[iaufwg] IAUFWG review of the new draft FITS Standard

Mon Mar 17 19:12:38 EDT 2008

Dear all

I have a few minor comments. As is appropriate to my position on this
committee as Comm. 5 Pres, rather than because of my (miniscule)
technical expertise, my comments will mainly be about the form rather
than about the technical content.

* I congratulate all the groups involved for an excellent document, and,
most importantly, for a very substantial development and updating of the
standard, which continues and develops the authority, integrity, and
consistency of the successive iterations of FITS. The WCS section is
excellent, significantly extending the power, precision, and sheer
usefulness of the FITS standard. In addition to the technical
developments, I notice a number of very sensible changes and updates to
the wording and definitions that further strengthen FITS.

* The preamble (Sections 1 and 2) is especially good, placing FITS in an
appropriate historical context, and, even more importantly identifying
some issues which may have been self-evident to the original authors but
which may not be self-evident to scientists in 100 years time who are
trying to understand some historical 21st century database. 

* In "Defined Terms", do you really mean to use a value-laden statement:
"Deprecated : To express disapproval of." If you deprecate an obsolete
practice, you are not necessarily saying that this was a bad choice by
its originators, but merely that it's no longer appropriate. So perhaps
a definition such as "Deprecate : To discourage usage of" may be more
appropriate.

* In Table 8.5, I think there should be a footnote defining "radio
velocity" and "optical velocity", as they do not have a physical basis
(but are a computational convenience) and so may not be obvious to a
scientist in 100 years time. 

* I also have a recollection that the use of the term "radio velocity"
was formally deprecated by the IAU around 20 years ago, but I've been
unable to find the reference. Does anybody else have any record of this?

Cheers

Ray

Ray Norris
CSIRO Australia Telescope National Facility
PO Box 76, Epping, NSW 1710, Australia
Phone +61 2 9372 4416
http://www.atnf.csiro.au/people/RNorris/

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> -----Original Message-----
> From: iaufwg-bounces at donar.cv.nrao.edu 
> [mailto:iaufwg-bounces at donar.cv.nrao.edu] On Behalf Of William Pence
> Sent: Tuesday, 18 March 2008 04:20
> To: IAU-FWG
> Subject: [iaufwg] IAUFWG review of the new draft FITS Standard
> 
> Dear IAU FITS Working Group Members,
> 
> It is now time for us (the IAU FWG) to conduct a final review of the 
> proposed new FITS Standard document, leading eventually to a vote on 
> whether or not to accept it as the official Standard.  To jog your 
> memories, here is a brief chronology of how we got to this point:
> 
>    12/2006: Technical Panel is appointed (Chiappetti, Page, Pence,
>             Shaw, and Stobie) to draft updates and clarifications
>             to the FITS Standard.
>    07/2007: Technical Panel releases version 3.0 for comments
>    10/2007: Public comment period closes
>    11/2007: Technical Panel produces revised draft 3.0a
>    12/2007: Draft 3.0a sent to Regional FITS committees for review
>    02/2008: Regional committees generally endorse the new draft, with
>             a few further comments
>    03/2008: Technical Panel produces revised draft 3.0b
> 
> This latest draft of the FITS Standard is available for your 
> review at 
> http://fits.gsfc.nasa.gov/fits_draft.html along with other supporting 
> documents, including,
> 
> - A 12 page summary of the Technical Panel's response to the 
> suggestions 
> that were received during the public comment period and the Regional 
> FITS committee reviews.
> 
> - A 137 page color-coded document that highlights the differences 
> between this latest draft version 3.0b and the current 
> official version 
> 2.1b.
> 
> While reviewing this material, please keep in mind that all 
> the proposed 
> changes to the FITS standard are only recommendations at this point. 
> Any IAU FWG member can propose further amendments to the 
> document during 
> this final review period, either to introduce new changes, or 
> to revise 
> or withdraw any of the currently proposed changes.  If necessary, we 
> will conduct procedural votes (which only require a simple 
> majority to 
> be accepted) on any proposed amendments prior to conducting a formal 
> vote on the whether or not to accept the document as the new official 
> FITS Standard.
> 
> In particular, there are 2 issues that were raised back in 
> November that 
> we still need to resolve:
> 
> 1.  Arnold Rots suggested that it might be useful to add ISO-8601 
> data-time to the recognized data types (presumably in Chapter 
> 5 of the 
> latest draft).   In response, 3 of you (Shaw, Forveille, and Gabriel) 
> felt that while this was perhaps worthy of further discussion, it is 
> rather late in the process to make this change to the current 
> draft, so 
> it may be better to defer this to the next revision of the Standard 
> (whenever that might be).   Do the rest of you agree to defer this 
> suggestion for now?
> 
> 2.  Mark Calabretta reiterated his desire for the new 
> Standard to note 
> any inconsistencies in syntax between previous versions of 
> the Standard, 
> either as an appendix or as footnotes throughout the document. An 
> example might be where version 2 of the Standard turned the 
> widely used 
> convention of using a slash character to separate the keyword 
> value and 
> comment fields, into a requirement. The Technical Panel had 
> declined to 
> implement this suggestion, mainly on the grounds that it 
> could require a 
> significant effort to make a detailed comparison of all the different 
> versions of the FITS Standard (and the original FITS papers too).  So 
> far, there has been no discussion of this issue here on this 
> email list.
> 
> My own feeling on this is that I would not object to adding 
> footnotes to 
> highlight a few cases where a current FITS requirement was 
> not clearly 
> stated in some previous versions of the Standard or in the 
> original FITS 
> papers.  I don't think however that this issue warrants the time and 
> energy that would be needed to try to document every change that has 
> occurred in the history of FITS.  Perhaps Mark (and others) could 
> propose a list of instances where a footnote would be appropriate.
> 
> 
> So with this preamble, I would like to now open up the 
> discussion period 
> here on IAU FWG email list about any issues regarding the 
> proposed new 
> FITS Standard document.  Please try to post your comments here within 
> the next 2 to 3 weeks if possible, so as to not needlessly delay the 
> final vote on this matter.
> 
> regards,
> Bill Pence
> -- 
> ____________________________________________________________________
> Dr. William Pence                       William.Pence at nasa.gov
> NASA/GSFC Code 662       HEASARC        +1-301-286-4599 (voice)
> Greenbelt MD 20771                      +1-301-286-1684 (fax)
> 
> 
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