(cba:news) cba, iraf, & y2k

[Jonathan Kemp]

Hi CBAers,

Just a few quick notes...

* There were no Y2K-associated problems at all with the CBA server.  The
  web site, electronic mail, and data archive performed flawlessly and
  without interruption during the turnover.

* As we will do every month, the list of files submitted to the data
  archive for the month of December has been posted at the CBA web site
  (www.cbastro.org).  You might want to take a look at this page on
  a monthly basis.

* Those of you who use older versions of IRAF may have noticed a few
  problems with header information.  If you're using IRAF, you may wish to
  read the appended message.  If you need to upgrade and have difficulty
  obtaining the entire set of IRAF installation files, please let me know
  and I'll provide them to you.

Jonathan

--

IRAF Y2K Compliance

The now familiar Year-2000 or "Y2K" problem is a result of many different
software packages relying on two-digit representations of the year. This
can cause any number of different bugs to appear when the century wraps
around on 1 January 2000. There are many potential work-arounds for these
bugs, but the only way to completely solve the problem is to modify each
software package to understand and use four-digit year representations.

NOAO is required to submit quarterly Y2K reports to the NSF and this
includes an analysis of IRAF's Y2K status and an implementation plan and
schedule for fixing the small number of IRAF routines involved. This web
page summarizes the steps being taken to ensure that IRAF is
Y2K-compliant, and will be updated periodically as this this effort
proceeds.

The majority of IRAF tasks will be unaffected by the Y2K problem. This
includes most general purpose image processing tools as well as most
astronomical reduction chores (flat fielding a CCD doesn't require the
date, for instance). Those tasks that rely on the DATE-OBS keyword will
need to be modified, however. This includes such areas as data acquisition
and astrometry.

This is the same DATE-OBS problem that is faced by the FITS standard,
since IRAF adopted the FITS keyword for its own use. You can read about
the plans for resolving the problem in the FITS standard at:

     http://www.cv.nrao.edu/fits/documents/proposals/year2000.txt

The IRAF plan to support the provisions of this change to the FITS
standard has been implemented and is in the process of being released in
IRAF v2.11.2 and later patches for the various IRAF platforms.

While most IRAF tasks will be unaffected by the Y2K problem and the
changes needed for the remaining tasks are well understood, unforeseen
IRAF Y2K bugs are always possible, and some are expected in any large
software system like IRAF. To assist in detecting and fixing such bugs we
have taken the step of setting the clock forward on one of the IRAF
workstations by 11 years, and periodically running a suite of IRAF tests
on the machine. The 11 year time span was chosen since 2009 is the next
year to use the same monthly calendar as 1998 - likewise 2010 will have
the same calendar as 1999. This reduces the confusion of using the
workstation during day-to-day testing. This testbed computer has been
running time-shifted for over half a year with no major problems
encountered in either Unix or IRAF.

IRAF V2.11.2 was thoroughly tested on this IRAF Y2K testbed prior to its
initial release. We encountered and fixed one Y2K-related bug in v2.11.2
(this bug is also found in all older IRAF versions).

Further Y2K testing will take place on the Y2K testbed system for any
further IRAF patches released during 1999. In addition, NOAO/IRAF will
provide technical support including Y2K-related system patches to the IRAF
developer community as the need arises. It is the responsibility of the
individual projects to assess and address the Y2K compliance of their own
layered IRAF software packages.

The IRAF V2.11.2 patch was released over the summer for selected
platforms. The V2.11.3 patch is currently being prepared and will be
released for all supported platforms during fall, 1999. All IRAF sites
will need to update to versions later than V2.11.2 in order to be Y2K
compliant. We will update this web page whenever there are any new
Y2K-related developments.