Subject: Re: DATE-OBS='31/12/99'

From: Mike Corcoran <corcoran at barnegat.gsfc.nasa.gov>
Date: Thu, 27 Jun 1996 11:35:06 -0400

Rob Seaman wrote:

> 
> I suggest the DATE-OBS definition simply be relaxed to allow a four
> digit year as well as a two digit year:
> 
>     DATE-OBS= '24/06/96          '  /  UT date
>     DATE-OBS= '24/06/1996        '  /  UT date
> 

In general I don't like altering definitions of keyword values of previously
standardized keywords, since this can cause problems.  For example some poor
guy might have a FITS reader which extracts only the 1st 8 characters from
DATE-OBS, and if so 24/06/19 & 24/06/1996 would be confused.  I don't know of
any such poorly written code (I of course would never write any!) but it may
be lurking out there somewhere.

A better approach in this spirit would be to explicitly define the year in a
totally new keyword (YEAR-OBS or some such).  I.e.

	YEAR-OBS='1996            '  / year corresponding to DATE-OBS

Absence of YEAR-OBS would imply the 20th century.  This is similar to Peter
Bunclark's CENT-OBS but without the ambiguity of whether 20 means yr+2000 or
20th century.

my $0.02

Mike

-- 

***********************************************************
Dr. Michael F. Corcoran
High Energy Astrophysics Science Archive Research Center
Goddard Space Flight Center
Greenbelt, MD 20771
corcoran at barnegat.gsfc.nasa.gov
LHEAVX::CORCORAN
http://lheawww.gsfc.nasa.gov/users/corcoran/bio.html
***********************************************************