[fitsbits] start of Public Comment Period on the INHERIT convention

[Mark Calabretta]

On Thu, 2 Jul 2015 09:08:59 -0700
Frank Valdes <valdes at noao.edu> wrote:

>I will respond with the DECam raw data from the telescope.  This is a
>good question for this discussion.  If this goes somewhere interesting
>I can look at the other NOAO mosaic cameras and the calibrated files.
> 
> The keywords from the list at
>http://heasarc.gsfc.nasa.gov/docs/fcg/standard_dict.html that are
>inherited are:
> 
> DATE-OBS, INSTRUME, OBJECT, OBSERVER, TELESCOP

I think it is generally understood that data in a bintable HDU
describing the operation of an instrument might reasonably be expected
to apply to the whole FITS file.  Putting that same data in the primary
header doesn't seem so different to me, the main proviso being that the
data be of local interest only, i.e. not critical to an outsider's
interpretation of the data.

Of the above five keywords, the only one I would question is DATE-OBS,
since that may be important in computing Doppler shifts, precession
etc.

If the other uses of INHERIT as as benign as for DECam, then I don't
see much of a problem with it.  So yes, please look at the other NOAO
files.

The other relevant question is, how often, if at all, are the PHDU
keyrecords subordinated by keyrecords in the extension headers?

> I might also mention a couple that are important but not on the list:
> 
> EXPTIME, FILTER, RA, DEC

These aren't standard so don't count.
 
Regards,
Mark Calabretta