[Spice_announce] New Leapsecond takes effect January 1, 2006

[Charles H. Acton]

    >>>>>>> IMPORTANT ANNOUNCEMENT REGARDING A NEW LEAPSECOND <<<<<<<<<

This is a repeat of NAIF's August 12, 2005 announcement about the new 
leapsecond
that will take effect on January 1... just a few days away. If you 
are a user of
"SPICE" data please pay attention to this announcement! If you have colleagues
who use SPICE data, please consider forwarding this message to them.

Thanks from the NAIF Team.



On 2005 August 5, NAIF released the updated leapseconds kernel

   naif0008.tls

You may download the file using anonymous ftp from the NAIF server:

   naif.jpl.nasa.gov

in the path

   pub/naif/generic_kernels/lsk

Or use the URL:

    ftp://naif.jpl.nasa.gov/pub/naif/generic_kernels/lsk

The new kernel is a text file with Unix line termination. It is suitable for
unix, PC/Linux and Mac/OSX machines.

A version suitable for PC/Windows or NT machines is also in the same location;
it is named naif0008.tls.pc.

You may alternatively use your browser to get one of these files:

   http://naif.jpl.nasa.gov/naif/data.html

and then select "generic kernels" and then "lsk".


This update includes the addition of a leapsecond at the end of 2005, announced
in IERS bulletin C, dated July 4, 2005.  The URL for this bulletin is:

  http://hpiers.obspm.fr/eoppc/bul/bulc/bulletinc.dat

On 2006 January 1 00:00:00 UTC, the time offset between UTC and
international atomic time (TAI) will be

   33 seconds

At that time, the offset between UTC and barycentric dynamical time
("TDB," "ephemeris time," "ET") will be approximately

   65.183926 seconds

The new kernel affects SPICE ET/UTC and spacecraft clock (SCLK)/UTC
conversions for dates on or after

   January 1, 2006 UTC

Results of time conversions performed with this kernel for earlier dates will
match those obtained using the previous leapseconds kernel (naif0007.tls).


If not already accomplished, SPICE users are strongly encouraged to make this
update *NOW* before it takes effect in a few days..

It is *not* necessary to have a current version of the SPICE Toolkit
in order to read this file:  it is readable by all older SPICE 
Toolkits as well.



Using an Inappropriate Text Kernel
----------------------------------

If you inadvertently use an LSK made for an operating system using a text line
termination standard different from the OS you're using (e.g. you use
naif0008.tls instead of naif0008.tls.pc, or vice-versa) you will likely see a
SPICE error message that looks like this:

================================================================================

Toolkit version: N0058

SPICE(INCOMPATIBLEEOL) --

Text file 'naif0008.tls.pc' contains lines terminated with 'CR-LF' while the
expected terminator for this platform is 'LF'. This text file cannot be
processed.

A traceback follows.  The name of the highest level module is first.
FURNSH --> ZZLDKER --> ZZASCII

================================================================================


or, if using an Toolkit older than N0057, an error message like this:

================================================================================

Toolkit version: N0058

SPICE(MISSINGTIMEINFO)

The following, needed to convert between the uniform time scales, could not be
found in the kernel pool: DELTET/DELTA_T_A, DELTET/K, DELTET/EB, DELTET/M.

A traceback follows.  The name of the highest level module is first.
SPACIT --> SPASUM --> SUMSPK --> SPKWSS --> ET2UTC --> UNITIM

================================================================================

See the instructions above for obtaining the correct format LSK for 
your machine type.
Or, convert your file using either the dos2unix or the unix2dos 
utility, as appropriate.
(These are available on many machines.)



Note to users of C and IDL versions of the Toolkit (CSPICE and Icy)
-------------------------------------------------------------------
If you obtain Version N0060 of the Toolkit (available starting 
12/23/2005), it will
not be required that the leapsecond kernel you acquire uses the line 
termination
style native to your computer's operating system. New code in the 
CSPICE and Icy
Toolkits will detect and account for the non-native text file line termination.
Unfortunately this capability is NOT possible in FORTRAN Toolkits (SPICELIB).

-- 


Charles.H.Acton at jpl.nasa.gov                       Phone (818) 354-3869
Navigation and Ancillary Information Group/JPL     Fax   (818) 393-6388
================================================================================
NAIF website: http://naif.jpl.nasa.gov
SPICE news:   http://naif.jpl.nasa.gov/mailman/listinfo/spice_announce
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