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Post-Mission IUEDAC Software Changes

Although no further software development was planned, some IUEDAC software was modified after the IUE project ended. Most of these were Y2K-related changes and are listed below. The changes were made because the IUEDAC library was still being used for developing other MAST-supported mission archives including Copernicus and IMAPS.

The programs can basically be grouped into 3 categories: general, IUE-specific, and Copernicus-specific. Since the IUE project ended in 1997, it was felt unnecessary to modify this group of programs. Projects modifying these routines to work with other data sets however, may need to make the appropriate date changes although its doubtful that many programs in this category would be useful to other projects. The same applies for the Copernicus-specific programs. Some of the low-level programs and the FITS-handling routines however, are general enough to be used by other projects, so these programs were modified.


The following changes were made:

  1. 2-digit dates are now assumed to refer only to the years 1900 through 1999 (i.e.,a date entry of 0 is assumed to refer to year 1900). All other years must now be specified with 4 digits.
  2. Tests for leap year were modified to include the special case for years divisible by 400 (i.e., centuries NOT divisible by 400 are NOT leap years). Some programs which did have this test were found to be incorrect (i.e., they assumed centuries not divisible by 400 were leap years).
  3. Starting Jan 1, 1999, a new format will be adopted for the DATE and DATE-OBS FITS keywords which use 4-digit year entries. As a result, the primary date conversion routine DATECONV was modified to include a new mode called "newfits" which generates the new FITS date format. Programs calling DATECONV to create the DATE and DATEOBS keyword entries must be modified to use this new mode at the end of this year.

Changes made to specific programs are listed below:

DATECONV primary IUEDAC date-conversion routine added 'newfits' mode, and use 4- (rather than 2-) digit dates internally
FDATE convert yr,gmtday to dd/mm/yy format fix leap year test and bug found for years 1900-1909 (program mainly replaced by DATECONV)
FINDELT extract IUE orbital elements add comment about non-y2k compliance
GEXCAL calibrate gaussian extracted fluxes use DATECONV for date conversions
IDBDATE convert dd-mon-yyyy to julian date and yr & day of yr correct leap year calculation
IDBFPARSE convert dd-mon-yyyy to string yyddd.nnn call DATECONV rather than the astron routine DATE_CONV(?)
IUNJD convert julian date to [yr,dofyr,mon,d,h,m,s] fix leap year calculation
JULDATE converts [yr,d,h,m,s] to Julian date add prolog information
KEYGEN generate FITS headers call DATECONV instead of FDATE for date conversions
YDTOYMD convert YYDDD dates to YYMMDD correct leap year calculation and output dates in YYYYMMDD format for other centuries (mainly replaced by DATECONV)

IUE-specific Routines

The following programs perform various date calculations but were not modified because they are specific to IUE data analysis:

  • FES2V
  • LABT
  • MIDTIME (note incorrect century leap year test)
  • RBS
  • READDV (note incorrect century leap year test)
  • READELT (note incorrect century leap year test)
  • SDC

Copernicus-Specific Routines:

The IDL stacking routines (i.e., STACK, WSTACK, PSTACK,...) used to coadd Copernicus spectral scans, use DATECONV to create FITS header keywords, and will need to be modified to use the new 'NEWFITS' mode starting 1/1/99.

No other changes were found necessary.