[fitsbits] Representation of polarimetry data in WCS

Steve Allen sla at ucolick.org
Wed Apr 26 15:07:54 EDT 2006


On Wed 2006-04-26T09:24:16 -0700, Marshall Perrin hath writ:
> But first I need to actually be sure I understand what the standard is!

So do we all.

> Paper III says that the CTYPEn keyword for a -TAB axis should follow
> the 4-3 format, using the 4-letter axis type.  So then the proper
> value to use is 'STOK-TAB', correct?

That seems right to me.

> Next question: Table 7 of WCS Paper I presents the mapping between
> integer codes and polarimetry measurements such as Stokes Q or right-
> circular polarization. But there are a few possible polarimetry
> measurements which are left out of this table, in particular
> polarized intensity
> (P = sqrt(Q^2+U^2+V^2). Is there any convention on an integer code to
> denote that with?

Let's make a convention.

I say that anticipating seeing the process in action for establishing
new tweaks on existing standards, particularly regarding the point of
distinction between things which are simply conventions and things
which are standards.

--
Steve Allen                 <sla at ucolick.org>                WGS-84 (GPS)
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