🚀 go-pugleaf

Lucio Chiappetti (LUCIO@IFCTR.MI.CNR.IT) writes

> YES, conventions are needed to avoid those incompatibilities, which can
> be very annoying.
> And I would say those conventions are needed beyond the area of databases,
> but, for instance, in the area of keywords describing the content of a
> photon list.
> At the moment I am using provisional, local conventions for the designation
> of columns for a photon list : for instance I call THETA and PHI the angular
> cooordinates of a photon (from the optical axis), X and Y the coordinates in
> micron on the focal plane, and XPOSITN YPOSITN the coordinates in detector
> pixels ...or I call ENERGY true energy in keV, but PHA energy in channels,
> and I ignore whether they are consistent e.g. with EXSAS or PROS - which
> I am told are not compatible among them)

I certainly agree that conventions for keywords names should be agreed upon 
in the various subfields of astronomy, but they should at least be compatible
with the existing standard. Specifically, A VALID FITS FILE MUST USE SI
UNITS. This tends to be repeatedly forgotten, even though it was already 
explicitly specified in the original FITS paper.
X and Y should therefore be stored in metres, not microns, ENERGY in Joules
not kev (or cm**-1, or Kelvin, or GHz),  and so on...
Also, there are some well established conventions to store projected angular
coordinates (RA---GLS or GLAT-ATF or...) though I am not sure they are part
of the standard yet.


	Thierry Forveille
	Observatoire de Grenoble
	forveill@gag.observ-gr.fr