselian epoch discussion a couple of sections prior.
—

On May 23, 2014, at 8:34 AM, Steve Allen <sla at ucolick.org> wrote:

> On Fri 2014-05-23T07:19:08 -0700, Rob Seaman hath writ:
>> So in this case you wouldn't necessarily be denoting the quantity as
>> a FITS keyword token like "XPOSURE" but rather as "exposure_time",
>> "time.exposure", or "exptime".  (In any event it isn't clear why such
>> a keyword name would be truncated since "EXPOSURE" fits into 8
>> characters :-)
> 
> XPOSURE is from the FITS WCS time paper now being voted.
> 
> Much like the case where the original FITS document
> specified DATE-OBS but did not define exactly when
> during an exposure it should indicate, we believed that
> EXPOSURE was likely to have significant prior use with
> variant definitions, so we chose XPOSURE with a specific
> definition.