KPL/SCLK

MER-1 SCLK File Implementing Approximate Hybrid LST at TM20B3 (Meridiani) Site
===========================================================================

     This file is a SPICE spacecraft clock (SCLK) kernel that
     implements Approximate Hybrid Local Solar Time (HLST) accepted by
     the MER project. This file contains information required to
     convert between HLST at the MER-1 landing site TM20B3 (Meridiani)
     and Ephemeris Time (ET) using SPICE SCLK time conversion
     routines/tools.

Version 
--------------------------------------------------------

     2.0.0 -- 2003-09-11/12:00 -- BVS/NAIF

         Updated the mean local second duration to match the value
         from the MER Planetary Constants document. The old value was 
         1.02749127; the new value is 1.02749125.

     1.0.0 -- 2003-08-19/12:00 -- BVS/NAIF

         Initial Release


References
--------------------------------------------------------

         2.   Ken Fujii, "MER LST - Continuous Time Option", 09/06/01

         1.   SCLK Required Reading Document
 
 
Implementation Details
--------------------------------------------------------

     Per [1], the MER-1 HLST starts at "True" LST0 - 13 local minutes
     and runs at a constant rate of 1.02749125 ET seconds in 1 local 
     Martian second.

     To implement correct counting of these fields in the SCLK
     subsystem, the HLST0 is computed as "True" LST0 for the midnight
     of SOL 1 shifted by 13 minutes, which at the TM20B3 (Meridiani)
     landing site corresponds to ET 128229003.0.

     The second-to-second rate given above translates to the SCLK rate 
     of 88775.24400000 ET seconds in 1 local day, which appears 
     in the COEFFICIENTS keyword below.

     The ID for this clock is chosen to be 253900 to indicate that 
     this is NOT a actual SCLK for the MER-1 but rather a convenient 
     way to implement HLST using SCLK subsystem of SPICE.


HLST Format
--------------------------------------------------------

     The HLST string, the conversion for which is provided by this SCLK
     file, consists of four fields:

          DDD:HR:MN:SC

     where:

          DDD  -- count of HLST (SOL) days
          HR   -- count of HLST hours
          MN   -- count of HLST minutes
          SC   -- count of HLST seconds


Usage
--------------------------------------------------------
 
     This file must be loaded into the user's program by a call to the
     FURNSH subroutine
 
          CALL FURNSH( 'this_file_name' )
          furnsh_c   ( "this_file_name" );
 
     in order to use the SPICELIB SCLK family of subroutines to convert
     MER-1 HLST at the landing site TM20B3 (Meridiani) to ET and vice
     versa.

     Once loaded, the SCE2S/sce2s_c.f routines can be used to convert 
     an ET time to an HLST string in the format DDD:HR:MN:SC:

          CALL SCE2S( -253900, ET,         HLST )
          sce2s_c   ( -253900, et, maxlen, hlst );
 
     and the routines SCS2E/scs2e_c can be used for backward conversion --
     from HLST in DDD:HR:MN:SC format to ET:

          CALL SCS2E( -253900, HLST,  ET )
          scs2e_c   ( -253900, hlst, &et );
   

Production/History of this SCLK file
--------------------------------------------------------
 
     This file was generated manually using the MER HLST definition 
     provided in [1] and the HLST0 reference point computed for the 
     landing site TM20B3 (Meridiani).
 
 
Inquiries
--------------------------------------------------------
 
     If you have any questions regarding this file contact NAIF  at JPL
 
           Charles H. Acton, Jr
           (818) 354-3869
           Chuck.Acton@jpl.nasa.gov
 
           Boris V. Semenov
           (818) 354-8136
           Boris.Semenov@jpl.nasa.gov
 

Kernel DATA
--------------------------------------------------------

     \begindata

	 SCLK_KERNEL_ID               = ( @2003-09-11/12:00 )

	 SCLK_DATA_TYPE_253900        = ( 1 )
	 SCLK01_TIME_SYSTEM_253900    = ( 2 )
	 SCLK01_N_FIELDS_253900       = ( 4 )
	 SCLK01_MODULI_253900         = ( 24855 24 60 60 )
	 SCLK01_OFFSETS_253900        = ( 1     0  0  0  )
	 SCLK01_OUTPUT_DELIM_253900   = ( 2 )

	 SCLK_PARTITION_START_253900  = ( 0.0000000000000E+00 )

	 SCLK_PARTITION_END_253900    = ( 1.0995116277750E+12 )

	 SCLK01_COEFFICIENTS_253900   = ( 
	     0.0000000000000E+00     128229003.0    88775.24400000 
				  )

     \begintext