[fitsbits] [Fwd: PV index perhaps wrong in version 3.0]

[William Pence]

The question below regarding WCS keyword usage was sent to the FITS
support office.  Is Table 8.1 in the FITS Standand incorrect?  (See
http://fits.gsfc.nasa.gov/fits_standard.html ).
Should it state that LONPOLEa and LATPOLEa
are associated with PVi_3a and PVi_4a instead of PVi_1a and PVi_2a?

Bill

-------- Original Message --------
Subject: PV index perhaps wrong in version 3.0
Date: Mon, 08 Sep 2008 14:35:34 +0200

L.S.,

Table 8.1 section 8, page 74 lists for the native longitude and latitude
of the celestial pole the keywords LONPOLEa= and LATPOLEa= which,
according to the table is equivalent to PVi_1a and PVi_2a.
However, in the same table these keywords were previously attached to
the fiducial point. Also Calabretta and Greisen use PVi_3a and PVi_4a in
their article 'Representations of celestial coordinates in FITS'.
Please can you inform me about what is right (i.e. standard FITS) in
this case?

-- 
____________________________________________________________________
Dr. William Pence                       William.Pence at nasa.gov
NASA/GSFC Code 662       HEASARC        +1-301-286-4599 (voice)
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