Subject: Interoperability trials of DATExxxx='yyyy-mm-dd'

From: Don Wells <dwells at nrao.edu>
Date: Fri, 25 Jul 1997 11:47:55 -0400 (EDT)

Dear IAU FITS Working Group and other friends of FITS,

As Preben Grosbol (former Chair of IAU-FWG) has pointed out, it has
been and still is an IAU-FWG rule that proposed additions to the FITS
standards must be tested in two-way interoperability trials involving
at least two independent implementations. The purpose of this rule is
to assure that at least two independent implementors care enough about
any proposed addition to actually code support for it and that their
readings of the text of the proposed agreement are consistent. Such
testing also reduces the likelihood that there are hidden flaws in
proposed FITS agreements.

The proposed year-2000 agreement needs to be tested as soon as possible.

I know of two major astronomy data analysis systems which have already
been modified to read DATExxxx='yyyy-mm-dd' as well as 'dd/mm/yy'. One
of these systems has also been modified to write the new date format
beginning 1998-01-01. Private discussions are underway between the
developers of these two systems to exchange test files which could be
read by the two systems. The first such sample FITS file for
interoperability testing is available via anonymous-FTP (the
'newdate.lst' file contains an ASCII listing of the header):

    ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/newdate.fits.gz
    ftp://fits.cv.nrao.edu/fits/data/samples/year-2000/newdate.lst

This FITS file contains three DATExxxx keywords in the new style:

DATE-OBS= '1979-09-19'         /OBSERVATION START DATE DD/MM/YY
DATE-MAP= '1992-09-18'         /DATE OF LAST PROCESSING DD/MM/YY
DATE    = '1997-07-25'                  / File written on yyyy-mm-dd

I will be pleased to receive other sample FITS files containing
DATExxxx values in the new style, and will place them in the same
anonymous-FTP directory.

I encourage other developers to modify their software systems to
either read or write the new style, and to join in the
interoperability trials. 

Regards,
Don Wells (Chair, IAU FITS Working Group)
-- 
  Donald C. Wells         Associate Scientist         dwells at nrao.edu
                    http://fits.cv.nrao.edu/~dwells
  National Radio Astronomy Observatory                +1-804-296-0277
  520 Edgemont Road,   Charlottesville, Virginia       22903-2475 USA