Bug 91823

Is this some kind of standard, or something only known within Planck?

-----Original Message-----
From: Marc-Antoine Miville-Deschenes [mailto:mamd@cita.utoronto.ca]
Sent: Thursday, October 21, 2004 5:53 AM
To: kst@kde.org
Subject: [Kst] [Bug 91823] New: time convention for Planck 


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http://bugs.kde.org/show_bug.cgi?id=91823        
           Summary: time convention for Planck
           Product: kst
           Version: unspecified
          Platform: unspecified
        OS/Version: Linux
            Status: NEW
          Severity: wishlist
          Priority: NOR
         Component: general
        AssignedTo: kst kde org
        ReportedBy: mamd cita utoronto ca


Version:            (using KDE KDE 3.2.1)
OS:                Linux

Planck uses a time reference called AIT
which starts on January 1st 1958 (please don't ask me why).
The exact difference in seconds between UT and AIT is
86400L * (365*12 + 3) - 32  (seconds)

Could you please add this time reference to the list ?
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Added AIT to list of understood time formats.

This is to correct little errors I made
in the definition of the Planck reference time (so-called AIT).
In fact it is a general standard named TAI (for Temps Atomique International)
based on an atomic clock in Paris. There is not a direct
transformation from UTC to TAI as some "leap seconds" are added
periodically to the UTC (because of the earth precession).
Nowadays the relation is TAI = UTC + 32 seconds  (and not UTC-32 seconds
as I said previously).
So, this is to suggest
2) Modify name of the conversion (the official name is TAI)
1) Correct transformation (TAI = UTC + 32 seconds)

CVS commit by arwalker: 

Correctly identify the TAI time standard.

CCMAIL: 91823-done@bugs.kde.org


  M +7 -1      kst2dplot.cpp   1.352
  M +1 -1      kstplotdefines.h   1.8


--- kdeextragear-2/kst/kst/kst2dplot.cpp  #1.351:1.352
@@ -1282,5 +1282,11 @@ double Kst2DPlot::convertTimeValueToJD(d
       break;
     case X_AXIS_INTERP_AIT:
-      value -= 86400.0 * (365.0 * 12.0 + 3.0) - 32.0; // difference (seconds) between standard C time and AIT
+      value -= 86400.0 * (365.0 * 12.0 + 3.0);
+      //
+      // current difference (seconds) between standard C time and AIT
+      // refer to the following for more information:
+      //  http://hpiers.obspm.fr/eop-pc/earthor/utc/TAI-UTC_tab.html
+      //
+      value -= 32.0; 
       value /= 24.0 * 60.0 * 60.0;
       value += JD1970;

--- kdeextragear-2/kst/kst/kstplotdefines.h  #1.7:1.8
@@ -58,5 +58,5 @@ const XAxisInterpretation XAxisInterpret
   { I18N_NOOP2("Modified Julian Date", "MJD"), X_AXIS_INTERP_MJD },
   { I18N_NOOP2("Reduced Julian Date", "RJD"), X_AXIS_INTERP_RJD },
-  { I18N_NOOP2("Time format specific to Planck project", "AIT (Planck)"), X_AXIS_INTERP_AIT }
+  { I18N_NOOP2("Temps Atomique International", "TAI"), X_AXIS_INTERP_AIT }
 };