[fitsbits] start of Public Comment Period on the Green Bank convention

[Peter Weilbacher]

Dear all,

On Fri, 19 Jun 2015, Lucio Chiappetti wrote:

> The proposed draft text is available at
> http://sax.iasf-milano.inaf.it/~lucio/FITS/Conventions/greenbank-upd2.pdf

I have to say I find way of storing images pretty confusing. What's the
advantage of storing them this way instead of creating separate FITS
extensions? Is it just of historical interest? How do I know which of
the table columns contains that actual data of the image? (Ah, I see
that Bob has answered these questions in the meantime.)

The text as suggested for the standard also promotes use of a dash in
TTYPEn keywords ("DATE-OBS"), which according to 7.3.2 is "not
recommended". Additionally, it mentions "FITS binary table" at the start
of the added new section 8.2.1 but in the last paragraph applies it to
both ascii and binary tables.

> Supporting material is provided in the FITS Convention Registry at the
> http://fits.gsfc.nasa.gov/registry/greenbank.html

I don't think the material there helps the case. That old (?) PDF
spec says that TDIMn would be use for the table arrays but the example
FILE shown actually uses TFORMn. I also put the demo FITS file there
through fitsverify which says:
[...]
=================== HDU 2: BINARY Table ====================
*** Warning: Column #3: Name "DATE-OBS" contains character '-' other than
             letters, digits, and "_".
*** Warning: Keyword #13, CTYPE4: index 4 is not in range 1-2 (NAXIS).
[...]
=================== HDU 3: BINARY Table ====================
*** Warning: The HDU 3 and 2 have identical type/name/version
*** Warning: Column #3: Name "DATE-OBS" contains character '-' other than
             letters, digits, and "_".
*** Warning: Keyword #13, CTYPE4: index 4 is not in range 1-2 (NAXIS).

To me this says that this convention is mostly of historical interest
and should not be part of the main FITS standard.

> The Public Comment Period starts today 19 June 2015 and will last formally
> for 3 weeks until July 9 included.

As others have noticed, this is far from ideal.
Looking at specifications for a FITS convention requires a different
level of attention than now for inclusion in the standard.

Best regards,
   Peter.
-- 
Dr Peter Weilbacher                 http://www.aip.de/People/PWeilbacher
Phone +49 331 74 99-667                       encryption key ID 7D6B4AA0
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