[fitsbits] fitsverify and "implied" table columns themselves...?

[Bob Garwood]

That appears to be the SDFITS convention, which predates the WCS papers 
and agreements.  The WCS information in those tables is unlikely to be 
widely understood as a result.  The SDFITS convention needs to be 
updated to take into account the accepted ways of conveying WCS 
information in binary tables.  If the DATA array column dominates the 
table size, then I suspect adding a few extra scalar columns won't 
greatly increase the table size.

-Bob

Mike Nolan wrote:
> We're writing radio data in binary tables, and fitsverify hates them:
>
> (nolan at mofongo.naic.edu 133) fitsverify /share/pdata1/pdev/x108.20080826.b0s1g0.
> 00800.fits
>  
>               fitsverify 4.13 (CFITSIO V3.090)              
>               --------------------------------              
>  
>  
> File: /share/pdata1/pdev/x108.20080826.b0s1g0.00800.fits
>
> 2 Header-Data Units in this file.
>  
> =================== HDU 1: Primary Array ===================
>  
>  16 header keywords
>  
>  Null data array; NAXIS = 0 
>  
> =================== HDU 2: BINARY Table ====================
>  
> *** Error:   Keyword #29, CTYPE1 is not allowed in the Bin/ASCII table.
> *** Error:   Keyword #31, CTYPE2 is not allowed in the Bin/ASCII table.
> *** Error:   Keyword #44, CTYPE2G is not allowed in the Bin/ASCII table.
> ... many more similar errors
>
> Some of the WCS parameters are table columns:
> COMMENT  axis 1 is the frequency axis
> TTYPE6  = 'CRVAL1  '           / Center frequency
> TFORM6  = '1D      '           /
> TUNIT6  = 'Hz      '           /
> TDISP6  = 'D13.5   '           /
> TTYPE7  = 'CDELT1  '           / Frequency interval
> TFORM7  = '1D      '           /
> TUNIT7  = 'Hz      '           /
> TDISP7  = 'D13.5   '           /
> TTYPE8  = 'CRPIX1  '           / Pixel of center frequency
> TFORM8  = '1D      '           /
> TUNIT8  = '        '           /
> TDISP8  = 'D13.5   '           /
>
> but others are constant, so we're putting them in the table header
> per the "Green Bank Convention". 
> CTYPE1  = 'FREQ    '           / Type of coordinate
> CUNIT1  = 'Hz      '           / Unit of center frequency
>
> These files are massive and written at 80 MB/s, so we really don't want to make them any bigger than they have to be.
>
> Does that really make us bad people? Or have I missed something?
>
> Thanks,
>
> -Mike
>
>
>